Health Benefits of Phytochemicals of Fruits and Vegetables
Rui Hai Liu
Department of Food Science, 108 Stocking Hall, Cornell
University, Ithaca, NY 14853
Epidemiological studies have consistently shown that regular
consumption of fruits and vegetables is associated with reduced risk of
chronic diseases, such as cancers, cardiovascular disease, stroke,
Alzheimer¹s disease, cataracts and some of the functional declines
associated with aging. In 1989, a report from the National Academy of
Sciences on diet and health recommended consuming five or more servings
of fruits and vegetables daily for reducing the risk of both cancer and
heart disease. The Five-a-Day program was developed as a tool to
increase public awareness of the health benefits of fruit and vegetable
consumption and promote adequate intakes of known vitamins. Plant-
based foods, such as fruits, vegetables and whole grains, which contain
significant amounts of bioactive phytochemicals, may provide desirable
health benefits beyond basic nutrition to reduce the risk of chronic
diseases. It is now widely believed that the actions of the
antioxidant nutrients alone do not explain the observed health benefits
of diets rich in fruits and vegetables because taken alone, the
individual antioxidants studied in clinical trials do not appear to
have consistent preventive effects. Work performed by our group and
others have shown that fruit and vegetable phytochemical extracts
exhibit strong antioxidant and antiproliferative activities; we
proposed that the additive and synergistic effects of phytochemicals in
fruits and vegetables are responsible for these potent antioxidant and
anticancer activities, and that the benefit of a diet rich in fruits
and vegetables is attributed to the complex mixture of phytochemicals
present in whole foods. Our hypothesis may explain why no single
antioxidant can replace the combination of natural phytochemicals in
fruits and vegetables to achieve the health benefits. We believe that
the evidence suggests that antioxidants are best acquired through whole
food consumption.
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