About 50 of these can potentially yield vitamin A activity and are thus referred to as provitamin A carotenoids. However, inside the body, beta-carotene is only partially converted to vitamin A and the rest is stored as such. Currently available evidence suggests that in addition to being a safe source of vitamin A, beta-carotene plays many important biological roles that may be independent of its provitamin status. The beta-carotene content of fruits and vegetables can vary depending on the season and degree of ripening. The bioavailability of beta-carotene from fruits and vegetables depends on the method of preparation before ingestion.
Any indications concerning the beta-carotene content of foods are therefore only approximate values.
Body stores Bile salts are needed for the absorption of beta-carotene in the upper small intestine. Many factors in the diet, e.g. fat and protein, affect absorption. The proportion of carotenoids absorbed decreases as dietary intake increases. This mechanism is regulated by the individual's vitamin A status. The adult's fat stores are often yellow from accumulated carotene while the infant's fat stores are white.