Dietary factors that affect the bioavailability of carotenoids

Carotenoids are thought to contribute to the beneficial effects of increase d vegetable consumption. Various dietary factors have an effect on the bioa vailability of carotenoids. The type of food matrix in which carotenoids ar e located is a major factor. The bioavailability of beta-carotene from vege tables in particular has been shown to be low (14% from mixed vegetables) c ompared with that of purified beta-carotene added to a simple matrix (e.g., salad dressing), whereas for lutein, the difference is much smaller (relat ive bioavailability of 67% from mixed vegetables). Processing, such as mech anical homogenization or heat treatment, has the potential to enhance the b ioavailability of carotenoids from vegetables (from 18% to a sixfold increa se). The amount of dietary fat required to ensure carotenoid absorption see ms low (similar to 3-5 g per meal), although it depends on the physicochemi cal characteristics of the carotenoids ingested. Unabsorbable, fat-soluble compounds reduce carotenoid absorption, and interaction among carotenoids m ay also result in a reduced carotenoid bioavailability. Research into the f unctional benefits of carotenoids should consider the fact that the bioavai lability of beta-carotene in particular is one order of magnitude higher wh en provided as a pure compound added to foods than when it is present natur ally in foods.