Balanced, Low-Fat Diet Reduces Risk of Death from Breast Cancer

A new clinical trial that assessed nearly 20 years of data on dietary modification found that women who followed a balanced diet low in fat and including daily servings of fruits, vegetables, and grains had a 21% lower risk of death from breast cancer than those who continued their normal diet, which was higher in fat overall.

This study was presented at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting held in Chicago, Illinois, during a poster discussion session.

Through the federally funded Women’s Health Initiative, the study looked at approximately 49,000 postmenopausal women from ages 50 to 79 with no previous history of breast cancer. From 1993 to 1998, the researchers randomly assigned women to their normal diet, in which fat accounted for 32% or more of their daily calories or a diet with a goal of reducing fat consumption to 20% or less. Women in the balanced, low-fat diet group adhered to the diet for approximately 8.5 years, according to the study abstract.

Most women in the balanced diet reduced daily fat consumption to 25% or less and increased their intake of fruits, vegetables, and grains. On average, there was a 3% weight loss, although losing weight did not affect the risk of death, according to abstract.

So far, the trial has followed participants for a median of 19.6 years, with 3374 cases of breast cancer diagnosed in the group between 1993 and 2013. The findings revealed a 15% lower risk of death from any cause after a breast cancer diagnosis in the balanced, low-fat diet group and a 21% lower risk of death solely from breast cancer in the balanced, low-fat diet group.

Diet and nutrition are crucial to the incidence of obesity, which has dramatically increased over the past several decades. If current trends continue over the next 20 years, it is estimated that obesity will lead to more than 500,000 additional cases of cancer. Five million women in the United States today have poor metabolic function and are have a 3-fold greater risk of mortality from breast cancer than women with normal metabolic function, according to the study.

Overall, the authors concluded that the adoption of a low-fat dietary pattern reduces the risk of death from breast cancer in postmenopausal women.

“It’s a dietary change that we think can be achievable by many because it represents dietary moderation which was achieved by 19,000 participants,” lead study author Rowan Chlebowski, MD, PhD, from the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, said in an ASCO presscast held prior to the meeting.

“To our review, this is the only study providing randomized clinical trial evidence that an intervention can reduce a woman’s risk of dying from breast cancer,” Dr Chlebowski concluded.

For the next phase of research, investigators collected blood samples from the women when they joined the trial and will continue to do so periodically so that they can follow the women’s health based on a variety of blood biomarkers.

Reference

Chlebowski RT, Aragaki AK, Anderson GL, et al. Low-fat dietary pattern and long-term breast cancer incidence and mortality: The Women’s Health Initiative randomized clinical trial. J Clin Oncol 37, 2019 (supply; abstr 520). Presented at: 2019 ASCO Annual Meeting. May 31-June 4, 2019. Chicago, Illinois.