Breast cancer is the most commonly diagnosed cancer among women as well as the leading cause of cancer-related deaths among women.  In 2018, for example, there were an estimated 2.1 million new breast cancer cases and an estimated 600,000 deaths due to breast cancer worldwide.

Unfortunately, our understanding of the causes of breast cancer is still limited; however, researchers have identified a number of risk factors that are associated with an increased risk of breast cancer.  Some of these risk factors, such as a family history of cancer, can’t be modified.  Other risk factors, however, are modifiable.

Among the most important modifiable risk factors is diet.  Several studies have been conducted to determine how individual foods and food groups as well as overall dietary patterns are associated with breast cancer risk.  To date, these studies have found moderate evidence suggesting that dietary patterns higher in vegetables, fruits, and whole grains and lower in animal-source foods and refined carbohydrates are associated with a decreased risk of postmenopausal breast cancer.  The evidence is not as strong concerning the link between diet and premenopausal cancer, as few studies have focused on this area.

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Published in Advances in Nutrition, the international review journal of the American Society for Nutrition, “Intake of Various Food Groups and Risk of Breast Cancer: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies” has taken a novel approach to investigating the link between diet and breast cancer.  Authors Asma Kazemi et al. performed linear and nonlinear dose-response analyses in order to better understand the association between breast cancer risk and particular food groups.

In order to gather their data, the authors conducted a comprehensive search of the scientific literature.  Their efforts led them to 75 relevant studies that examined the link between breast cancer risk and at least one of 13 food groups: grains and cereals, vegetables, fruit, eggs, dairy, fish, poultry, red meat, processed meat, nuts, legumes, soy products, and sugar-sweetened beverages.

Upon conducting their analyses, the authors identified “decreased risks of breast cancer with increased intakes of fruits, vegetables, soybeans, and cheese.”  On the other hand, “there was a positive association between red meat and processed meat consumption and the risk of breast cancer.”

Interestingly, the authors found a complex relationship between dairy consumption and breast cancer risk.  Overall, no association was found between dairy products, milk, and yogurt consumption and breast cancer risk in linear dose-response analyses.  However, “a positive nonlinear dose-dependent association was seen for milk intake.”  Specifically, the authors found no association between the consumption of less than 450 grams per day of milk and breast cancer risk.  However, in amounts greater than 450 grams of milk per day, or just under 2 cups, up to 1,300 grams per day, the risk of breast cancer increased by approximately 30%.  The authors posited that “the association between milk consumption and breast cancer risk might be related to the presence of fat-soluble hormones in the milk, which come from pregnant cows, leading to an increased risk of hormone-dependent cancers, such as breast, ovarian, and corpus uteri cancers.”

Overall, the results of this scientific review suggest that diets rich in fruits, vegetables and whole grains may help women lower their risk for breast cancer.  Women should, however, seek dietary advice from their healthcare providers as individual health and nutrition needs vary.

Reference

Kazemi A, Barati-Boldaji R, Soltani S, Mohammadipoor N, Esmaeilinezhad Z, Clark CCT, Babajafari S, Akbarzadeh M. Intake of Various Food Groups and Risk of Breast Cancer: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies.  Advances in Nutrition, nmaa147 (Epub ahead of print; DOI: https://doi.org/10.1093/advances/nmaa147).

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