A nurse and an economist walk into a coffee bar...

A nurse and an economist walk into a coffee bar...

Summary: Does coffee really cause cancer? A nurse and an economist discuss the issue.

TOPICS: Health

Hi everybody,

You may have noticed that I didn't blog last week. That's because I was moving my home office into my new house, including my trusty blogging computer. It was the last leg of a lengthy moving process which started in March, when my husband and I established our new home as our primary residence.

I couldn't have done it without coffee. It was my fuel.

I bring this up because of your thoughtful responses to my recent It’s official: your cell phone may cause cancer article about the correlation between cell phone use and brain cancer.

One of the letters I received was from an economist, Donald Robbins, PhD, who wanted to know if the mention I made in the article about coffee being a carcinogen was supportable by studies.

With his permission, I am sharing the interesting correspondence that transpired between us about the coffee/cancer connection (or lack thereof).

Donald's original letter to me

Thank you for your article.

I have a question, however: I have never seen evidence that coffee causes cancer. This concerns me greatly as a "serious" coffee drinker. I have tried to read all articles (BBC health, NY Times, and at one point searched on the Internet).

I would be very grateful if you could direct me to reports on the dangers of coffee drinking, particularly what you mention: that it causes cancer.

Thank you very much.

My first reply

I listed the coffee as carcinogenic because it was cited in so many of the reference articles I used to write my blog post, and I seemed to remember it being true (though I was saddened to see it on the list). I love coffee, too, and that's why I made the lame joke about how it seems safer than lead and exhaust fumes.

However, I am so glad you wrote, because you make a good point. The answer is more nuanced.

Caffeine seems to be relatively safe when used in moderation, and can actually be beneficial to many people (for example, a cup of coffee a day may help mild asthma symptoms because it can act as a bronchodilator).

When enjoyed in moderation, health benefits probably outweigh the risks for most people. Here's a Mayo Clinic article about it.

What I was taught in nursing school (and my current understanding of it from the research I did today in the Davis' Nursing Library) is that because of the acidic nature of coffee, people with stomach conditions such as gastritis, ulcers, etc., can have a problem with coffee in terms of cancer risk. That's thought to be because of the stomach and esophageal linings being repeatedly exposed to more and more irritation, and becoming more vulnerable to cancer.

High amounts of caffeine also are implicated in increased risk of bladder cancer because of damage to the bladder's lining.

Epithelial tissue is the lining tissue of the digestive tract (esophagus, intestines, stomach) and some other organs. It is more vulnerable to cancer than other tissue types because of its regular replacement by new cells. This increases the percentage of possibility by some degree that those new cells will be cancer cells.

Also, it's good to avoid caffeine if BPH (benign prostatic hyperplasia) is a problem. In terms of other ill effects on health, I also remember hearing that huge amounts are hard on the kidneys and adrenals. It can increase paranoia.

It can interfere with sleep (which is probably half the point of using it for most people). It can worsen iron deficiency anemia. It can increase blood pressure and increase coronary artery disease.

However, I just finished reading the Wikipedia article on the health effects of coffee.

The article (which seems to have been written by a coffee lover and doesn't have a neutral tone, in my opinion) mentions there are rat carcinogens in coffee but asserts that we can't just assume those are human carcinogens.

There are a whole pile of studies at the bottom of the article. If you want, use your browser to do a search on the page for the word "cancer" and check them out.

After a quick perusal, it looks like some of them are inconclusive, some of them seem to contradict my nursing resources and may indicate caffeine can actually have positive effects against cancer, and some of them seem to indicate there may be a risk.

I'd love to hear your conclusions after digging through these studies. Please keep in touch and let me know what you think about the verdict for our beloved java.

Also, I'd love to know, what's your favorite brewing method? What's your opinion of the popular Keurig brewers?

Donald's follow-up

I greatly appreciate your detailed and thoughtful response regarding coffee's possible carcinogenic effects.

I will peruse several of the references you've mentioned and share my personal evaluation with you (I'm a PhD economist, so can offer a critical reading, but cannot offer any medical or biological expertise).

My quick understanding from glancing at what you've written (paraphrasing you) is: there are two potential channels, the first indirect and the second direct.

First, via coffee's effect on the linings of the digestive system and intestinal-cancers (there seems to be a heightened emphasis in the medical community on these cancers and hence the recommendation of a glass of wine per day for its circulatory-system effects seem to have fallen into disrepute).

The second, direct, channel seems to be via the carcinogens contained in coffee, where the issue of dosage is probably determinant: whether the risk levels and typical consumption levels are of the similar orders of magnitude.

Certainly this is a potentially major health issue, given widespread (and yes, for techies, notably) coffee consumption. I've been surprised and relieved in the past to see no serious health risks with coffee. But if that is incorrect it means millions ought to change their habits (fortunately not that hard), as happened with cigarettes.

What I have read recently is that coffee use causes people to awaken with more grogginess than for non-coffee drinkers, and they need the coffee dosage in the morning to attain the normal alertness levels of people who don't consume coffee. So people develop a modest behavioral-biological dependency on coffee without any net increase in alertness.

A comment on medical research and recommendations: as an economist, we are carefully trained in statistical inference and its pitfalls. Great emphasis is placed upon how small or problematic samples often lead to incorrect inferences, or conclusions where none may be coherently drawn(statistically insignificant results), the conclusions are simply medical research and recommendations often seem silly.

My sense is that the radical and frequent changes in medical research "conclusions" result from this problem. When one looks at the study details, the sample sizes and controls are often clearly inadequate to be more than suggestive.

Medical researchers are often very statistically sophisticated and fully understand the problems, but the costs and inherent difficulties in design (because of moral issues with human-subject experiments) prevent larger, better studies.

Nonetheless, the result often seems that the medical community presents "conclusions" and recommendations, which should be no more than suggestions.

Some reversals: (20-30 years ago) cardio is good including running (to no, it causes bone-joint damage); moderate alcohol consumption is good; prostate cancer interventions now often seem as counterproductive because the intervention can be worse than the cure (many cancers treated would be mortal only well after death would occur); increasing "good" cholesterol is good (recently published research questions this); etc.

This leaves medical professionals and lay persons with an enormous, real, if uncomfortable, margin of doubt. And great difficulty for drawing practical conclusions. Given so much doubt, individuals might do best by taking the conservative path: avoid behavior, consumption, that might cause problems, until more is known.

But then there are cases like the recommending moderate wine consumption, which could actually (as seen today) be harmful. Or where one avoids consumption of something that is later shown to be good for us.

I try to glean what conclusions of the moment seem to be more robust. Sometimes this is made easier by the way in which the scientific evidence is presented (in scientific and journalistic publications), so that one needed go to the original studies to try to figure it all out.

Given the small sample sizes and inherent design limitations in medical research, however, this situation is not likely to improve, at least in the foreseeable future. Evaluating the evidence and recommendations is necessary and complex and often cannot provide the kind of clarity and certainty we would like.

Economics confronts enormous problems as well in reaching inferences. It shares some of the experimental design problems of medicine, because of moral problems with human subjects, and because most data is not from experiments at all; econometrics is largely an attempt to similar experiments with non-experimental data.

Astronomy also depends mostly on non-experimental data. And in economics, there are additional epistemological questions about the clarity of the concepts used by economists, and the continuing evolution of object of observation, economic systems.

Sorry for the methodological digression, but my sense is that these issues are central and not always appreciated and certainly not easy to overcome.

Thanks again, and best regards, Donald

My wrap-up

Until either Donald or I have time to wade through piles of studies (right now there is not enough coffee in the world to make me willing to contemplate that), I have no immediate plans to cut my coffee consumption. I am especially loving the Keurig Platinum B70 coffee brewer enshrined in my tiny new kitchen.

What about you? How much coffee are you drinking and how are you brewing yours? Do tell in the TalkBacks below.

Topic: Health


Denise Amrich is a Registered Nurse, the health care advisor for the U.S. Strategic Perspective Institute, and a mentor for the Virtual Campus at Florida's Brevard Community College.

Nothing in this article is meant to be a substitute for medical advice, and shouldn't be considered as such. If you are in need of medical help, please see your doctor.

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  • RE: A nurse and an economist walk into a coffee bar...

    I totally stopped taking coffee as I believe it increases BP and switch to green tea.I usually go for 2 or 3 time a day and not more than that.

    And do I agree with above comment that "Medical conclusions are close to suggestions and does not apply to all. And I also believe a same yardstick cannot apply across all.
    Manpreet Singh Brar
  • RE: A nurse and an economist walk into a coffee bar...

    We just check history, Thomas Edison is a heavy coffee drinker yet he reached the age of 80+.<br><br>My late father didn't drink even a cup of coffee all his life, yet he died at the age of 49 due to his BP.
    • RE: A nurse and an economist walk into a coffee bar...


      That is how NOT to "check history". Yours is just the fallacy of the small sample size.
      • RE: A nurse and an economist walk into a coffee bar...


        No, "small sample size" is you in the actual world. You are not an average statistic. You can be anywhere on the curve, to the right or left of it. In fact you are well to the right or left of it. This may be hard to accept, but your chance of being somewhere near normal is so low you can fuggedaboudit. In a huge population taken in a statistic your chance of being normal is 0.
  • Time to adopt new science

    Ignore statisical uncertainties, claim the science is settled and bully anyone that disagrees with you with labels of grandchildren killers or liken to acts of genocide.<br><br>I rarely drink coffee, for no particular reason.
    Richard Flude
  • RE: A nurse and an economist walk into a coffee bar...

    Guys, for the love of god, please leave this to the scientists!
    Unless you read very carefully and fully understand what these studies say, do not try to interpret them!
    • RE: A nurse and an economist walk into a coffee bar...

      @kirovs@... It is not detrimental to try interpretting some studies, besides, the point was that there are several studies and they came to different conclusions. So what is the overall consensus of the studies? Coffee is both good and bad, so unless you have conditions that make it worse, it is probably fine to drink coffee. Though moderation in all things (including moderation).
    • Absolutely. Do not question the priest. He has access to knowledge

      beyond your limited capability. Simply bow and follow his pronouncements.
  • RE: A nurse and an economist walk into a coffee bar...

    I'm not a coffee drinker, never could develop a taste for it. From what I read it has some health benefits which you pointed out. As for causing cancer, its hard to say because some alternative medicine centers will give coffee enemas to help fight disease. I'd probably lean more on the side of it not causing cancer.
    • RE: A nurse and an economist walk into a coffee bar...

      "some alternative medicine centers will give coffee enemas to help fight disease."
      I suspect they do it to make money out of people who are desperate and frightened enough to try anything, with no clear evidence to support its viability, and no guarantee of a desirable outcome.
      bicycle repair man
      • RE: A nurse and an economist walk into a coffee bar...

        @bicycle repair man

        Actually, there is one guarantee: the placebo effect! Still, I would rather choose a different placebo...
  • RE: A nurse and an economist walk into a coffee bar...

    I'll go thing about it over a cup of coffee, or maybe two.
  • RE: A nurse and an economist walk into a coffee bar...

    I used to brew 12 cups of coffee per day at my work because that was the pot I had - and drank most of it. I recently brought a little 5-cup drip pot to work because there's no place in my new building to wash pots and baskets. So, I drip brew at work and melita or press at home on weekends. I'm down to two cups per day at work and about the same on the weekends - probably a good thing.
  • Everything in moderation

    The fact is, small amounts of many hazardous substances are necessary to stimulate our immune systems. In fact, in small quantities, our health actually improves.
  • RE: A nurse and an economist walk into a coffee bar...

    I have a 10 cup Braun. Funny how the cup size from the manufacturer has no reality in practice. I get 4-5 mugs out of it, and drink 1 pot per day, unless I happen to spy my jug of orange juice.

    I love my coffee, I love my Ginger Ale, I love my OJ.
    IF I had to only stick with one, it would probably be coffee.
    Long before I met my wife of 31 years, I maintained if the perfume houses ever developed a coffee scented perfume for the ladies, my bachelor dayswould come to a screeching halt. I've never encountered a coffee scented perfume or cologne, but I do enjoy my coffee.

    I quit smoking in 1975, coffee and a a cigarette were synonamous, and I wonder, how many coffee statistics come from coffee drinking smokers and actually reflect on tobacco use instead?
  • RE: A nurse and an economist walk into a coffee bar...

    I have found that people in the medical profession sometimes make poor inferences from statistics. Our own (my wife any myself) review of the numbers leads us to believe that for example, if your aim is to have a healthy pregnancy, you are better off Iin general) not doing amniocentesis. The risks of mishap through that procedure are larger than the probability of an actual abnormality proceding to term.

    I still remember the doctor looking at me as if I had two heads. Frankly, I think some procedures and investigations are driven more by "need to know" than by improvement in outcome.
  • RE: A nurse and an economist walk into a coffee bar...

    The very thought of life without coffee makes me unhappy. Denying me my 20 or so cups a day makes everyone around me unhappy. <br><br>Frankly, I would far prefer to live 60 happy years enjoying life than 90 miserable ones denying myself of those things I find enjoyable.
    • RE: A nurse and an economist walk into a coffee bar...


      20 cups a day is certainly too much. Better figure out a way to quit or cut back.
    • RE: A nurse and an economist walk into a coffee bar...

      @deewheat@... With that attitude, you should be smoking pot and mainlining heroin.

      i watched my mother die a slow death. She fought to her dying breath to stay alive. I bet you would too.
  • RE: A nurse and an economist walk into a coffee bar...

    Still hunting for the punch line ... could use some help here! ;-)