L-carnitine supplementation of a soybean-based formula in early infancy: plasma and urine levels of carnitine and acylcarnitines

The absence of carnitine in the diet of normal infants results in marked reduction of plasma carnitine levels. In order to evaluate the effects of L-carnitine supplementation of soybean formula, plasma and urine levels of free carnitine and acylcarnitine were compared in infants receiving carnitine-free soybean protein-based formula and the same formula supplemented with 50 and 250 nmol/ml L-carnitine. In infants receiving soybean formula with 50 nmol/ml L-carnitine, the plasma levels of free carnitine were not significantly different from those in infants receiving formula with 250 nmol/ml L-carnitine; however, urine levels of free carnitine were significantly increased when the infants received formula with 250 nmol/ml L-carnitine. In normal full-term infants, supplementation of soybean formula with 50 nmol/ml L-carnitine was sufficient to maintain normal plasma levels that were comparable to breast-fed infants.