The Link Between Milk and Prostate Cancer

Researchers have expressed concern about the fact that cow milk contains estrogens and could stimulate the growth of hormone-sensitive tumors. The assertion is that the consumption of dairy products could both “promote the conversion of precancerous lesions or mutated cells to invasive cancer and enhance the progression of hormone-dependent tumors.”

This was initially postulated based on suggestive population-scale data like a 25 fold increase in prostate cancer in Japan since World War II. What was happening to their diets during that period? A 5, 10, and 20 fold increase in eggs, meat, and dairy consumption, respectively, whereas the rest of their diet remained pretty stable.

But diet wasn’t the only major change in Japanese lifestyles over the latter half century. Similarly, even though countries with higher milk consumption tend to have more prostate cancer deaths and countries with lower milk consumption fewer deaths, there could be hundreds of confounding variables. But it certainly does spur interest in studying the possibility.

A recent study from Clemson University represents the other extreme, controlling for as many factors as possible by isolating prostate cancer cells out of the body in a petri dish and dripping cow milk on them directly. The researchers chose organic cow’s milk, because they wanted to exclude the effect of added hormones so that they could test the effect of all the growth and sex hormones found naturally in milk.

They found that cow’s milk stimulated the growth of human prostate cancer cells in each of 14 separate experiments, producing an average increase in cancer growth rate of over 30%. In contrast, almond milk suppressed the growth of these cancer cells by over 30%.

But just because something happens in a petri dish or a test tube doesn’t mean the same thing happens in a person. It’s just suggestive evidence that we can use in a grant application to get money to study actual people with a retrospective (looking backward) study where we take prostate cancer patients and figure out what they ate in the past, or a prospective (looking forward) study where we look at people’s diets first and follow them for a few years and see who gets cancer. The looking back kind are called case-control studies, because researchers look at cases of cancer and compare their diets to controls. The looking forward kind are called cohort studies because a cohort of people are followed forward. Then, if we want to get fancy, we can do a so-called meta-analysis, where you combine all the best studies done to date and see what the balance of available evidence shows.

The latest meta-analysis of all the best case control studies ever done on the matter concludes that milk consumption is a risk factor for prostate cancer. And the latest meta-analysis of all the best cohort studies ever done also concludes that milk consumption is a risk factor for prostate cancer. An even newer study suggests that milk intake during adolescence may be particularly risky in terms of potentially setting one up for cancer later in life.

Despite hormone-related cancers being among our top killers, as pointed out in the Journal of the National Cancer Institute, “we simply do not know which hormones, and how much, are in the food that we ingest. More effort has been directed at the investigation of illicit use of designer steroids by Olympians and ballplayers than to the investigation of the effect of dietary hormones on cancer and other diseases that affect millions.” A proposal is therefore made to monitor levels of steroid and other hormones and growth factors in all dairy and meat-containing foods, though to date this has not been done.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death and More Than an Apple a Day.

Prostate Cancer Survival: The A/V Ratio
Flaxseeds for Prostate Cancer
Treating an Enlarged Prostate With Diet


Hannah A
Hannah A11 days ago

Thanks for posting

Marie P
Marie P11 months ago


Josue D.
Josue D.1 years ago

milk consumption is a risk factor for prostate cancer, the second-most common cancer in men. In some ways, it makes sense, since even organic milk is naturally full of hormones, which help both calves and tumors get bigger. I drink about 4 liters of wate per day plus lots of weak tea- maybe 10-12 cups.Don’t each much dairy, ,don’t drink milk,eat a cake( brownie type) maybe one ,like spicy food – a curry/chili twice per month occasional egg(fried),very little alchohol but still had troubles with my prostate, I used to to pee twice/three times a night but usually a good stream, my doctor prescribed me a supplement named alpharise for it and after 5 months taking it I can say it works really well!

Jennifer F.
Jennifer F2 years ago

Yes it is 2016 now and this article from 2014 shows Greger didn't know anything two years ago either!

Debbie Crowe
Debbie Crowe4 years ago

I need to show my husband this article! He drinks a big glass of milk every single day!!
As for me, I can't stand the taste of milk. But, I do eat eggs and cheese sometimes!!

Elena T.
Elena Poensgen4 years ago

Thank you :)

Erin H.
Erin H4 years ago

Interesting article, thank you!

Jeffrey Stanley
Jeff S4 years ago

Another good reason to stick with rice milk. Thank you.

Winn Adams
Winn A4 years ago


Eric Lees
Eric Lees4 years ago

So the studies only suggest there may be a link but have not proven a link. What about raw milk vs. pasteurized milk on our overall health?