UCSF Cancer Resource Center nutritionist Sarah O'Brien, MS, RD, says diet and lifestyle are key factors in cancer prevention, with genetics playing a secondary role. O'Brien discussed a study that investigated the relationship between the westernization of culture across the globe and a parallel increase in cancer in Asian countries. When determining which foods have cancer-preventing potential, O'Brien takes a big-picture approach and looks at dietary patterns of Asian populations over time. "Since Asian cultures have lower incidence of cancer, let's look at what they've eaten for generations, as opposed to giving a small research group a cancer-fighting food and measuring the effects," says O'Brien. "Not one food, such as fish, green tea or soy, will make a huge impact on its own. But changing your overall dietary patterns and leading a more active lifestyle will." O'Brien recommends adopting these eating habits from the Asian diet to ward off cancer and other chronic diseases:

1. Increase consumption of whole-food soy products.
2. Increase consumption of cold-water fish.
3. Decrease consumption of meat and dairy products.
4. Eat a variety of colorful fruits and vegetables.
5. Drink one to three cups of green tea every day.

1. Soybean products contain phytoestrogens called isoflavones, which have been highly studied to determine their health benefits. The estrogenic and antioxidant properties of isoflavones may explain the link to cholesterol reduction, bone health, and prevention against heart disease and certain types of cancer. O'Brien says that whole-food soy products - edamame, tempeh, tofu and natto - provide these health benefits, while soy isolates or powder, often used as fillers in Western foods, do not yield these health benefits to the same degree. 

"Soy products are not all the same," says O'Brien. "Kikkoman soy sauce is very different than tamari, which undergoes an aging and fermentation process, while soy protein concentrate in energy bars is highly processed."

2. Although there has been much debate about fish consumption recently, O'Brien recommends eating salmon, mackerel, halibut and other cold-water fish to boost the intake of omega-3 fatty acids. Studies show omega-3 fatty acids may reduce risk of some cancers, as well as inhibit cancer growth. 

O'Brien advises balancing the intake of omega-3 with omega-6 fatty acids. Omega-6 sources include sunflower oil, safflower oil, corn oil and processed foods made with these oils. Omega-3 fatty acids are found in cold-water fish, flaxseed, pumpkin seeds, walnuts, soybeans and canola oil. O'Brien recommends increasing the intake of omega-3 fatty acids and using olive oil and avocados as fat sources because they don't affect the omega-3-omega-6 balance. 

3. The US diet is very high in fat, and high-fat diets stimulate hormone levels, which increase risk of hormone-related cancers. O'Brien recommends a diet of less than 25 percent fat. Since meats and dairy products are high in saturated fat, O'Brien recommends a vegetarian or vegan diet, as well as steaming or poaching foods instead of frying or grilling. 

4. O'Brien advises eating eight to 10 servings of colorful fruits and vegetables. "Eating a wide variety of fruits and vegetables increases your chances of getting all the bioactive agents you need, such as the reds in tomatoes or the purples in blueberries, which serve as antioxidants," says O'Brien. 

5. Although it is difficult to study the effects of green tea due to its variability, the bioactive agent - a polyphenol called epigallocatechin-3-gallate (EGCG) - has proven to be a potent antioxidant. Daily consumption of green tea has been linked to cancer prevention, particularly of prostate cance

Source: UCSF.com