Of course on the internet you can pretty well find evidence to support anything you want, but despite my bias in favour of coffee, I hope I present here a fair overview of some of the research into coffee and cancer. And of course, like all the blogs I write, this is not a recommendation to anyone else about the path they should choose.
Firstly it seems some effects of coffee depend very much on our own metabolism; if you have a fast metabolism coffee acts as a protective against heart attack but for slow metabolism four cups a day of coffee can quadruple your risk. The suggestion being that the efficient elimination of caffeine might unmask protective effects of other chemicals in coffee (i)? Is this the same for its impact on cancer? And how to best measure your metabolism? It seems not enough research has been done yet….
Certainly there are a number of aspects of coffee to be concerned about….caffeine for example has a well known diuretic effect - it can increase your urge to go to the loo. As it is already difficult for many men with an enlarged prostate to empty bladders caffeinated drinks may add to the problem? Coffee can also worsen symptoms of Irritable Bowel Syndrome (IBS).There are also aspects of temporary "caffeine withdrawal”, usually in the form of a headache, if regular coffee drinkers don’t get their ‘fix’. These symptoms rarely last more than 48 hours or after getting a new dose of caffeine.The 2019 DeVita cancer textbook raises concerns about caffeine’s effects on stomach acid, ulcers and heart rate. And my beloved coffee was indeed classified as a possible cause of cancer in 1991.
The good news is that the International Agency for Research on Cancer (IARC), which is part of WHO, reconsidered the evidence about three years ago (ii). It reviewed the many studies and found much to my delight that coffee drinkers have no reason to worry in terms of cancer. Although there were, and are, still concerns about any drink that is too hot; for example it is thought that thermal injury from hot liquids is can lead to cancer of the oesophagus.
The research gets better still - Coffee cuts risk of prostate cancer by half
Scientists with the IARC also found an inverse relationship between drinking coffee and certain types of cancer. Research particularly showed benefits of coffee drinking regarding colorectal, prostate, breast, liver and endometrial cancers (iii).
One Italian study I like involves 7,000 men who drank more than 3 cups of Italian style coffee a day (eg expresso or cappuchino), amazingly they had a 53 per cent lowered prostate cancer risk (iv).
Another study showed coffee may protect against the most aggressive prostate cancers; nearly 50,000 men drank six cups or more of caffeinated or decaffeinated coffee daily and this was correlated with a 60% lower risk of lethal prostate cancer compared with drinking no coffee (v). One limitation to the study was that it relied on men to recall how much coffee they had drunk over the previous year and this information was only updated every four years. There could have been errors in this?
Japanese scientists wrote last year (vi): “Coffee inhibits the progression of prostate cancer; however, the direct mechanism through which coffee acts on prostate cancer cells remains unclear.”
How does it work? Hormones and more
Well we don’t know….there are several thoughts. For example the reason for the impact on cancer in the Italian study above was put down to the intake of caffeine, as decaffeinated coffee didn’t have the same benefit. However this does not always seem to be the case as in some studies like the second one mentioned above, decaffeinated coffee seemed to also have an impact.
I recently came across a VitaJing video that helps explain some of why caffeine may be a player…
In the video, which is backed by research papers, it explains how estrogen rises under stress and with many other health issues, plus it is a driving force behind prostate cancer (vii). Caffeine has anti-estrogen effects; the caffeine tries to find the estrogen receptors in the body to bind with them and if it gets there before the estrogen it leaves the estrogen nullified.
However, the research indicated that it was also the coffee and caffeine that played a key role together. Interestingly caffeine from drinking green tea, which has lots of research to show how it can help prostate cancer, doesn’t impact on the estrogen, so must work in a different way. While caffeine in high fructose drinks was also found, perhaps unsurprisingly, not to work (blogs here on green tea and sugar sometime in future).
Another bit of research looking at caffeine and its opposite number in tea, theobromine, found that they both enhance the effects of chemotherapy against some cancer cells. Again the mechanisms aren’t clear.
In fact, coffee can contain more than 1,000 nonvolatile chemical compounds and in excess of 1,500 volatile ones! Both decaffeinated coffee and caffeinated coffee contain many phytochemicals that have demonstrated anticancer properties. For example kahweol and cafestol have particularly been considered recently and shown to prevent cancer in lab studies (viii).
Lastly in this rather confusing, and by no means complete picture, the 2019 edition of the DeVita cancer textbook suggests that beneficial effects of coffee come from it reducing the availability of blood glucose to cancer cells.
Why Italian? How to have coffee?
Well, Italians know how to make coffee - espresso shots are 5 to 8 times as concentrated as American drip coffee and unfiltered (ix). As a result it contains more of the beneficial natural compounds that are removed from filtered brew. Again I am delighted to learn this! It is also good to read that unfiltered coffee is not worse than filtered when it comes to heart attacks. I had bought an Aero-press (which has a filter) and it makes a very nice coffee which I still occasionally have, but it is a different drink to my usual very strong espresso or cafetiere that I love.
Coffee varies so widely it is no wonder it is hard to unpick the evidence. There is some suggestion that darker roasts like Starbucks may be less good in terms of the benefits, but then Starbucks is higher in caffeine? Then again I don’t like the taste of their coffee - and much, much prefer supporting independent and artisan coffee makers.
Another interesting aspect is chlorogenic acid which is the main ingredient in coffee beans. It has long been known as an antioxidant that slows the release of glucose into the bloodstream after a meal - and one of the reason why DeVita talks about beneficial properties of coffee. However there are a limited number of studies that have investigated its anticancer properties, but those that have been done are promising - it was also interesting piece to learn that it seems adding cow’s milk to coffee (or indeed tea) means that the chlorogenic acid benefits are lost completely (x).
On the other hand it seems soy milk doesn’t block the nutrients so is OK to add. Similarly dark chocolate is good but milk chocolate doesn’t have the same good effects.
Organic coffee wins over non-organic - the organic coffees are not made with synthetic types of fertilisers and no pesticides or herbicides. Of course some non-organic coffees are made with lots of care but you need to know more about their production.
The time of day can also be key and the advice is to limit coffee later on in the day as it takes the body over 8 hours to remove caffeine from the body.
Lastly there is lots of info about coffee and Ketogenic diets and even a Keto Coffee made with butter. I’m not going to get into that here as I am not following Keto largely because prostate cancer likes to feed on fats - that will be a blog sometime (xi).
How much coffee?
In short more research is needed but I am persuaded to continue with my espressos! We are all so different and coffees are so different that I think it would be unhelpful to suggest numbers. Goditi il tuo espresso! Ciao!
Update 10/10/19: Coffee good or bad blog by Cytoplan supplement maker: https://blog.cytoplan.co.uk/coffee-is-it-good-or-bad-for-you-can-a-cup-a-day-keep-the-doctor-away/
To finish here is local guy Mr Jonny Fluffypunk talking coffee:
(iii) https://www.coffeeandhealth.org/topic-overview/coffee-consumption-and-bladder-kidney-and-prostate-cancers/ and http://www.greenmedinfo.com/article/coffee-intake-was-associated-reduced-risk-oral-pharynx-liver-colon-prostate-en
(v) Wilson 2011: https://www.lifeextension.com/Protocols/Cancer/Cancer-Adjuvant-Therapy/Page-05
(vii) https://youtu.be/13WoEZHF3c4 More from VitaJing about daily coffee impact on thyroid: https://youtu.be/j3f7hD7LGCM Update 1/08/19: and great piece looking at some of the bad research about coffee:
(xi) https://lowcarbalpha.com/coffee-on-ketogenic-diet/and Keto Coffee: https://perfectketo.com/keto-coffee/ and https://ketodietapp.com/Blog/lchf/caffeine-on-a-ketogenic-diet-friend-or-foe