“Drink your milk, it’s good for your bones.” If your mother was like mine, a glass of milk was set at my place for many meals at home that I can remember. She was right, of course, about milk as a source of calcium necessary for developing bones. What she didn’t know, though, is milk’s possible link to prostate cancer (PCa).

Back in 2003, a paper was published on a specific hormone and its connection to (PCa).^[i] The hormone is called insulin-like growth factor-I (IGF-I), and it manages the effects of growth hormone in your body. Growth hormone itself is necessary for kids to attain normal growth range as they come into adulthood. It is produced by the pituitary gland, and WebMD explains that it also has a hand in “body composition, body fluids, muscle and bone growth, sugar and fat metabolism, and possibly heart function.” In addition to helping regulate these developmental processes, IGF-I may also possess qualities that promote cancer cell growth.

IGF-I levels are measured by a blood test. A 2004 study found that high levels of IGF-I are a causal factor in PCa, noting that “…circulating IGF-I levels measured at a comparatively young age may be most strongly associated with prostate cancer risk.”^[ii] Another paper that same year found that men with the highest level of milk consumption had a 68% higher chance of PCa than men with the lowest level.^[iii]

Dairy and prostate cancer?

The body biologically produces IGF-I by synthesizing it in the liver, bone, and other tissues. IGF-I is also present in milk and dairy products, and consuming dairy is linked with higher IGF-I blood levels.^[iv] However, it has not been established whether this increase is due to direct absorption of the hormone, or to the protein intake which can drive up physical IGF-I production. Either way, the authors of a 2017 paper analyzing over 100 published studies find that the IGF-I pathway is indeed “a potential mechanism underlying the observed associations between milk intake and prostate cancer risk.”^[v] This conclusion was also supported by pooled data on over 24,000 individuals that provided “strong evidence that IGF-I is highly likely to be involved in prostate cancer development.”^[vi]

While research is ongoing to understand the biological association between dairy consumption, particularly milk, and greater chance for developing PCa as well as aggressive disease, population studies demonstrate a very real connection. This brings me to the very latest publication in the American Journal of Clinical Nutrition, a large population-based study by Orlich, et al. (2022).^[vii] Out of the Adventist Health Study-2, the authors developed a cohort of 28,737 subjects who had completed dietary questionnaires. During an average follow-up period of 7.8 years, there were 1254 cases of PCa, of which 190 were advanced. The authors found that the development of PCa was proportionate to the amount of dairy intake: those with higher intake had a higher risk of prostate cancer compared with men having lower intakes.

For men who love milk, cheese and yogurt, this information must be concerning. But don’t be too alarmed. Low amounts of dairy products do not appear to make a significant difference in prostate cancer risk. Also, the biological mechanisms are not well understood. While there may be some degree of causality involved, for those who eat large amounts of dairy, lowering PCa risk may simply be a matter of moderating your intake.

Stick to the basic principles of a well-rounded, nutritious diet, vigorous aerobic exercise, good stress management, and healthy relationships. I am not suggesting you dump dairy altogether. Remember that what is good for the heart is also good for the prostate. If you are concerned about how much dairy you eat—in relation to your overall diet—talk with your doctor. If you take good care of yourself, rest assured you are also taking good care of your prostate.

NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.

[i] Giovannucci E, Pollak M, Liu Y, Platz EA et al. Nutritional predictors of insulin-like growth factor I and their relationships to cancer in men. Cancer Epidemiol Biomarkers Prev. 2003 Feb;12(2):84-9.
[ii] Stattin P, Rinaldi S, Biessy C, Stenman UH et al. High levels of circulating insulin-like growth factor-I increase prostate cancer risk: a prospective study in a population-based nonscreened cohort. J Clin Oncol. 2004 Aug 1;22(15):3104-12.
[iii] Qin LQ, Xu JY, Wang PY, Kaneko T, Hoshi K, Sato A. Milk consumption is a risk factor for prostate cancer: meta analysis of case-control studies. Nutr Cancer. 2004;48:22-7.
[iv] Ma J, Giovannucci E, Pollak M, Chan J et al. Circulating Levels of Insulin-Like Growth Factor-I, and Risk of Colorectal Cancer in Men. JNCI. 2001 Sep 5;93(17):1330-36.
[v] Harrison S, Lennon R, Holly J, Higgins JPT et al. Does milk intake promote prostate cancer initiation or progression via effects on insulin-like growth factors (IGFs)? A systematic review and meta-analysis. Cancer Causes Control. 2017 Jun;28(6):497-528.
[vi] Travis RC, Appleby PN, Martin RM, Holly JMP et al. A Meta-analysis of Individual Participant Data Reveals an Association between Circulating Levels of IGF-I and Prostate Cancer Risk. Cancer Res. 2016 Apr 15;76(8):2288- 2300.
[vii] Orlich MJ, Mashchak AD, Jaceldo-Siegl K, Utt JT et al. Dairy foods, calcium intakes, and risk of incident prostate cancer in Adventist Health Study-2. Am J Clin Nutr. 2022 Jun 8:nqac093.