What is the Association between Vegetarian Diets and Breast Cancer Risk?


vegetarian diet and breast cancer risk

According to many reports, breast cancer has been identified as one of the fastest increasing cancer types. A great deal of research has shown that there are varying risk factors for the development of breast cancer including genetic and environmental factors. Among the biggest risk factors, diet has generated a lot of attention because of the fact that it is something people can change. Furthermore, science has indicated that diet may be the most important modifiable risk factor. Some researchers have also gone on to report that sometimes diet could have an even greater impact on breast cancer development than genetics.

The role that diet plays in the development of breast cancer has been studied extensively. Research has shown that diets high in fats and sugars may increase breast cancer risk. Meanwhile, it’s been shown that poultry, vegetables, and fruits could decrease breast cancer risk.  However, there have been studies that have concluded some disagreeing or opposite results as the ones mentioned. Varying results have hindered scientists from concluding concrete dietary recommendations to help decrease cancer incidence. Furthermore, due to the fact that people don’t consume individual foods but rather a combination of different foods, it becomes difficult to determine the patterns between diet and cancer risk. A shift towards examining certain dietary patterns to assess risk is one reasonable way to make reliable conclusions between diet and cancer risk. Many Asian countries, such as Taiwan, have high levels of vegetarianism. There are few studies investigating the association between a vegetarian diet and breast cancer risk in Asian populations.

Yao-Jen Chang and colleagues investigated if dietary patterns were a risk factor for breast cancer and whether there was an association between a vegetarian diet and breast cancer risk in Taiwanese women. They published their findings recently in the Journal BMC Public Health. The dietary patterns of 233 breast cancer patients and 236 matched controls were compared. The criteria to be included in this study were to be a female participant that was under the age of 85 years and diagnosed with primary breast cancer. The control participants had to have no history of breast cancer, reside in the same neighbourhood and age within plus/minus 5 years with their cancer group participant counterpart.

All participants completed questionnaires. The first section of the questionnaire dealt with demographic information and body mass index (BMI). The second part of the questionnaire was a Food-Frequency Questionnaire (FFQ) that included 28 separate food items and how frequently participants consumed those foods per day, per week, or per month. The third section of the questionnaire contained questions about diet patterns. Vegetarian diets referred to ovo-vegetarian, lacto-vegetarian, lacto-ovo vegetarian, or vegan. The 28 food items were divided into five food types: meat, processed meat, fruit/vegetable/soybean, dessert/sugar, and fermented foods.

A complete statistical analysis showed that meat and processed meat were significantly associated with an increased breast cancer risk. A vegetarian diet and breast cancer risk were inversely associated; meaning that vegetarians were less likely to develop breast cancer.  Additionally, a higher BMI and older age of first pregnancy were also risk factors for breast cancer

In conclusion, vegetarian diet and breast cancer risk are inversely correlated to one another; those who follow a vegetarian diet were less likely to develop breast cancer. Vegetables and a vegetarian diet seem to have a protective role against breast cancer risk. Furthermore, meat and processed meats were highly associated with greater breast cancer risk in Taiwanese women. Larger study samples will need to be considered in order to further validate these associations.

Written by Ingrid Qemo, BSc

Reference: Chang, Y., Hou, Y., Chen, L., Wu, J., Wu, C., Chang, Y., and Chung, K. 2017. Is vegetarian diet associated with a lower risk of breast cancer in Taiwanese women? BMC Public Health. 17(1): 800