A new observational study claims that cheese increases breast cancer risk, while yogurt can lower it. Since both are dairy, that means they would be suggesting a dairy process causes or prevents cancer. The case control study has numerous confounders that will not be noticed by most journalists so media outlets looking for context beware.
The case-control study by Roswell Park Cancer Institute scholars examined the association between the types and quantity of dairy foods consumed among 1,941 women diagnosed with breast cancer and 1,237 control participants in the Roswell Park Data Bank and BioRepository between 2003 and 2014.
Participants’ usual intake of dairy foods was identified using a self-administered food frequency questionnaire, making recall bias a giant confounder, and grouped into monthly intakes of total dairy, milk, yogurt, low-fat cheese, other cheese and sweet dairy products. The authors numerically adjusted for age, race, body-mass index, menopausal status, energy intake, type of milk usually consumed, cigarette smoking status and family history of breast cancer.
“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,” says the lead author of the study, Susan McCann, PhD, RD, Professor of Oncology in the Department of Cancer Prevention and Control at Roswell Park.
Negatively and positively associated applies to all of the dairy processes as well. A different group of 1,000 could have lower breast cancer incidence and higher memory of eating cheese 10 years.