Nutrition and magnesium absorption: a review.

This paper reviews the evidence that certain dietary components can affect intestinal absorption of magnesium. Increased intakes of protein and fructose improve apparent magnesium absorption (magnesium intake minus fecal excretion) in humans, whereas a lowering effect occurs with consumption of cellulose and phytate. Although dietary concentrations of lactose, fat, calcium and phosphate have clear effects on magnesium absorption in experiments with rats, the impact of these nutrients on magnesium absorption in humans remains unsettled. Mechanisms underlying the effects of dietary components on magnesium absorption in humans are generally poorly understood. A change in magnesium absorption not necessarily results in a change in magnesium retention. When consuming practical diets, the fall of apparent magnesium absorption caused by phytate and cellulose is generally compensated by increased magnesium intake due to high magnesium concentrations in phytate- and cellulose-rich products. Furthermore, to maintain homeostasis, urinary magnesium excretion will be raised after stimulation of apparent magnesium absorption and it will be lowered after impairment of apparent magnesium absorption. Thus, the effects of dietary components on magnesium absorption probably are critically important only at low intakes of magnesium. At low magnesium intakes, differences in magnesium absorption may be expected to influence magnesium retention and thus can either induce or abolish magnesium deficiency.