Coffee cup with coffee country in background 1280 x 986
Photo credit: Saif Selim via Pexels

Pop quiz: What fruit did Eve give Adam that so infuriated God? You probably said, “Apple.” Wrong! The Bible does not name the fruit. Later translations named it, erroneously.

So, which fruit would you nominate to fill the void? My own favorite is the fruit of the coffee tree. Its seed is what we call the coffee bean.

The plant, Coffea arabica, originated in southern Arabia where its brewed extract was used in religious ceremonies by pre-Islamic Bedouin tribes in the region. This was enough to incur the wrath of god (and of the early Ethiopian Church, which banned its use for centuries because of its association with devil-worship).

Another religious association I love is that the coffee-growing region of Quindio in Colombia is fondly known as Paradiso. A vacation there a few years ago confirmed this impression.

Bedouin finjan
Bedouin finjan

Of course, the most important reason to nominate the coffee’s fruit is its wonderful flavor. I am not referring here to Starbucks coffee, which the cognoscenti rate between mediocre and poor. To really appreciate the magical properties attributed to coffee by the pre-Islamic tribes of the Arab peninsula and the ancient Middle-East, you would have to sample the Bedouin coffee, brewed over open fire in a metal pot called the finjan.

But, my most important reason to nominate the coffee bean as the fruit of the Garden of Eden is its health benefits.

Drink it, it’s good for you

Alexander Woolcott once famously quipped that “everything I like to do is either illegal, immoral, or fattening.” Well, my good fellow Woolcott, you should have tried coffee. It is none of those things.

According to the U.S. Department of Agriculture Center for Nutrition Policy and Promotion, a 6-ounce cup of black coffee contains just 7 calories. Add some half & half, and you’ll get 46 calories. If you favor a liquid non-dairy creamer, it will set you back 48 calories. A teaspoon of sugar will add about 23 calories. And last I checked, drinking coffee is still legal and moral.

Beating the odds of type 2 diabetes

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Australian scientists did a meta-analysis of 18 studies of nearly 458,000 people. They found a 7% drop in the odds of having type 2 diabetes for every additional cup of coffee drunk daily. There were similar risk reductions for decaf coffee drinkers and tea drinkers. Now, please note that the study does not claim an absolute reduction in the incidence of diabetes—just a reduction of risk compared to non-drinkers.

Rob Van Dam and Frank Hu, both of the Harvard School of Public Health, obtained similar results in another study of more than 193,000 people. Those who said they drank more than six or seven cups daily were 35% less likely to have type 2 diabetes than people who drank fewer than two cups daily. There was a smaller perk—a 28% lower risk—for people who drank 4-6 cups a day. They also have an average of 7% reduction in the risk of type 2 diabetes per additional cup of coffee. The findings held regardless of sex, weight, or geographic location (U.S. or Europe).

What could the mechanism be? Coffee contains about 1000 molecules, in addition to caffeine. Many of those molecules are antioxidants, which reduce tissue damage wrought by oxygen-free radicals. Also, coffee contains chromium and magnesium, two minerals that enhance insulin sensitivity. I hasten to add, this falls in the category of “it makes sense.” Until proper animal studies are done to demonstrate the anti-diabetic effect of coffee components, it remains a sensible hypothesis.

Benefiting the heart

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In a study of about 130,000 Kaiser Permanente health plan members, people who reported drinking 1-3 cups of coffee per day were 20% less likely to be hospitalized for abnormal heart rhythms (arrhythmias) than nondrinkers, regardless of other risk factors.

And, for women, coffee may mean a lower risk of stroke. In 2009, a study of 83,700 nurses enrolled in the long-term Nurses’ Health Study showed a 20% lower risk of stroke in those who reported drinking two or more cups of coffee daily compared to women who drank less coffee or none at all. That pattern held regardless of whether the women had high blood pressure, high cholesterol levels, and type 2 diabetes.

Lowering the risk of dementia

Coffee drinking has also been linked to lower risk of dementia, including Alzheimer’s disease. A 2009 study from Finland and Sweden showed that out of 1,400 people—followed for about 20 years—those who reported drinking 3-5 cups of coffee daily were 65% less likely to develop dementia and Alzheimer’s disease, compared with nondrinkers or occasional coffee drinkers.

Functioning cognitively

In a study published in the Journal of Experimental Psychology: Applied, researchers asked 36 college students who consumed low levels of caffeine—about a half-cup of coffee a day—to do a “language task.”

The students were given 5 minutes to read a one-page news story and needed to identify and correct as many spelling and grammatical mistakes as they found in that time.

Forty-five minutes before taking the proofreading test, students were randomly given a capsule containing one of four doses of caffeine: none; 100 milligrams (the amount found in 8-ounces brewed coffee); 200 milligrams (found in 16-ounces coffee); or 400 milligrams (found in 20-ounces of coffee).

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In a second study, researchers repeated the same experiment with 38 college students who consumed higher levels of caffeine each day. The java junkies typically had at least 300 milligrams of caffeine daily, roughly three 8-ounce cups of java.

Caffeine only seemed to make a difference in the student’s ability to spot and fix “complex global errors.” These were mistakes in subject-and-verb agreement (for example, billionaire inventor Tony Stark enjoy a lavish lifestyle) and verb tense (for example, customers were misled into believing they had got approved for low-interest loans).

The low-caffeine crowd was best at finding and correcting these grammatical goofs at 200 milligrams of caffeine; however, the highly caffeinated group needed 400 milligrams, or 4 eight-ounce cups, to achieve the highest detection rates.

Interestingly, caffeine didn’t affect the students’ skill at finding and correcting misspelled words. And it had no effect on noticing mistakes in words that sound alike, such as weather and whether or seams and seems.

Coffee and longevity

With all those wonderful benefits, would it be too much to expect a longer lifespan? Several small studies have suggested as much in the past, but a now a very large study published in the New England Journal of Medicine offers strong evidence that, indeed, coffee drinkers have a reduced risk of dying prematurely from all causes, and consequently live longer.

A very large study offers strong evidence that, indeed, coffee drinkers have a reduced risk of dying.

The new study is by far the largest of its kind to date. As part of a joint project with the AARP, researchers from the National Institutes of Health followed more than 400,000 healthy men and women between the ages of 50 and 71 for up to 13 years, during which 13% of the participants died.

Overall, coffee drinkers were less likely than their peers to die during the study; and the more coffee they drank, the lower their mortality risk tended to be. Compared with people who drank no coffee at all, men and women who drank six or more cups per day were 10% and 15% less likely, respectively, to die during the study.

This pattern held when the researchers broke out the data by specific causes of death, including heart disease, lung disease, pneumonia, stroke, diabetes, infections, and even injuries and accidents. Cancer was the only major cause of death not associated with coffee consumption.

Take home lesson

All these studies give a new meaning to “smelling the coffee.” So brew yourself a pot of Arabica coffee (much superior to the “Robusta” variety), and enjoy the good life.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.


  1. Avatar Quite an extensive study on the effects of coffee on the body. Would its benefecial effects be the same if one, uses a creamer, fat or non-fat, splenda or similar product or a little dash of ginger??

    And while I’m at it already, what about its effect on the nervous system, on vision hearing, urinary system? heartbeat or palpitation On the whole its benefits far outweigh any adverse effects unless advance.

  2. Dov, thanks for the info that my next cup of coffee will not only be enjoyable, but actually good for me. Cheers!

  3. This is great. I’m sharing this on Facebook and with my patients, most of whom suffer from Diabetes, heart disease, and dementia/Alzheimer’s.

  4. Wow, this is such great news! I love my cup of coffee (having it right now as a matter of fact) and I’m excited to hear of all the health benefits. I had no idea to the degree you have detailed here and appreciate learning about it. Thank you!


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