Various natural carotenoids, besides β-carotene, were proven to have anticarcinogenic activity, and some of them showed more potent activity than β-carotene. Thus, these carotenoids (α-carotene, lutein, zeaxanthin, lycopene, rbeta β-cryptoxanthin, fucoxanthin, astaxanthin, capsanthin, crocetin and phytoene), as well as β-carotene, may be useful for cancer prevention. In the case of phytoene, the concept of 'bio-chemoprevention', which means biotechnology-assisted method for cancer chemoprevention, may be applicable. In fact, establishment of mammalian cells producing phytoene was succeeded by the introduction of crtB gene, which encodes phytoene synthase, and these cells were proven to acquire the resistance against carcinogenesis. Antioxidative phytoene-containing animal foods may be classified as a novel type of functional food, which has the preventive activity against carcinogenesis, as well as the ability to reduce the accumulation of oxidative damages, which are hazardous for human health.
