Coffee health benefits – is it supported by real science?

coffee health benefits

I am an degenerate coffee addict. This has been so since I took my initial drink during my first chemistry finals as a college freshman. My coffee consumption hasn’t decreased much since then. I drink coffee because of its taste and the caffeine. Potential coffee health benefits are, personally, way down the list of reasons for drinking it. And frankly, I’m always skeptical of claimed health benefits for any food, unless there’s some really strong scientific evidence, which is generally lacking.

But recently, news outlets have been touting a couple of robust studies that seem to indicate that there are significant coffee health benefits. For those who know me, I rarely accept popular news sites analysis of scientific research. I think my loyal readers expect me to look at the science and see if there is any validity to the claims made by the press.

Claims about coffee health benefits and claims goes back centuries. It cured alcoholism. Coffee made you work longer. It was good for your heart. Drinking it was bad for your heart. It increases risks of some cancers. Wait, it decreases risks of some cancers. In other words, we really didn’t have vigorous evidence supporting anything definitive with respect to the drink’s health benefits or detriments.

It’s time to look at these two new studies and see what they tell us about drinking coffee.

Coffee health benefits – the first study

The first study we’re going to examine, from Gunter et al., published in the Annals of Internal Medicine. At a meta level, this epidemiological study was run by respected scientists, with the results published in a very high impact factor (17.2020) journal. Moreover, the study included around 520,000 participants in 10 European countries, which makes it one of the largest studies to date on coffee health benefits.

Compared to some of the horrifically bad studies that we have seen making outrageous claims about this or that food, drink or diet, this study is impressive. This is the kind of study that is equivalent to some of the best vaccine epidemiological research out there.

But what does the results say? To be blunt, they found that drinking more coffee would significant lower a person’s risk to all mortality.

The hazard ratio (HR), which compares the risk of dying between the coffee-drinking and non-coffee groups, was 0.88. In other words, there was a 12% reduction in all death causes in men who were in the upper quartile of coffee consumption. The HR for women in the upper quartile of consumption was 0.93, or a 7% reduction.

Frankly, a 12% or 7% difference in mortality is interesting and intriguing, but from a perspective of evidence-based medicine, it’s difficult to say this is clinically meaningful. However, if there are no known risks to coffee, which would have been uncovered by this study, the importance of those decreases in mortality become more substantial.

There were more significant results for certain diseases. The HR for coffee consumption and digestive disease mortality for men was 0.41 (a 59% reduction), and for women was 0.60 (a 40% reduction). Interestingly, for women, the HR for coffee drinking and circulatory disease mortality was 0.78 and cerebrovascular disease mortally was 0.70. However, the HR for coffee drinking and ovarian cancer mortality was 1.31, or a 31% increase.

The authors concluded, without much wiggle room:

Coffee drinking was associated with reduced risk for death from various causes. This relationship did not vary by country.

Review of the first study

Although the results appeared to fairly solid, I think it’s important to be critical of the results. First, we have no data that shows us whether or not coffee drinkers are just a healthier subgroup of people irrespective of their coffee drinking (they did separate out smokers from this study). Maybe coffee drinkers exercise more or eat less fats than the average person – these confounding factors have not examined carefully.

Second, like I discussed before, dose makes the poison, and dose also makes the medicine. Is there a level of coffee consumption at which point the risks outweigh the benefits? That’s not clear in this paper.

The best I could tell you from the data from this particular study of coffee health benefits is that if you’re a coffee drinker, maybe there is a slight decrease in risk of mortality, so keep on drinking. But if you don’t like coffee (yeah, there are those types around), or the caffeine effects of coffee are not to your liking, I’m not sure you should worry about suddenly taking up the habit.

Coffee health benefits – the second study

This second study, from Park et al., was also published in the Annals of Internal Medicine, once again, a very high quality journal. At a meta level, it’s as high quality as the study from Gunter et al., although this study looked at coffee consumption from a slightly different perspective.

Park et al. surveyed over 185,000 African-Americans, Native Americans, Hawaiians, Japanese-Americans, Latinos and whites, a broader ethic diversity than the first study. The researchers compared coffee consumption at various levels to a control group who drank no coffee. They adjusted for confounders such as smoking, age, alcohol intake, body mass intake, exercise, education and other factors.

For those who drank about 1 cup per day (in this case, they mean the English measurement of a cup, about 250 ml, not the standard “cup” in your local Starbucks which is about 500 ml), the HR was 0.88 or 12% reduction in total mortality. For 2-3 cups per day, the HR was 0.82. With consumption ≥ 4 cups per day, the HR was the same 0.82, or 18% reduction. All of these numbers were statistically significant.

Moreover, the researchers found that coffee increases longevity across various races.

Park et al. also found that drinking decaffeinated coffee had no effect, so you have to go for the real stuff to see these health effects.

The researchers concluded:

In summary, higher coffee consumption was associated with lower risk for all-cause death and death from heart disease, cancer, respiratory disease, stroke, diabetes, and kidney disease. Inverse associations were found in African Americans, Japanese Americans, Latinos, and whites; never-smokers, former smokers, and current smokers; those with preexisting heart disease or cancer; and healthy participants. Our findings support the recent dietary guidelines from the U.S. Department of Agriculture (33), which indicate that moderate coffee consumption can be integrated into a healthy diet and lifestyle, by confirming an inverse association with mortality and suggesting that association’s generalizability to different racial/ethnic groups.

Review of the second study

What I like about this study is that it had a better analysis of major confounders, which gives me more confidence that it’s showing a real decrease in mortality rates for coffee drinkers. Moreover, they have the semblance of a dose response which shows 3-4 cups probably gives you the best reduction in death rate, but I’d like to see much higher consumption, like 10 cups. Maybe there’s a lowered benefit as you drink more, so further research will be informative.

But I have to point out again, the reduction in mortality was, at best, 18%, which may not have any clinical significance.

Coffee health benefits – the summary

These two studies show that there is a strong biological possibility that there is some relationship between lowered mortality and coffee drinking. The European study showed that coffee lowered the risk of dying from liver disease, cancers in women, digestive diseases and circulatory disease.

Moreover, both studies showed that those who drank three or more cups a day had a lower risk for all causes of death than people who did not drink coffee.

Of course, these two studies don’t mean drinking coffee is for everyone. For some people, for example, drinking coffee can lead to serious issues such as cardiac arrhythmias. And of course, excess caffeine can lead to sleep disorders and other issues.

Finally, we don’t know what compound in coffee has this protective effect against mortality. Coffee may contain over 200 different chemicals and compounds, and it might take decades of additional research to identify what chemical (or chemicals) in coffee may provide these health benefits.

I’m going to stand by my point that I previously made. These results are interesting, but they’re not overwhelming. The large numbers in both of these studies to give credibility to the quality of the statistical analyses, but still the risk reduction from drinking coffee seems less than impressive.

I think my skepticism would be reduced if I knew what may be the contributing factor – is it that coffee drinkers are just better people? Or is it some chemical in the coffee? Maybe unhealthy people don’t drink coffee because of a physician’s recommendation, which adds bias to these studies?

So at this time, drink coffee if you like it. It may provide you with some benefit. If you shouldn’t drink coffee, or don’t like it, I don’t think there is enough evidence for you to suddenly change your habits. Coffee health benefits are intriguing, but not quite overwhelming yet.


  • Gunter MJ, Murphy N, Cross AJ, Dossus L, Dartois L, Fagherazzi G, Kaaks R, Kühn T, Boeing H, Aleksandrova K, Tjønneland A, Olsen A, Overvad K, Larsen SC, Redondo Cornejo ML, Agudo A, Sánchez Pérez MJ, Altzibar JM, Navarro C, Ardanaz E, Khaw KT, Butterworth A, Bradbury KE, Trichopoulou A, Lagiou P, Trichopoulos D, Palli D, Grioni S, Vineis P, Panico S, Tumino R, Bueno-de-Mesquita B, Siersema P, Leenders M, Beulens JWJ, Uiterwaal CU, Wallström P, Nilsson LM, Landberg R, Weiderpass E, Skeie G, Braaten T, Brennan P, Licaj I, Muller DC, Sinha R, Wareham N, Riboli E. Coffee Drinking and Mortality in 10 European Countries: A Multinational Cohort Study. Ann Intern Med. 2017 Jul 11. doi: 10.7326/M16-2945. [Epub ahead of print] PubMed PMID: 28693038.
  • Park SY, Freedman ND, Haiman CA, Le Marchand L, Wilkens LR, Setiawan VW. Association of Coffee Consumption With Total and Cause-Specific Mortality Among Nonwhite Populations. Ann Intern Med. 2017 Jul 11. doi: 10.7326/M16-2472. [Epub ahead of print] PubMed PMID: 28693036.

Shingles increase heart attacks – time for the vaccine

Shingles increase heart attacks

Shingles, a reactivated form of the chickenpox virus, is a painful rash that afflicts many people decades after the initial chickenpox infection. Now, we have data that shingles increase heart attacks (myocardial infarction) and strokes. This is more evidence that we need to end chickenpox with the chickenpox vaccine, and reduce the risk of shingles in those who have had chickenpox with the shingles vaccine.

Let’s take a look at shingles and this new study. Continue reading “Shingles increase heart attacks – time for the vaccine”

Benefits of omega 3 fish oil – something’s fishy

I have been skeptical of supplements for a long period of time. The supplements are generally of low quality, they don’t prevent or cure cancer, they don’t prevent colds, they can’t boost the immune system, and they don’t prevent heart disease. Now it’s the time to take a look at the benefits of omega 3 fish oil, something that is claimed by Big Supplement over and over. Is there anything there?

Unless one has a chronic disease or is chronically malnourished, there are precious few instances where supplements are necessary. A couple of cases where supplements may be critical include prenatal folic acid supplements to prevent neurological defects in the developing fetus and vitamin D supplements for individuals who do not produce enough endogenous vitamin D. However, just to keep this in perspective, excess folic acid for a long period of time may be correlated with increased rates of certain cancers.

The benefits of omega 3 fish oil has always been intriguing to me, because it is a supplement that I thought might be useful to improving health, especially cardiovascular health. Omega 3 fatty acids are generally found in fish, as it is produced by the phytoplankton that is the primary food source of much of the prey for larger fish and bio-accumulates up the food chain. However, for humans, there are other sources of omega 3 oils including walnuts and edible seeds, eggs, and other non-fish foods.

Epidemiological studies done in the late 1980s seem to indicate relatively low death rates due to cardiovascular disease in Inuit populations with high seafood consumption. These results began the rush to consume omega 3 supplements, and created a booming supplement industry.

However, since publication of those initial studies, much research has been done on seafood and heart disease. And the results don’t give much credence to the cardiovascular benefits of omega 3 fish oils as a useful supplement.


Continue reading “Benefits of omega 3 fish oil – something’s fishy”

Diet soda increases risk of stroke and dementia – does it?

diet soda increases risk

Two recent studies published in respected journals seem to indicate that diet soda increases risk of stroke and dementia. Not to give a free pass to sugary drinks, one of the studies seemed to indicate that either artificially sweetened or sugar filled drinks might be linked to a higher risk of Alzheimer’s disease.

Typical of the popular press and your average website, they accept the findings of these studies without any serious critique of these studies. US News blares a headline that says, “Health buzz: drinking diet soda linked to stroke, dementia risk, study says.” Thankfully, many of the headlines use the qualifier “may be linked,” but I’m afraid most people will overlook that nuanced discussion of these studies.

But what does the actual science say? Do these studies provide us with robust evidence that cutting out diet soda will suddenly decrease our risk of stroke, dementia or Alzheimer’s disease? Probably not, but let’s see what this data actually tells us.


Continue reading “Diet soda increases risk of stroke and dementia – does it?”

HPV vaccine adverse events – this time, POTS

I make my goal that if you’re going to make some claim that goes against the scientific consensus, then it must be done with high quality evidence, preferably published in a high quality medical or scientific journal. It better be peer reviewed. And it better be good research.

Even if the evidence meets that standard, there is an hierarchy of published evidence from meta- or systematic-reviews at the very top, and junk science published in pseudoscience-pushing websites at the bottom. But there is a range of scientific scholarship, and sometimes, even if an article is published in a top quality journal, the results may be misinterpreted, or even be poorly analyzed.

Continue reading “HPV vaccine adverse events – this time, POTS”

Drug company withholds critical data for physician decision making

pradaxa-boxes-imageBecause I give full-throated support to the development, manufacturing and use of vaccines, one might think I was some sort of promoter of the pharmaceutical industry. In fact, I care about vaccines generically, and do not care about the system that gets vaccines into the hand of physicians. Frankly, pharmaceutical companies have the money and means to investigate new vaccines and improve old ones, which means it’s our only choice.

Maybe it would be better if the CDC or WHO were responsible for vaccines (and more or less, they are, but not for the manufacturing), but governments come and go, and there would be varying levels of support for the research. I could imagine a time where an antivaccination candidate running for US President would demand the cessation of government support of vaccine research and manufacturing, thus ending supplies of vaccines to US citizens. That would be a horrible scenario. But let’s assume that the 90-95% of Americans who vaccinate won’t vote for someone that delusional.

Pharmaceutical companies have done many wonderful things for humanity, and part of the reason we can live longer, while still being productive, is almost exclusively a result of pharmaceutical and medical innovations, especially over the past 20 years. I’m not going to list out every single revolutionary invention out of the pharmaceutical industry, but in the areas of cancer medications, antibiotics, vaccines, cardiovascular and orthopedic devices, and a few other areas, Big Medical (because it’s really more than just pharma) allows you to live longer and better. Continue reading “Drug company withholds critical data for physician decision making”

The false ideology of science deniers–research is easy

tyson-science-trueA few days ago, a fellow pro-science person was concerned about a tweet she received. Her antagonist was claiming that if my friend had all that time to tweet, then she obviously wasn’t working in academics as she claimed.

I have a Twitter feed that flies across the top right corner of my screen. I have over 1200 followers, and I follow the tweets well over that number. I have varied interests, but to be honest, there are too many tweets. I only respond or retweet things I happen to see when I look up to that upper right corner of my computer’s screen. I know I miss some good stuff. But I think I find a few dozen every day that lead me to read news articles or peer-reviewed journals. Occasionally, I run across a Tweet that makes me laugh or think.

Yes it takes time, but from the moment I wake up until I go to bed, I’m reading, writing, texting/messaging other scientists for ideas. We discuss books we’ve read. All of us in science writing work very hard to get where we are, which cause an epiphany bout the science deniers. I have a theory about their behavior and dismissal of science. I cannot be sure it applies to everyone; for example, there are some seriously deranged people who blame everything in science on Reptilians, Illuminati, Jews, and the US Government (run by Jews I suppose). There’s no logic with those types. Continue reading “The false ideology of science deniers–research is easy”

Vitamin supplements do not lower risk of cancer and heart disease

pile-of-supplementsVitamin and mineral supplements are important to maintaining proper levels of these nutrients when they aren’t obtained from the diet. Generally, if a human consumes a diet of broad based foods, there is little need for supplementation, unless they are afflicted with a chronic medical disorder which requires additional nutrients.

Vitamins and minerals do not have an impact on the immune system. Numerous articles have been published in peer-reviewed journals that have found very little evidence that supplements can lower risk of heart disease or one of the over 200 forms of cancer. What we need next, in the hierarchy of scientific evidence, is a systematic review published in an important journal.

And we got one. Continue reading “Vitamin supplements do not lower risk of cancer and heart disease”

Why we vaccinate-flu vaccine reduces cardiovascular risks

senior-flu-vaccineIn addition to preventing the infection, the flu vaccination may have a more important benefit for those who get the shot. A new systematic review, published this week in the Journal of the American Medical Association (JAMA), found that individuals vaccinated against the flu had a significantly lower risk of a major cardiovascular events, such as a heart attack or stroke, compared with those who received no flu vaccine.

In the meta-review, researchers from the University of Toronto analyzed five published studies and one unpublished study. They then rolled-up the data to investigate the connection between those who were vaccinated against the flu and various cardiovascular events. Altogether, the studies included approximately 6000 patients. Moreover, the patients had an average age of 67, while about one-third had a medical history of heart disease.

The results were dramatic–individuals who were vaccinated against the flu had a 2.9% risk of having a major cardiovascular even with the next eight months. The risk for those who were not vaccinated (or received a placebo) increased by 150% to 4.7%, a statistically significant difference.

Just to be clear, the study did not show that getting the flu virus caused the development of cardiovascular disease. However, patients with diagnosed cardiovascular disease (or who have had cardiovascular events, such as myocardial infarction) are at a significantly greater risk of another one if they catch the flu. As the authors state, “the greatest treatment effect was seen among the highest-risk patients with more active coronary disease.”

According to the study, less than 50% of people under the age of 65 with high-risk conditions (such as cardiovascular disease) receive the flu vaccine, which puts them at risk of complications like heart attack and stroke. Older individuals, who often have existing health problems, appear to be more likely to be vaccinated, although up to one third still skip their annual flu shot.

One last point–getting the vaccine, whether the patient has underlying cardiovascular disease or not, does not increase the risk of any cardiovascular effects.

We’ve all heard the excuses and myths about the flu vaccines. They just aren’t trueNo, they really really really aren’t true. By the way, Mark Crislip, MD, thinks those of you who make up whiny excuses for not getting the flu vaccine are dumbasses. His words, but quite apropos.

So, if you have had cardiovascular disease, or are at risk from it (like those who have type 1 or 2 diabetes), then get a flu vaccination no matter what your age is. If you have any other risk factors, like being under the age of 5, pregnant, or other important chronic conditions, get a flu immunization. If you’re a healthy adult, and you’re going to visit your parents or grandparents who could catch the flu from you, get vaccinated, even if they’ve been vaccinated (because there is some small chance that the vaccine didn’t give them full immunity). Just get vaccinated for the flu.

The clinical value of preventing the flu is huge. The mythical risks of getting the vaccine are invisible.

If you need to search for accurate information and evidence about vaccines try the Science-based Vaccine Search Engine.

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Vaccines save lives–even more evidence

Vaccines-save-lives;-fear-endangers-them.-It's-a-simple-message-parents-need-to-keep-hearing.One of my favorite tropes (of so many) of the vaccine denier gang is that vaccines are not effective, thereby implying that the limited usefulness is not worth the risks of vaccines, real or imagined. But the fact is vaccines do save lives in measurable and sometimes fascinating ways. Two peer reviewed papers, recently published, provided clear evidence of some of the ways vaccines directly save lives.

The first article analyzed the relationship between flu vaccines and reduction of cardiovascular events; while the second one examined how vaccines might reduce morbidity and mortality from pneumococcal meningitis.

Let’s start with the flu vaccine, which has a high safety profile and most people receive for the obvious reasons–flu prevention. However, we are aware of other benefits of the flu shot, including providing somewhat better outcomes during pregnancy. In an article published on 21 August 2013 examined a previously suspected, but not firmly established, benefit of the flu vaccine was examined. This study found that the risk of getting a heart attack was about 50% less amongst patients who were vaccinated against the flu compared to a group that was not.

Now, the study does not show that the flu vaccine has some miraculous anti-heart attack component, it might reduce the risk of catching the flu, or possibly reducing the severity of the infection, which reduces the risk of having a heart attack. In fact, the study’s original hypothesis was that catching the flu might actually increase the risk of a cardiovascular event, specifically a heart attack.

Furthermore, the researchers observed that the flu vaccine reduced heart attack risk even when the vaccine’s effectiveness was shown to be not very high. This conclusion itself debunks one of the huge myths of the antivaccination crowd (which is essentially that if it’s not 100% effective then we must conclude that it’s 0% effective, an application of the Nirvana logical fallacy); sometimes even when a vaccine isn’t completely effective, it still has some net positive effects. Continue reading “Vaccines save lives–even more evidence”