New Studies Show Importance of Diet for Lowering Breast Cancer Risk and Preventing Recurrence

Niyati Parekh, PhD, RD

Two recent studies outline the importance of nutrition in preventing obesity-related cancers as well as the potential benefits of a nutrition education intervention in preventing breast cancer recurrence.

A study from New York University has found that eating a plant-based diet and low alcohol consumption, which align with current cancer prevention guidelines, are more specifically associated with reducing the risk of obesity-related cancers.

The study, published in Cancer Causes & Control, set out to evaluate whether healthy behaviors aligning with the diet and physical activity cancer prevention guidelines are in fact associated with reduced risk for obesity-related cancers and the most common site-specific cancers (breast, prostate, and colorectal).

“Based on the study’s results, dietary advice on preventing cancer should emphasize the importance of eating a plant-based diet and restricting alcohol consumption,” Niyati Parekh, PhD, RD, associate professor of nutrition and public health at NYU Steinhardt and the study’s senior author said in a statement.

Researchers analyzed medical and dietary data of 2983 men and women who were part of the Framingham Heart Study, a 60-year population study tracking factors related to cardiovascular disease as well as cancer. Focusing on data from 1991 through 2008, they identified 480 obesity-related cancers among the participants.

The researchers created a seven-point score based on the recommendations for body fat, physical activity, foods that promote weight gain, plant foods, animal foods, alcohol consumption, and food preparation and processing in order to calculate the relationship between cancer prevention recommendations and cancer incidence.

After adjusting for other factors that could contribute to cancer risk, including age, smoking, and preexisting conditions, researchers found that the overall score, as a proxy for overall concordance to the guidelines, was not associated with obesity-related cancer risk. However, when score components were evaluated separately, two different measures emerged as strong predictors of cancer risk.

The study found that limiting alcoholic drinks to two per day for men and one for women was protective against obesity-related cancers combined and against breast, prostate, and colorectal cancers. The study also found that among the participants who consumed starchy vegetables, eating sufficient non-starchy plant foods (fruits, vegetables, and legumes) was associated with a lower risk of colorectal cancer.

In a second study, published in the Journal of Nutrition Education and Behavior, researchers from Federal University of Santa Catarina saw that providing Brazilian breast cancer patients with nutrition education benefitted patients and may help prevent the recurrence of the cancer.

In Brazil, 5-year breast cancer survival rates are just 58.4%, which is lower than many other regions.

The study enrolled 18 patients in the intervention group, who were compared with a 75-patient control group. Over 12 months, the patients in the intervention group were educated about proper nutrition, asked to record their food consumption on a calendar, and contacted via phone by the researchers to learn about their food consumption and offer recommendations for improvement. Patients in the intervention group also attended meetings and received a monthly bulletin to further their nutrition education.

The main goals of the nutrition education were to reduce the patients’ consumption of red and processed meat and increase fruit and vegetable intake since red and processed meats are purported to have a negative effect on cancer patients, and the antioxidant effects of fruit and vegetables have been shown to help reduce the aggravating effects of chemotherapy treatment and, consequently, may reduce the risk of cancer recurrence.

The researchers based their conclusions on the fact that patients in the intervention group showed significant reductions in red and processed meat, consuming 50% less than peers in the comparison group. Comparison group patients also had two-times greater body weight increase during the study. Fruit and vegetable intake was also increased among the intervention group and likely helped those patients limit BMI, unlike the comparison group, whose BMI was three times higher over the course of the study.

“Although the sample size was small and data were collected at different times, this study provides evidence that women undergoing breast cancer treatment might benefit from immediate, individualized, and detailed nutrition monitoring,” lead author Cecilia C. Schiavon, MsC, said in a statement, adding that further studies should be conducted to verify the conclusions.