Study Examines Vegetarian Diet and Breast Cancer Risk

Background on Breast Cancer in Taiwan

Recent research has sought to clarify the relationship between dietary choices and breast cancer risk, particularly focusing on vegetarian diets amid rising breast cancer incidence in Taiwan. This disease has become the most prevalent form of cancer among Taiwanese women. While genetics play a role, diet is also a significant factor influencing breast cancer risk. Despite numerous studies, there remains a lack of consensus on which specific foods may contribute to this risk.

Study Overview

A study featured in BMC Public Health investigated dietary patterns linked to breast cancer and assessed the potential protective effects of a vegetarian diet. Researchers recruited women under 85 years old diagnosed with primary breast cancer from Taipei Tzu Chi Hospital between 2010 and 2013. Participants were divided into two groups: a cancer group consisting of those diagnosed with breast cancer and a control group made up of women who underwent breast examinations during the same period but had no prior history of breast cancer.

Methodology

Before surgery, participants in the cancer group completed a comprehensive questionnaire, while the control group filled out theirs prior to their clinic visit. The questionnaire included demographic information and asked participants about their consumption of 27 specific foods over the past month. Additional questions addressed alcohol, tobacco, vitamin, mineral, and supplement use, as well as various vegetarian dietary practices, including ovo-vegetarian, lacto-vegetarian, lacto-ovo vegetarian, and vegan diets. Blood samples were analyzed for serum levels of albumin, estradiol, triglycerides, along with soy flavanone intake.

Findings on Dietary Patterns and Breast Cancer Risk

Analysis of the data revealed that the average body mass index (BMI) for the cancer group was 24.32, compared to 22.98 for the control group. Dietary patterns were classified into categories: meat, processed meat, fruits/vegetables/soybean, desserts/sugars, and fermented foods. Among these, only meat and processed meat consumption showed a clear association with increased breast cancer risk. Notably, the cancer group reported lower frequencies of vegetarian diets and physical exercise, alongside reduced soy flavanone intake and lower serum albumin levels. Additionally, more women in the cancer group were either primiparous or over 30 years of age compared to those in the control group.

The study utilized “odds ratios” to evaluate the likelihood of various dietary patterns impacting breast cancer risk. A vegetarian diet, higher serum albumin levels, and soy isoflavone intake above 22 mg were associated with odds ratios of 0.42, 0.30, and 0.37, respectively. In contrast, BMI and primiparity had odds ratios of 2.00 and 2.38, respectively. Estradiol levels were found to be similar across both groups.

Vegetarian Diet and Its Protective Effects

While BMI, serum triglycerides, and estradiol levels were comparable between vegetarians and non-vegetarians, vegetarians exhibited higher soy isoflavone intake. The findings suggest that vegetarian diets may offer protective benefits against breast cancer, whereas diets rich in meat and processed meat appear to heighten risk. It is important to note that vegetarian diets in Taiwan often include greater amounts of soy, which may elevate beneficial soy flavanone levels, contributing to reduced breast cancer risk. However, these results contrast with studies from other regions that link high consumption of poultry, fish, fruits, and vegetables with decreased breast cancer risk.

Limitations and Future Research

The study’s limitations include a small sample size and the failure to consider the duration of vegetarianism in relation to breast cancer risk. Future research should address these limitations and incorporate longer follow-up periods to deepen understanding of the dietary factors influencing breast cancer.

References

(1) 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(800). https://doi.org/10.1186/s12889-017-4819-1.
(2) Szumilas, M. (2010). Explaining Odds Ratios. J Can Acad Child Adolesc Psychiatry. 19(3): 227-229.