Meeting requirements for vitamin A.

When the intake of foods or pharmaceutical preparations containing sufficient nutrients of adequate bioavailability are consumed, nutrient requirements are met and optimal nutritional status is maintained. Recent studies have shown that the basis for describing vitamin A activity of carotenoids overestimates the bioavailability of provitamin A carotenoids and their bioconversion to retinol (vitamin A). It is therefore proposed that instead of 6 microg from a mixed diet, 21 microg beta-carotene are required to provide 1 microg of retinol or 1 RE (retinol equivalent) of vitamin A. Based on this assumption and on data from food balance sheets, estimates of daily per capita vitamin A intake expressed in RE in Africa, South America, and Asia are reduced from 895, 599, and 667, respectively, to 371, 372, and 258, respectively. Such intakes are well below the recommended daily intake of 600 RE for adult males. A new combination of approaches will therefore have to be used to combat vitamin A deficiency rather than that used up until now.