Magnesium and Energy Expenditure in Postmenopausal Women.




Journal of Nutrition

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Magnesium is involved in the interaction of more than 300 enzyme reactions in the body. It is necessary for the transmission of nerve impulses, temperature regulation, detoxification, energy production and the formation of healthy bones and teeth. It is also vital for cardiovascular health. Good food sources include nuts, legumes, cereal grains, and dark green leafy vegetables.

A U.S. Department of Agriculture study found that 75 percent of Americans do not get an adequate supply of magnesium in their diet. This is probably due to the absence of magnesium in many processed foods and the depletion of magnesium from agricultural soils in the U.S.

A study published in the Journal of Nutrition stated that lack of sufficient magnesium in the American diet is specifically strong among older women. This study conducted by the U.S. Department of Agriculture investigated the effects of low magnesium levels in postmenopausal women during aerobic exercise. The participants were between the ages of 45 and 71 years and were not receiving hormone replacement therapy. Both groups received 112 mg of magnesium. For 35 days, the control group additionally received a supplement that contained 200 mg of magnesium daily. For 93 days, the experimental group did not obtain any further intake of magnesium. After the 93 days, they began to take a 200 mg magnesium supplement for 49 days, in a depletion-repletion method. Red blood cell magnesium concentration and retention were lower in the depleted group. Also among the depleted women, peak oxygen uptake, total oxygen uptake, and heart rate all increased when compared to the control group during aerobic exercise. The authors concluded that "these findings indicate that dietary magnesium depletion can be induced in otherwise healthy women; it results in increased energy needs and adversely affects cardiovascular function during submaximal work."1


1. Lukaski HC. Dietary Magnesium Depletion Affects Metabolic Responses during Submaximal Exercise in Postmenopausal Women. J Nutr. May 2002; 132:930-935, 2002.