Breast cancer is a complicated disease. But studies have shown that a vegetarian diet can help some women reduce their risk of cancer and can also increase chances of survival.
A recent study in the Journal of Clinical Oncology reinforced existing evidence that women with breast cancer can greatly reduce their risk of recurrence by eating a healthy plant-based diet rich in fruits and vegetables and making other healthy lifestyle choices.
The study, conducted by researchers with the University of California, San Diego, tracked dietary patterns and exercise habits among about 1,500 women who were diagnosed with early-stage breast cancer between 1991 and 2000. It found that the death rate for women who consumed a high-fiber diet rich in fruits and vegetables and practiced good exercise habits was 44 percent lower than the rate for women who exercised little and ate few plant-based foods.
The Women’s Healthy Eating and Living (WHEL) study showed that women previously treated for breast cancer who consume at least five fruit and vegetable servings per day and are physically active have a nearly 50 percent reduction in mortality risk.
The WHEL study included more than 3,000 pre- and postmenopausal women. Half the participants (the intervention group) were asked to have five vegetable servings, 16 ounces of vegetable juice, and three fruit servings daily, as part of a low-fat, high-fiber diet. A comparison group was asked to consume at least five fruit and vegetable servings per day.
After seven years, those women in the comparison group who followed the guideline of eating at least five fruit and vegetable servings daily and who were physically active turned out to have nearly a 50 percent lower rate of mortality, compared with women who did not meet these healthful guidelines.
A 2005 National Cancer Institute study found that breast cancer patients in the study who reduced their fat consumption lowered their risk of tumor recurrence by as much as 42 percent. High-fat foods, including beef, vegetable oils, and chicken, can boost the hormones that promote cancer cell growth. But most plant-based foods are naturally low in fat and offer people a healthy way to stay slim.
Researchers followed 2,437 postmenopausal breast cancer patients for five years after standard surgery and cancer treatments. They instructed 1,462 of the patients to continue their regular diets, while 975 patients were given intensive counseling with a dietitian to reduce their fat intake. The control group consumed an average of 51.3 grams of fat per day, which is still lower than the average American’s fat intake. The low-fat group averaged 33.3 grams per day—slightly more than in a typical vegetarian diet. After five years, 12.4 percent of the women eating their usual diet had cancer recurrences, compared with only 9.8 percent of the low-fat diet group: that’s a 24 percent reduction in recurrence. Low-fat dieters with estrogen-negative tumors experienced a 42 percent reduction in recurrence.
In 1982, the National Research Council linked eating habits—particularly high-fat, meat-heavy diets—to cancer of the breast and other organs. The Journal of the National Cancer Institute recently reported that the rate of breast cancer among premenopausal women who ate the most animal fat was one-third higher than that of women who ate the least animal fat.
Consuming meat only increases a woman’s risk of developing breast cancer. A study of postmenopausal Danish women looked at 378 women who developed breast cancer and matched them to control subjects who did not develop breast cancer. A higher intake of meat—including poultry and fish, as well as red meat and processed meat—was associated with a significantly higher breast cancer incidence rate.
Every 25 gram increase (about one ounce) in consumption of total meat, red meat, and processed meat led to a 9, 15, and 23 percent increase in risk of breast cancer, respectively. However, the degree of risk may depend on genetics. Certain genes activate the carcinogens (heterocyclic amines) found in cooked meat. The study showed that women with genes that rapidly activate these carcinogens are at particular risk of breast cancer if they eat meat.
There are more than 2 million breast cancer survivors in the United States, but many of these women eat fewer than five servings of fruits and vegetables a day, consume too much fat, and lead sedentary lifestyles.
Simply adding healthy foods to an otherwise poor diet, rather than getting rid of the troublemakers—meat, dairy products, and fried foods—may not offer the same benefits of adopting a fully plant-based diet. But science has repeatedly shown that a plant-based diet composed of legumes, whole grains, fruits, and vegetables can help prevent cancer and cancer recurrence.
While scientists are hard at work searching for specific breast cancer-fighting compounds, the best approach is to apply what we already know: Diets that are highest in a variety of plant foods and stay away from heavy oils, meat, and dairy products help prevent many diseases. The earlier in life we start, the better.
Need help making dietary changes? Visit http://www.CancerProject.org for delicious vegetarian recipes, information on nutrition and cooking classes, fact sheets on nutrition and cancer, DVDs, videos, books, and a free copy of The Cancer Project’s booklet Healthy Eating for Life: Food Choices for Cancer Prevention and Survival.
By Jennifer K. Reilly, R.D.
The Cancer Project