The single most important dietary change to lower cancer risk is to become a vegetarian. Animal products are associated with cancers of the prostate, colon, breast, ovary, and pancreas. Nevertheless, some studies show that those who use some milk have a lower risk of cancers than those who use none at all. 

Seventh-day Adventist men have approximately one-half the cancer rate found in the general population. This occurs even in cancers unrelated to tobacco and alcohol both of which are known carcinogens. A likely factor is that many Seventh-day Adventists are vegetarians. This diet contains less animal fat and more fruits and vegetables. This increased use of fruits and vegetables doubles the intake of vitamin A and quadruples the vitamin C consumption compared to that of the general population. 

Can you be more specific? 
One of the major problems with consuming animal products is the fat. Animal fats make up over half of the fats in the American diet. Fat does not likely initiate cancer, but it is considered to be a promoter of it. The U.S. National Academy of Sciences states that total dietary saturated fat correlate best with an increase in cancer risk, and that 70 percent of saturated fat comes from animal products. If the public reduced its fat intake to around 20 percent of the calories, we would see an estimated 33 percent decrease in breast, colon, rectal, ovary, and endometrial
cancer. 

Reducing the fat in your diet to 20 percent of the calories, will most likely reduce the risk of a number of cancers. Animal studies suggest that there is no additional benefit in reducing fat intake below 20 percent of the calories. However, a 30 percent fat diet for a vegetarian may reduce cancer risk to the same level as a 20 percent fat diet for those who get considerable amounts of animal fat. 

Don't try to eliminate all fat from your diet. Your body needs some types of fat to stay healthy. If there are no essential fatty acids in the diet, normal tissue cannot develop. Some individuals are derived because they have read reports that certain essential fatty acids of 20 percent of the calories increase cancerous tumors in animals. However, the essential fatty acids as found in vegetable oils are essential for the function of normal cells in the tissue of animals and man. The answer to this concern is that neither normal nor cancerous tissue will develop on
a 0 percent fat diet. Little tissue growth occurs between 3 and 20 percent. Epidemiological evidence clearly demonstrates an inverse relationship between an increase in vegetable oils and fats and cancer rate. 

In the process of reducing animal and total fat, you also will reduce another cancer risk-obesity. Obesity increases the risk for cancers of the gallbladder, breast, endometrium, ovary, prostate, and colon. 

Where fat appears on your body is also important. To be pear shaped (larger around the hips than around the abdomen) is healthier than to be apple shaped. Being apple shaped increases risk of diabetes, cardiovascular disease, hypertension, and cancers of the endometrium and breast. 

Perhaps, in addition, lowering total caloric intake may reduce cancer risk even further than reducing fat. A 30-percent reduction in calories would decrease breast and endometrial cancer risk by an estimated 90 percent. Animal studies suggest that decreasing your caloric intake by 25 percent would result in a 75 percent reduction in tumors. Reducing calories by 12 percent decreases tumors by 40 percent, but it takes a 75 percent reduction in fat to do the same. A high-fat diet may also be low in fiber. The best way to lower fat and calories in the diet is to
consume a high-fiber diet. A diet of high fiber foods would include generous servings of whole grain breads, cereals, and legumes. This is one more good reason to lower total fat to less than 30 percent of calories. 

Do vitamins help reduce my cancer risk? 
Vitamin A and beta carotene appear to reduce the risk of cancer of the epithelial tissues such as skin, uterine, cervix, larynx, as well as lungs, urinary bladder, gallbladder, some gastrointestinal, and some breast cancers. Beta carotene is found in foods such as sweet potatoes, cantaloupe, carrots, papayas, mangoes, pumpkins, and dark green leafy vegetables. It is converted to vitamin A in the body. Preformed vitamin A comes only from milk, eggs, and other animal products. Beta carotene is the effective ingredient in risk reduction rather than vitamin A, although a few studies demonstrate that vitamin A effectively reduces cancer risk. 

Adequate vitamin C is thought to reduce the risk of stomach and esophageal cancers. Vitamin C is found in such foods as fresh green leafy vegetables, citrus fruits, tomatoes, and strawberries. 

All of these important vitamins-beta carotene, vitamin A, and vitamin C-should be obtained from food rather than from vitamin pills. For example, there are over 200 carotenoid in foods and if you only get beta carotene in your vitamin pill, then you're missing the other 199. Another example of what you would miss is lycopene. Lycopene produces the red color in strawberries and tomatoes. Risk of pancreatic cancer is greatly reduced by using lots of fruits and vegetables, and this reduction correlates most closely to tomato use, which is thought to be due to the lycopene. 

Are there other factors I should be aware of? 
Cruciferous vegetables, which include cabbage, broccoli, and cauliflower, also reduce the risk of colon and rectal cancer. They may also reduce risk of breast cancer. These vegetables fight cancer because they contain indoles, which activate enzymes that inactivate certain cancer-producing substances. One of these substances is
benzopyrene, commonly found in some prepared and processed foods. It is recommended that you eat a cruciferous vegetable at least once a week. 

Avoiding alcohol will likely reduce risk of cancers of the esophagus, liver, rectum, and possibly the pancreas and breast. Even moderate drinking (four drinks a week) increases risk of breast cancer by 50-100 percent. Drinking coffee has been shown to increase risk of colon cancer and also of bladder cancer in men. Highly salted or pickled
foods may increase risk of some gastrointestinal cancers. 

There is no evidence, as some have suggested, that if there is no oil in the diet, sunlight will not cause skin cancer. The more linoleic acid (high amounts are found in corn and other such polyunsaturated oils) in the diet, the lower the skin cancer risk. It should be noted though, with or without oil in the diet, great amounts of sun exposure without a sun screen may result in skin cancer. 

What guidelines will reduce cancer risk?
To reduce cancer risk, the General Conference Nutrition Council recommends: 

1. Eat five to nine servings of fruits and vegetables each day. At least one fruit or vegetable should be high in vitamin C and one high in vitamin A. Resolve to eat one or more servings of cruciferous vegetables each week (where a serving is equal to 1 cup raw or ½ cooked). 

2. Eat six to eleven servings of whole grain breads, cereals, pastas, legumes (beans and peas) each day (where a serving is equal to ½ cup cooked or 1 cup dry cereal). 

3. Attain or maintain ideal weight by limiting total calories so your weight is at the lower end of the range for your height and weight. Keep your waist-to-hip circumference ratio to under 1.0 for men and 0.85 for women. To control weight:

• Make breakfast the largest meal of the day;
• Eat more fruits, vegetables, and whole grains and less fatty foods;
• Exercise daily; and 
• Avoid snacks.

5. Avoid the use of coffee, tea, and alcohol.