What are phytochemicals?
Phytochemicals (or “plant chemicals”) contribute to the vivid colors found in fruits and vegetables and have a major positive impact on human health. It should be obvious that vegetables and fruits are healthful — this is probably due to some balance of phytochemicals, carotenoids, fibers, vitamins and minerals.
What are polyphenols and flavonoids?
Polyphenols include flavonoids (or “catechins”) and appear to be powerful antioxidants. Certain flavonoids, including quercetin, are more active than others. Laboratory studies have shown that flavonoids suppress tumor growth, interfere with sexual hormones, may help prevent blood clots, and have anti-inflammatory properties. Flavonoids are found in celery, cranberries, onions, kale, broccoli, apples, cherries, berries, tea, red wine, parsley, soybeans, tomatoes, eggplant and thyme. Most common berries, which contain flavonoids, are particularly rich in potent antioxidants.
What are isothiocyanates?
Isothiocyanates and the related substances, indoles, are often referred to as mustard oils, and are responsible for the sharp taste in cruciferous vegetables (broccoli, cabbage, Brussels sprouts, cauliflower, collards, kale, kohlrabi, mustard greens, rutabaga, turnips, bok choy). They stimulate enzymes that convert estrogen to a more benign form and may block steroid hormones that promote breast and prostate cancers. Cruciferous vegetables are also high in fiber, vitamin C and selenium.
What are monoterpenes?
Monoterpenes have two important phytochemicals, perillyl alcohol and limonene. They block proteins that stimulate cell growth and reproduction and are being tested for actions against cancer.
Limonene is found in the peels of citrus fruits.
What are phytoestrogens?
Phytoestrogens, also called isoflavones, have actions that are similar to the female hormone estrogen. Important phytoestrogens are genistein, daidzein, enterolactone and equol. Phytoestrogens act as antioxidants and tumor suppressors. These compounds may improve cholesterol, prevent bone loss and suppress enzymes that stimulate breast cancer.
Phytoestrogens are found in soy products (not soy sauce), whole grains, berries, fruit, vegetables and flax seed.
What are organosulfur compounds?
Organosulfurs, which include allicin, boost the immune system, assist the liver in rendering carcinogens harmless, and may reduce production of cholesterol in the liver. These compounds are found in garlic, leeks, onions, chives, scallions and shallots.
What are saponins?
Saponins are forms of carbohydrates that neutralize enzymes in the intestines that may cause cancer. They also may boost the immune system and promote wound healing. Saponins are found in ginseng, beans (including soybeans) and whole grains.
What is capsaicin?
Capsaicin seems to reduce levels of substance P, a compound that contributes to inflammation and the delivery of pain impulses from the central nervous system. Research suggests it may inhibit cancer-generating substances. Capsaicin is found in hot red peppers.
What are plant sterols?
Plant sterols, which include sitosterol and squalene, are found in vegetable oils and may have cholesterol-lowering effects.
What are the benefits of vitamins and phytochemicals?
Currently, the most important benefit claimed for vitamin A, vitamin E, vitamin C and many of the carotenoids and phytochemicals is their role as antioxidants, which are scavengers of particles known as oxygen-free radicals. These unstable particles are by-products of many of the body’s normal chemical processes and are increased by smoking, environmental toxins and stress. They can damage cell membranes and interact with genetic material, possibly contributing to the development of a number of disorders, including cancer, heart disease, cataracts and the aging process. Oxygen-free radicals can also enhance the dangerous properties of low-density lipoprotein (LDL) cholesterol, a major player in the development of atherosclerosis.
Antioxidant vitamins and many phytochemicals can neutralize free radicals and may reduce or even prevent some of their damage. Although it is clear that vitamins are required to prevent deficiency diseases, the possible benefits of higher-dose supplements are still unproven in most cases. In fact, there is some evidence that in high doses vitamin C, vitamin E and beta-carotene have pro-oxidant effects that can be harmful. The best way to obtain combinations of antioxidant vitamins and nutrients is to eat plenty of dark-colored fresh fruits and vegetables.
