Carotenoids and cancer: prevention and potential therapy

Epidemiological studies suggest that cancer risk is related to dietary inta ke of carotenoid-rich fruit and vegetables. Whether or not carotenoids are the active component has pet to be definitively proven, although some of th ese studies have shown that after elimination of obvious factors, such as f ibre content, these foods still possess anticancer properties. On the other hand, two large intervention studies have shown that beta-carotene supplem entation increases the risk of lung cancer in smokers. However, high doses of beta-carotene were used in these studies. Experimental work on animals a nd cells has shown that treatment with carotenoids can inhibit the developm ent of cancer. Such studies have revealed a variety of mechanisms, in addit ion to antioxidant and conversion to vitamin A, including up-regulation of gap junctional communication, induction of detoxifying enzymes and inhibiti on of proliferation. Studies on tumour cells indicate that carotenoids can interfere with the growth of transformed cells, suggesting that they may be effective in the treatment of some cancers.