|Nielsen, Forrest - Frosty|
Submitted to: Journal of the American College of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2006
Publication Date: 4/1/2007
Citation: Nielsen, F.H., Milne, D.B., Klevay, L.M., Gallagher, S., Johnson, L.K. 2007. Dietary magnesium deficiency induces heart rhythm changes, impairs glucose tolerance, and decreases serum cholesterol in post menopausal women. Journal of the American College of Nutrition. 26(2):121-132. Interpretive Summary: Epidemiological surveys, supplementation trials, and animal studies have suggested that magnesium deficiency in humans may result in changes that could result in cardiovascular disease and contribute to the complications of diabetes. However, direct evidence that primary magnesium deficiency of a severity similar to that which may occur in the general population causes changes in glucose, lipid and electrolyte metabolism that could lead to pathologic consequences is limited. Thus, an experiment of 136 days in duration was conducted in which 13 postmenopausal women were fed a diet that provided about 101 mg magnesium with an intake of 2000 calories for 52 to 78 days. The subjects were replenished by supplementing the diet with 200 mg magnesium per day for 58 to 74 days with the length of time dependent upon the time of exit from the depletion period. During magnesium depletion, heart rhythm changes appeared in 5 women. During the magnesium-low period, the women lost magnesium from their body and had lower magnesium concentrations in their red blood cells. Magnesium deprivation decreased serum cholesterol and an anti-oxidant enzyme in red blood cells (superoxide dismutase), and increased serum glucose. The findings indicate that magnesium deficiency resulting from feeding a diet that would not be considered having an atypical menu induces heart arrhythmias, impairs glucose homeostasis, and alters cholesterol and oxidative metabolism in postmenopausal women. Thus, a dietary intake of about 100 mg of magnesium per day is inadequate for healthy adult women and may result in compromised cardiovascular health and glucose metabolism.
Technical Abstract: Objective: Show that inadequate dietary magnesium causes changes in glucose, cholesterol and electrolyte metabolism that could lead to pathologic consequences. Design: The length of the experiment was 136 days. Subjects were fed a basal Western-type diet that provided 4.16 mmol (101 mg) magnesium per 8.4 MJ (2000 kcal) for 52 to 78 days. Heart rhythm changes resulted in the entry of four subjects into the magnesium repletion period before 78 days. The subjects were replenished with magnesium by supplementing the diet with 200 mg magnesium as the gluconate per day for 58 to 74 days with the length dependent upon the time of exit from the depletion regime. Setting: The metabolic unit of the Grand Forks Human Nutrition Research Center. Subjects: A total of 14 post menopausal women were recruited by advertisement throughout the United States. Thirteen women (ages 47 to 75 years) completed the study. Results: During magnesium repletion, heart rhythm changes appeared in 5 women. Three women exhibited atrial fibrillation and flutter that responded quickly to magnesium supplementation. Magnesium deprivation resulted in a non-positive magnesium balance that became highly positive with magnesium repletion. Magnesium deprivation decreased red blood cell membrane magnesium, serum total cholesterol and erythrocyte superoxide dismutase concentrations, increased the urinary excretion of sodium and potassium, and increased serum glucose concentration. Conclusions: Magnesium balance may be a suitable indicator of magnesium depletion under experimental conditions. Magnesium deficiency resulting from feeding a diet that would not be considered atypical induces heart arrhythmias, impairs glucose homeostasis, and alters cholesterol and oxidative metabolism in post menopausal women. A dietary intake of 4.16 mmol (101 mg) Mg/8.4 MJ is inadequate for healthy adults and may result in compromised cardiovascular health and glycemic control in post menopausal women. Key Words: magnesium deficiency, magnesium balance, heart arrhythmia, glucose tolerance, cholesterol