LOMA LINDA, Calif. — Drinking milk can increase a man’s risk for prostate cancer, according to new research. A large-scale study found those who chug just three-quarters of a pint each day are still 25 percent more likely to develop the disease.
This is in comparison to peers consuming less than a quarter of a pint each week. Researchers from Loma Linda University add milk contains stimulants that fuel cell division. Scientists urge milk lovers to switch to trendy vegan varieties such as soy, oat, and cashew.
Interestingly, there was no such link between prostate cancer and yogurt or cheese. Study authors explain that potentially harmful hormones and proteins leave these products during fermentation. Lead author Professor Gary Fraser says the phenomenon applied to reduced and non-fat milks, as well as whole milk.
“Our findings add important weight to other evidence associating dairy products, rather than non-dairy calcium, as a modifiable risk factor for prostate cancer,” Fraser says in a statement, according to SWNS.
The findings come from a review of more than 28,000 men in the U.S. Study authors tracked the group for an average of eight years and each participant was initially cancer-free. Food frequency questionnaires revealed the dairy and calcium intakes of these men varied greatly.
By the end of the study period, state cancer registries reported 1,254 new prostate cancer cases among the participants. The team separated non-dairy calcium from nuts, seeds, green vegetables, legumes, fruits, and fortified cereals from dairy food intake.
“Because our study cohort showed a great disparity and divergence of dairy intake and calcium levels, we could ask the question with unusual strength,” Prof. Fraser tells SWNS.
Two-thirds of a cup is the magic number
Interestingly, results did not show a uniform rise in risk among men with incrementally more dairy intake. In other words, increasing dairy intake by 50-gram increments did not yield the same risk increases as the portions 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,” the researcher says. “It is 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 missed the non-uniform rise in risk between dairy consumption and prostate cancer if most of those participants already drank more than one cup of milk per day. This study allowed researchers to compare an extensive range of dairy consumption, including very low levels. Data provided little evidence of an association between calcium intake and prostate cancer.
“One interpretation is that dairy foods, or some closely associated unknown risk factor, are causally related to the risk of prostate cancer,” Fraser explains.
The sex hormone content of dairy milk could be the key. Up to 75 percent of lactating dairy cows are pregnant, and prostate cancer is responsive to hormones. Further, prior reports have associated intake of dairy and other animal proteins with higher blood levels of a hormone, insulin-like growth factor-1 (IGF-1), which is thought to promote certain cancers, including prostate.
Links between prostate and breast cancer development
The same team recently identified a link between drinking milk and breast cancer in women.
“The parallels between our breast cancer in women paper a year ago and this paper relating to men, are striking. It seems possible that the same biological mechanisms are at work,” the study author tells SWNS.
As further studies investigate how dairy consumption could increase prostate cancer risk, he advises prudent men with a family history of prostate cancer or other risk factors would “be cautious” about consuming even moderate levels 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,” Prof. Fraser concludes.
In the U.S., the disease kills 26,000 men each year.
The study is published in the American Journal of Clinical Nutrition.
South West News Service writer Mark Waghorn contributed to this report.