HEALTH BENEFITS OF PHYTOCHEMICALS
Phytochemicals—the bioactive nonnutrient plant compounds
in fruit, vegetables, grains, and other plant foods—have been
linked to reductions in the risk of major chronic diseases. It is
estimated that more than 5000 phytochemicals have been identified,
but a large percentage still remain unknown (7) and need to
be identified before their health benefits are fully understood.
However, more and more convincing evidence suggests that the
benefits of phytochemicals in fruit and vegetables may be even
greater than is currently understood because oxidative stress
induced by free radicals is involved in the etiology of a wide
range of chronic diseases (8).
Cells in humans and other organisms are constantly exposed to
a variety of oxidizing agents, some of which are necessary for life.
These agents may be present in air, food, and water, or they may
be produced by metabolic activities within cells. The key factor is
to maintain a balance between oxidants and antioxidants to sustain
optimal physiologic conditions in the body. Overproduction of
oxidants can cause an imbalance, leading to oxidative stress, especially
in chronic bacterial, viral, and parasitic infections (9).
Oxidative stress can cause oxidative damage to large biomolecules such as proteins, DNA, and lipids, resulting in an increased risk
for cancer and cardiovascular disease (8, 10). To prevent or slow
down the oxidative stress induced by free radicals, sufficient
amounts of antioxidants need to be consumed. Fruit and vegetables
contain a wide variety of antioxidant compounds (phytochemicals)
such as phenolics and carotenoids that may help protect
cellular systems from oxidative damage and lower the risk of
chronic diseases.