Breast Cancer Prognosis May Be Improved With Low-Fat Diets


The Women’s Health Initiative (WHI) is one of the most comprehensive and influential national studies ever conducted in the United States. Spanning for more than two decades, the project led to significant changes in the way medical professionals approach treating and preventing the major diseases which threaten postmenopausal women.

Between 1993 and 1998, approximately 162,000 women enrolled in one or several of the three main components of the study. The Hormone Therapy Trials (HT) focused on the effects of combined hormones or estrogen regarding the prevention of heart disease and osteoporotic fractures. The Calcium/Vitamin D Trial (CaD) investigated the effects of calcium and vitamin D supplementation on the prevention of osteoporotic fractures and colorectal cancer. Finally, the Dietary Modification Trial (DM) evaluated the impact of a low-fat and high fruit, vegetable, and grain diet on the prevention of breast and colorectal cancers and heart disease.


Results of the DM trial, in particular, were considered ground-breaking as researchers determined a clear link between nutrition and mortality rates. A number of 1,764 incidence breast cancers were reported during the 8.5 year dietary intervention period, and in this time 8% fewer breast cancer deaths were recorded. Additionally, mortality rates after breast cancer were also reduced, 40 vs. 94.

Overall, for the 16 year follow-up interval, fewer deaths occurred as a result of the disease in the dietary group (111 vs. 185), and also deaths after breast cancer were significantly reduced, 234 vs. 443.

Participants were women age 50 to 79, with no previous signs of breast cancer and having a dietary fat intake of over 32% on average. They were assigned regimens designed to reduce the fat consumption to 20% of the total energy and increase vegetable, fruit and grain intake. Trained certified nutritionists were brought in to help participants improve their eating patterns, while the comparison group received written diet-related education materials. Women underwent regular check-ups and mammogram screenings, while also providing food records.

The study highlighted the importance of nutrition and concluded that “a low-fat dietary pattern had a nonsignificantly lower risk of death as a result of breast cancer and a significantly reduced risk of death after breast cancer”.

While there are many factors that can influence the development of the disease, diet is something that everyone can control and manage.