|
Food as Medicine: Guide to Phytonutrients by Marcia Zimmerman, M.Ed., C.N.
What are Phytochemicals?
The term phytochemical (some prefer phytonutrient) refers to natural plant-based chemicals that have been identified as active compounds in disease prevention. These vitamin-like molecules help regulate bodily functions. Thousands of different phytochemicals work to fine-tune metabolic processes that help maintain health.
To be classified as a vitamin, a substance must alleviate specific symptoms that return when the vitamin is withdrawn. An example of a classic nutritional deficiency is scurvy, which vitamin C prevents and alleviates. Vitamins are required in small amounts, usually measured in milligrams (mg.) or micrograms (mcg.).
Phytochemicals, on the other hand, may be required in fairly large amounts and haven't yet been linked to specific nutritional deficiencies. However, scientific research in this area is moving quickly, and we will no doubt see some of these phytochemicals reclassified as essential in the next century. Today, we know that phytochemicals have these functions:
- reduce the risk of cardiovascular disease; reverse high cholesterol, triglycerides, free radical damage, platelet stickiness and degeneration of vessel walls
- reduce cancer risk by activating the body's defense mechanisms and blocking the action of carcinogens
- detoxify cancer promoters and free radical inducers
- modify hormone levels, reduce the risk of cancers from excess hormone action
- act as potent antioxidants in both fat-soluble and water-soluble body fluids and cellular components
- influence metabolic enzymes to increase or decrease speed to benefit the entire body boost immune response by activating different classes of immune-system components
- inhibit destructive enzymes and bacterial, viral, fungal and parasitic attack
- protect the body's structural components.
What foods contain phytochemicals?
Every plant food contains several classes of phytochemicals. That's why a varied diet is so important. It's difficult to measure the benefits of one group of phytochemicals against the benefits of others. It's quite clear that we need them all.
Scientists began examining the connection between diet and resistance to disease early this century. They discovered that people who ate diets high in fruits and vegetables had reduced incidence of heart disease, diabetes and some cancers. Citrus fruits became popular as a means of preventing or alleviating colds. Besides vitamin C, citrus contains phytochemicals called bioflavonoids. Whole grains and beans were promoted for their phytochemicals, including fiber, phytosterols and lignan. These foods help manage cardiovascular disease, diabetes and hypoglycemia.
The sulfur compounds, also phytochemicals, in garlic were found to kill bacteria and parasites, boost the immune system and reduce atherogenesis (thickening of artery walls) and platelet stickiness. All members of the cruciferous family — broccoli, cauliflower, cabbage, bok choy, Brussels sprouts, collards, cress, kale, kohlrabi, mustard, horseradish and radishes — contain a group of closely related sulfur compounds known as glucosinolates.
Glucosinolates, as phytochemicals, can be isolated and sold in capsules as dietary supplements for protection against some types of cancer and stimulation of protective liver detoxification enzymes. They may be further divided into specific nutraceuticals within the group — sulforaphane, indole-3-carbinol, dithiothiones and isothiocyanates. Researchers have identified how each of these work in the body.
Soyfoods get a lot of press because scientists have discovered that people who traditionally eat a soyfood-rich diet have reduced incidence of cancers of the breast, colon and prostate. The soy components that have been identified as biochemically active are isoflavones. There are six different isoflavones: daidzin, daidzein, genistin, genistein, glycitin and glycitein. Besides anticancer activities, soy isoflavones lower cholesterol and can behave like estrogens. For menopausal women seeking natural relief, this is good news. Phytoestrogens are substances that bind to estrogen receptors in the body, conferring the benefits of estrogen but not the risks. Because phytoestrogens resemble estrogen, they fool the body into thinking it has the real thing. Soy isoflavones' effects also include reduction of inflammation, cardioprotection, free radical scavenging and protection against kidney and gall bladder disease.
In the January 10, 1997 issue of Science, researchers discussed the chemoprotective activity of resveratrol, a natural phytochemical derived from grapes. Resveratrol, a phytoalexin (protective compound) is produced by grapes in response to environmental stress. It protects the grape from mold, bacteria and other dangers. In humans, resveratrol inhibits cellular events associated with tumor initiation, promotion and progression. It acts as an anti-inflammatory and chemical-detoxifying agent.
Grape seeds contain protective compounds called oligomeric proanthocyanidins that scavenge free radicals and promote growth and repair of connective tissue. They inhibit destructive enzymes and also reduce inflammation.
Researchers have reported on the superior antioxidant effects of oligomeric proanthocyanidins, which are derived from grape seeds or the bark of Bordeaux pine trees. Research has also demonstrated multiple angioprotective and anti-inflammatory benefits from these compounds. Perhaps their most remarkable benefit is repair of connective tissue including skin, tendons, ligaments, blood vessels, and organ and body cavity linings.
What are nutraceuticals? Why would I need them as supplements?
In 1986, Stephen L. DeFelice, M.D., from New York formed the Foundation for Innovation in Medicine, a nonprofit organization dedicated to promoting natural therapies. Early in his medical career, DeFelice promoted the idea of natural substances in foods as healing agents. These natural substances, found only in whole, unadulterated "functional foods": foods whose biochemically active components haven't been removed through processing were called nutraceuticals, a term coined by DeFelice. The term implies the ability of a single chemical agent to act as powerfully as, and in some cases better than, pharmaceutical agents. Understanding the mechanism by which a nutraceutical works in the body has been the goal of intense research.
Nutraceuticals can be isolated from natural food sources and sold as dietary supplements. For example, a woman concerned about breast cancer but allergic to soyfoods might supplement her diet with isoflavones isolated from soyfoods. A man who is not particularly fond of tomatoes but wishes to benefit from their prostate cancer-protective properties might choose a lycopene supplement. Nutraceuticals have few side effects but may cause adverse reactions in a few specific situations. Nutraceuticals can be found in animal (such as shark and bovine cartilage) as well as plant sources.
What is the difference between phytochemicals and nutraceuticals?
Phytochemicals are one class of nutraceuticals. The primary difference between phytochemicals and nutraceuticals is that phytochemicals are plant-based, whereas nutraceuticals are plant- or animal-based. Phytochemicals are often derived from plants that are known more for their medicinal value than their food value.
Are there scientific studies that support the use of nutraceuticals?
Thousands of studies have defined the disease-preventing benefits of nutraceuticals. They're published in peer-reviewed scientific journals and have been conducted by world renowned researchers.
This information is for educational purposes only. Visit a health care professional if you think phytochemical supplementation might benefit you.
Marcia Zimmerman, M.Ed., C.N., is a researcher, writer and lecturer. She is founder and CEO of The Zimmerman Group, Inc., headquartered in Alameda, Calif.
|
