The Complete Magnesium Manual

Magnesium is an essential mineral that doesn’t get the attention it deserves. You’d be hard pressed to find any activity in the body that doesn’t use magnesium in some way. It has literally hundreds of functions.

Cellular energy production, protein synthesis, DNA and RNA synthesis, and cell signaling—which controls the secretion of certain hormones, among other things—all depend on magnesium. It plays an important role in ion channels that allow nerves to fire, potassium and sodium to cross cellular membranes, and muscles to contract. Production of ATP, the energy currency of the body, depends on magnesium. Your heart beats rhythmically thanks to magnesium.

Not surprisingly, then, magnesium deficiencies seem to factor into a wide range of health issues. Let me tell you about some of the biggies.

Health Issues Related to Magnesium

Before getting into the details, I want to draw your attention to a few challenges with the research literature. One, which I’ll return to later, is that magnesium levels in the body are tough to measure.

Second, lots of studies try to link dietary magnesium intake to specific health outcomes. Foods that contain magnesium, like leafy greens and fish, also contain a host of other vitamins and minerals, fiber, sometimes amino acids. This makes it hard to isolate the effects of any single nutrient.

The way magnesium intake is measured, usually with the Food Frequency Questionnaire (FFQ) or food diaries, is also fraught with error. I don’t put too much stock in studies that correlate dietary intake with any specific health outcome. Correlation doesn’t prove causation anyway, as you know. I’ll mention them here to give you a complete picture of what researchers are working with. Ideally, though, I like to see randomized controlled trials.

Magnesium and Inflammation

It’s increasingly clear that inflammation is at the heart of many, if not most, chronic disease states. Studies have shown that people who consume less than half the recommended daily allowance of magnesium have higher levels of C-reactive protein (CRP), a marker of inflammation.
https://pubmed.ncbi.nlm.nih.gov/15920065/’>¹² and the NHANES Study https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6040119/‘>¹⁴

The Link Between Heart Health and Magnesium

There are many well-documented metabolic pathways through which magnesium can affect heart health. Magnesium may reduce heart disease risk by reducing arterial stiffness, improving endothelial functionhttps://pubmed.ncbi.nlm.nih.gov/1418832/‘>¹⁶

Several large prospective studies have correlated higher magnesium intake or higher magnesium levels in the blood with reduced risk of cardiovascular disease and stroke.https://academic.oup.com/ajcn/article/93/2/253/4597608‘>¹⁸ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6692462/‘>²⁰ Magnesium deficiency is considered a risk factor for cardiac arrhythmia and hypertension (high blood pressure).

A recent review of the available evidence concluded that while it’s fair to say that magnesium intake is important for cardiovascular health overall, more randomized controlled trials are needed to understand the particulars better.https://pubmed.ncbi.nlm.nih.gov/28724644/‘>²² https://pubmed.ncbi.nlm.nih.gov/20228010/‘>²⁴

Type 2 Diabetes and Insulin Sensitivity

Magnesium affects how cells take up glucose out of the bloodstream, glucose oxidation, and insulin sensitivity.https://pubmed.ncbi.nlm.nih.gov/9589224/‘>²⁶

Diabetes and magnesium deficiency is a vicious cycle. Prospective studies suggest that people with lower magnesium intake are at greater risk for insulin resistancehttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC5133122/‘>²⁸. Once they have the disease, they lose more magnesium through urine, making them more susceptible to ongoing magnesium deficiency. This then exacerbates the problems of poor glucose management and insulin resistance, increasing the chances of diabetic complications.https://pubmed.ncbi.nlm.nih.gov/27530471/‘>³⁰ A second meta-analysis found better insulin sensitivity and fasting glucose, particularly when supplementation lasted at least four months.The results of this analysis also indicate that the effects are greatest among people who start out with low magnesium.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3775240/‘>³²

In correlational studies, dietary intake is positively associated with bone mineral density in postmenopausal and premenopausal women https://pubmed.ncbi.nlm.nih.gov/10197575‘>³⁴, and older white, but not Black, folks https://pubmed.ncbi.nlm.nih.gov/9709941/‘>³⁶ postmenopausal women,https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2995550/‘>³⁸

Magnesium and Migraines

A fair number of studies find that migraine sufferers have lower magnesium levels than people who don’t get migraines.https://pubmed.ncbi.nlm.nih.gov/12786918/‘>⁴⁰ and adultshttps://pubmed.ncbi.nlm.nih.gov/25278139/‘>⁴²

The American Academy of Neurology and the American Headache Society agree that magnesium is probably effective for the treatment of migraines.https://pubmed.ncbi.nlm.nih.gov/22426836/‘>⁴⁴

Magnesium Could Help with Depression and Anxiety

Magnesium has many complex actions in the brain, including affecting neurotransmitter and hormone release and neuronal firing. Although research provided promising evidence a century ago that magnesium can be used to treat depression, nobody took much notice.https://pubmed.ncbi.nlm.nih.gov/25748766/‘>⁴⁶ Supplementation may alleviate symptoms of mild-to-moderatehttps://www.sciencedirect.com/science/article/abs/pii/S0899900716302441‘>⁴⁸ and major depression.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5452159/‘>⁵⁰

But Wait, There’s More!

More research is needed, but magnesium may be a factor in:

• Restless leg syndromehttps://pubmed.ncbi.nlm.nih.gov/27296515/‘>⁵²
• PMShttps://pubmed.ncbi.nlm.nih.gov/9368236/‘>⁵⁴

What about Sleep?

Magnesium supplementation is often touted for sleep, but there’s actually not that much direct evidence that it helps. One small study involving 12 elderly participants concluded that magnesium supplementation enhanced sleep quality.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3703169/‘>⁵⁶ That’s about it.

Still, many sleep aids contain magnesium because it is needed to convert 5-HTP to serotonin, which in turn converts to melatonin. It also blocks NMDA receptors in the brain and promotes GABA, both of which are important for sleep. (These same mechanisms may explain why magnesium helps with depression, by the way. Some scientists have also suggested magnesium’s action on NMDA receptors is why it alleviates migraines.)

Exercise Performance

Magnesium plays a key role in glucose metabolism and energy production. Since glucose is mobilized during exercise, it makes sense that magnesium would be important. Research in mice shows that giving them magnesium increases the amount of available glucose during exercise. It also delays the accumulation of lactate in the muscles, which may prevent fatigue.https://pubmed.ncbi.nlm.nih.gov/24015935/‘>⁵⁸ Triathletes likewise improved their swim, bike, and run times.https://pubmed.ncbi.nlm.nih.gov/1299490/‘>⁶⁰

Even if it doesn’t yield a performance benefit, though, it’s clearly important that athletes make sure their electrolyte intake is sufficient. More on that next week.

Normal Levels and Magnesium Deficiencies

It’s difficult to test magnesium levels. The most common method is a blood test. Normal serum concentrations fall between 0.75 and 0.95 mmol/L.

However, less than 1 percent of total body magnesium is in the bloodstream, and serum level is tightly regulated by the kidneys, as well as bone and intestines. Blood tests are poor indicators of total body magnesium levels. Your doctor may use a combination of blood, saliva, and urine tests if they suspect a severe deficiency. No single method seems to work very well.

Clinical deficiencies in healthy adults are rare, but data from the large NHANES study suggests that perhaps only one-third of Americans hits the recommended daily intake.https://pubmed.ncbi.nlm.nih.gov/9494787/‘>⁶²

How to Choose a Magnesium Supplement

As with any nutrient, it’s best to get magnesium from food. The Food and Nutrition Board of the US Institute of Medicine designates 350 mg/day as the tolerable upper intake level (UL) for supplementing.

When choosing a magnesium supplement, look for a chelated form, the ones ending in -ate. They have the best bioavailability. Magnesium glycinate and malate are both good choices. Magnesium citrate is probably the most common since it is inexpensive and widely studied, but it can have undesirable laxative effects for some people. L-threonate is particularly noted for its cognitive benefits. Avoid magnesium oxide unless you specifically want diarrhea.

Certain pharmaceutical drugs can interact with magnesium. Talk to your doctor, especially if you take medications for osteoporosis or HIV, if you are on a diuretic, or if you are prescribed tetracycline or quinolone antibiotics.

Can You Get Too Much Magnesium?

While magnesium toxicity is possible, it’s very rare. Most forms of magnesium will cause gastrointestinal distress before that point. Stick to recommended doses, though.

Transdermal Magnesium: Epsom Salts Baths and Magnesium Oil

Both epsom salt baths (magnesium sulfate) and magnesium oil sprays (usually magnesium chloride) are touted as alternatives for boosting magnesium levels. However, there is almost no research verifying that it is effectively absorbed through the skin.