“If you think you’re at higher-than-average risk, consider the alternatives,” the authors recommend.

Men who consume more dairy items, especially milk, have an increased risk of prostate cancer, according to Loma Linda University Health researchers. The study revealed no such links between increased prostate cancer risk and non-dairy calcium intake, implying that chemicals other than calcium are involved in the risk of prostate cancer associated with dairy diets.

“Our findings add important weight to other evidence associating dairy products,” says Gary Fraser, principal investigator, “rather than non-dairy calcium, as a modifiable risk factor for prostate cancer”.

Those who drank roughly 430 grams of dairy per day (1/34 cups of milk) had a 25 percent higher risk of prostate cancer than men who consumed only 20.2 grams of dairy per day (1/2 cup of milk per week), according to the findings. In addition, males who consumed roughly 430 grams of dairy per day had an even higher risk than guys who did not consume any dairy at all.

Full-fat vs reduced or nonfat milk intake was shown to have little effect on the results; there were no significant relationships with cheese or yogurt consumption.

The findings of the study were published today in the American Journal of Clinical Nutrition by Fraser and co-authors.

The study looked at the diets of over 28,000 North American men who had a wide range of dairy and calcium exposure and were all cancer-free at the start. Food frequency questionnaires (FFQ) and repeated 24-hour recalls were used to assess dietary consumption. Demographics, family history of prostate cancer, physical activity, alcohol intake, prostate cancer screening, and BMI were all included in a baseline questionnaire.

The researchers subsequently tracked the patients’ prostate cancer status for an average of nearly eight years using cancer state registries. During follow-up, state cancer registries recorded 1,254 additional prostate cancer cases among the participants by the conclusion of the trial period.

Fraser said that he and his co-authors separated the calcium that people got from foods other than dairy as part of their analysis. This calcium came from nuts, seeds, cruciferous and other green vegetables, legumes, fruits, and fortified cereals. They employed a statistical model to focus on dairy food consumption regardless of other characteristics such as calcium intake from non-dairy sources, family history of prostate cancer, race, or age.

Fraser said that the large and varied group made it easy for the study authors to figure out these differences. “Because our study cohort showed a great disparity and divergence of dairy intake and calcium levels, we could ask the question with unusual strength.”

One intriguing point to note, according to Fraser, is that the data did not demonstrate a uniform increase in risk in males who consumed progressively more dairy. To put it another way, increasing dairy intake by 50 grams did not result in the same increases in risk as the servings grew larger and larger.

“Most of the continuing increase in risk is done with by the time you get to 150 grams, about two-thirds of a cup of milk per day,” Fraser said, “It’s almost as if some biological or biochemical pathway is saturated at about two-thirds of a cup of milk per day .”

Prior studies may have overlooked the curvilinear effect or non-uniform increase in risk between dairy consumption and prostate cancer if the majority of patients consumed more than one cup of milk daily. However, the cohort of this study enabled researchers to compare a wide range of dairy consumption, including extremely low levels.

There was little indication of a link between calcium consumption and prostate cancer incidence. According to the study, “One interpretation is that dairy foods, or some closely associated unknown risk factor, are causally related to the risk of prostate cancer.”

The sex hormone concentration of dairy milk, according to Fraser, could be one of the causes of these connections between prostate cancer and dairy milk. Prostate cancer is a hormone-responsive malignancy, and up to 75% of lactating dairy cows are pregnant. Furthermore, previous studies have linked dairy and other animal protein consumption to higher blood levels of an enzyme called insulin-like growth factor-1 (IGF-1), which is thought to promote malignancies including prostate cancer.

According to Fraser, a previous Adventist Health Study-2 study on the impact of dairy on breast cancer risk in women found comparable results in terms of the non-uniform risk associated with greater intake levels as well as the degree of risk.

“The parallels between our breast cancer in women paper a year ago and this paper relating to men, are striking,” he said. “It seems possible that the same biological mechanisms are at work.” However, according to Fraser, this study does not prove that milk causes prostate cancer.

As additional research investigates how dairy consumption may increase the risk of prostate cancer, Fraser advises men with a family history of prostate cancer or other risk factors to “be cautious” when consuming even moderate amounts of dairy milk as part of their diet until this is clarified.

“If you think you’re at higher-than-average risk, consider the alternatives of soy, oat, cashew, and other non-dairy milks,” he advised.

Image Credit: Getty

You were reading: A Healthy Diet Linked To Increase Prostate Cancer Risk In Men