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Natural Phytochemicals in Fight against Cancer

A few decades ago, scientists in cancer research began focusing their attention on a group of non-nutritive plant chemicals called phytochemicals. Plants produce phytochemicals to protect themselves from bugs in the fields or against too much sun and to prevent diseases. Research shows that these common natural substances could also be used to protect humans against serious diseases such as cancer or heart disease.

Whether phytochemicals are the key to controlling human diseases such as cancer has yet to be proved. What we know about them so far suggests that they can indeed provide the body with multiple ways to prevent cancer and even destroy cancer cells before they can start to proliferate. Their activity is particularly strong in the epithelial cells that line body organs such as the lung, esophagus, mouth, throat, bladder, cervix, larynx, stomach, pancreas, colon and rectum.

Phytochemicals is a term used to describe various chemical substances that occur naturally in plants. They fulfil different functions and each works differently. They can have anti-oxidative or anti-bacterial effects, hormone or enzyme stimulating effects, they can interfere with DNA replication and they possess anti-adhesion properties (keeping pathogens from adhering to human cell walls). In the research spotlight today are the phytochemicals present in a variety of foods, including cruciferous vegetables (see the table below for complete list), garlic, onions, licorice root, soybeans, citrus fruits, tomatoes, carrots, barley, celery, ginger root, green tea and hot peppers. Substances showing the greatest promise include:

P-coumaric acid and chlorogenic acid, which are present in carrots, tomatoes, pineapples, strawberries, garlic, peanuts and other vegetables and fruits, remove nitric oxide from cells before it can combine with chemicals called amines to form the cancer-causing nitrosamines. In some countries, chlorogenic acid extract is used as a food additive and is also available as a dietary supplement.

Sulforaphane, a molecule found in cruciferous vegetables, has been shown to prevent breast cancer in laboratory animals. This compound possesses strong anti-oxidative effects that persist for hours after ingestion. It is believed that sulforaphane mobilize certain enzymes in breast cells, which locate cancer-causing substances and attach them to molecules that escort them out of the cell.

Allyl sulfides, contained mainly in garlic and onions, are also thought to stimulate enzymes that defuse carcinogenic chemicals in cells. Studies suggest that allylic sulfides may also decrease the risk of heart disease by inhibiting the formation of cholesterol.

Indole-3-carbinol, abundant in cruciferous vegetables, has been found in some studies to inhibit the formation of cancer-causing estrogens in the breast. Other indoles present in cruciferous vegetables seem to activate enzymes that break down cancer-causing substances into harmless ones, which can be particularly beneficial in fight against cancers of the stomach and intestine.

Phenethyl isothiocyanate is yet another phytochemical commonly found in cruciferous vegetables. It is studied for its potential to inhibit lung cancer and for chemoprevention.

Flavonoids are substances widely distributed in plants, fulfilling diverse roles. Some flavonoids, which are thought to interfere with hormones promoting cancer, are contained in tomatoes, carrots, peppers, soybeans, yams and many other plants. Limonene, a flavonoid present in citrus fruits, is reported to promote the production of enzymes that may help destroy potential carcinogens.

Some other possible actions of phytochemicals include depriving tumors of their blood supply, getting in the way of cancer-causing hormones that are trying to become attached to the cell, protecting the DNA inside cells as well as a lot of other things that scientists have not discovered yet. Food companies and consumers should be careful, though. Just like vitamins and minerals, phytochemicals can be toxic if ingested in large amounts. For the time being, the best way to get beneficial phytochemicals is to eat plenty of fruits, vegetables and beans.

Where to Get More Information: American Institute for Cancer Research