Other isoprenoid-like antioxidants and unsaturated long chain hydrocarbons might interfere with the actions of vitamin E if the beneficial response is mediated though a biological receptor. This type of competitive phenomena might help to explain recent results in a large population of smokers that led to serious questions about the benefits of beta-carotene in cancer prevention. Melatonin , another potent antioxidant available for the time being without a doctor's prescription, is of interest as a supplement for individuals over 40, for some cancer patients, and for others having trouble sleeping . Stimulation of immunity has been observed in vivo , but melatonin in cell culture has an inhibitory effect upon immune responses, results consistent with possible interactions with the monooxygenase. The production of this antioxidant and sleep-facilitating hormone decreases with age and levels are low in individuals with at least some forms of cancer .
Benefits derived from melatonin supplements pose some interesting social questions.
Unfortunately, melatonin in the diet now probably partitions into the fat of meats along with environmental carcinogens and preservatives such as ethoxyquin . Expect the etiology of many diseases to be made clearer in the near future if it turns out that melatonin controls the expression of the flavin-containing monooxygenase.