Melatonin in plant-based food: Implications for human health

The utilization of dietary compounds to target, treat, and even prevent certain diseases has become an area of great and fundamental interest. The Mediterranean diet, rich in fruits and vegetables, is associated with a low incidence of chronic degenerative disorders common to Western populations, and compelling evidence points to a reduced risk of cancer and cardiovascular and neurodegenerative diseases in Mediterranean countries compared with other industrialized countries. These observations may be related to beneficial compounds in the diet, including antioxidants, minerals, fiber, and many biologically active molecules. A new diet element has recently contributed to improve the phytochemical diversity of healthy diets and their beneficial potential effects: melatonin. Melatonin was first identified in plants in 1995, and its medicinal and nutritional relevance to both animals and humans and its functions in plants have acquired diffuse interest. In particular, melatonin has been identified in a very large number of plant species. So far, it has been detected and quantified in the roots, shoots, leaves, flowers, fruits, and seeds of a considerable variety of spermatophyte species that are relevant to humans as food and medicinal plants. When plant products are eaten, melatonin is absorbed through the gut and influences the levels of indoleamine in the blood as well as improving antioxidant status. The concentration of melatonin in edible plants varies widely and, to date, it is difficult to calculate how a specific diet may positively influence human health. This chapter will summarize and update current knowledge about melatonin in plant foods and medicinal herbs, and provide an overview of the major implications of the consumption of plant foods containing melatonin for the maintenance of a healthy lifestyle and protection against diseases.