The results of published scientific research that studied the effect of food on cancer prevention are conflicting and can cause confusion.
Take, for example, the results of the recent Nurses’ Health Study and the Health Professionals’ Follow-up Study, versus the 1997 study done by the American Institute of Cancer Research and the World Cancer Research Fund.
In the Nurses’ Health Study and the Health Professionals’ Follow-up Study, the researchers found no link between eating fruits and vegetables and cancer risk. Whether people consumed two servings a day or 10, the risk of developing cancer over the 15-year study period was the same.
Whereas the 1997 study, funded by the American Institute of Cancer Research and the World Cancer Research Fund, concluded that healthy diets, combined with regular physical activity and appropriate body mass, could reduce cancer incidence. Unlike the later two studies, however, this study involved reviewing 4,500 scientific research articles published worldwide.
Though there appears to be an association between diets high in fruits and vegetables and lower risk of cancer, exactly which dietary components reduce cancer risk has not been clearly identified.
What we do know is that the highest cancer rates are found in the U.S., Canada, Australia, and the U.K. These are the countries that indulge in the most alcohol and processed foods that are high in fats and low in nutrients and fiber. You might say that this is a coincidence, but studies suggest otherwise. Studies looking at Asian immigrants who immigrate to North America and start adopting the standard high-fat and low-fiber diet have higher cancer rates than their compatriots living in their homeland. This clearly shows that, even though there has been no change in genetics, the change in diet results in increased cancer risk.
So, what foods can help to reduce the cancer risk? Fruits, vegetables, whole grains, and nuts and seeds are consistently associated with reducing cancer risk.
Vegetables and fruits are high in antioxidants and flavonoids that stimulate and support the immune system. Consume fresh fruits and vegetables in season. Frozen fruits are a good option when fresh fruits and vegetables are out of season.
In addition, include variety and color in your choices. Colorful pigments such as lycopene (found in tomatoes, watermelon, and pink grapefruit) and anthocyanin (found in blueberries) provide powerful protection against damage that can occur at the cellular level. In addition, cruciferous vegetables like broccoli, kale, cauliflower, and cabbage contain sulforphane, which helps the liver in breaking down and eliminating carcinogens.
Grains, beans, fruits, and vegetables in their whole form contain both soluble and insoluble fiber. Fiber is not only important for regularity, but also has been shown to reduce certain cancer risk. Fiber also helps to lower cholesterol level, increase satiety, and control blood sugar.
Nuts and seeds provide important fatty acids that play a role in immune function. They are also a good source of lignans. Even the color of nut, seed, and bean skins have phytochemicals that act as protective agents in our bodies.
As mentioned above, currently, there is a lack of clear evidence. However, nutrition experts and researchers are optimistic that further studies will bear out the benefits of a diet high in fruit, vegetables, and whole grains. In the mean time, as Dr. Rachael Stolzenberg-Solomon, a researcher at the National Cancer Institute, said, “the easiest, least expensive way to reduce your risk for cancer is just by eating a healthy diet.”
Some Helpful Hints
Here are some general tips to get started on a healthier path.
- Eat a variety of foods. Many foods contain protective substances, some of which researchers are still discovering. And getting nutrients from a varied, balanced diet will prevent you from getting too much of a potentially harmful substance.
- Eat more fruits and vegetables. In fact, fruits and vegetables should cover half of your plate.
- Choose high-fiber foods. Besides fresh fruits and vegetables, add more whole grain breads and cereals and legumes (dried peas and beans) to your diet.
- Eat less fat. Choose low-fat meat, poultry, and dairy foods. Avoid high-fat snacks and desserts. Use low-fat cooking methods; bake, broil, stir-fry, or steam. Don’t fry foods or add fatty extras.
- Limit highly salted, pickled, and smoked foods, including charcoaled, grilled, or broiled meats, fish, and poultry.
- Avoid sugary drinks, and highly processed foods that are low in fiber.
- If you drink alcohol, drink in moderation: no more than two drinks for men, and one for women, per day.
- Control your weight and be physically active at least 30 minutes every day.
- Don’t use supplements to protect against cancer.
Young Hee Kim is the clinical nutrition manager at Mercy Medical Center.