Cancer is among the most feared of the many diseases that affect people these days .But despite a wealth of scientific data, most people remain unaware of how they can reduce their risk of developing cancer. According to the National Cancer Institute, as much as 80 percent of all cancers are due to identified factors, and thus are potentially preventable. Thirty percent are due to tobacco use, and as much as 35 percent to 50 percent are due to foods. It is easy to control these and other risk factors.

What Is Cancer?
Cancer begins as a single abnormal cell that begins to multiply out of control. Groups of such cells form tumors and invade healthy tissue, often spreading to other parts of the body. Carcinogens are substances that promote the development of cancerous cells. They may come from foods, from the air, or even from within the body. Most carcinogens are neutralized before damage can occur, but sometimes they attack the cell’s genetic material (DNA) and alter it. It takes years for a noticeable tumor to develop. During this time, compounds known as inhibitors can keep the cells from growing. Some vitamins in plant foods are known to be inhibitors. Dietary fat, on the other hand, is known to be a promoter that helps the abnormal cells grow quickly.

Factors Contributing to Cancer
Eighty percent of cancers are due to factors that have been identified and can potentially be controlled. And not only can we potentially prevent most cancers, we can also improve the survival rates of people who have cancer. Cancers of the breast, prostate, and colon have received more research attention than other forms of the disease, but, as we will see, certain principles apply to many forms of cancer.

Cancer starts when one cell begins to multiply out of control. It begins to expand into a lump that can invade healthy tissues and spread to other parts of the body. But there is a lot we can do about it. Thirty percent of cancers are caused by tobacco. Lung cancer is the most obvious example, but by no means the only one. Cancers of the mouth, throat, kidney, and bladder are also caused by tobacco.

Dietary factors also play a significant role in cancer risk. At least one-third of annual cancer deaths in the U.S. are due to dietary factors.  A recent review on diet and cancer estimates that up to 80 percent of cancers of the large bowel, breast, and prostate are due to dietary factors.

The link between diet and cancer is not new.  Numerous research studies have shown that cancer is much more common in populations consuming diets rich in fatty foods, particularly meat, and much less common in countries eating diets rich in grains, vegetables, and fruits. One reason is that foods affect the action of hormones in the body. They also affect the strength of the immune system and other factors. While fruits and vegetables contain a variety of vitamins, minerals, antioxidants, and phytochemicals to protect the body, by contrast, recent research shows that animal products contain potentially carcinogenic compounds which may contribute to increased cancer risk.

In addition to tobacco use and diet, other factors, including physical activity, reproductive and sexual behavior, bacterial and viral infections, and exposure to radiation and chemicals, may also contribute to the risk of certain forms of cancer.

Estimated Percentages of Cancer Due to Selected Factors
Diet 35% to 60%

Tobacco 30%

Air and Water Pollution 5%

Alcohol 3%

Radiation 3%

Medications 2%

Fibre  Fights Cancer
A  high-fibre  diet reduces diseases of the digestive tract. In countries where diets are high in fibre (that is, plant-based diets), there were fewer cases of colon cancer. Around the world, this has proven true. The highest fibre  intakes are found in nonindustrialized nations where meat is scarce and plant foods fill the menu. Animal products contain no fibre . The U.S. and other Western nations whose diets are based upon animal products have the highest rates of colon cancer.

Fibre  is also protective against other forms of cancer. Studies have shown that stomach cancer and breast cancer are less common on high-fibre diets.  Fibre  affects levels of estrogens in the body. Estrogens are normally secreted into the intestine, where the fibre  binds with the hormone and moves it out of the body. Without adequate fibre , the estrogen can be reabsorbed from the intestine into the bloodstream. High levels of estrogen are linked to a higher risk of breast cancer.

Experts recommend 30 to 40 grams intake of fibres per day. The best sources of fibre are whole grains, beans, peas, lentils, vegetables, and fruits. Foods that are closest to their natural state, unrefined and unpeeled, are highest in fibre.

Fat Raises Cancer Risks
Cross-cultural studies have revealed that the populations with the highest levels of fat consumption are also the ones with the highest death rates from breast and colon cancer. The lowest rates are in groups with the lowest consumption of fats.   Many studies indicate that fat in foods increases one’s risk for cancer, and it may also adversely affect breast cancer survival rates for those who have cancer.

Although the total amount of fat one eats is of concern, there is evidence that animal fat is much more harmful than vegetable fat. One study noted a 200 percent increase in breast cancer among those who consume beef or pork five to six times per week. Dr. Sheila Bingham, a prominent cancer researcher from the University of Cambridge, notes that meat is more closely associated with colon cancer than any other factor. Meat and milk are also linked to both prostate and ovarian cancers. Fat has many effects within the body. It increases hormone production and thus raises breast cancer risks. It also stimulates the production of bile acids which have been linked to colon cancer.

The Importance of Vegetables
Not only are vegetables low in fat and high in fibre , they also contain many cancer-fighting substances. Carotenoids, the pigment that gives fruits and vegetables their dark colors, have been shown to help prevent cancer. Beta-carotene, present in dark green and yellow vegetables, helps protect against lung cancer and may help prevent cancers of the bladder, mouth, larynx, esophagus, breast, and other sites.

Vegetables such as cabbage, broccoli,   turnips, cauliflower, and Brussels sprouts contain flavones and indoles which are thought to have anti-cancer activities.

Vitamin C, found in citrus fruits and many vegetables, may lower risks for cancers of the esophagus and stomach. Vitamin C acts as an antioxidant, neutralizing cancer-causing chemicals that form in the body. It also blocks the conversion of nitrates to cancer-causing nitrosamines in the stomach.Selenium is found in whole grains and has the same antioxidant effects as vitamin C and beta-carotene. Vitamin E also has this effect. Caution is advised in supplementing selenium, which is toxic in large doses.

Alcohol
Excessive intake of alcohol raises one’s risks for cancers of the breast, mouth, pharynx, and esophagus. When combined with smoking, these risks skyrocket. It also raises risks for stomach, liver, and colon cancers.

Vegetarians Are Better Off
All the evidence points to a low-fat, high-fibre  diet that includes a variety of fruits, vegetables, whole grains, and beans, as being the best for cancer prevention. Not surprisingly, vegetarians, whose diets easily meet these requirements, are at the lowest risk for cancer. Vegetarians have about half the cancer risk of meat-eaters.

Vegetarians have higher blood levels of beta-carotene. They consume more vitamin C, beta-carotene, indoles, and fibre than meat-eaters. Vegetarians also have stronger immune systems. German researchers recently discovered that vegetarians have more than twice the natural killer cell activity of meat-eaters.  Natural killer cells are specialized white blood cells that attack and neutralize cancer cells. Also, vegetarians tend to eat more soy products than meat-eaters. Soybeans contain many substances that are anticarcinogens, including lignans and phytoestrogens. A diet that is rich in soybeans may be one reason for the lower incidence of breast cancer in Asia.

Conclusion
A cancer prevention diet is one that is high in fibre , low in fat (especially animal fat), and includes generous portions of fruits and vegetables. It also minimizes or excludes alcohol. The best diets are pure vegetarian diets.

Dr.Brajnish Kumar
e-mail: info@drbrajnish.com