Phytochemical

A nonnutritive bioactive plant substance, such as a flavonoid or carotenoid, considered to have a beneficial effect on human health. Also called phytonutrient.

 

Phytochemicals are sometimes referred to as phytonutrients; these terms are often used interchangeably. Phytochemicals naturally occur in vegetables and fruit. In broad terms, they can be said to be any chemical or nutrient derived from a plant source. However, in common usage, they have a more limited definition. They are usually used to refer to compounds found in plants that are not required for normal functioning of the body but that nonetheless have a beneficial effect on health or an active role in the amelioration of disease. Thus, they differ from what are traditionally termed nutrients in that they are not a necessity for normal metabolism, and their absence will not result in a deficiency disease -- at least not on the timescale normally attributed to such phenomena. A minority claim that many of the diseases afflicting the people of industrialized nations are the result of those people's lack of phytonutrients in their diet. What is beyond dispute is that phytonutrients have many and various salubrious functions in the body. For example, they may promote the function of the immune system, act directly against bacteria and viruses, reduce inflammation, and be associated with the treatment and/or prevention of cancer, cardiovascular disease and any other malady affecting the health or well-being of an individual.

 

Cancer prevention

There is abundant evidence from epidemiological studies that the phytochemicals in fruits and vegetables can significantly reduce the risk of cancer, probably due to polyphenol antioxidant and anti-inflammatory effects. But studies of supplementation with large doses of beta-carotene in smokers have shown an increase in cancer risk (possibly because excessive beta-carotene results in breakdown products that reduce plasma Vitamin A and worsen the lung cell proliferation induced by smoke). Many preclinical studies suggest that phytochemicals can prevent Colorectal cancer or other cancers: for instance, the Chemoprevention Database reports more than 250 studies where a given phytochemical significantly reduced the number of carcinogen-induced tumors in rats or mice. However, the same database does not report a single clinical trial showing cancer prevention by a phytochemical in human volunteers. Several trials are ongoing, and may report positive results next years.