Eating Plants to Reduce Breast Cancer Risk

Vegetable and fruit based diets linked to lower risk of breast cancer

(RxWiki News) Eating nutritious fruits and vegetables is an important part of keeping your body strong and healthy. A new study shows that a plant-based diet may also play a role in preventing cancer.

Researchers looked at thousands of women's dietary patterns to see if certain types of diets were associated with breast cancer risk.

They found that women who adhered to a plant-based diet had a reduced risk of developing breast cancer compared to those who ate a low amount of fruits and vegetables. On the other hand, women with a diet high in wine, salad and low-fat salad dressing had an increased risk.

The researchers suggested that eating mostly vegetables and fruits could play a role in breast cancer prevention.

"Eat plenty of fruits and vegetables."

Lilli Link, MD, of the Mailman School of Public Health at Columbia University in New York and Pamela Horn-Ross, PhD, of the Cancer Prevention Institute of California, led this study to see how a woman's diet affected her risk of developing breast cancer.

According to the researchers, previous studies have been conducted on the effects of certain foods on breast cancer risk. However, those studies have been inconsistent and have not addressed the complexity of a whole diet.

This study included 91,779 participants who were active and retired teachers and school administrators in California. Every year until 2010, the researchers followed up with the participants to check for a cancer diagnosis or death.

The researchers also gathered available information about hormone receptor status from participants who had developed breast tumors. Hormone receptors affect how breast cancer tumors grow and how to treat them.

The participants had received a questionnaire in 1995-1996 that asked for information on their health status, behaviors and lifestyle. The questionnaire also asked for details about the participants' diet, including alcohol consumption, vitamin supplements, types of food consumed, portion sizes, frequency of food consumption and total daily caloric intake.

The researchers found five major dietary patterns among the participants:

  • A plant-based diet consisting mostly of fruits and vegetables
  • A high-protein, high-fat diet consisting largely of meats, eggs, fried food and high-fat condiments like butter or mayonnaise
  • High-carbohydrate diets including lots of pasta, bread and convenience food like ready-made meals
  • The ethnic dietary pattern was high in legumes, foods with soy, rice and dark green leafy vegetables
  • The salad and wine diet consisted mostly of salad, low-fat dressing, fish, wine, coffee and tea

A total of 15 percent of the women surveyed had diets that conformed to one of the five dietary patterns, and 82 percent of participants had diets that were some combination of the five. Only 3 percent had diets that could not be characterized by the five patterns.

The researchers found that the plant-based diet was associated with a reduction in breast cancer risk, while the salad and wine diet was associated with an increased risk.

Women in the top fifth of the plant-based diet, meaning those whose diets were most closely fruit- and vegetable-based, were 15 percent less likely to develop breast cancer than the women in the bottom fifth.

The researchers suggested that the fiber in a plant-based diet may reduce breast cancer risk, as fiber can reduce the concentration of the hormone estrogen in the body. They added that previous research has linked heavier alcohol consumption to breast cancer risk.

The authors noted that their study had limitations because diets frequently change and people do not always abide by certain dietary patterns. However, they emphasized that the large group of participants and widely used diet questionnaire lend validity to the study's conclusions.

"This large prospective study adds further evidence to the growing body of studies that show women who [eat] higher amounts of fruits and vegetables have a lower risk of developing breast cancer," said Graham Colditz, MD, DrPH, deputy director of the Institute of Public Health of Washington University in St. Louis.

"Greater emphasis on plant based diets remains a promising avenue for breast cancer prevention," Dr. Colditz added. "The importance of this diet pattern earlier in life cannot be forgotten, as almost one quarter of breast cancer diagnoses are among women under age 50."

This study was published in the American Journal of Clinical Nutrition on October 9.

The research was funded by grants from the National Cancer Institute and the California Breast Cancer Research Fund. The authors reported no conflicts of interest.

Review Date: 
October 15, 2013