A study (known as the WHEL trial) was designed to see if a stringent low fat, high fruit, high vegetable, high fiber diet made a difference in survival or the cancer coming back in women treated for breast cancer. The results showed that the diet had no effect on survival or the cancer coming back.
The findings surprised many people and contradict the results of many other studies looking at how diet affects breast cancer risk, the cancer coming back, and survival. In the WHEL trial, women who received telephone counseling, newsletters, and cooking lessons promoting a structured, healthy diet had the same results as women who were given dietary guidelines but managed their own diet however they wanted.
The study was well-designed and included many women with a history of breast cancer. There are several possible reasons the results didn't show a benefit from a structured healthy diet:
- Even though the women whose diet was actively managed ate less fat and more fruits and vegetables than the women who didn't get counseling, the difference might have been too small to show benefits the way other studies have.
- The study depended on women self-reporting their diets during the study. Sometimes what people report in a study like this is different than what they actually did and that can affect the results.
- Other lifestyle factors may have affected the results. For example, even though they ate a healthier diet, the women whose diets were actively managed lost only a little weight compared to the other women in the study. Maintaining a healthy weight probably affects how much a healthy diet can influence breast cancer risk and recurrence. We also don’t know if there were any differences in other lifestyle factors such as exercise or alcohol use, which can affect breast cancer risk and outcomes.
Many studies have looked at how diet and other lifestyle changes affect the risk of developing breast cancer or having breast cancer come back after treatment. One study showed that eating a traditional Western diet, compared to a traditional Eastern diet, nearly doubled breast cancer risk in Chinese women. Another study showed that women diagnosed with breast cancer who stuck to both a healthy diet and a regular exercise routine improved their chances of survival.
Overall, the available evidence supports the Breastcancer.org view that adopting a healthy lifestyle can reduce your risk of developing breast cancer and can improve survival and reduce the risk of recurrence if you've been diagnosed with breast cancer. The cornerstones of a healthy lifestyle include:
- a well-balanced diet that is low in trans fats and processed foods and that includes lots of fruits and vegetables
- exercising every day
- maintaining a healthy weight
- limiting or avoiding alcohol
- not smoking
Making these changes in your life can be quite difficult. But it's worth it because there's only one of you and you deserve the best life you can possibly have.