- High consumption of dairy products such as milk and cheese could lead to an increased risk of prostate cancer, according to a review of literature by Mayo Clinic researchers. The study was published in The Journal of the American Osteopathic Association.
- While researchers identified no clear association of increased prostate cancer risk with consumption of red and white meat, processed meat or fish, they noted a decreased risk associated with plant-based diets. Their conclusions came from an updated review of three databases and 550 references dating from 2006 to February 2017 involving more than 1 million participants, resulting in 47 references eligible for inclusion.
- The lifetime risk of prostate cancer in the U.S. is 11.6%, according to a release from the American Osteopathic Association that highlighted this new research. Prostate cancer has the highest incidence and second-highest mortality rate of all cancers in men, with more than 30,000 deaths annually, the AOA said.
Results from this research suggest high consumption of dairy products may be cause for concern among consumers. The researchers pointed out prior studies showing dairy products are the main source of calcium in Western countries, which have higher prostate cancer rates. But where dairy intake is low, such as in Asian countries, the prostate cancer rates are also low, they said.
These findings won't please the dairy industry, which is reeling from oversupply, low prices, competition from private-label brands and the rise of plant-based beverages. More farmers are leaving the business, and large companies such as Dean Foods have canceled milk contracts and closed processing faciltiies. The dairy industry has been trying to improve its situation by emphasizing the nutritional benefits of its products. Should consumers view these study results as a warning to cut back on dairy, it could be one more blow to the beleaguered industry.
For the growing plant-based food sector, though, the study's association of a plant-based diet with decreased prostate cancer risk will no doubt come as even more good news. John Shin, a Mayo Clinic oncologist and lead author of the study, said in the release the findings support the "growing body of evidence of the potential benefits of plant-based diets."
Plant-based food sales jumped 11% during the past year, reaching $4.5 billion, according to figures released by The Good Food Institute and the Plant Based Foods Association. Sales of plant-based milk products expanded 6% in the past year, while sales of cow's milk dropped 3%. The plant-based segment now makes up 13% of the entire milk category, the groups said. As research continues to promote the positive aspects of plant-based foods, more consumers could decide to give these products a try.
The study does have shortcomings, however. The Mayo Clinic researchers highlighted several limitations of their review such as the significant heterogeneity they found among the studies, which they said precluded meaningful quantitative analysis. Another problem was the data can't definitively prove causation, so any change in the risk of prostate cancer by association may be subject to other factors such as smoking and drinking alcohol.
Other studies have found inconsistent links between dairy product consumption and an increased risk of death from cancer, coronary heart disease and cerebrovascular disease. In 2018, Polish researchers found dairy consumption was associated with a 2% lower risk of death from any cause, while consuming mostly cheese was associated with an 8% lower total mortality risk. Risk of death from a stroke was 4% lower with total dairy consumption and 7% lower with consumption of milk alone, they said.
Future research might benefit from some different approaches, the Mayo Clinic researchers said. Additional reviews of diet and lifestyle data would benefit from more standardized methods, they said. In addition, the validity of their findings could be helped by more randomized controlled trials. Although more research is needed to develop a definitive link between dairy and cancer risk, this study could still mean bad press for the struggling dairy industry. As more plant-based dairy brands gain traction among consumers, a study like this could push even more people to abandon dairy.