Can Drinking Milk Increase Your Risk of Cancer?

I have never been much of a milk drinker because I unfortunately am lactose intolerant.  Aside from that though, I never really liked the taste anyways.  My cousin on the other hand would always have a glass of milk with every single meal and my Mimi would always say “You’re going to be so big and strong if you keep drinking all this milk!”  It is a commonly held believe among most humans that drinking milk is a good source of calcium and beneficial to your bone growth, and maybe that is true, but what if milk actually is causing you harm and you didn’t even realize it?


Harvard College ran a study to try to find out if a high consumption of milk lead to increases in the likelihood of developing prostate cancer in males.  The null hypothesis would be that drinking milk has no affect on a male’s chances of contracting prostate cancer and the alternative hypothesis would be that an high consumption of milk can lead to an increase in the likelihood of contracting prostate cancer.  This study consisted of more than 20,000 men over a course of eleven years, making the results of this study very unlikely to be due to chance based on the sheer size of the observational study.  They ended up finding a link between the amount of calcium consumed, not just the amount of milk consumed.  Out of the group of male participants, the men who drank no milk were two times less likely to acquire prostate cancer than the men who drank around two or more glasses of milk each day. That surely is a staggering difference.  After what I assume to be a meta-analysis of their findings, Harvard College expanded their argument that the problem lies within the amount of calcium a man consumes.  A more shocking development in their study was that the man who had been reported to be consuming the most milk of all the men in the study which equated to around 2,000 milligrams of calcium daily was not only twice as likely of contracting prostate cancer, but actually was twice as likely to contract fatal prostate cancer rather than male milk-drinkers who were consuming less calcium than that.  Although these statistics are striking, Harvard College even agrees that more research needs to be conducted before reaching a final decision, but it is definitely wise to keep watch on your amount of calcium intake a day if you are a male.  Harvard was not the first institution to look into the idea that drinking too much milk can cause prostate cancer.  The World Cancer Research Fund published an extensive report on prostate cancer which included studies that were done exactly on this topic.  Although I could not understand most of the science talk they used in the journal I was able to pull out the essential information regarding the amount of studies and their results.  There were 15 in total that focused on the link between calcium intake via milk and prostate cancer, of those 15 studies 13 of them came back positive for a link between the two things.  These particular studies broke down the numbers into a chart and deduced that a male’s chances of developing prostate cancer increased per every 400mg of calcium that were consumed a day.  As of right now there is not a known mechanism for why drinking too much calcium can cause an increased chance of developing prostate cancer, but just because there is not a mechanism for something, does not mean it isn’t true.  Surely many more tests need to be done in order to say for certain if this is a concern every man should start thinking about, but this connection could be much like the affects of smoking as discussed in class in which we did not see that excessive tobacco use caused lung cancer until about 40 years down the road.  It could be that we will not see the affects of excessive milk drinking for males until way down the road.


I am not saying these studies have enough evidence to prove that if you are a male you should go to your mini fridge and throw out every single bottle of milk or dairy product you have in your possession and go completely cold turkey, but I do think the evidence that is there is substantial enough to be able to role out the null hypothesis and conclude something is definitely going on here,  Every study has the possibility of being due to chance and that could very well be the case when it comes to this topic, but as a rational person I would the threat is present enough that I would say that if you are a male, lessening your intake of calcium, could not do any harm.

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