Magnesium nutrition of infants.

Our knowledge of magnesium absorption in infants and dietary factors affecting magnesium bioavailability from infant diets is limited. The magnesium concentration of human milk is about 30 mg/litre, while infant formulas provide about 40-80 mg/litre and cows milk approximately 130 mg/litre. Most of the magnesium in these diets is present in soluble form and in vitro digestibility studies show the remainder to be easily solubilized. The soluble magnesium in infant diets is largely in a low molecular weight form, most likely explaining the high bioavailability of magnesium from infant diets in experimental animals (50-90 per cent). Limited studies in preterm and term infants also indicate a high level of magnesium absorption (55-75 per cent) from human milk and milk-based formulas. Thus, infant diets are likely to supply adequate amounts of magnesium for the growing infant. Magnesium deficiency and toxicity are therefore rare in term infants and usually a consequence of hormonal abnormalities and maternal use of pharmacological doses of magnesium. Low birth weight infants may exhibit hypomagnesaemia and benefit from magnesium supplementation.