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What Is It About Coffee That Protects Your Brain?

Scientists tested dark roast and light roast coffee as well as decaf to see what components of coffee may prevent amyloid plaques.

Java lovers appear to enjoy a variety of health benefits, including a reduced risk of developing Alzheimer’s or Parkinson’s disease. Most recently, Australian scientists discovered that coffee drinkers develop less beta-amyloid plaque in their brains (Frontiers in Aging Neuroscience, Nov. 19, 2021).

More Coffee Linked to Less Plaque:

The researchers tracked more than 200 older adults for over 10 years. At the start of the study, no participant showed any signs of cognitive impairment. Careful cognitive testing throughout the study revealed that people who drank more coffee maintained better cognitive function. In addition, the investigators conducted brain imaging on 60 individuals and measured brain volume of 51. The brain images detected levels of A-beta amyloid accumulation. Because this is a marker for Alzheimer disease, lower levels seen in people who drank more coffee suggests coffee consumption could be a protective factor against this type of dementia.

What Compounds in Coffee Protect Your Brain?

It is certainly good to have that confirmation. But what precisely offers the benefit? A team of Canadian researchers reported that they 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, so they didn’t show how much neurological protection people might get from drinking dark roast coffee on a regular basis. The more recent Australian study seems to confirm that it’s significant. Together, these studies indicate 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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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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  • Gardener SL et al, "Higher coffee consumption is associated with slower cognitive decline and less cerebral Aβ-Amyloid accumulation over 126 months: Data from the Australian Imaging, Biomarkers, and Lifestyle Study." Frontiers in Aging Neuroscience, Nov. 19, 2021. https://doi.org/10.3389/fnagi.2021.744872
  • Mancini RS et al, "Phenylindanes in brewed coffee inhibit amyloid-beta and tau aggregation." Frontiers in Neuroscience, Oct. 12, 2018. https://doi.org/10.3389/fnins.2018.00735
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