Is Dairy consumption a risk factor for Prostate Cancer?

Updated: Nov 1

For a long time, researchers have been investigating potential factors in the lifestyle of men diagnosed with prostate cancer that could explain the growing incidence making it the second most common cancer in men over 50. In this article, I will attempt to dissect through the maze of conflicting information to help the reader answer the question.

"Is dairy consumption associated with increased incidence and risk of prostate cancer?

A study type called “meta-analysis” has a particular design that helps us find a specific result by pooling together results from all previous studies on a single topic. This way, researchers can better estimate an effect of an exposure (in this case, dairy consumption) on a particular outcome (in this case, prostate cancer in men).


In 2016 a meta-analysis done by researchers from China who brought together 11 studies with a total population of 778,829 participants found that men who consumed the highest amounts of the whole (high-fat) milk had a staggering 50% increased risk of prostate cancer mortality compared to male participants with the lowest consumption of whole milk. They also found a so-called “upward linear trend”, meaning the higher the whole milk intake, the more problematic it became. See the chart below. Notice the curve bending up with increasing consumption per day.

Interestingly, in the same study, no other dairy products (butter, yoghurt, semi-skimmed milk or cheese) had any association or link to prostate cancer risk. Was the fat in the milk contributing to the risk of prostate cancer? It would certainly seem so. But some scientists thought that it might be something else, the calcium.


In 2017, another meta-analysis by Rahmati and colleagues was published. They pooled results from 12 smaller observational studies. They found that men with the highest dietary calcium intake (from foods or supplements) had an 11% increased risk of prostate cancer compared to those in the study with the lowest calcium intake.


In a subcategory analysis, they found that studies lasting over 10 years were likely to find a statistically significant increase in total prostate cancer risk by 22% but not the studies that lasted less than 10 years. What this could mean is that there is a duration effect. The longer men are observed and studied, the more likely it is that, eventually, some get diagnosed. Especially if the men were in the critical age gap, usually around 65-75 years old, and the longer such group would be observed, the more power the study would get and the more likely it would be to observe an effect.


So now we had two possible factors: saturated fat content & calcium content. The question remained, and the research continued.


In 2021, another massive study called Systematic Review by Sargsyan and colleagues pooled together results from 20 observational studies to bring more clarity to this complex topic. In this study, the association between whole (high-fat) milk consumption and prostate cancer was very strong and overwhelming. In contrast, in the case of semi-skimmed milk, the results were mixed, and there appeared to be no risk increase for prostate cancer with semi-skimmed milk consumption.


The researchers in the 2021 review concluded that:

QUOTE “The overwhelming majority of the studies included in this systematic review suggest a link between milk consumption and increased risk of developing prostate cancer. While the research findings are inconclusive, clinicians may recommend to the patients at higher risk of prostate cancer development to eliminate or reduce the consumption of milk or milk products, especially those with high-fat content.”


With growing evidence, the association has been strengthening. Indeed it seemed that high-fat milk is problematic while its low-fat cousin perhaps not as much.


One year later, in August this year, published in the British Journal of Nutrition (Zhao et al. 2022) found a dose-dependent association between several dairy products and prostate cancer. Dose-dependent means the more substantial the exposure, the stronger the outcome. This is what the researchers found:

  • For each 400g of dairy (total dairy) per day, the risk of PC was increased by 2%

  • For each 200g of dairy milk (not specified) per day, the risk was increased by 2%

  • For each 40g of cheese per day, the risk of PC was increased by 1%

  • For each 50g of butter per day, the risk was increased by 3%

Interestingly for each 100g/day of whole milk, the risk of PC was decreased by 3%. This was a finding going in completely opposite to what the other studies mentioned previously found. And I have no idea why that is because I could not obtain the full paper of this study and could not figure out how to reach out to the researchers as they did not leave their email contact on Pubmed.


In this study, the risk reduction for whole milk is what we call “borderline significant” because it came very close to being “null” and showing no association. Perhaps all it would take is one more study to bring this effect to zero. Should I get my hands on the research and make sense of it, I will update this post.


WHAT IS DRIVING THE EFFECT

There are a few possible answers, but nothing conclusive yet.

  1. Saturated fat content – It would explain why whole milk but not semi-skimmed milk seems potentially problematic. But it would not explain why butter is only harmful in excessive quantities, considering it has way more fat than milk.

  2. Bovine Hormones– dairy products, especially milk, contain a higher concentration of bovine (cow’s) oestrogens. Some studies have associated higher content of sex hormones with prostate cancer in men and breast cancer in women. However, it is not fully known to what extent this is an issue in n

  3. Growth factors – consumption of animal foods and dairy stimulates specific molecules called “growth factors”. These are very important in growing children to accelerate the development of bones, muscles, organ and the child's physical growth. Yet some research speculatively associates a higher concentration of growth factors in older adults with the development of prostate cancer in men and breast cancer in women because they can stimulate excessive replication of cells once in the age when we are not growing anymore. But many things stimulate growth factors, including resistance exercise, which has been shown to be protective, so we don't know if this is it.

  4. Calcium – In the 2017 study above, I mentioned that high calcium intake was associated with a higher risk of prostate cancer. This might be the theory that makes the most sense and would explain why whole milk, despite having less saturated fat than butter, was more strongly associated with prostate cancer because milk has way more calcium than butter which practically has none.

  5. It may also be a combination of all or some of the above (or none)


 

SUMMARY & CONCLUSION

Overall, based on the totality of the evidence, some types of dairy may indeed be problematic when consumed regularly or in excess, while others not so much.


High consumption of whole (full-fat) milk seems to be associated with higher rates of prostate cancer in men, and this has been demonstrated across numerous cohort studies and also across a few large meta-analyses, however not in the latest 2022 meta-analysis where it was shown to be protective at 100 grams per day. Unfortunately, I was not able to obtain the entire paper of the 2022 study, and my interpretation is based on the abstract only.


For cheese, the association is very mixed, and it only appears to become problematic when consumed in very high amounts. For every 40 grams of cheese, the risk of prostate cancer increased by 1%. But 40 grams is a reasonably high amount; when used in moderation, cheese may help maintain cholesterol levels or protect against colorectal cancer. The benefits: cost ratio of cheese consumption need to be evaluated by each individual.


For butter, there was a marginal yet statistically significant 3% increased risk for each 50g per day consumed in a dose-dependent manner. But unlike cheese, butter is one of those foods where the restriction is generally recommended due to its association with cardiovascular disease and stroke. Perhaps the harmful effects of butter on prostate cancer are not as strong as its adverse effects on the heart. Public Health guidelines recommend minimising butter in favour of plant-derived fats such as plant butter, vegetable oils and seed oils.


There appears to be no association between prostate cancer between yoghurt and semi-skimmed milk. Some types of dairy, such as fermented dairy (e.g. kefir), seem most beneficial.


10-SECOND SUMMARY

While the topic remains somewhat convoluted, certain dairy products may increase cancer risk when consumed in excess. The main culprits appear to be: whole milk, butter, and cheese when consumed in large quantities. It is unclear what drives this effect, but it may come from high calcium or saturated fat content (or a combination).


For people with a family history of prostate cancer, caution with high-fat dairy consumption, especially whole milk, butter and very high amounts of cheese, would be advised in favour of low-fat alternatives, which do not seem harmful. Always consult your doctor, and for older men concerned, a proper medical examination is necessary.

 

Would you like to learn more?

If you have a history of prostate cancer in the family or this is a particularly concerning the topic, and you would like to ensure that your diet and lifestyle are adjusted to minimise your risk, I could help you on that journey.


Much research has been conducted on identifying factors that may contribute to prostate cancer risk in men but also helpful characteristics. I could help you put that information into practice by helping you create a life-long commitment to optimal diet and lifestyle associated with much more significant risk reduction, even though there is no such thing as 100% prevention in health.


However, If that seems interesting, please follow this link and book a 30-minute, free-of-charge call where we can talk more about it.


Stay in touch

If you liked this content and want to learn more, you may follow me on Instagram, Facebook, or YouTube. I will explore this and other topics related to men's health in much more detail. You may also check out one of my free E-Books designed to provide easily digestible health advice for other men.


A new e-book on cognitive protection should be out this week (on the 31st of October)

Thank you for your time! Take Care!

 

References:

Lu W, Chen H, Niu Y, Wu H, Xia D, Wu Y. Dairy products intake and cancer mortality risk: a meta-analysis of 11 population-based cohort studies. Nutrition Journal. 2016 Oct 21;15(1):91.


Rahmati S, Azami M, Delpisheh A, Hafezi Ahmadi MR, Sayehmiri K. Total Calcium (Dietary and Supplementary) Intake and Prostate Cancer: a Systematic Review and Meta-Analysis. Asian Pacific Journal of Cancer Prevention. 2018 Jun 25;19(6):1449-1456.


Sargsyan A, Dubasi HB. Milk Consumption and Prostate Cancer: A Systematic Review. World Journal of Men's Health. 2021 Jul;39(3):419-428.


Zhao Z, Wu D, Gao S, Zhou D, Zeng X, Yao Y, Xu Y, Zeng G. The association between dairy products consumption and prostate cancer risk: a systematic review and meta-analysis. British Journal of Nutrition. 2022 Aug 10:1-18.


Vasconcelos A, Santos T, Ravasco P, Neves PM. Dairy Products: Is There an Impact on the Promotion of Prostate Cancer? A Review of the Literature. Frontiers of Nutrition. 2019 May 14;6:62.

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