I have a confession to make: I, Mark Sisson, suffer from keto crotch.
It’s embarrassing, really. I thought maybe it was just the change in climate moving from Malibu to Miami—the humidity, the heat, the fact that I’m paddling and swimming more often now. There’s a whole lot of moisture down there. Perpetual steaminess.
But then I met up with my writing partner and good pal Brad Kearns, who’s been working with me on my upcoming book. Brad lives in Northern California, which is far from hot or humid right now. He’s also a staunch keto guy most of the time, and, well, let’s just say I could smell him before I could see him. We met up at a coffee shop and cleared out everyone in a fifteen foot radius. We sampled a new exogenous ketone product he’s been trying and not one, not two, but three separate individuals approached to inquire if we were salmon fishermen.
Okay, let’s get serious. Does “keto crotch” really exist? And, if it does, what can you do to prevent it?
I’m writing this not because of overwhelming demand from loyal followers of the Keto Reset plan. In fact, I hadn’t ever heard of “keto crotch” before last week. There’s a good chance almost no one heard of it before March 2019, if Google Trend data for “keto crotch” searches is any indication. I’m writing this post because the barrage of news articles, Twitter hashtag campaigns, and extremely serious warnings from people with lots of acronyms after their name has led people to ask me if it’s a legitimate phenomenon. A few acquaintances have brought it up in social situations. Our marketing director found herself fielding keto crotch questions at a dinner for Expo West last week.
So, are women following a ketogenic diet experiencing an epidemic of stinky vaginas?
Is Keto Crotch Even Physiologically Plausible?
Vaginal odor does change. It fluctuates naturally, and sometimes it can get worse. The most common cause of unpleasant changes to vaginal odor is bacterial vaginosis, which occurs when something upsets the balance between the beneficial lactobacilli bacteria that normally live in the vagina and pathogenic bacteria. What can upset the balance?
The vagina is supposed to be an acidic environment; that’s how the healthy lactobacilli thrive. If something upsets that pH balance, tilting it toward alkalinity, unhealthy bacteria gain a foothold and become predominant, and begin producing unpleasant-smelling amines like putrescine, tyramine, and cadaverine. This is bacterial vaginosis. As it turns out, the lactobacilli bacteria normally present in the vagina are instrumental in maintaining an acidic pH. They consume glycogen, spit out lactic acid, and exert antimicrobial and antifungal effects that block common vaginal pathogens like candida, e. coli, and gardnerella from taking hold and causing trouble.
The interaction between diet and vaginal biome is understudied. To my knowledge, there exist no direct controlled trials that address the issue. It’d be great to have a study take a cohort of women, split them up into different dietary groups, and follow them for a year, tracking their vaginal pH and bacterial levels. Alas, we do not.
We do have a study that provides a hint. In 2011, researchers looked for correlations between dietary patterns and bacterial vaginosis in a cohort of nearly 2000 non-pregnant mostly African-American women aged 15-44. While there probably weren’t many keto dieters, and the diets as a whole were of the standard American variety, glycemic load—which basically boils down to carb load—was the strongest predictor of bacterial vaginosis. Other markers of food quality, like a person’s adherence to “healthy eating guidelines,” initially seemed to reduce the chance of bacterial vaginosis, but those relationships were almost abolished after controlling for other factors. Only glycemic load remained highly significant.
This connection between dietary glycemic load and bacterial vaginosis starts looking more causal when you realize that diabetes—a disease where one’s “glycemic load” is perpetually elevated and exaggerated—is another risk factor for bacterial vaginosis.
There’s also a 2007 study that found “high” intakes of dietary fat, particularly saturated and monounsaturated fat, were a significant predictor of bacterial vaginosis. In this study, “high fat” meant around 39% of energy from fat. That leaves 61% of energy from carbohydrate and protein, the kind of “high-fat, high-carb” Standard American No-Man’s-Land that’s landed the country in the current metabolic predicament. High-fat intakes in the presence of high-carb intakes may very well be bad for your vagina, but it says nothing about the likelihood of keto crotch.
At any rate, neither study was a controlled trial, so we can’t say anything about causality.
What about a yeast infection? The most common offender is candida, which usually favors sugar for fuel, but there’s also evidence that it can metabolize ketones. Could keto make a latent yeast infection worse and lead to smelly “keto crotch”?
Perhaps keto can make candida worse (that’s for another day), but that’s not the cause of “keto crotch.” Candida vagina infections don’t smell very much, if at all, and they certainly don’t smell “fishy.” That’s only caused by bacteria and the aforementioned amines they can produce.
Free glycogen levels in vaginal fluid are a strong predictor of bacterial vaginosis. If ample glycogen is available, the good lactic acid bacteria have plenty of food and produce plenty of lactic acid to maintain the acidic pH conducive to vaginal health. If inadequate glycogen is present, the lactic acid bacteria have less food and produce less lactic acid, increasing the chances of the pH tilting toward alkalinity. An alkaline vagina is a vagina where pathogenic bacteria—the ones that produce stinky amines—can establish themselves.
The question then is if ketogenic diets lower free glycogen in the vaginal fluid. That’s a fair question. I wasn’t able to find any solid answers. I guess “ketosis effect on vaginal glycogen” isn’t the most lucrative avenue of scientific inquiry.
Should I Worry?
Even assuming this is a real phenomenon, it’s a rare one. The vast, vast majority of people following a ketogenic diet aren’t coming down with keto crotch. Other than a few Reddit posts from the past 5 years, I haven’t seen anyone at all in our neck of the woods complain.
Maybe people doing Primal keto are eating more nutrient-dense ketogenic diets than people doing conventional (or caricature) keto. Salads, steaks, eggs, and lots of non-starchy veggies are a great way to stay keto and obtain micronutrients. And there are links between micronutrient status and bacterial vaginosis. The most common relevant deficiencies include vitamin D (correcting the deficiency can cure the vaginosis) and folate. Hard to get adequate folate if your diet is based on salami and cream cheese.
We also know that the health of your skin biome tracks closely with that of your gut, and that eating plenty of non-starchy veggies, fermented foods (yogurt, kefir, sauerkraut, kimchi, etc), and colorful produce can provide prebiotic fiber, prebiotic polyphenols, and probiotic bacteria that nourish your gut biome. If the vaginal biome is also connected to the gut biome (and it is), tending to the latter should also have positive effects on the former.
The Primal brand of keto tends to emphasize micronutrients and gut health a bit more than some other types of keto I see floating around. If—and it’s a very big “if”—keto crotch is legit, that may explain some of the discrepancy.
Finally, be sure to check out this very interesting Twitter thread where the author lays out his suspicions that the whole “keto crotch” phenomenon might be a manufactured stunt designed to vilify the ascendant ketogenic diet. Nothing definitive, but it’s certainly food for thought.
If You’re Concerned…
Okay. Say you’ve recently gone keto and your vagina is smellier than usual. (And you’ve ruled out other, more obvious potential causes like changes in soaps, etc.) It’s hard to ignore, and I wouldn’t want you to. What can you do?
- Confirm that you have bacterial vaginosis. Seriously, get it checked out.
- Make sure you’re getting enough folate and vitamin D. Supplement if need be.
- Eat prebiotics and probiotics. Fermented food and/or a good probiotic supplement.
- Try a carb refeed. If ketosis depletes vaginal glycogen and increases pH, the occasional carb refeed could restore glycogen by 30-50 grams and should do the trick. Note that this is entirely theoretical; I’m not saying it’s a “problem” on keto.
- Hang out in the keto zone. I’ve written about the keto zone—that metabolic state where you’ve reached full keto and fat-adaptation and find yourself shifting in and out of ketosis as you please due to increased metabolic flexibility. A few carbs here, a fasting day there, a few more days of keto. Again, if full keto is theoretically depleting vaginal glycogen, maybe relaxing your restrictions will solve the issue while maintaining your fat adaptation. This is actually where I hang out most of the time.
That’s it for today, folks. Do you have “keto crotch”? Do you know anyone who does? Or did your vaginal health improve on keto? I’m curious to hear what everyone’s experiences have been, so don’t be shy.
Take care and be well.
Thoma ME, Klebanoff MA, Rovner AJ, et al. Bacterial vaginosis is associated with variation in dietary indices. J Nutr. 2011;141(9):1698-704.
Kalra B, Kalra S. Vulvovaginitis and diabetes. J Pak Med Assoc. 2017;67(1):143-145.
Taheri M, Baheiraei A, Foroushani AR, Nikmanesh B, Modarres M. Treatment of vitamin D deficiency is an effective method in the elimination of asymptomatic bacterial vaginosis: A placebo-controlled randomized clinical trial. Indian J Med Res. 2015;141(6):799-806.
Dunlop AL, Taylor RN, Tangpricha V, Fortunato S, Menon R. Maternal vitamin D, folate, and polyunsaturated fatty acid status and bacterial vaginosis during pregnancy. Infect Dis Obstet Gynecol. 2011;2011:216217.
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One thing I’ve realized being in this game for so long is that if you’re convinced that meat truly is deadly, you’re not going to stop looking for reasons why. They’ve tried blaming just about every part of meat over the years, including the protein itself, the saturated fat, the cholesterol, the methionine, the char on BBQ, and even the obscure compounds like TMAO or Neu5gc. The latest component of meat they’ve zeroed in on is iron—the essential mineral responsible for energy production and a host of other vital functions.
The experts’ track record with all the other “evil meat components” has many of my readers skeptical, so they asked me to weigh in on iron.
Iron is an essential mineral, integral in the production of energy and the creation of blood cells. If pregnant women don’t get it, they can’t deliver oxygen and nutrients to their growing babies. If kids don’t get it, they shortchange their mental and physical development. If adults don’t get it, their basic day-to-day physiological function falls apart. Without adequate iron, our antioxidant defenses, our immunity, and our metabolic function all suffer. Hell, most countries even mandate the fortification of refined flour with large amounts of iron to prevent these tragedies.
Iron also has a dark side. A large body of observational evidence links elevated iron levels to diseases and disease states like type 2 diabetes, heart disease, insulin resistance, inflammation, Alzheimer’s disease, hypertension, fatty liver, hypothyroidism, arthritis, and cancer. You name it, it’s probably linked to elevated iron. And as much as I’d like to, I can’t dismiss these connections as non-causal.
For one, iron is inherently reactionary: The very same proclivity for electron exchange that makes iron so integral in biochemical reactions that address stress and support health means it can also create free radicals that damage DNA, cells, blood lipids, and increase stress and harm health.
Two, there’s a little something called hereditary hemochromatosis.
Hereditary hemochromatosis is a genetic condition increasing a person’s absorption and retention of dietary iron. This has benefits in certain contexts—carriers have a natural resistance to the bubonic plague, as one effect of hemochromatosis is to render white immune cells iron-deficient and thus resistant to the plague virus which feeds on iron—but it’s mostly negative in today’s relatively plague-free world. Most of the hemochromatosis literature focuses on homozygotes (carriers of two copies of the gene) and specific “iron overload-related diseases,” which include cirrhosis, liver fibrosis, liver cancer, elevated liver enzymes, “physician-diagnosed symptomatic hemochromatosis,” or finger arthritis. Those are bad conditions to have, to be sure, but that’s not even a complete list. Homozygous carriers of the mutation also have greater risks for diabetes, arthritis, fatigue, liver disease, and frailty and muscle loss. They’re more likely to experience neurodegenerative diseases like Parkinson’s and Alzheimer’s. Even heterozygous carriers (those who carry just one copy of the variant) have an elevated risk of iron overload compared to the general population.
Okay, okay. But couldn’t it be that the hemochromatosis gene is increasing disease risk through another, non-iron route? Perhaps high iron is just a marker of disease, not a cause. After all, most genes are pleiotropic—they have more than one effect.
Probably not. The most reliable treatment for hereditary hemochromatosis is phlebotomy. Literally removing iron from the body by draining blood is the first (and often only necessary) line of defense against hereditary iron overload. And it works really well.
Besides, phlebotomy may also be beneficial in people without clinical iron overload or hemochromatosis. It’s the most effective way to reduce iron stores and tends to increase insulin sensitivity. In insulin resistant men with fatty liver, blood donation normalized insulin sensitivity and liver enzymes. In meat eaters, blood donation reduced ferritin levels to match those of lacto-ovo-vegetarians and improved insulin sensitivity. One study even tested the effect of randomized phlebotomy on cancer incidence. After four and a half years, those subjects placed in the phlebotomy group lived longer, had less cancer, and had lower ferritin levels than the subjects who didn’t donate blood.
I can’t argue with the research, but the idea that a primary component of a food we’ve been eating for millions of years and to which we may even owe much of our brainpower—the iron in meat—still rankles. Is iron truly inherently “bad,” or is there anything about our modern environment that makes it so?
Possible Modern Influences On Iron Levels
One factor is that we don’t shed as much blood as before. Most men engage in far fewer bouts of direct violent conflict. Most people have fewer parasites feasting on their blood. And when’s the last time you exchanged blood oaths with anyone? We have fewer opportunities to bleed, in other words. That’s why regular phlebotomy can be such a useful tool for men (and some women) with too much iron in their bodies—it emulates all the bloodletting we used to do in a controlled, safe fashion.
Less Intense Activity
We use iron to generate energy. The more physical activity in which we engage, the more iron we utilize. This is usually couched in warnings for female athletes engaged in intense training, but it can also explain the beneficial effects of exercise in people with iron overload. There are even cases of “mild exercise” causing iron deficiency, so everything that increases energy expenditure—walking, gardening, hiking—will at least subtly reduce iron stores. More activity, less iron sitting around idle getting into trouble.
Too Many Seed Oils
I strongly suspect that the unprecedented dissemination of high-omega-6 seed oils throughout our food systems, our body fat, and our cellular membranes are exacerbating—if not causing—the relationship between excess iron and various diseases. Take the supposedly ironclad (pun intended) relationship between heme iron and colon cancer, which is mediated by iron’s peroxidative alteration of fatty acids in the colon. In animal studies that seek to show this relationship, you can’t get the colon cancer to “take” unless you feed the animal high-PUFA oils along with their heme iron. In one study, feeding heme iron to rats promoted colon cancer only when fed alongside high-PUFA safflower oil. Feeding MUFA-rich and far more oxidatively-stable olive oil alongside the heme prevented the colon carcinogenesis. In another paper, only mice consuming fish oil-based and safflower oil-based diets exhibited carcinogenic fecal peroxides after eating heme iron; a coconut oil-based group of mice had no negative reaction to heme.
Among a cohort of US nurses, where PUFA intake is around 7% of calories and comes from seed oil, iron intake has moderate links to colon cancer. Among a cohort of Swedish women, where PUFA intake is under 5% of calories with a greater proportion coming from fish, the association is far weaker.
What To Do About All This?
First, men and postmenopausal women should figure out their hemochromatosis status. Both men and women with hereditary hemochromatosis have elevated risks of iron overload-related diseases, but they are much higher for men. (Premenopausal women have a handy built-in mechanism for shedding excess iron—menstruation.) Modern men and older women, with our absence of intestinal parasites and our lower tendency to engage in bloody hand-to-hand fighting, have few opportunities to shed iron. Your doctor will be able to order the test, or you can go through a genetic testing service and look for positive hits on C282Y and H63D.
Do it earlier rather than later. Studies indicate that one of the biggest predictors of whether someone with genetic iron overload develops liver cancer is their age at diagnosis of hemochromatosis. Those who wait risk incurring more damage.
Even if you’re negative for hereditary hemochromatosis, you can still have iron overload. Determine this by asking your doctor for a ferritin test. According to the Mayo Clinic, for men, the ferritin reference range is 24 to 336 ng/ml, and for women, it is 11 to 307. That is a wide range, and levels that your doctor would probably classify as technically normal have been associated with insulin resistance, atherosclerosis, and reduced telomere length (a marker of aging).
From what I can tell, levels approaching 200 ng/ml in men should definitely be classified as “high.” And lower may be even better. In one study, egg-and-dairy-eating vegetarian men had ferritin levels of 35 ng/ml and better insulin sensitivity than meat-eating men with ferritin levels of 72 ng/ml. After donating enough blood to hit 35 ng/ml, the meat eaters insulin sensitivity improved.
Dr. F. S. Facchini has used blood donation to induce “near iron deficiency”—the lowest body iron store that allows normal red blood cell production—in his gout patients, clearing them of gout attacks for as long as they maintained it. His patients at high risk for heart disease also saw major benefits from hitting very low ferritin levels (“to levels commonly seen in premenopausal females”), including increased HDL and lower blood pressure, even if they started with normal ferritin.
What seems safe is to stay on the low end of normal—say, from 50-150 ng/ml—as long as no symptoms of low iron arise.
As for women? Higher levels don’t seem to correlate with the same health issues in women. Lucky.
Now, say you have high iron, whether it’s hereditary hemochromatosis or just high normal ferritin levels….
What Should You Do About High Iron Levels?
The quickest, safest way that also does the most social good (if you care about that sort of thing) is to donate blood. When you donate blood, your body must upregulate hemoglobin production to replace the lost blood. That requires iron, which is taken from body stores.
Don’t Manage Iron Overload With Diet
By that I mean stuff like:
- Don’t give up red meat.
- Don’t stop eating liver every week.
- Keep eating oysters.
- Don’t religiously adhere to reverse-kosher (only eating meat in the presence of dairy to inhibit iron absorption).
If you make dietary iron the focal point, you’ll miss out on all the incredible nutrients iron-rich foods like red meat and liver can offer. Besides, you’ll run yourself ragged following even more food restrictive rules that increase the chance of other nutrient deficiencies.
Don’t Manage an Iron Overload That Doesn’t Exist
I’ve seen people go down the rabbit hole of iron obsession without actually confirming they even had too much iron. They started giving blood (even self-administered), trying to reduce iron absorption by pairing dairy and calcium with their iron-rich foods, avoiding iron-rich foods—totally blind. Iron is an important nutrient. Deficiency is real. Anemia is no joke. Get tested before you start messing around with iron.
Follow a Healthy Primal Eating Plan
Whether it’s keto, low-carb, moderate-carb, or even vegetarian, going Primal will mitigate many of the potential effects of high iron by:
- Avoiding Seed Oils and Excess Omega-6 Fats. Seed oils almost certainly make the “iron overload problem” worse, and may even be responsible for its negative effects and link to various diseases.
- Including Phytonutrient-rich Fruits, Vegetables, Herbs, Teas, and Coffee. Polyphenols both inhibit iron absorption and reduce the oxidative interaction between iron and lipids.
So to sum up, get tested and be aware of the iron issue, but don’t let it rule you. It’s iron overload, not overlord.
Take care, everyone. What do you think of iron? Ever get tested? Ever give blood? See any benefits?
Let me know down below!
Tamosauskaite J, Atkins JL, Pilling LC, et al. Hereditary Hemochromatosis Associations with Frailty, Sarcopenia and Chronic Pain: Evidence from 200,975 Older UK Biobank Participants. J Gerontol A Biol Sci Med Sci. 2019;
Burke W, Imperatore G, Mcdonnell SM, Baron RC, Khoury MJ. Contribution of different HFE genotypes to iron overload disease: a pooled analysis. Genet Med. 2000;2(5):271-7.
Allen KJ, Gurrin LC, Constantine CC, et al. Iron-overload-related disease in HFE hereditary hemochromatosis. N Engl J Med. 2008;358(3):221-30.
Nowak A, Giger RS, Krayenbuehl PA. Higher age at diagnosis of hemochromatosis is the strongest predictor of the occurrence of hepatocellular carcinoma in the Swiss hemochromatosis cohort: A prospective longitudinal observational study. Medicine (Baltimore). 2018;97(42):e12886.
Larsson SC, Rafter J, Holmberg L, Bergkvist L, Wolk A. Red meat consumption and risk of cancers of the proximal colon, distal colon and rectum: the Swedish Mammography Cohort. Int J Cancer. 2005;113(5):829-34.
Liu B, Sun Y, Xu G, et al. Association between Body Iron Status and Leukocyte Telomere Length, a Biomarker of Biological Aging, in a Nationally Representative Sample of US Adults. J Acad Nutr Diet. 2018;
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A commenter wrote a great comment that got me wondering:
As far as “the more exercise the better” study I wonder if folks who had to drop out of long distance cardio training due to injuries or cortisol driven exhaustion are considered in the equation? In other words, if you can tolerate chronic cardio you may live longer, otherwise it might break you down. Everyone has a sweet spot for exercising is my gut feeling and you have to “listen to your body”. I still like the primal mantra along the lines of (if I may be so presumptuous as to paraphrase Mark) “walk a lot, do sprints once a week, lift heavy things once or twice a week, spend time outdoors, take part in sports or recreational activities that are fun for you”.
What do I think is going on? How do the results of this paper jibe with my take on Chronic Cardio?
First off, we have to acknowledge the basic structure of the study.
This study didn’t actually measure “hours spent training.” They gave subjects treadmill tests (stress tests) to determine their cardiovascular fitness, then divided everyone into different tiers of fitness based on the results. In fact, the authors of the study criticized the shortcomings of previous studies which used self-reported training data instead of objective measurements of cardiorespiratory fitness like the treadmill test. This makes the study far more accurate and useful. It also means you can’t make any ironclad proclamations about the connections between hours spent training and longevity. You can certainly make inferences—people who had better cardio fitness probably spent more time training to get it—but there are other interpretations. All you can say for certain is that higher levels of cardio fitness predict greater longevity.
I don’t see how anyone could argue with that. Of course being fitter is better.
But my criticism of chronic cardio isn’t a criticism of cardiovascular fitness. It’s a criticism of how most people go around obtaining that fitness—by destroying their bodies.
That doesn’t have to happen anymore. Tons of top guys these days are finally figuring out that you don’t have to log as many laps/miles/etc as possible to maximize your performance, but that wasn’t always the case. I grew up convinced that the more miles I ran, the healthier I’d be. That’s how I did it back in my marathon and triathlon days, and it almost destroyed me and an entire generation of my peers.
You can train twice as much as the next guy yet have worse fitness, either because you’re not training intelligently, you’re overtraining and hampering the adaptive process, or you’re not sleeping. That’s chronic cardio. You can train less and get better results, if you’re optimizing your recovery, nutrition, and sleep. That’s Primal Endurance.
As for these subjects, there is some serious genetic confounding occurring. Those dudes with elite fitness levels well into their 70s are often a different breed. They’re hard to kill. They’re tough. They can withstand the discomfort of grueling mile after mile. What other types of discomfort can they bear and even grow from? They’re just more robust than the average 70-year-old. It may not be the elite training itself that’s making them resist death. It’s just as likely they have the genetic capacity to excel in endurance training, and even if they didn’t exercise they’d still live longer than average.
There’s also the healthy user bias. The kind of lifestyle regular exercisers follow emphasizes sleep, plenty of rest and recuperation, smart supplementation and nutrition, and all sorts of other things that are also linked to longer, better health.
This paper makes a strong case for using something like Primal Endurance to build great cardiorespiratory fitness without risking chronic cardio territory.
Thanks for writing and reading, folks. Take care!
The post Dear Mark: Is There No Upper Limit to Endurance Training? appeared first on Mark’s Daily Apple.
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Many of you have asked about prostate health in a Primal context. Men are interested because they know men have a decent chance of getting prostate cancer. Women are interested because they’re worried about the men in their lives getting prostate cancer. Today, I’m going to delve deep into the topic, exploring the utility (or lack thereof) of standard testing, the common types of treatment and their potential efficacy, as well as preventive and unconventional ways of reducing your risk and mitigating the danger of prostate cancer.
First, what does the prostate do, anyway? Most people only think about it in terms of prostate cancer.
It’s a gland about the size of a small apricot that manufactures a fluid called prostatic fluid that combines with sperm cells and other compounds to form semen. Prostatic fluid protects sperm against degradation, improves sperm motility, and preserves sperm genetic stability.
What Goes Wrong With the Prostate?
There are a few things that can happen.
Inflammation of the prostate, usually chronic and non-bacterial. A history of prostatitis is a risk factor for prostate cancer.
Benign Prostatic Hyperplasia
Non-cancerous enlargement of the prostate. As men age, the prostate usually grows in size. This isn’t always cancer but can cause similar symptoms.
What most of us are interested in when we talk about prostate health… After skin cancer, prostate cancer is the most common cancer among men and the sixth most common cause of cancer death among men worldwide. Yet, most men diagnosed with prostate cancer do not die from it; they die with it. The 5-year survival rate in the US is 98%.
That said, there is no monolithic “prostate cancer.” Like all other cancers, there are different grades and stages of prostate cancer. Each grade and stage has a different mortality risk:
- Low-grade prostate cancer grows more slowly and is less likely to spread to other tissues.
- High-grade prostate cancer grows more quickly and is more likely to spread to other tissues.
- Local prostate cancer is confined to the prostate. The 5-year relative survival rate (survival compared to men without prostate cancer) for local prostate cancer is almost 100%.
- Regional prostate cancer has spread to nearby tissues. The 5-year relative survival rate for regional prostate cancer is almost 100%.
- Distant prostate cancer has spread to tissues throughout the body. The 5-year relative survival rate for distant prostate is 29%. Distant prostate cancer explains most of the prostate-related mortality.
What Are Symptoms of Prostate Cancer?
The primary symptom is problems with urination. When the prostate gland grows, it has the potential to obstruct the flow of urine out of the bladder, causing difficulty urinating, weak urine flow, painful urination, or frequent urination. This can also be caused by benign prostatic hyperplasia, a non-cancerous enlargement of the prostate.
What Causes Prostate Cancer?
A big chunk is genetic. People with “knockout” alleles for BRCA, which codes for tumor suppression, have an elevated risk of some forms of prostate cancer. That’s the same one that confers added risks for breast cancer.
Ethnicity matters, too. Men of Sub-Saharan African descent, whether African-Americans in the U.S. or Caribbean men in the U.K., have the highest risk in the world for prostate cancer—about 60% greater than other ethnic groups. White men have moderate risks; South Asian, East Asian, and Pacific Islander men have lower risks.
Testosterone has a confusing relationship with prostate cancer. Conventional wisdom tends to hold that testosterone stimulates prostate cancer growth, and there’s certainly some evidence of a relationship, but it’s not that simple.
In one study, men with low free testosterone levels were less likely to have low-grade (less risk of spreading) prostate cancer but more likely to have high-grade (higher risk of spreading) prostate cancer.
In Chinese men, those who went into treatment with low testosterone were more likely to present with higher-grade localized prostate cancers.
Other studies have arrived at similar results, finding that “hypogonadism represents bad prognosis in prostate cancer.”
Many prostate cancer treatments involve testosterone deprivation, a hormonal reduction of testosterone synthesis. This can reduce symptoms and slow growth of prostate tumors during the metastatic phase, but prostate cancer tends to be highly plastic, with the ability to adapt to changing hormonal environments. These patients often see the cancer return in a form that doesn’t require testosterone to progress.
What About Testing?
If you have a prostate, should you get tested starting at age 40?
Not necessarily. The value of early testing hasn’t been established. Some researchers even question whether early testing is more harmful than ignoring it, and most of the research finds middling to nonexistent evidence in favor of broad testing for everyone. Early testing has a small effect on mortality from prostate cancer, but no effect on all-cause mortality.
PSA testing can also be inaccurate. PSA is prostate specific antigen, a protein produced by the prostate. It’s normal to have low levels of PSA present in the body, and while high levels of PSA are a good sign of prostate cancer—even years before it shows up in imaging or digital probes—they can also represent a false positive. Those two other common yet relatively benign prostate issues—benign hyperplasia and prostatitis—can also raise PSA levels well past the “cancer threshold.”
Other causes of high levels of PSA include:
- Urinary tract infections
- Recent sex or ejaculation
- Recent, vigorous exercise
- Certain medications.
In fact, if you have a PSA reading of 4 (the usual threshold), there’s still just a 30% chance it actually indicates cancer.
What About Treatment?
Let’s say you do have prostate cancer, confirmed by PSA and a biopsy (or two, or three, as needle biopsies often miss cancers). What next? Should you definitely treat it?
It’s unclear whether treatment improves survival outcomes. One study took men aged 50-69 with prostate cancer diagnosed via PSA testing, divided them among three treatment groups, and followed them for ten years. One group got active monitoring—they continued to test and monitor the status of the cancer. One group received radiotherapy—radiation therapy to destroy the tumor. And the last group had the cancer surgically removed. After ten years, there was no difference among the groups for all-cause mortality, even though the active-monitoring group saw higher rates of prostate cancer-specific deaths (8 deaths—in a group of 535 men— vs 5 in the surgery group and 4 in the radiotherapy group), cancer progression, and metastasis.
In another study of men with localized prostate cancer, removing the prostate only improved all-cause mortality rates among men with very high PSAs (more than 10). In men with lower PSAs, “waiting and seeing” produced similar outcomes as surgery.
Prostate removal also carries many unwanted side effects, like incontinence and sexual dysfunction. No one wants prostate cancer, but it’s no small thing to have problems with urination and sex for the rest of your life. Those are major aspects of anyone’s quality of life.
Before you make any decisions, talk to your doctor about your options, the relative mortality risk of your particular cancer’s stage and grade, and how the treatments might affect your quality of life.
How Can You Reduce the Risk of Prostate Cancer?
1. Inflammation is definitely an issue.
For one, there’s the relationship between prostatitis, or inflammation of the prostate, and prostate cancer that I already mentioned above.
Two, there’s the string of evidence linking anti-inflammatory compounds to reductions in prostate cancer incidence. For example, aspirin cuts prostate cancer risk. Low-dose aspirin (under 100 mg) reduces both the incidence of regular old prostate cancer and the risk of metastatic prostate cancer. It’s also associated with longer survival in patients with prostate cancer; other non-steroidal anti-inflammatories are not.
Third, anti-inflammatory omega-3 fatty acids (found in seafood and fish oil) are generally linked to lower rates of prostatic inflammation and a less carcinogenic environment; omega-6 fatty acids can trigger disease progression. A 2001 study of over 6,000 Swedish men found that the folks eating the most fish had drastically lower rates of prostate cancer than those eating the least. Another study from New Zealand found that men with the highest DHA (an omega-3 found in fish) markers slashed their prostate cancer risk by 38% compared to the men with the lowest DHA levels.
2. The phytonutrients you consume make a difference.
A series of studies on phytonutrient intake and prostate cancer incidence in Sicilian men gives a nice glimpse into the potential relationships:
The more polyphenols they ate, the less prostate cancer they got.
The more phytoestrogens they ate, the more prostate cancer they got. Except for genistein, an isoflavone found in soy and fava beans, which was linked to lower rates of prostate cancer. The Sicilians are eating more fava than soy, I’d imagine.
How about coffee, the richest source of polyphenols in many people’s daily diets? It doesn’t appear to reduce the incidence of prostate cancer, but it does predict a lower rate of fatal prostate cancer.
3. Your circadian rhythm and your sleep are important.
Like everything else in life, tumor suppression follows a circadian pattern. Nighttime melatonin—which is suppressed if your sleep hygiene is bad and optimal if your sleep hygiene is great—inhibits the growth of prostate cancer cells and reduces their ability to utilize glucose. One way to enhance nighttime melatonin is by getting plenty of natural, blue light during the day; this actually makes nighttime melatonin more effective at prostate cancer inhibition. On the other hand, getting that blue light at night is a major risk factor for prostate cancer.
4. Get a handle on your fasting blood sugar and insulin.
In one study, having untreated diabetic-level fasting blood sugar was a strong risk factor for prostate cancer. Another study found that insulin-lowering metformin reduced the risk, while an anti-diabetic drug that raised insulin increased the risk of prostate cancer. Metformin actually lowers PSA levels, which, taken together with the previous study, indicates a causal effect.
5. Keep moving, keep playing, keep lifting.
This has a number of pro-prostate effects:
It keeps you insulin sensitive, so neither fasting insulin, nor fasting glucose get into the danger zone.
Oh, and do some deadlifts. Men with prostate cancer who trained post-surgery had better control over their bodily functions, as long as they improved their hip extensor strength. If you don’t know, hip extension is the act of standing up straight, of moving from hip flexion (hip hinging, bending over) to standing tall. It involves hamstrings, glutes, and the entire posterior chain. Deadlifts are the best way to train that movement pattern.
The prostate cancer issue is frightening because it’s so common. Almost all of us probably know someone who has or had it, even unknowingly. But the good news is that most prostate cancers aren’t rapidly lethal. Many aren’t lethal at all. So whatever you do, don’t rush into serious treatments or procedures without discussing the full range of options in a frank, honest discussion with your doctor.
That’s it for today, folks. Thanks for reading. If you have any questions, comments, or concerns about prostate cancer, feel free to chime in down below. I’d love to hear from you.
Perletti G, Monti E, Magri V, et al. The association between prostatitis and prostate cancer. Systematic review and meta-analysis. Arch Ital Urol Androl. 2017;89(4):259-265.
Ilic D, Djulbegovic M, Jung JH, et al. Prostate cancer screening with prostate-specific antigen (PSA) test: a systematic review and meta-analysis. BMJ. 2018;362:k3519.
Brawer MK, Chetner MP, Beatie J, Buchner DM, Vessella RL, Lange PH. Screening for prostatic carcinoma with prostate specific antigen. J Urol. 1992;147(3 Pt 2):841-5.
Castro E, Eeles R. The role of BRCA1 and BRCA2 in prostate cancer. Asian J Androl. 2012;14(3):409-14.
Watts EL, Appleby PN, Perez-cornago A, et al. Low Free Testosterone and Prostate Cancer Risk: A Collaborative Analysis of 20 Prospective Studies. Eur Urol. 2018;
Neuzillet Y, Raynaud JP, Dreyfus JF, et al. Aggressiveness of Localized Prostate Cancer: the Key Value of Testosterone Deficiency Evaluated by Both Total and Bioavailable Testosterone: AndroCan Study Results. Horm Cancer. 2018;
Dai B, Qu Y, Kong Y, et al. Low pretreatment serum total testosterone is associated with a high incidence of Gleason score 8-10 disease in prostatectomy specimens: data from ethnic Chinese patients with localized prostate cancer. BJU Int. 2012;110(11 Pt B):E667-72.
Teloken C, Da ros CT, Caraver F, Weber FA, Cavalheiro AP, Graziottin TM. Low serum testosterone levels are associated with positive surgical margins in radical retropubic prostatectomy: hypogonadism represents bad prognosis in prostate cancer. J Urol. 2005;174(6):2178-80.
Banerjee PP, Banerjee S, Brown TR, Zirkin BR. Androgen action in prostate function and disease. Am J Clin Exp Urol. 2018;6(2):62-77.
Zhou CK, Daugherty SE, Liao LM, et al. Do Aspirin and Other NSAIDs Confer a Survival Benefit in Men Diagnosed with Prostate Cancer? A Pooled Analysis of NIH-AARP and PLCO Cohorts. Cancer Prev Res (Phila). 2017;10(7):410-420.
Russo GI, Campisi D, Di mauro M, et al. Dietary Consumption of Phenolic Acids and Prostate Cancer: A Case-Control Study in Sicily, Southern Italy. Molecules. 2017;22(12)
Russo GI, Di mauro M, Regis F, et al. Association between dietary phytoestrogens intakes and prostate cancer risk in Sicily. Aging Male. 2018;21(1):48-54.
Discacciati A, Orsini N, Wolk A. Coffee consumption and risk of nonaggressive, aggressive and fatal prostate cancer–a dose-response meta-analysis. Ann Oncol. 2014;25(3):584-91.
Dauchy RT, Hoffman AE, Wren-dail MA, et al. Daytime Blue Light Enhances the Nighttime Circadian Melatonin Inhibition of Human Prostate Cancer Growth. Comp Med. 2015;65(6):473-85.
Kim KY, Lee E, Kim YJ, Kim J. The association between artificial light at night and prostate cancer in Gwangju City and South Jeolla Province of South Korea. Chronobiol Int. 2017;34(2):203-211.
Murtola TJ, Vihervuori VJ, Lahtela J, et al. Fasting blood glucose, glycaemic control and prostate cancer risk in the Finnish Randomized Study of Screening for Prostate Cancer. Br J Cancer. 2018;118(9):1248-1254.
Haring A, Murtola TJ, Talala K, Taari K, Tammela TL, Auvinen A. Antidiabetic drug use and prostate cancer risk in the Finnish Randomized Study of Screening for Prostate Cancer. Scand J Urol. 2017;51(1):5-12.
Park JS, Lee KS, Ham WS, Chung BH, Koo KC. Impact of metformin on serum prostate-specific antigen levels: Data from the national health and nutrition examination survey 2007 to 2008. Medicine (Baltimore). 2017;96(51):e9427.
Galvão DA, Taaffe DR, Spry N, Joseph D, Newton RU. Combined resistance and aerobic exercise program reverses muscle loss in men undergoing androgen suppression therapy for prostate cancer without bone metastases: a randomized controlled trial. J Clin Oncol. 2010;28(2):340-7.
Ying M, Zhao R, Jiang D, Gu S, Li M. Lifestyle interventions to alleviate side effects on prostate cancer patients receiving androgen deprivation therapy: a meta-analysis. Jpn J Clin Oncol. 2018;48(9):827-834.
Uth J, Fristrup B, Haahr RD, et al. Football training over 5 years is associated with preserved femoral bone mineral density in men with prostate cancer. Scand J Med Sci Sports. 2018;28 Suppl 1:61-73.
Park J, Yoon DH, Yoo S, et al. Effects of Progressive Resistance Training on Post-Surgery Incontinence in Men with Prostate Cancer. J Clin Med. 2018;7(9)
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A Primal woman’s first reaction to the prospect of taking synthetic hormone replacements for menopause? Probably a healthy dose of skepticism. We in the ancestral health community, after all, tend to view pharmaceuticals as a last resort—interventions that are overprescribed by vested interests, create their own set of side effects, and may even do more harm than good. To suggest that we “need” this or that prescription raises our hackles.
Besides, it’s not like menopause is a product of modernity or an aberration our ancestors never experienced; it’s a physiological stage that evolution has protected and selected in humans. It’s perfectly natural. Rather than the debilitating, miserable experience many women report having, menopause should be easier. Graceful, even. But it often isn’t.
And nature unfortunately doesn’t care about that. Menopause is nature’s way of preventing undue discomfort and reducing genetic damage to the group. Your average 50-year-old woman has a lot to offer the tribe in terms of wisdom, child care, and general know-how, but natural selection has also determined that it’s better for everyone if middle-aged women don’t easily get pregnant. Menopause achieves this by down-regulating the hormones and weakening the tissues necessary for conception. The problem is that these same hormones and tissues also figure prominently in a woman’s enjoyment of life and overall health.
What can happen when Mother Nature decides to step in?
- Loss of libido, vaginal atrophy
- Night sweats
- Hot flashes
- Weight gain
Longer-term, menopause increases the risk of serious diseases like osteoporosis, heart disease, and breast cancer.
Those aren’t mere inconveniences. They can mar the beauty of what should be an enjoyable part of a woman’s life, interfering with her relationships, her productivity, her cognitive function, her sleep, and her basic ability to enjoy living.
Mother Grok didn’t take pharmaceutical hormone replacements, you might counter. She didn’t hit up the shaman for a compound blend of hormones, so why should you?
First of all, maybe she did. Pre-scientific peoples have been known to develop folk cures that seem primitive but end up getting scientific validation. Think of the medieval garlic-based concoction that we just found out can eliminate medication-resistant staph infections. Or the indigenous Amazonian tribes who somehow figured out if you brewed a certain vine with a certain leaf and drank the finished product you’d visit the spirit world, all without knowing the vine contained DMT and the leaf contained an MAO-inhibitor that made the DMT orally active. Or, to bring it back to menopause, the yam, which cultures have used for hundreds of years for menopause treatment without actually knowing it contains an estrogen mimetic with clinical efficacy.
Second of all, the basic Primal stance on pharmaceutical interventions is that they are useful and suitable when correcting a deficiency, a genetic proclivity, or an evolutionary mismatch—particularly when dietary and lifestyle interventions aren’t cutting it. If they can help us treat a condition that seriously impedes our life or pursuit of health, we should avail ourselves of the fruits of modern science. Hormone replacement therapy may very well qualify.
Philosophical qualms aside—does hormone replacement therapy (HRT) work? What factors play into its effectiveness—and safety?
First, Is It Safe?
This might just be the most contentious topic in medicine.
For decades, HRT was the standard treatment for postmenopausal women. Not only was it given to treat the symptoms of menopause, it was billed as an antidote to many of the chronic diseases that increased in frequency after menopause like breast cancer, osteoporosis, and heart disease. Most of this was based on observational data and small pilot studies. That changed with the Women’s Health Initiative (WHI), a massive series of randomized controlled trials involving tens of thousands of postmenopausal women. Finally, the establishment would get the solid backing they needed to continue prescribing HRT to millions of women for prevention of chronic disease.
Except it didn’t turn out so well. Midway through, they stopped the trial because they weren’t getting the desired results.
There were two different HRT study groups. In one study, women without uteruses either got placebo or estrogen alone. In the other, women with uteruses got a combo of estrogen and progestin (a progesterone analogue) or placebo. The estrogen was Premarin, a conjugated estrogen. The progestin was Prempro, or medroxyprogesterone acetate.
The E/P combo increased the risk of heart disease, breast cancer, pulmonary embolism, and stroke, and reduced the risk of colorectal cancer and fractures (but not enough to offset the increased risks).
The estrogen alone had no effect on heart disease (contrary to their hypotheses), but it did appear to increase the risk of stroke while decreasing the risk of breast cancer and fractures.
Following the publication and wide dissemination of the WHI results, HRT use plummeted among women. Breast cancer cases subsequently dropped by 15-20,000 per year. Hormone replacement therapy developed a bad rap that it has yet to shake.
Is it deserved? Yes and no.
While the WHI results highlight some very real risks associated with HRT, they don’t tell the whole story. There are other variables to consider when deciding on HRT.
How Early You Start Taking HRT Matters
Most of the women in the WHI study began HRT when they were very post-menopause: older, in their 60s and upward. They got worse results.
A much smaller proportion of the women in the study were under 60 when they started HRT. They had better results. In fact, among those women who initiated HRT before age 60, total mortality actually dropped by 30%.
Another analysis of the Women’s Health Initiative data found that women who started taking HRT during early pre-menopause were less likely to see the negative effects, like increased breast cancer and heart disease.
Another study found that older post-menopausal women taking estrogen took hits to their working memory that remained after therapy cessation, while younger post-menopausal women had no such reaction.
Women who took oral estradiol 6 years after menopause saw their subclinical atherosclerosis slow down. Those who took it later (10 years after) did not.
A recent large Cochrane meta-analysis found that while in general postmenopausal women taking HRT had a moderately increased risk of heart disease, breast cancer, and other diseases, a subgroup of healthy, 50-59 year old (so, younger) HRT users only had a slightly increased risk of venous thromboembolism.
The longer you wait to initiate HRT after menopause, the more adverse effects occur. Start earlier, if you do start
How You Administer the HRT Matters
Oral hormones have different metabolic fates than transdermal hormones. When you swallow a hormone, it goes to the liver for processing. This creates various metabolites with different bioactivity. One example is oral estrogen. When you take estrogen orally, you raise CRP, a marker of inflammation. Transdermal estrogen has no effect on CRP.
Oral HRT has been shown across multiple studies to increase the risk of venous thromboembolism, while transdermal HRT does not. This is because oral HRT increases thrombin generation and clotting, while transdermal HRT does not.
In the Women’s Health Initiative that found negative effects, the HRT given to the subjects was oral. Perhaps this was the issue.
For local vaginal symptoms, local application is probably ideal, while oral application is suboptimal. In one study, vaginal estriol was far more bioactive than oral estriol, despite the latter resulting in higher serum levels of the hormone.
However, topical isn’t always best. In one study, sublingual users of bioidentical hormones saw relief from night sweats, irritability, hot flashes, anxiety, emotional lability, sleep, libido, fatigue, and memory loss, while topical users only saw relief from night sweats, emotional lability, and irritability.
The Type Of Hormone You Take Matters
Another factor the WHI failed to address was the composition of the medication itself. They used synthetic hormones—conjugated estradiol and medroxyprogesterone acetate. Could bioidentical hormones, exact replicas of endogenous hormones which exploded in popularity following the WHI, have a different effect?
The amount of research into conventional HRT dwarfs bioidentical hormone therapy (BHT) research, but what we have looks pretty compelling.
Breast cancer is a major concern for HRT users. Most breast cancers respond to estrogen, just over half respond to progesterone, and traditional HRT seems to increase their risk. Yet, at least in healthy postmenopausal women, a combination percutaneous estradiol gel (inserted into the skin) and oral micronized progesterone—both bioidentical to their endogenous counterparts—had no effect on epithelial proliferation of the breast tissue, while reducing activity of a protein that protects cancer from cell death. The conventional HRT had the opposite effect, increasing epithelial proliferation and breast volume (a risk factor for breast cancer). This wasn’t about cancer, but it’s suggestive.
In another study, postmenopausal women on BHT (which included estriol, estradiol, progesterone, testosterone, and DHEA) saw improvements across all measured cardiovascular, inflammatory, immune, and glucoregulatory biomarkers despite being exposed to high levels of life stress.
Then again, in a recent study, bioidentical hormones performed poorly compared to the pharmaceuticals equine estrogen and medroxyprogesterone acetate. The pharmaceutical hormones resulted in a lower risk of breast cancer, although the bioidentical hormones still reduced the risk compared to placebo.
Which Hormones You Take Matters
The vast majority of postmenopausal women take estrogen, progesterone, or some combination of the two. But there’s another hormone that, despite plummeting during menopause, gets ignored—testosterone.
Although testosterone is the “male hormone,” it also plays a vital role in female physiology, especially sexual function. Menopause reduces testosterone by about half, and studies indicate that topical testosterone replacement therapy can improve sexual function and desire (combined with estrogen) as well as musculoskeletal health and cognitive performance in postmenopausal women. More importantly, topical testosterone improves sexual function without causing any of the adverse effects commonly associated with testosterone usage in women, like hair loss, voice deepening, body hair growth, facial hair growth, breast pain or tenderness, or headaches.
Adding low-dose testosterone to a low-dose estrogen regimen may even be better at reducing somatic symptoms of menopause (sleep disturbances, hot flashes, and other physical symptoms) than a higher dose of estrogen alone.
Your Expectations Matter
Our big mistake was treating HRT as a panacea for the chronic conditions of aging. It’s not that smart hormone replacement can’t or won’t reduce the risk of certain diseases, like osteoporosis or heart disease. It’s that we’re still figuring it out.
A better, safer move is to focus on what we know HRT can treat: the symptoms of menopause.
Want to reduce hot flashes and get more sleep? HRT works.
Want to reduce anxiety? HRT works.
Want to improve cognitive function and your sense of smell? HRT works.
The use of bioidentical hormones may be safer or more effective against the bigger stuff. It remains to be seen. Until then, treat symptoms, not chronic disease—but keep in mind your overall risks and discern whether treating the symptoms is worth any additional risk for that bigger stuff.
Your Personal Context Matters
Women with a history of estrogen-responsive breast cancer (80% of breast cancers) should exhibit caution and check with their oncologist before taking any kind of HRT.
ApoE4 carriers should seriously look into taking HRT. In one recent study, postmenopausal ApoE4 carriers exhibited rapid cellular aging—except if they were taking HRT.
Whatever You Decide…
Don’t feel guilty if you decide to take some form of it. I myself take a small dose of testosterone to get my levels up to where they should be. My wife, Carrie, has taken bioidentical hormones in the past (a modest compound blend of estrogen, progesterone, and testosterone) to deal with the symptoms of menopause, including persistent brain fog that didn’t respond to any other herbal or alternative measure in her case. There’s no shame. This is restoration of what’s healthy and supportive of a good life.
Heck, I know women who are both aware of the potential long term risks—heart disease, breast cancer, and the like—and enthusiastic about the shorter-term, more immediate quality-of-life benefits they currently enjoy. They prefer the definite benefits over the small and uncertain absolute risk increases. Some have even said that feeling better day-to-day gives them the energy to continue living a healthy life in other ways.
I also know women who do the opposite, who either are lucky enough to not experience any profound symptoms in their transition or who prefer to use other methods and interventions to deal with their symptoms in order to avoid any increased long-term complications. (I’ll delve more into this in the future if there’s interest.) Regardless, it’s all a choice.
Hopefully after today you feel better equipped to make an informed one.
What about you, folks? I know I have thousands of readers who are facing this very question—or who have already faced it. What did you choose? How did you handle the HRT question?
Thanks for reading. Take care!
Wu WH, Liu LY, Chung CJ, Jou HJ, Wang TA. Estrogenic effect of yam ingestion in healthy postmenopausal women. J Am Coll Nutr. 2005;24(4):235-43.
Murkes D, Lalitkumar PG, Leifland K, Lundström E, Söderqvist G. Percutaneous estradiol/oral micronized progesterone has less-adverse effects and different gene regulations than oral conjugated equine estrogens/medroxyprogesterone acetate in the breasts of healthy women in vivo. Gynecol Endocrinol. 2012;28 Suppl 2:12-5.
Ruiz AD, Daniels KR. The effectiveness of sublingual and topical compounded bioidentical hormone replacement therapy in postmenopausal women: an observational cohort study. Int J Pharm Compd. 2014;18(1):70-7.
Stephenson K, Neuenschwander PF, Kurdowska AK. The effects of compounded bioidentical transdermal hormone therapy on hemostatic, inflammatory, immune factors; cardiovascular biomarkers; quality-of-life measures; and health outcomes in perimenopausal and postmenopausal women. Int J Pharm Compd. 2013;17(1):74-85.
Zeng Z, Jiang X, Li X, Wells A, Luo Y, Neapolitan R. Conjugated equine estrogen and medroxyprogesterone acetate are associated with decreased risk of breast cancer relative to bioidentical hormone therapy and controls. PLoS ONE. 2018;13(5):e0197064.
Schiff I, Tulchinsky D, Ryan KJ, Kadner S, Levitz M. Plasma estriol and its conjugates following oral and vaginal administration of estriol to postmenopausal women: correlations with gonadotropin levels. Am J Obstet Gynecol. 1980;138(8):1137-41.
Scarabin PY. Hormone therapy and venous thromboembolism among postmenopausal women. Front Horm Res. 2014;43:21-32.
Espeland MA, Rapp SR, Manson JE, et al. Long-term Effects on Cognitive Trajectories of Postmenopausal Hormone Therapy in Two Age Groups. J Gerontol A Biol Sci Med Sci. 2017;72(6):838-845.
Hodis HN, Mack WJ, Henderson VW, et al. Vascular Effects of Early versus Late Postmenopausal Treatment with Estradiol. N Engl J Med. 2016;374(13):1221-31.
Santoro N, Allshouse A, Neal-perry G, et al. Longitudinal changes in menopausal symptoms comparing women randomized to low-dose oral conjugated estrogens or transdermal estradiol plus micronized progesterone versus placebo: the Kronos Early Estrogen Prevention Study. Menopause. 2017;24(3):238-246.
Yazici K, Pata O, Yazici A, Akta? A, Tot S, Kanik A. [The effects of hormone replacement therapy in menopause on symptoms of anxiety and depression]. Turk Psikiyatri Derg. 2003;14(2):101-5.
Doty RL, Tourbier I, Ng V, et al. Influences of hormone replacement therapy on olfactory and cognitive function in postmenopausal women. Neurobiol Aging. 2015;36(6):2053-9.
Jacobs EG, Kroenke C, Lin J, et al. Accelerated cell aging in female APOE-?4 carriers: implications for hormone therapy use. PLoS ONE. 2013;8(2):e54713.
Kingsberg S. Testosterone treatment for hypoactive sexual desire disorder in postmenopausal women. J Sex Med. 2007;4 Suppl 3:227-34.
Davis SR, Wahlin-jacobsen S. Testosterone in women–the clinical significance. Lancet Diabetes Endocrinol. 2015;3(12):980-92.
Achilli C, Pundir J, Ramanathan P, Sabatini L, Hamoda H, Panay N. Efficacy and safety of transdermal testosterone in postmenopausal women with hypoactive sexual desire disorder: a systematic review and meta-analysis. Fertil Steril. 2017;107(2):475-482.e15.
Simon J, Klaiber E, Wiita B, Bowen A, Yang HM. Differential effects of estrogen-androgen and estrogen-only therapy on vasomotor symptoms, gonadotropin secretion, and endogenous androgen bioavailability in postmenopausal women. Menopause. 1999;6(2):138-46.
The post The Pros & Cons of Hormone Replacement Therapy for Primal Women appeared first on Mark’s Daily Apple.
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For today’s edition of Dear Mark, I’m answering a single, significant question. It concerns the latest “anti-low-carb” study claiming that we’re all killing ourselves by not eating bread. A reader wonders if the study is legit and if we should be worried about eating fewer carbs than “normal” people.
I don’t think we should be concerned, and I’ll explain why in detail. Let’s take a look and break it down.
I’m sure you’ve seen this latest study to claim that low-carb diets will kill us all: https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(18)30135-X/fulltext
Is it legit?
Yes, I’ve seen it.
Where to start?
This study came from Walter Willet, he of the voluminous mustache and unbridled enthusiasm for seed oils.
The most glaring weakness is the way they gathered the data. Over the course of 25 years, participants were asked to accurately report their diet reaching back as far as six years. This is an inherent issue in most nutrition data gathering, so it’s not unique to this study, but come on. Can you remember what you ate 6 years ago? Did your diet change at all, or was it stable enough to encompass with a curt summary?
The characteristics of the participants differed greatly.
Low-carbers were far more likely:
- To be men—Males have a higher risk of mortality than women.
- To be diabetic—Diabetes lowers lifespan, especially in the 1980s (when the bulk of the data was collected).
- To be sedentary—Failure to exercise is a major risk factor for early death, and ill health in general.
- To smoke cigarettes—Again, this is an elementary variable. Nothing like being able to smoke indoors. Remember smoking sections on airplanes? I do.
- To eat fewer fruits and vegetables—Carnivory is popular these days, and may work for some, but plants are still good for you and actually complement a low-carb, high-meat diet quite nicely.
- To be overweight—All else being equal, the fatter you are, the unhealthier you are.
Even if they were able to “control for” all those variables, you can’t control for the overall health and wellness trajectory of a person hellbent on ignoring their personal health. What other unhealthy things are they doing that weren’t captured and accounted for by the researchers?
For instance, alcohol intake. They didn’t look at alcohol intake in this trial. Seriously, search for “alcohol” in the paper and you’ll come up blank. It’s very likely that the low-carbers were drinking more alcohol, as similarly-conducted epidemiological research has found that “carbohydrate intake [is] the first to decrease with increasing alcohol consumption.” (2) Alcohol can take a serious toll on health and lifespan if you aren’t careful with your intake.
Oh, and low-carbers were also more likely to be on a diet. This might be the most crucial variable of all. Who goes on a diet, typically? People who have a health or weight problem. Who doesn’t diet? People who are happy with their health and weight. There are exceptions to this, obviously, but on a population wide scale, these trends emerge. Did the low-carb diet actually reduce health and lifespan, or did the health conditions that prompted the diet in the first place reduce health and lifespan?
Ultimately, this was all based on observational studies and epidemiological data. It can’t establish cause-and-effect, it can only suggest hypotheses and avenues for future research.
Luckily, we have controlled trials that demonstrate the health benefits of low-carb dieting, all of which correspond to better longevity:
- Improved cardiovascular risk factors. (3)
- Improved metabolic and vascular health. (4)
- Reduced inflammation. (5)
- Improved insulin sensitivity. (5)
You could make the argument that the positive health effects are purely short-term and that in the long run, those benefits turn to negatives. It wouldn’t be a very good argument, though, because we don’t have any indication that it actually happens. If you go reduce carbs or go keto and you lose body fat, gain lean muscle, improve your fasting blood sugar, normalize your lipids, and reduce inflammatory markers, I see no plausible mechanism by which those improvements lead you to an early grave. Do you?
It seems the burden of proof lies in the Willet camp. If the only healthy range of carbohydrate intake is between 50-55%, he would have to show that:
- No healthy, long-lived cultures or individuals have a carbohydrate intake that strays from the 50-55% range. Anthropological and ethnographical evidence must confirm.
- The benefits of low-carb diets, established through randomized controlled trials, are illusory and/or transitory, eventually giving way to health decrements that lower lifespan.
That’s a tough one. Hats off if he can pull it off. I doubt he can.
Thanks for writing in. I hope I allayed any concerns you might have had.
Take care, all, and be sure to share down below with your own comments and questions.
1. Seidelmann, Sarah, MD, et al. Dietary Carbohydrate Intake and Mortality. Lancet. 2018. (Online First)
2. Liangpunsakul S. Relationship between alcohol intake and dietary pattern: findings from NHANES III. World J Gastroenterol. 2010;16(32):4055-60.
3. Thorning TK, Raziani F, Bendsen NT, Astrup A, Tholstrup T, Raben A. Diets with high-fat cheese, high-fat meat, or carbohydrate on cardiovascular risk markers in overweight postmenopausal women: a randomized crossover trial. Am J Clin Nutr. 2015;102(3):573-81.
4. Ballard KD, Quann EE, Kupchak BR, et al. Dietary carbohydrate restriction improves insulin sensitivity, blood pressure, microvascular function, and cellular adhesion markers in individuals taking statins. Nutr Res. 2013;33(11):905-12.
5. Rajaie S, Azadbakht L, Saneei P, Khazaei M, Esmaillzadeh A. Comparative effects of carbohydrate versus fat restriction on serum levels of adipocytokines, markers of inflammation, and endothelial function among women with the metabolic syndrome: a randomized cross-over clinical trial. Ann Nutr Metab. 2013;63(1-2):159-67.
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For today’s edition of Dear Mark, I’m answering six questions from readers. First, is funding from a biased source sufficient to negate a study’s results? Second, what are some good high intensity interval training workouts that people might not have considered? Third, what can someone recovering from an ACL tear do for HIIT without triggering knee pain flareups? Fourth, how do I like to eat spinach? And finally, how and when do I like to take collagen?
On the nuts vs. carbs study, I want to say ‘follow the money’ since it was funded by the International Tree Nut Council Nutrition Research and Education Foundation. Then again, it was also funded by the Peanut Institute, so I don’t know what to think…
“Following the money” isn’t enough to come to any conclusions about the worth of a study. We can’t declare a study tainted based on bias alone, especially because we can’t avoid bias. Every person reading studies and deciding which one to write about is biased. Every organization meting out funding has biases. Every entity in the known universe has an agenda. It’s not “bad” (or good). It simply is.
If the cow consortium funds the “red meat is actually good for you” study, red meat is still good for you. The bias doesn’t negate the facts. Big Soy funds the “don’t worry about the quarter cup of soybean oil in your restaurant food” study, but it’s only a mark against the paper if the science was shoddy and the conflict of interest exerted influence (which it probably was and did).
But I totally understand where you’re coming from. There’s an entrenched bias against most of the health advice we support. The powers that be have spent decades telling us to avoid the sun, restrict meat (especially red meat), go vegetarian, eat low-fat, get “more complex carbohydrates,” use seed oils, do cardio over weights, eat less salt, and blindly drink more water. They’re not just going to go away—and they aren’t.
So whenever I see a study’s been funded by an obviously biased source, I can’t help but wonder and look more deeply at the paper with a skeptical eye. It sounds like you do the same. That’s great. It’s the kind of healthy skepticism we should all have and employ in our search for good information.
We just can’t stop there.
If the results of a study are unfavorable to the funders, it’s a strong indication that the funding didn’t interfere with the science.
If the results are favorable to the funders, our hackles rise. We examine the study methods, design, and results to see if bias affected the results. Many times it doesn’t. Sometimes it does.
Can you point us in the direction of a good HIIT workout and what it should look like?
Here are a couple ideas:
Hill sprints. Find a hill and run up, then walk down. Walking down serves as active recovery. Steeper hills, shorter sprints with more rest. Hills with a gradual incline, longer sprints. All permutations work. Though extremely difficult, hill sprints are good options for many people with lower body injuries that flare up on flat ground sprints; running up a hill is gentler on your joints.
Barbell complexes. Pick 3-4 barbell movements. Clean and press for 5 reps. Romanian deadlift for 5 reps. Clean to shoulders, then front squat for 5 reps. Finish with 5 bent over rows. Do that without stopping or dropping the weight. That’s a complex. Drop the bar and rest a minute or two, then do another complex. Repeat. This works with any barbell movement, and you can even do kettlebell or bodyweight complexes. Adjust weight and reps accordingly. These complexes should be hard (but over quickly).
I tore my ACL 6 months ago. Although I am walking 5-7 miles a day and doing heavy lifting for my upper body. I am only able to do ball squats carefully at this point. Any HIIT ideas for me at this point? The bike causes pain on the front of my knee still.
Check with your doctor, but deadlifts are probably safe during knee rehab. Do them right and there’s very little knee flexion (it sounds like flexion hurts the knee); it’s all hip extension.
Deadlifts can become “cardio” if you drop the weight and increase the reps. Just maintain impeccable form. Don’t sacrifice technique (and back health) for a couple extra reps.
If you can deadlift safely for high reps without pain, the next thing to try is the kettlebell swing. Swinging a kettlebell is very similar to deadlifting a barbell—it’s all hip extension—and lends itself well to high-rep, HIIT-style workouts.
I’m one of few people I know who enjoys eating basically any type of offal (no problems with raw), but can’t handle spinach by itself. Any advice? Also, ever tried meditatin’?
And here’s where I’ll get thrown out of my own movement because of one of the ingredients.
Sauté spinach (frozen or fresh) in butter for a minute, add a handful of corn kernels (fresh or frozen, but organic or at least non-GMO), add salt, pepper, and dried chipotle pepper powder (as much as you can tolerate), cover, and turn heat to low. After about ten minutes, it’s ready. Finish with grated sharp cheddar or pecorino romano.
I don’t eat this often (never while keto), and it’s certainly not the only way I enjoy spinach. A good raw spinach salad is fantastic, as is basic sautéd spinach without the corn. But I’ve never met anyone who didn’t like the spinach-corn-chipotle recipe, even avowed spinach haters like yourself.
I’m curious about when Mark was supplementing heavily with collagen. Did he do that at breakfast as his only food, lunch in lieu of some other protein, a shake between lunch and dinner? What have other folks done?
I’m wary of too much protein in one sitting.
I would have 2-3 tablespoons of collagen with a little vitamin C half an hour before a workout. That’s been shown to increase collagen synthesis, a necessary step for healing tendons and other tissues.
That’s it for today, folks. Thanks for reading and take care!
Be sure to add your own comments, questions, and input down below.
The post Dear Mark: Following the Money, HIIT Workouts, HIIT and ACL Recovery, Spinach, Collagen Timing appeared first on Mark’s Daily Apple.
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For today’s Dear Mark, I’m answering just one question from a reader. What are we to make of the new study purporting to show that saturated fat is the most harmful substance a liver can encounter? Should we remove all traces of it from our diets? Should we eat pure sugar? Quaff soybean oil? How relevant is an overfeeding study to a community of people dedicated to eating a sustainable, weight-reducing or -maintaining diet that includes saturated fat?
Let’s find out:
Did you see this study? http://care.diabetesjournals.org/content/early/2018/05/24/dc18-0071
What’s your take on it? Just got one of those classic emails from my vegetarian friend with only a link to the study and a smug emoji.
Oh yes, I knew this would come up after I linked to in on Weekend Link Love.
The title is “Saturated Fat is More Metabolically Harmful for the Human Liver Than Unsaturated Fat or Simple Sugars.”
I have a human liver. Do you? Probably. This is highly relevant to all of us, right?
Well, the first thing to understand is that this was an overfeeding study. Participants didn’t just eat a eucaloric diet with different energy sources. They each got a daily 1000 calorie snack on top of their normal diet for three weeks.
The SFA group ate 1000 extra calories in the form of butter, coconut oil, and blue cheese. The SFA:MUFA:PUFA ratio was 76%:21%:3%. Their liver fat increased by 55%.
The UFA group ate 1000 extra calories in the form of pecans, olive oil, pesto, and butter. Their SFA:MUFA:PUFA ratio was 21%:57%:22%. Their liver fat increased by 15%.
The Sugar group ate 1000 extra calories in the form of orange juice, soda, and candy. Their snack had no fat, all sugar. Their liver fat increased by 35%.
Saturated fat also increased lipolysis—the breakdown of fatty acids for energy—while unsaturated fat decreased it. Lipolysis normally increases during fasting or exercise. In that context, it’s a good thing and you end up losing body fat. If you have a steady stream of extra fat calories coming in, you won’t lose body fat. The researchers could have seized on this point and screamed “unsaturated fat inhibits lipolysis!” but they didn’t. Wonder why.
Also notable is the observation that overeating sugar increased de novo lipogenesis (creation of fat from sugar) in the liver by 98%. I was told that didn’t happen in humans, that de novo lipogenesis was a myth. Guess it can happen.
But, again, the most important thing to realize is that this was an overfeeding study. It wasn’t a weight loss study. It wasn’t designed to see which kind of diet spontaneously results in the most weight loss. It was designed to get people to eat 1000 extra calories from different nutrient sources to see how they affect liver fat. And they didn’t construct the entire diets around the hypothesis. From what I can tell, the participants ate their normal diets. Only the 1000 calorie overfeeding snacks were provided by the researchers.
You also have to consider choline. The more fat you eat, the more choline your liver needs to process that fat. In rats with fatty liver, supplementing with extra choline directly reduces liver fat. In Chinese women, a high choline intake protects against fatty liver. If the subjects didn’t increase choline as they increased fat overfeeding, they were bound to gain more liver fat. Remember: this was the whole point of the study.
Now with that out of the way, who is this study relevant for?
Those people who think keto gives them free license to consume as many calories as they can cram into their mouths. Don’t do that. Especially don’t do that with isolated sources of fat, including saturated fat. Overfeeding anything is bad news, unless you’re trying to gain lean mass, lifting hard and heavy on a regular basis, and the thing you’re overfeeding is whole food rather than isolated fat.
That’s it for today, folks. What are your thoughts? Does this study tell you anything new, or is it old news?
Let me know what you think down below. Take care, be well, and have a great day.
The post Dear Mark: Saturated Fat More Harmful to Liver Than Sugar? appeared first on Mark’s Daily Apple.
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The tricky thing about fiber is that it’s not a monolith. There are dozens of varieties. Some of them perform similar functions in the body, but others have extremely unique effects. Some rend your colonic lining to stimulate lubrication. Some turn into gelatinous slurries. But we can’t talk about fiber without understanding that the word describes a variety of compounds. As such, anyone making declarative statements about “fiber” without differentiating between the different types and their effects isn’t being accurate (except for me in that exact sentence).
This leads to a lot of confusion. People make blanket statements that might be true for some types of fibers and incorrect for others.
Today’s post will attempt to illuminate the bulk of the matter. I’ll go through some of the most common misconceptions and myths about fiber from all corners of the dietary world. Whether you’re keto, low-carb, vegan, carnivore, or breatharian, you’ll find something to love and hate in today’s post.
1) “Fiber makes you full.”
This is theoretically sound. Mechanoreceptors in the gut respond to physical fullness by triggering satiety hormones. Big loads of insoluble fiber increase intestinal bulk, while some soluble fibers can gel up and increase the size of the stuff moving through your gut. Both result in added pressure on gut mechanoreceptors.
How does it work in practice?
A review found that while soluble fiber reduced appetite more than insoluble fibers, the overall effect on body weight was quite small, unimpressive, and inconsistent. More recently, a soluble fiber supplement failed to have any effect on satiety hormones, appetite, and subsequent food intake for the first 150 minutes after eating in healthy adults. The plucky researchers aren’t giving in, however, promising “further research… to quantify how soluble fiber influences appetite several hours after consumption.”
2) “Every diet needs the same amount of fiber.”
As it turns out, fiber becomes more critical the more carbohydrates you eat.
Soluble fiber slows down digestion, reducing the rate at which energy is absorbed. This can be helpful for people with glucose intolerance or type 2 diabetes by slowing the release of glucose into the blood.
The byproducts of fiber fermentation in the colon by gut bacteria often have beneficial effects on carbohydrate metabolism. Eating resistant starch, for example, lowers the postprandial blood glucose spike. This reduction may also extend to subsequent meals, indicating it’s honing your ability to handle glucose. Everyone can benefit from better glucose management, but it’s far more critical for people eating significant amounts of glucose.
3) “All the healthiest people studied eat fiber!”
Observational studies are fun and all, but they’re not a good way to prove the healthfulness of fiber. Looking at fiber intake is just about the best way to capture the “healthy user”—that person who does everything right, like walk daily, exercise regularly, abstain from tobacco, avoid binge drinking, and eat whole foods rather than refined ones. It doesn’t say anything definitive about the health effects of the specific dietary variable they’re observing.
That said, the fact that most healthy populations eat whole foods containing fiber indicates that fiber probably isn’t actively harmful.
4) “Fiber is just roughage for big impressive poops. No functional use.”
That’s mostly true of insoluble fiber, which is pure waste material that shreds your intestinal lining and increases stool volume.
There’s considerable evidence that people with type 2 diabetes can really benefit from prebiotic fiber supplementation:
- Chicory-derived inulin, a potent prebiotic fiber, reduces liver enzymes and HbA1c, improves blood pressure and fasting glucose, and increases calcium homeostasis.
- Inulin improves immune markers and glycemic control.
- Resistant starch lowers insulin resistance and inflammation.
A review of studies found that while the prebiotic inulin reduces LDL-C (an imperfect biomarker of dubious utility) in all populations, only in type 2 diabetics does inulin improve HDL and blood glucose control.
Prebiotic fiber may also help certain patients with non-alcoholic fatty liver disease (NAFLD). The usual therapy for NAFLD patients is weight loss. You lose enough body fat elsewhere and the fat you’ve accumulated in the liver starts to disappear, too.
What about lean NAFLD patients without any real weight to lose?
In lean patients with NAFLD, a synbiotic—blend of prebiotic fiber with probiotic bacteria—reduces liver fat and fibrosis by improving inflammatory markers. Pre-emptive consumption of prebiotics may even protect against the development of NAFLD.
Another function of fiber that occurs in everyone is the production of short chain fatty acids by gut bacteria. When gut bacteria ferment prebiotic fiber, they produce short chain fatty acids, many of which have beneficial metabolic effects.
Butyrate is the most important short chain fatty acid. It fuels colon cells and may prevent colon cancer. Its relationship with existing colon cancer cells is more controversial. Read more about that here.
One interesting line of research is studying the interaction between the ketone body beta-hydroxybutyrate and the short chain fatty acid butyrate. Initial indications suggest that the two may have synergistic effects on cognition, inflammation, and overall health. That alone may be a reason to make sure you get prebiotic fiber on your ketogenic diet, just to hedge your bets.
Now, might a low-carb or ketogenic diet work better for people with type 2 diabetes than adding fiber to their normal diet? Sure. Could such a diet reduce the need for fiber? Yeah, I could see it. The same goes for NAFLD—low carb diets are also excellent in this population. And perhaps people who aren’t eating so many carbs don’t need the short chain fatty acids to improve their metabolic function and insulin sensitivity. But the evidence for fiber in type 2 diabetes and NAFLD stands, and I suspect short chain fatty acid production matters even in low carb or keto dieters.
5) “Fiber cures constipation.”
In one 2012 study, patients with idiopathic constipation—constipation without apparent physiological or physical causes—had to remove fiber entirely to get pooping again. Those who kept eating a bit or a lot of it continued to have trouble evacuating. The more fiber they ate, the worse their constipation (and bloating) remained.
A 2012 review found that while fiber may increase stool frequency, it doesn’t improve stool quality, treatment success, or painful defecation. Similarly, glucomannan, a soluble fiber, moderately improves defecation frequency in constipated kids, but has no effect on stool quality or overall treatment success.
However, galactooligosaccharides, a class of prebiotic fiber, do appear to improve idiopathic constipation. And inulin, another prebiotic fiber, improves bowel function and stool consistency in patients with constipation.
6) “Fiber aggravates gut issues.”
Some say fiber cures gut issues like IBS and IBD. Others say fiber aggravates them. Who’s right? Maybe both.
Both IBS-D (irritable bowel syndrome with diarrhea) and IBS-C (irritable bowel syndrome with constipation) patients can benefit from soluble fiber (psyllium) while insoluble fiber (bran) is far less effective.
Wheat bran works okay for IBS, if the patients can tolerate it. They tend to tolerate something like hydrolyzed guar gum much better.
For IBD, the evidence is mixed. One survey of Crohn’s patients found that those eating more fiber (23 grams/day) had fewer flareups than those eating less (10 grams/day), while colitis patients reported no difference in symptoms based on fiber intake.
On the other hand, studies indicate that a low-FODMAP diet, which eliminates most sources of fiber, especially fermentable prebiotic fiber, is an effective treatment for IBS and IBD. Low-FODMAP diets have been shown to reduce bloating, abdominal pain, quality of life, and overall symptoms in intestinal disorders.
These contrary results may not even be contradictory. If your gut’s messed up, one solution could be to add back in the fibers you’re missing. Another could be to take all the fiber out and start from scratch.
7) “Fiber reduces nutrient absorption.”
For a long time, the consensus was that fiber tends to bind with minerals in the gut and thus reduce their absorption. These days, researchers understand that many of these fiber-bound minerals become available after fermentation in the colon.
Another wrinkle is that dietary fiber often comes with phytic acid, which binds minerals and prevents their absorption. Take wheat bran. Often deemed “wheat fiber” and lambasted for its tendency to bind minerals, wheat bran isn’t just fiber. It’s also a significant source of mineral-binding phytic acid.
Prebiotics increase absorption of magnesium, heme iron, and calcium. This makes sense. Even if the prebiotics are binding minerals, they release them once they reach the colon for fermentation by gut bacteria.
Fiber may reduce absorption of plant polyphenols, however.
8) “No one needs fiber.”
On the surface, this appears to be a sound conclusion. The human host digestive system cannot digest it. The majority of the fiber we eat gets pooped out as literal waste material. Certain classes of fiber may improve our gut health, but no one is keeling over from a lack of fiber in their diet.
Some have argued that a sterile gut is ideal if you have the right diet, that employing vast hordes of gut bacteria is just an adaptive measure taken to deal with a substandard diet full of roughage. The problem is that most people throughout history and prehistory have eaten that roughage, employed those gut bacteria, utilized the metabolites those bacteria produce. I suspect thinking long and hard before you consider it immaterial to human health.
If that were true, why would breast milk—the only food specifically designed for human consumption—contain loads of indigestible oligosaccharides that feed the growing gut biome? Even if it turns out that feeding the gut biome is only vital during infancy, that’s still a population of humans who truly need fiber.
Here’s where I come down: Fiber is an intrinsic part of many whole plant foods (and even whole animal foods, if it turns out that our gut bacteria can utilize “animal fibers” like other top carnivores). The Primal-friendly plants, the ones our ancestors grew up eating approximations of, like fruits, vegetables, roots, and tubers, are mostly higher in soluble fiber and lower in insoluble fiber. The only way to get huge doses of insoluble fiber these days is with supplementation or by eating grains. I don’t suggest eating grains or supplementing with insoluble fiber. I do suggest eating fruits, vegetables, roots, and tubers (while managing your carbs).
As for the carnivore issue, I’m open to the possibility that a properly-constructed carnivorous diet (which may, remember, include gristly animal fiber) obviates the need for plant fiber, prebiotic or otherwise. I’m not confident enough to try it myself, though.
Do I think everyone should be supplementing with prebiotic fiber? No. I add inulin to my Primal Fuel protein powder, mostly to improve mouth-feel but also to feed beneficial microbes and increase butyrate production. I add prebiotic cassava fiber to my collagen bars, again to improve texture and feed gut bacteria. And I’ll sometimes use raw potato starch for its considerable resistant starch content, often just mixing it into sparkling water and drinking it straight. But for the most part, the fiber I eat is incidental to the foods I consume. Berries, non-starchy vegetables, jicama, garlic, onions, green bananas, nuts—these are all foods rich in fiber, particularly prebiotic fiber, and I eat a fair amount of them while remaining low-carb and often keto.
As you can see, the fiber story isn’t simple. At all. There are many variables to consider. If you’re confused and unsure of how to think about fiber, you’re on the right track.
What do you think, folks? How has fiber helped or harmed you? I’d love to hear from everyone.
Take care and be well.
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