Drinking Milk May Put You at Risk for Prostate Cancer

Men who chug milk — or even sip a little — every day would be smart to cut back or even eliminate it from their diets. That’s because several recent studies conclude that milk, though not necessarily other dairy products, may put them at higher risk for prostate cancer.

An article published in 2023 in the International Journal of Disease Reversal and Prevention reviewed several large studies linking cancer to dairy consumption and pointed to two possible reasons why milk may increase prostate cancer risk: estrogen and something called insulin-like growth factor 1 (IGF-1), which are hormones produced naturally in cow’s milk.

“IGF-1 is a growth hormone, and growth hormones can cause cancers to grow,” says Anna Herby, DHSc, RD, nutrition education program manager for the Physicians Committee for Responsible Medicine (PCRM) and corresponding author of the review article.

One of the studies that were reviewed followed nearly 22,000 men for almost three decades, and determined that those who consumed 2.5 servings of dairy daily had a 34 percent higher risk of developing prostate cancer compared with men who consumed half a serving or less. One surprising finding: The study found that low-fat and skim milk brought a higher risk of prostate cancer than regular or high fat milk. Dr. Herby says that may be due to estrogen’s ability to “bind” with more watery products (like skim milk).

Even a Small Amount of Milk May Increase Prostate Cancer Risk

Merely cutting back on milk might not be enough to reduce your risk: A recent study found that even a little milk in your coffee every day could boost your risk of prostate cancer. The results were published in The American Journal of Clinical Nutrition.

Researchers at Loma Linda University followed the health and self-reported dietary habits of nearly 30,000 men in the United States and Canada over a five-year period. They compared their data with state cancer statistics and concluded that men who consumed 430 grams of dairy per day (about 1 ¾ cups of milk) had a 25 percent higher risk of prostate cancer compared with men who consumed 20 grams of dairy per day (about a tablespoon of milk).

What’s more concerning is that even a very small amount of milk may increase prostate cancer risk, according to Gary Fraser, MBChB, PhD, the study’s principal investigator and distinguished professor at Loma Linda University School of Medicine and School of Public Health in California.

“The lowest risk of cancer is [seen with] close to zero milk consumption, and the risk increases dramatically up to about three-quarters of a cup of milk a day. But above that level, the risk doesn’t continue to increase,” he says.

Dr. Fraser cautions that pinpointing the exact risk of cancer from milk, or any food, is challenging because people self-report — and misreport — their consumption, and because there are so many other factors (such as overall diet and lifestyle) that can increase or reduce risk. Still, he believes milk is a real concern for men.

“Our study and a number of other studies raise a very serious question as to whether dairy and milk consumption is related to prostate cancer, and a prudent person may seriously consider reducing consumption or eliminating milk from their diet,” he says.

Many Factors Affect Prostate Cancer Risk

Diet is just one risk factor for prostate cancer, and having one or more risk factor does not mean you’re likely to get cancer. Top risk factors for prostate cancer include but are not limited to:

• Age Prostate cancer mainly affects older men. The risk rises after age 50, with about 6 in 10 prostate cancers discovered in men over 65. Testicular cancer, however, is mostly a disease of young and middle-aged men, according to the American Cancer Society, with only 8 percent occurring in men over age 55.
• Race and Ethnicity While it’s not clear why, men of African and Caribbean descent have a much higher incidence of prostate cancer than non-Hispanic white men, while Asian and Latino men have a lower incidence of prostate cancer than non-Hispanic white men.
• Genetics Although men with a family history of prostate cancer account for a minority of prostate cancer cases, having a father or brother with prostate cancer significantly increases a man’s chances of developing it, according to the American Cancer Society. Men with the relatively rare BRCA1 or BRCA2 gene mutation or Lynch syndrome, a genetic condition, also have an increased risk for several types of cancer, including prostate cancer.

Alternative Sources of Calcium

Should men worry about a higher risk of prostate cancer if they consumed a lot of milk as a child? The answer to that question is unclear, as any study attempting to investigate that would have to follow males for 50 years or more (remember, prostate cancer usually shows up in older men). Herby says that parents who worry about a child’s risk of developing prostate cancer much later in life might want to think twice about giving them cow’s milk.

“Children can live without dairy, and there are many nondairy products that provide a good source of calcium, including almond milk,” she says. “And soy milk, a good source of calcium, has been found to be protective against some types of cancer.”

Herby also points to the growing body of research showing that a plant-based, vegan diet (no animal products and no dairy) can further reduce the risk of prostate cancer and other cancers. “We can always use more data on how a fully plant-based diet can reduce the risk of all types of cancer, but I can say avoiding dairy is a good way to go,” she says.

Nondairy sources of calcium (including nonvegan foods) include:

• Canned salmon and sardines, with the bones
• Tofu
• Soybeans and soy milk
• Spinach, turnip greens, and kale
• Broccoli
• Fortified orange juice
• Sweet potatoes
• Nuts (especially almonds) and seeds