Vitamin A intake of captive rhesus monkeys exceeds national research council recommendations

The specific vitamin A (VA) requirements of nonhuman primates have not been adequately determined via species-specific scientific experimentation. Recommendations are considered to be similar to human requirements, particularly for Old World monkeys. Manufacturers of primate diets add an excess of most nutrients in order to compensate for losses that occur during storage and handling. Moreover, the form of VA used in these diets is synthetic VA esters, which are readily absorbed and stored. Primates in the wild obtain much of their VA from provitamin A carotenoids, which are cleaved as needed to form active VA and are considered nontoxic, unlike preformed VA. The purpose of this study was to determine what types of feed are used at the National Primate Centers and to estimate the amount of VA that rhesus macaques are consuming. Five of the eight centers responded to a short survey that was administered through telephone and electronic mail contacts. VA intakes are well above those that are considered adequate for humans, and VA concentrations in commercially prepared standard primate diets exceed National Research Council (NRC) recommendations by as much as four times. Thus, the VA provided in primate diets should be reevaluated with regard to the concentration and form of the vitamin used.