Chapter 7 – Phytochemicals & Whole Foods
Phytochemicals are non-nutrient chemicals found naturally in plants (especially fruits and vegetables) that contain health-enhancing or disease-preventing compounds. It is these phytochemicals that give certain foods their cancer-preventing properties. In some cases, these phytochemicals can be isolated from the natural food and turned into supplements. However, for most of the phytochemicals described in this chapter, it is highly recommended to get them by consuming the whole food they come from. They are listed in order of importance.
Green tea
There are three categories of teas: green, oolong, and black. Each of these comes from the leaf of Camellia sinensis, which is a shrub native to Asia. The main difference between these teas is the duration of fermentation: "black" is fully fermented, "oolong" is partially fermented, and "green" is only steamed and not fermented at all. Green tea is one of the most popular beverages in China, Japan and many other countries in Asia, and it has been gaining popularity in the West over the years. It has been used medicinally in the Far East for centuries. It is believed that green tea consumption is responsible for the lower incidences of certain cancers in Japan and China, where people drink green tea as a daily cultural habit.
Green tea is believed to be a strong preventive agent against cancer because it contains a large quantity of strong antioxidants. The most important active component in green tea is a family of polyphenols called catechins. The dominant and most important catechin is Epigallocatechin Gallate (EGCG), which is believed to be 100-200 times more powerful an antioxidant than vitamins C and E respectively. EGCG is believed to have an inhibitory effect on the production of an enzyme, urokinase, that is required for cancer cell growth and tumor formation, while it also promotes apoptosis in cancer cells. In other words, it helps stop cancer cell growth, and it forces these cells to commit suicide. In addition, it has immunoprotective qualities in the sense that it stimulates the production of white blood cells even when the body is undergoing radiation treatment or chemotherapy. For these reasons, it is an excellent cancer-preventing and cancer-reversing agent. It is believed to be especially effective in preventing lung, stomach, mouth, esophageal, skin and prostate cancers.
A study funded by the UCLA Jonsson Comprehensive Cancer Center and NCI found that green tea consumption can reduce stomach cancer rates by about 50 percent. It found a similar reduction in the likelihood of developing chronic gastritis, a condition that sometimes leads to stomach cancer. The study also revealed that the likelihood of developing cancer was affected proportionately by the amount of green tea consumed and the length of time it had been consumed for. In other words, the more green tea you drink and the longer you have done it for, the lower your probability of developing stomach cancer. Another study from the Shanghai Cancer Institute determined that the risk of gastric and esophageal cancers is reduced by around 60 percent for green tea drinkers.
Santosh K. Katiyar, Ph.D., and his colleagues in the department of dermatology at Case Western Reserve University, reviewed several studies on green tea and determined that it may be useful in preventing and treating various human skin disorders including cancer. Dr. Katiyar says that although it is better to drink green tea, skin care products with green tea extract might also protect the skin by directly fighting the free radicals that can turn skin cells cancerous. Having the antioxidant in direct contact with the skin cells might be the best protection they can get. More research is needed to verify whether the topical application of polyphenols might work as theorized.
Green tea is considered by many the reason that the Japanese have such low lung cancer rates. The Japanese actually have one of the highest smoking rates in the world, yet they have among the lowest lung cancer rates. Studies in Japan have shown that green tea drinkers have lower rates of cancer than the average Japanese person. It is also hypothesized that Chinese people have a much lower incidence of oral cancer because of their high green tea consumption. Dr. Stephen Hsu has demonstrated in laboratory studies at the Medical College of Georgia's School of Dentistry that oral cancer cells are killed when exposed to the polyphenols in green tea, while normal cells are unaffected.
Green tea's antioxidant activity helps prevent heart disease by preventing the oxidation of LDL cholesterol and by reducing the free radicals that cause general cell damage, which in turn prevents atherosclerotic plaques from forming. It has also been recommended as a diet aid since it aids in the metabolism of fat. It has been shown to increase energy expenditure necessary for fat burning. The great thing about green tea is that it does not increase the heart rate as do many other diet aids. So any way you look at green tea, it's good for your health.
Lycopene and tomatoes
Carotenoids are natural compounds that give colorful fruits and vegetables their colors. Numerous studies have shown that different carotenoids prevent cancer. Although there are over 600 carotenoids, so far only a few appear to have significant cancer-fighting properties.
Lycopene is the carotenoid that gives tomatoes and watermelons their red color. It is also a potent antioxidant that has shown the greatest potential for preventing cancer from the carotenoid family. It is also found in grapefruits, apricots, guava, and papaya. The antioxidant activity of lycopene is about twice as high as that of beta-carotene. Unlike beta-carotene, lycopene is not converted to vitamin A, which allows it to retain more of its special properties. Besides cancer-prevention, lycopene is also known to lower the risk of heart disease, lower LDL cholesterol, boost the immune system, prevent lipid peroxidation, and prevent DNA damage.
Studies suggest that diets high in tomato intake prevent cancers of the lungs, prostate, stomach, colon and rectum. It may also have a hand in protecting against cancers of the mouth, skin, cervix, breast, esophagus, and pancreas. It has been noticed that lycopene levels in the blood are up to 50 percent lower in smokers. This leads one to the conclusion that lycopene is probably used up in the fight against oxidative damage that smoking causes to cellular tissue.
According to Moss, pharmacologists in Italy have found that high tomato consumption is associated with a 61percent reduction in colon cancer, a 58percent reduction in cancer of the rectum, a 57percent decrease of stomach cancer, and a 35percent reduction in cancer of the oral cavity, pharynx and esophagus. A Canadian study that took place between 1994 and 1997 determined that people that consume the most lycopene compared with those that consume the least have a 31 percent lower probability of developing pancreatic cancer.
Dr. Edward Giovannucci, M.D. of the Harvard School of Public Health found that prostate cancer risk is lowered by a diet rich in tomato-based products. After studying the dietary habits and health of over 40,000 men, he found that men that consumed ten or more servings of tomato products weekly had a 45percent lower risk of developing prostate cancer. He later found in a second study in 1999 that giving lycopene supplements to prostate cancer patients helped prevent the spread of their cancer and reduced or limited the size of their tumors. Other studies show that lycopene inhibits the growth of cancer cell cultures. Yet another study found that older Americans with a high-lycopene diet have a 50 percent lower probability of developing any kind of cancer.
The great thing about lycopene is that even if you don't like raw tomatoes, you can get your lycopene from tomato sauces comprising foods such as spaghetti sauce, pizza sauce, and Mexican salsa, which most of us like. What's more, ideally, people should try to eat as much tomato sauce (or other cooked forms of tomato) as possible since the cooking process increases the bioavailability of lycopene and makes it more readily absorbable. It is also best to consume your lycopene with some fat, such as olive oil (which is often an ingredient in sauces), since this makes it even more absorbable. The Mediterranean diet is known to be good for the heart and for your health in general. This diet happens to be very rich in tomato sauces, which is probably the reason for its health benefits. This is probably the reason that people from southern Mediterranean countries such as Italy and Greece have a low incidence of prostate and other cancers as well as heart disease.
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