Eating Dairy Products Linked to Prostate Cancer, With Plant-based Diets Reducing Risk

Eating dairy products has been linked to an higher chance of developing prostate cancer, while a plant-based diet appears to cut the risk.

Past studies have found a link between consuming dairy products—like milk and cheese—and prostate cancer, as the disease is more prevalent in Western countries where they are the biggest source of calcium. In contrast, prostate cancer is less common in Asian countries where such foods are consumed much less, the team explained in the Journal of the American Osteopathic Association.

To find out more, a team of researchers at the Mayo Clinic pored over 47 existing scientific journal articles published between 2006 and February 2017, and involving more than 1 million participants in total.

The resulting study linked plant-based diets, such as vegetarian and vegan regimes, with a lower or unchanged risk of developing prostate cancer from the baseline.

However, eating animal products, and dairy in particular, was associated with an increased or unchanged risk of being diagnosed with the disease.

Each year, around 174,650 new cases of prostate cancer are diagnosed, making it the most prevalent form of the disease among men other than skin cancer.

The disease is the second leading cause of cancer death in the U.S. after lung cancer, and kills around 31,620 people annually. It is most common in men over the age of 66, and African Americans.

pizza, cheese, food, stock, getty
Scientists believe eating dairy products, like the cheese shown on this stock image of a pizza, are linked to prostate cancer. Getty

Study co-author Dr. John Shin, an oncologist at the Mayo Clinic in Rochester, Minnesota, commented in a statement: "Our review highlighted a cause for concern with high consumption of dairy products.

"The findings also support a growing body of evidence on the potential benefits of plant-based diets."

However, the researchers said their study was limited because it included a range of different papers with varying methods. Future research could test the validity of the findings by carrying out randomized control trials, they wrote, and by looking at the effects of other lifestyle factors like smoking and exercise.

Tom Sanders, a professor emeritus of nutrition and dietetics at King's College London who did not work on the paper, said in a statement that the methods used in the review "suffer from a number of weaknesses, notably in the statistical analysis and presentation of the results that do not justify the strong conclusions drawn regarding dairy product consumption and risk of prostate cancer."

"The World Cancer Research Fund, in a far more rigorous review, finds being overweight/obese or tall were the only dietary factors probably associated with risk of prostate cancer; that review only considered dairy and calcium intake as a possible cause (i.e. insufficient evidence)," he argued.

He pointed out vegans have around a 35 percent lower risk of prostate cancer than meat-eaters "but this may reflect the fact they are usually much lighter than meat-eaters rather than the absence of dairy foods from their diets."

Earlier this year, a separate study similarly suggested diet could affect a man's chances of developing prostate cancer by linking lower rates of the disease to mushroom consumption.

But Weilin Wu, a health information officer at Cancer Research U.K. who did not work on the study, cautioned to Newsweek at the time: "Since not much is known about preventing prostate cancer, studies like this are intriguing. But we need a lot more research to back it up and explain any possible link before we can say that people should stock up on mushrooms to cut their prostate cancer risk."

Wu stressed: "It's unlikely that one single 'miracle food' will reduce the risk of cancer by itself.

"And your overall diet is much more important than eating any one particular type of food," he argued.

"So instead of packing your shopping basket full of mushrooms, try thinking about having a range of vegetables, whole grains and fruits as part of a balanced diet and a way to help you keep a healthy weight," Wu said.

This article has been updated with comment from Tom Sanders.