Upper limits of vitamin A in infant formulas, with some comments on vitamin K.

Current Food and Drug Administration (FDA)-approved levels of adequacy and of upper limits in infant formulas for vitamin A are 250 and 750 IU per 100 kcal, respectively. The level of adequacy is generous relative to need. Because vitamin A toxicity has been noted in infants at intakes of 2,100 IU per 100 kcal, an upper limit might well be selected in the range of 750-1,000 IU per 100 kcal for healthy infants. Some children and adults, however, are intolerant of relatively low intakes. The current FDA-approved adequacy level for vitamin K is 4 micrograms per 100 kcal, which also is generous relative to need. An upper limit has not previously been set. Neither single intramuscular doses of phylloquinone that are 100 times the RDA (RDI) for infants nor diets that contain 10-20 times the RDA (RDI) for adults show any adverse effects. Some allergic reactions to injected vitamin K have been reported, however, and menadione, even in low doses, shows significant toxicity in neonates. Thus, although toxicity to phylloquinone is unlikely, it has been suggested that the upper limit of phylloquinone in infant formulas be set at 20 micrograms per 100 kcal, primarily to discourage nutritionally unwarranted supplementation.