In this randomized trail of a dietary intervention a reduction in death from breast cancer for women who consumed a balanced, low-fat diet as well as daily portions of fruits, vegetables and grains could be seen. The data sohw that diet can make a difference in the risk of dying from breast cancer.
The federally funded Women’s Health Initiative (WHI) clinical trial of dietary modification in nearly 49,000 postmenopausal women with no previous history of breast cancer reported that women who followed a balanced diet that was low in fat and included daily servings of fruits, vegetables, and grains had a 21% lower risk of death from breast cancer than women in the control group who continued their normal diet, which was higher in fat overall. This is the first large, randomized clinical trial to show that diet can reduce the risk of dying from breast cancer.
“Ours is the first randomized, controlled trial to prove that a healthy diet can reduce the risk of death from breast cancer,” said lead study author Rowan Chlebowski, MD, PhD, FASCO, from the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center in Torrance, CA. “The balanced diet we designed is one of moderation, and after nearly 20 years of follow-up, the health benefits are still accruing.”
About the Study
WHI, launched in 1993, is a set of ongoing randomized, controlled clinical trials that are looking at methods for preventing heart disease, breast and colorectal cancer, and osteoporotic fractures in postmenopausal women.
This analysis comes from a WHI trial of dietary modification that enrolled 48,835 postmenopausal women age 50 to 79 with no previous breast cancer history. From 1993 to 1998, researchers randomly assigned women to their normal diet, where fat accounted for 32% or more of their daily calories, or a diet with a goal of reducing fat consumption to 20% or less of caloric intake as well as requiring at least one serving of a vegetable, fruit, and grain in their daily diets. Women in the balanced, low-fat diet group adhered to the diet for approximately 8.5 years. The investigators continued to follow all of these women after completion of the intervention period to see if they died from any cause or from breast cancer.
Most women in the balanced, low-fat diet group reduced daily fat consumption to 25% or less (the majority did not reach the 20% goal) and increased their intake of fruits, vegetables, and grains. Among patients who maintained the balanced diet, there was an average 3% weight loss, although weight loss did not affect risk of death, according to the researchers.
So far, the trial has followed participants for a median of 19.6 years, and 3,374 cases of breast cancer were diagnosed in the group between 1993 and 2013.
Altogether, women in the intervention group experienced a range of short- and long-term health benefits as compared with women in the normal diet group:
- Deaths after breast cancer from any cause: There was a 15% lower risk of death from any cause after a breast cancer diagnosis in the balanced, low-fat diet group.
- Breast cancer-specific death: There was a 21% lower risk of death solely from breast cancer in the balanced, low-fat diet group.
The researchers 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 a of blood biomarkers.