Gradual increase of carnitine in plasma, tissues and urine after birth is a normal response of breast-fed infants and those receiving carnitine-containing formulas. Marked reduction of carnitine and acylcarnitines was noted in infants given diets not containing carnitine. These differences prompted the evaluation of the rationale for adding carnitine into soy-based formulas. In healthy term infants the lack of dietary carnitine did not induce deficiency symptoms but reduced the uptake of fatty acids for beta-oxidation. The cumulative effect of various metabolic disorders and carnitine deficient diets may culminate to carnitine deficiency.