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Magnesium is one of the most abundant minerals in the body and is a cofactor in over 300 enzymatic reactions. It is required for protein and nucleic acid synthesis, the cell cycle, cytoskeletal and mitochondrial integrity, and the binding of substances to the plasma membrane (1). Magnesium deficiency is quite common in the western world (1-3), with certain groups at high risk, one of them being athletes (3). A high calcium intake can compound the problem, as calcium and magnesium play antagonistic roles towards each other (4). Foods high in magnesium include green vegetables, unmilled grains, legumes, and nuts, while processed food items are usually completely absent of magnesium (1). Magnesium deficiency has been implicated as playing a role in a wide range of conditions.
2. What are the benefits of magnesium supplementation?
- Exercise performance - Magnesium is especially important for
athletes as physical activity depletes magnesium stores (3, 6). A study with
competitive triathletes supplementing with magnesium orotate for 4 weeks
found that it decreased swimming, cycling and running times, as well as altering
glucose utilization and reducing various markers of stress response (such
as serum cortisol) (7). In contrast, a review of the literature was unable
to find a significant difference in exercise performance from magnesium supplementation,
but mentioned many variables that confounded the analysis (3). It is also
worth noting that magnesium deficiency for a long period would have a variety
of effects that could be detrimental to health.
- Cardiovascular health - Studies have indicated an inverse
relationship between dietary magnesium intake and both stroke and blood
pressure. Also, magnesium deficiency can play an important role in heart
disease, congestive heart failure, hypertension, and many other
cardiovascular problems.
- Other benefits - In the absence of a kidney problem, overdose from magnesium supplements is quite rare (1-2), although toxicity is possible if dietary intake of calcium or potassium is insufficient (1). The typical dosage is 400-800 mg per day or at least a 2:1 ratio with calcium intake (for example, if you get 3 grams of calcium per day you would want 1.5 grams of magnesium).
3. What form of magnesium is best?
Magnesium is available in many forms, most of which are highly bioavailable. The exception is magnesium oxide, which has very low bioavailability (11). Magnesium citrate, chloride, lactate, and aspartate all have high bioavailability (11, 12), with citrate being the highest. Magnesium may have lower bioavailability when taken with calcium, but the combination is often recommended because taking both together helps to prevent excesses of one or the other.
If you have any questions or comments regarding this article, please email dvdtlsn@bulknutrition.com.
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