For a long time, researchers have been investigating potential lifestyle factors of men diagnosed with prostate cancer. One that has received a particularly high attention is dairy consumption.
Dairy not only includes semi-skimmed & whole milk but also butter, cheese, clotted cream, whipped cream, yoghurt, fermented milk products, curd, cottage, casein, whey, custard, ghee and traditional variations of each across the globe.
In this article, we will specifically focus on the effect of different dairy products on the individual risk of prostate cancer in men.
In 2016 review by researchers from China pooling 11 previous studies with a total population of 778,829, found that men who consumed the highest amounts of 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). 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.
"What is it that is responsible for this effect?" , was one of the questions subsequent researchers started asking themselves. Saturated fat? Calcium? Hormones?
In 2017, another study was published looking a calcium intake rather than dairy specifically. They included data from 12 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 with the lowest calcium intake.
Interestingly, in the sub-group analysis, they found that studies lasting over 10 years were more likely to show increased risk than studies lasting less than 10 years.
What this could mean is that there is a temporal 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.
A while later, in 2021, another study attempted to clear the muddy waters. The pooled together results from 20 observational studies and found a strong & positive association between high consumption of whole milk and prostate cancer. However, no risk was observed with semi-skimmed milk consumption.
The researchers in this study concluded that:
“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 variant perhaps not as much.
One year later, in August 2022, the evidence got strengthened yet again. A study published in the British Journal of Nutrition found a dose-dependent association between several dairy products and prostate cancer. Their findings were the following:
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%
What drives this effect?
There are a few possible answers, but nothing conclusive yet.
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.
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, however it is known that prostatic tissue readily binds certain sex hormones more than any other tissue in the body.
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.
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.
It may also be a combination of all or some of the above (or none)
Summary & key Findings
Certain type of dairy foods do seem to increase the risk of prostate cancer
When consumed in high amounts, whole (high-fat) milk is the most likely of the group to be problematic
For every 40 grams of cheese, the risk of prostate cancer increased by 1%.
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 and yoghurt or semi-skimmed milk.
certain types of dairy such as fermented milk and low-fat yoghurt may even be beneficial for example in lower bowel cancer risk (see my blog on this topic)
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.
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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.