Portland, Ore.Women who eat four or more servings of fruits and vegetable per day have a 50 percent lower risk of breast cancer compared with women who eat two or fewer servings a day, according to a study presented by Oregon Health & Science University researchers at the second annual Frontiers in Cancer Prevention Research meeting of the American Association for Cancer Research.
"This study provides further evidence that low fruit and vegetable intake in the Western diet may be a major risk factor in developing breast cancer," said Jackilen Shannon, Ph.D., R.D., assistant professor of public health and preventive medicine in the OHSU School of Medicine, member of the OHSU Cancer Institute and lead author of the study. "Women should modify their diet to include more fruits and vegetables to help prevent breast cancer."
Though breast cancer is the primary cause of cancer death among women worldwide, the risk of breast cancer varies drastically from one part of the globe to the next. Studies have shown a doubling of breast cancer incidence among Chinese women who move from China to live in Hong Kong or the United States, suggesting that environmental and lifestyle differences, including diets, may be to blame.
For the study, which was conducted in Shanghai, China, researchers compared the diets of 378 women diagnosed with breast cancer to the diets of 1,070 age-matched, cancer-free women in a control group. Study participants answered a questionnaire about their eating habits. The questionnaire was designed to reflect the Chinese diet and included inquiries about intake of 108 individual food items, fried and restaurant foods, and dietary changes as well as use of nutrient supplements and Chinese herbal medicines.
"In addition to looking at associations with traditional food groupings, the results offer one of the few analyses between different botanical groups and breast cancer risk," Shannon said.
Researchers found that women who ate four or more servings of fruits and vegetable per day had a 50 percent lower risk of breast cancer compared with women who ate two or fewer servings per day. This association was even stronger for the highest fruit consumers. Consumption of six or more eggs a week was also associated with a reduced risk of breast cancer. However, this finding has not been supported by other research studies. No association was seen between intake of soy or soy products and breast cancer risk.
Botanical groupings were evaluated to help researchers determine if lower risk of cancer may be explained by consumption of a single type of fruit or vegetable. While persimmon and lotus root were associated with a significantly reduced risk of breast cancer, this association was not as strong as those seen for the combination of all fruits and vegetables and could be due to chance.
Data for the nutrition study was collected and analyzed by researchers from OHSU, the Fred Hutchinson Cancer Research Center and the Shanghai Textile Industry Bureau. It was an arm of a much larger study known as the Randomized Trial of Breast Self-Examination study. The National Cancer Institute funded both studies.
The American Association for Cancer Research (AACR) is a professional society of more than 20,000 laboratory and clinical scientists engaged in cancer research in the United States and more than 60 other countries. AACR's mission is to accelerate the prevention and cure of cancer through research, education, communication and advocacy.