Magnesium is an important macro-mineral needed for a number of biological functions in humans. Magnesium is required for the construction of healthy bone tissue, is incorporated into cell membranes bound to phospholipids, stabilises the ATP molecule and is a co‑enzyme in a number of important metabolic pathways including glycolysis, the Krebs cycle and phosphocreatine synthesis. The total body content of magnesium in a human adult is roughly 25 grams, just over half of which is located in bone tissue and around a quarter located in muscle. The governmental recommendations for magnesium vary from country to country but are around 350 mg per day for an average weight adult male and slightly less for a female. Research suggests that the diets of large proportions of Western nation are considered to be deficient in magnesium.
Research published in the Journal of Nutrition in 20031, investigated the magnesium intakes of 4257 American subjects from dietary recall data. Although not the most accurate way of assessing mineral intakes, dietary recall can provide a basic understanding. The study found that the most important contributors to magnesium intakes were milk (6.2 %) ground coffee (3.7 %), beer (3.2 %), bananas (1.8 %) and French fries (1.1 %). When this data was grouped into broad categories the top contributors to magnesium intakes were vegetables (12.9 %), milk (7.5 %), meat (7.3 %), bread (6.6 %), mixed dishes (6.5 %), pasta and pizza (5.6 %), coffee (5.3 %), sweets (4.6 %, cold cereal (4.1 %) and alcoholic beverages (3.8 %). One of the best sources of magnesium in the diet are green leafy vegetables and whole grains, but these appear to be eaten in only low amounts by the study participants.
The mean magnesium intakes was 290 mg per day for the study participants. Magnesium content decreased with increasing age in a linear trend, with men having slightly higher intakes than women. Amongst all the groups, Caucasian men had the highest intakes. Interestingly, 53 % of participants reported using dietary supplements, and the studies authors concluded that supplements can be an important source of magnesium intake. However, the researchers did not evaluate the contribution of dietary supplements, but did state that the most commonly available multivitamins they evaluated contained around 100 mg of magnesium. This they concluded would not be enough to push the median intake above the RDA. The overall conclusion from this study is that the American people select foods that are poor sources of magnesium and large proportions from all ethnicities are therefore deficient in magnesium.
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