UC Irvine

Carotenoids and retinoids can stimulate some human immune responses. These include cytoine release with anti-tumor cell activity, increased natural killer cells and activated lymphocytes after both in vitro and in vivo treatment with beta carotene. Such stimulations seem only partly due to retinoids formed from carotenoid metabolism and may be due to effects caused by the structure of beta carotene. Changes in immune functions could explain in part the cancer resistance provided by high carotenoid or retinoid intakes in animals. © 1990 Pergamon Press plc.