ABSTRACT
ABSTRACT Melatonin has been found in a wide variety of plants and plant products and is considered to have a functional role, protecting them against internal and environmental oxidative stressors and to cope with hash environments. Many fruits, vegetables, seeds, grains, herbs, and plant products have been shown to contain high levels of melatonin. These dietary components would be expected to contribute to circulating melatonin levels in human. This chapter reports on selected fruit that are reported to contain substantial amounts of melatonin or are frequently consumed. It reports on the bioavailability of melatonin from plant materials in animals and humans, based on evidence of dietary melatonin being absorbed into the blood or presenting in daytime urine. The best sources of melatonin and the amount of consumption required to achieve doses equivalent to endogenous nighttime levels are postulated. It also considers the interaction of dietary melatonin with drugs and other dietary constituents, particularly those that are substrates for the enzyme cytochrome P4501A2, and the effect of the polymorphism of this enzyme on melatonin uptake from dietary foods. Finally, the role of dietary tryptophan, as the source of precursor for melatonin synthesis, and its synergy with other benecial phytochemicals-for example, anthocyanins, vitamin C and E, polyphenols, and other antioxidants-is discussed.
