Closeup of barista making coffee and pouring milk, coffee

Java lovers appear to enjoy a variety of health benefits, including a reduced risk of developing Alzheimer’s or Parkinson’s disease. Now a team of Canadian researchers reports that they have figured out what it is about coffee that is helpful (Frontiers in Neuroscience, Oct. 12, 2018). Hint: it’s not the caffeine.

The Coffee Study:

The scientists tested three instant coffee extracts: light and dark roast with caffeine and dark roast without caffeine. (They used Starbucks Via Instant.) They also tested six different components of the brew. The tests were conducted on purified beta-amyloid and tau, complex brain proteins that lead to neurological problems when they aggregate to form plaques and tangles.

What these laboratory tests revealed is that dark roast coffee, both regular and decaf, slows the agglomeration of both amyloid and tau more than light roast does. In the testing of the separate coffee constituents, caffeine had no effect. However, a compound called phenylindane strongly inhibited the aggregation of both tau and amyloid. Roasting the beans longer for a dark color and more intense flavor creates more phenylindane.

These are laboratory findings, and we don’t yet know how much neurological protection people might from drinking dark roast coffee on a regular basis. But it does seem that you shouldn’t fear that your morning cup of joe will harm your brain, regardless of whether you prefer decaf or high-test. Presumably, though, it makes sense to choose dark roast rather than light.

Caffeine Is Okay for People with Heart Failure:

Sometimes people are told that they must give up on coffee because of their medical condition. This may be prudent advice in some cases; for example, certain people develop heartburn when they drink coffee. For years, cardiologists have warned their heart failure patients to avoid coffee. That’s because they worried that caffeine would trigger irregular heart rhythms.

High-Dose Caffeine Vs. No Caffeine:

A randomized placebo-controlled study found that this is unlikely (JAMA Internal Medicine, Dec. 2016). The researchers included 51 patients with chronic heart failure and gave them five doses of caffeine or placebo over the course of five hours. Each dose was accompanied by a small cup of decaf coffee. This resulted in a total dose of 500 mg caffeine or 0 mg caffeine for those who got the placebo. (For comparison, 20 ounces of coffee from Starbucks has between 340 and 475 mg, depending on the blend.)

After a week of wash-out, the exercise was repeated; patients who had gotten placebo were given caffeine and vice versa. During both sessions, patients had continuous electrocardiographic monitoring.

The Results:

There were no significant differences between the groups with respect to any type of arrhythmia. The exercise stress tests also revealed no differences. The volunteers in this study did experience some rhythm disturbances, but these were equally common whether they were taking caffeine or placebo.

Based on these results, the investigators conclude,

“To date, there is no solid evidence to support the common recommendation to limit moderate caffeine consumption in patients at risk for arrhythmias.”

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  1. Cindy
    Seattle, WA

    One commenter says that dark-roast has less acrylamide than lighter roasts.(?!) I’m pretty sure it’s the other way around, i.e., dark-roast has MORE acrylamide, and that’s considered somewhat carcinogenic. I was considering having to go “lighter” due to that problem. But if the dark-roast actually inhibits the plaques associated with Alzheimer’s, I’m glad I didn’t do it!

  2. Mae

    I stopped drinking coffee thirty years ago, as it made me feel like my stomach was in knots, and I was very anxious all the time. A friend a few months ago gave me a pack of organic coffee with mushrooms. I can now drink coffee with no side effects, and the coffee is very delicious.

  3. Angie

    Apparently any type of stimulant cause heart palpitations (excessive caffeine, alcohol) in people susceptible to this. Use common sense here. If you are someone who is susceptible then cut down or stop. I am very susceptible to caffeine, with heart palpitations and lumps in my breasts. I now drink only decaffinated beverages and have no problems. My problem solved.

  4. Dorothy

    What about cold-brew coffee?

  5. John
    Croydon, PA

    Dark roast coffee also has less acrylamide (possibly associated with cancer).

    I have had palpitations off and on for many years. I switched from regular to decaf green tea, and palpitations rarely occur now.

  6. Ray

    What about the supposed irritating effect of caffeine on the prostate? True?

  7. Sherry Clark

    Is decaf coffee toxic? I’ve heard that the chemicals used in the decaf process are toxic.

    • Engineer10388
      metro Raleigh, NC

      Decades ago it was common for coffee companies to remove caffeine by soaking beans in a solvent such as Methylene Chloride. It was supposed to be driven off during roasting but some residue might possibly remain. The modern “Swiss water process” now universally(?) used just soaks the beans in plain carbonated water (caffeine being very soluble in water). My understanding is that “chemicals” are no longer used to decaffeinate coffee. By the way, the fact caffeine is highly soluble in water means when you brew a big pot of regular coffee the first several cups to pour through will have a *very* high caffeine content, in addition to being strong tasting.

  8. Trisha

    I’ve had herpes ‘simplex’ on my lips and nose since I was a child. Now, at the same time we are being told amyloid plaque build up in the brain is the body’s defense against herpes virus which may lead to dementia and Alzheimer’s, we are being told drinking coffee slows plaque buildup in the brain to reduce Alzheimer’s risk. Which is it ?? Try to reduce amyloid plaque buildup in the brain or try to increase amyloid buildup in the brain ??

    I’m thinking the whole thing is a load of crap and that I will continue to drink my morning coffee and stop worrying about my herpes virus ‘causing’ dementia and Alzheimer’s…

  9. Trey

    Two questions: Are the reported health benefits gained from coffee consumption diminished by the addition of milk/cream, as they are reported to be in tea? Is there concern about heavy metals, specifically cadmium, in chocolate powder? ( I am in the habit of adding both to my morning coffee.)

    Thank you for your column and radio information.

  10. Hugh J

    I think that the people doing the tests are coffee addicts themselves. What if the amyloids and tau they are testing against are actually evidence of a defense mechanism that the body has put up to fend against the operation of the alzheimer’s gene?
    Yes, they are correlatives of dementia BUT they are more like dead soldiers in a fort that has been over-run.
    I am aware of heavy users of coffee who exhibit Alzheimer’s.

  11. Becky
    Kemp, TX

    The only thing that might be a problem with lots of caffeine is breast lumps. As a breast cancer survivor, I am always asked if I drink a lot of caffeine. It appears that caffeine causes differences in breast tissue such as lumps or knots when having a breast exam. I have started drinking both decaf tea and coffee and it seems to help the situation. If there’s no difference in the decaf and caffeinated coffee, why not stick with decaf.

  12. Cass

    This was such a short study. I know from my own experience that a week of drinking more-than-usual amounts of coffee does not seem to affect me; however, if I continue, I begin to develop palpitations which become more obvious with continued excess consumption. If I were to continue for more than a month, I would be experiencing palpitations almost constantly and to the degree that I would be awakened at night. This is, of course, anecdotal, but I have a sister and friends who report similar experiences.

  13. Molly
    Santa Fe, NM

    Sometime in my mid-forties, when early menopause had begun but I was unaware of it, I started getting episodes of heart arrhythmia. This scared me, so I went immediately to the clinic and was scheduled for an EKG. During the test my heart kindly cooperated and the arrhythmia was recorded. “Hmm,” said the doctor, (or something like that) “there are lots of people walking around with this – it isn’t the bad kind. You’re not heading for a heart attack. Don’t worry.” As I left the office, the nurse leaned over and murmured that caffeine can cause arrhythmia and I might try giving up coffee. I switched to decaf immediately; the arrhythmia did not come back for a long time — except on occasion when I drank too much good wine, and, later, when I became a chocoholic. I don’t know why this experiment did not show an association between caffeine and arrhythmia, but I have to believe my own experience and suggest that more studies should be done.

  14. Jane

    I am an 89 year old, physically and mentally active retired RN(female). When I was in my late 40’s, one day at work, I developed a rather sudden onset of a cardiac arrhythmia with a very low blood pressure and weakness. I was seen by a cardiologist and without going into detail, it was determined that the many cups of coffee I drank each morning were the predisposing factor in these multiple runs of PVC’s. I stopped coffee and after a few days of caffeine withdrawal symptoms, I felt much better and there were no arrhythmia episodes. Some months later, at a conference, I drank several cups of coffee and developed the arrhythmia again. Now, many years later, I have learned that ONE cup of regular coffee each AM and one or two cups(mugs) of decaf were tolerable for me and that has become my pattern. I take a very small dose of a beta blocker each day as well. All of this to say, for ME, one cup of coffee is ok, but multiple cups cause runs of PVCs.

  15. Jay

    Despite the findings about caffeine not causing arrhythmia, I know that caffeine is a trigger for my Premature Ventricular Contractions (PVC). If I drink a cup of regular coffee (medium roast) first thing in the morning I will have a problem. I’ve switched to decaf and no longer have a problem.

  16. Andrew

    There have been many strong suggestions in recent years that amyloid plaque is the body’s defense mechanism against whatever the true cause of dementia may be–“dormant” herpes virus being perhaps most recent. How then do we know that reducing plaque formation is a good thing?

  17. Joe M.

    What about the effect of pesticides in coffee?

    • Mary

      It is not just pesticides. Sometimes coffee beans can have some mold on them. Not good at all.

  18. Gerry

    The only thing that’s ever given me a night-long session of a-fib was too much bourbon one evening. Never will do that again!

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