New research indicates that high consumption of certain dairy products may either increase or decrease the risk of developing breast cancer, depending on the food. These findings are significant because traditional food intake guidelines set by the USDA suggest that adults consume 3 cups of low-fat or fat-free dairy products per day.  

If these findings are confirmed in additional studies, dietary guidelines should be revised to include risks of consuming certain dairy products.

In a study published by Current Developments in Nutrition, the authors discovered that overall consumption of dairy, especially yogurt, can reduce the risk of breast cancer. However, a high intake of American, cheddar, and cream cheeses was linked to a higher risk of breast cancer.  

Included in the study were 1941 women diagnosed with breast cancer between 2003 and 2014, and 1237 control patients. All study participants were required to fill out a food frequency questionnaire, and were then grouped by monthly intake of dairy, milk, yogurt, low-fat cheese, other cheeses, and sweet dairy products.  

“Dairy foods are complex mixtures of nutrients and non-nutrient substances that could be negatively as well as positively associated with breast cancer risk. Future studies are needed to confirm the protective potential of yogurt in this type of cancer,” said lead study author Susan McCann, PhD, RD, professor of Oncology in the Department of Cancer Prevention and Control at Roswell Park Cancer Institute.  

The authors accounted for factors that may increase cancer risk, including age, race, body mass index, menopausal status, energy intake, milk consumed, smoking status, and family history of breast cancer.  

Even when other factors were accounted for, dairy intake was seen to increase or decrease breast cancer risk, depending on what was consumed, according to the study. Overall dairy intake was linked with a 15% reduction in risk, but the study authors said this association was not significant.  

The investigators found that milk consumption reduces the risk of ER- breast cancer, while the consumption of sweet dairy products increases the risk of ER+ breast cancer.  

Additional studies are needed to confirm these findings, and determine the potential protective effects associated with yogurt intake, the study concluded.  

“This study of the differences among women and their consumption of dairy products offers significant new understanding into the potential risk factors associated with breast cancer,” said senior author Christine Ambrosone, PhD, senior vice president for Population Sciences and Chair of the Department of Cancer Prevention and Control. “While diet is thought to be responsible for 30% of all cancers, we hope that further research will help us to more fully understand which food products are most valuable in terms of reducing risk for this disease.”