beta-carotene and cancer; It starts in the early 1980s, when the cumulative results of many studies suggested that people who eat a lot of fruits and vegetables are significantly less likely to get cancer. A close look at the data pointed to carotenes as the active ingredients in fruits and vegetables. It appeared that a high intake of dietary carotene might significantly reduce the risk of cancer of the lung, bladder, breast, esophagus and stomach.

However, as noted above, observational studies cannot prove cause and effect. When researchers gave beta-carotene to study participants, the results have been impressively negative.

Most studies enrolled people in high-risk groups, such as smokers, because it is easier to see results when you look at people who are more likely to develop cancer to begin with.

Beta-carotene alone is not efficient. Fruits and vegetables contain many carotenoids (carotene-like substances) that may be more important for preventing cancer than beta-carotene alone. One researcher has suggested that taking beta-carotene supplements and none other, actually depletes the body of other beneficial carotenoids. This is the reason that the Anti-Aging Clinic first measures the carotenoids in the tissue and follows up with testing each month testing the clients who are taking our antioxidant blends.

Lycopene, a carotenoid like beta-carotene, is found in high levels in tomatoes and pink grapefruit. Lycopene appears to exhibit about twice the antioxidant activity of beta-carotene and may be more helpful for preventing cancer.

In one observational study, elderly Americans consuming a diet high in tomatoes showed a 50% reduced incidence of cancer. Men and women who ate at least seven servings of tomatoes weekly developed less stomach and colorectal cancers compared to those who ate only two servings weekly.

In another study, 47,894 men were followed for 4 years in an observational study looking for influences on prostate cancer. Their diets were evaluated on the basis of how often they ate fruits, vegetables, and foods containing fruits and vegetables. High levels of tomatoes, tomato sauce, and pizza in the diet were strongly connected to reduced incidence of prostate cancer. After an evaluation of known nutritional factors in these foods as compared to other foods, lycopene appeared to be the common denominator.

Additional impetus has been given to this idea by the discovery of lycopene in reasonably high levels in the human prostate, evidence from test tube studies that lycopene might slow DNA synthesis in prostate cells and evidence that men with higher lycopene levels in the blood have a lower risk of prostate cancer.

Several observational studies have found a strong association between high dietary vitamin C intake and a reduced incidence of stomach cancer. It has been proposed that vitamin C may prevent the formation of carcinogenic substances known as N-nitroso compounds in the stomach.

Observational studies have also linked higher vitamin C in the diet with reduced risk of colon, esophageal, laryngeal, bladder, cervical, rectal, breast, and perhaps lung cancer.

One study found that vitamin C supplementation at 500 mg or more daily was associated with a lower incidence of bladder cancer.

Both green tea and black tea come from the plant Camellia sinensis, which has been cultivated in China for centuries. The key difference between the two is in preparation. For black tea, the leaves are allowed to oxidize, a process believed to lessen the potency of the presumed active ingredients in green tea, catechin polyphenols. Green tea is made by lightly steaming the freshly cut leaf, a process that prevents oxidation and possibly preserves more of the therapeutic effects.

Laboratory and animal studies suggest that green tea consumption protects against cancers of the stomach, lung, esophagus, duodenum, pancreas, liver, breast, and colon.

A study in Shanghai, China, found that those who drank green tea had significantly less risk of developing cancers of the rectum and pancreas than those who did not.

Another study in Shanghai found similar associations for stomach cancer. Green tea drinkers were 29% less likely to get stomach cancer than nondrinkers, with those drinking the most green tea having the least risk.

Green tea may exert an estrogen-blocking effect that is helpful in preventing breast and uterine cancer and another study suggests that it might prevent the development of tumors by blocking the growth of new blood vessels.

The main catechin polyphenol found in green tea is epigallocatechin gallate (EGCG). Preliminary experimental studies suggest that EGCG may help prevent skin cancer if it is applied directly to the skin.