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Secret Side Effects of Drinking Coffee, Says Science

Your cup of joe can do more than just give you a jolt of energy.
FACT CHECKED BY Olivia Tarantino

For most coffee drinkers, a day without a cup (or two or three…) of Joe is simply unthinkable. Pouring a cup of this morning brew is a daily ritual that gives coffee drinkers a boost of both mental and physical energy to face the day. Despite common warnings about the health consequences of drinking too much coffee or caffeine, there's resounding evidence that the right amount of coffee may reduce the risk for many chronic conditions and add years to your life.

As one of the most widely enjoyed beverages in the world, coffee has been studied extensively for decades. Coffee is a complex beverage that provides more than 1,000 plant-based bioactive compounds, including antioxidants, polyphenols, fatty acids, and caffeine. Together, these compounds provide significant health benefits. A review of the coffee studies published in the New England Journal of Medicine revealed that coffee can improve cardiovascular health, insulin resistance, gallstones, certain cancers, and even liver and mental health.

Caffeine is a well-known stimulant and some 80% of the caffeine in a typical Many of the benefits we expect from coffee are from its caffeine. Caffeine is what helps wake us up, increases energy, improves concentration, and helps us exercise longer and harder. According to the Dietary Guidelines for Americans, about 400 milligrams of caffeine per day is considered a healthy amount of caffeine and that is equal to about four cups of coffee a day. (Pregnant women should discuss their caffeine consumption with their healthcare provider.)

But wait, there's more! Read on to learn about the secret side effects of drinking coffee, and for more on how to eat healthy, don't miss 7 Healthiest Foods to Eat Right Now.


It may add years to your life.


One of the landmark studies published in the journal Circulation found that those who drank 1 to 5 cups of coffee per day had longer lifespans compared to those who reported drinking little or no coffee.

In fact, the researchers reported that drinking 1 to 3 cups of coffee per day was associated with a 15% reduction in risk of dying.

There are many reasons why coffee may add years to your life, but the researchers believe that the antioxidants, caffeine, and other bioactive compounds in coffee help improve blood glucose levels and cardiovascular health. While up to four cups may be ideal, there are studies that do suggest that heavy coffee consumption (>5 cups per day) may be associated with an increased risk of dying.

Read more: The 13 Drinks To Sip On For A Longer Life, Say Doctors


It improves your mood.

iced coffee

There's a reason why you feel decidedly better after your first cup of coffee. Studies show that the caffeine that coffee provides perks up your mood. In a study published in the Archives of Internal Medicine, Harvard researchers studied more than 50,000 middle-aged women and reported that those who drink the most coffee are less likely to suffer from clinical depression.

In another study, published in the Journal of Affective Disorders, scientists studied more than 80,000 subjects and concluded that regular and moderate caffeine intake likely reduces depression among women. That said, other studies have linked excessive coffee intake (more than four cups per day) with depression, but researchers believe that it is likely other behaviors that are linked.

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It may help protect against Parkinson's Disease.


According to Parkinson's Foundation, coffee consumption has been suggested to play a protective role in developing Parkinson's Disease. A significant number of large, population-based studies dating back to 1968 report an inverse, dose-responsive relationship between coffee consumption and the risk of developing Parkinson's Disease.

Scientists have recently made progress in determining how coffee help protect the brain against the debilitating disease. Recent studies have suggested that the caffeine and fatty acid in coffee may work together to help protect neurons in the brain from some of the hallmark indicators of Parkinson's Disease.


It acts as a performance-enhancer.

black coffee

As most sports dietitians will attest, coffee is one of their favorite go-to performance-enhancers. When consumed at normal amounts, it is currently not banned by the International Olympic Committee and there is significant agreement that caffeine helps increase power, speed, and accuracy of sports that last anywhere from 60 seconds to several hours. When coffee is enjoyed before exercise, it stimulates the central nervous system and epinephrine to give a burst of energy, reduce pain receptors, and increases fat burning so that the muscles can burn more fat as fuel. In a review of several studies about caffeine and performance, the researchers concluded that caffeine boosts exercise performance by an average of 11.2%.


It may protect against Alzheimer's Disease.

friends drinking coffee

There are several studies that suggest coffee drinkers may have a reduced risk for developing Alzheimer's Disease (AD). In one review study published in Neurological Research, researchers reported that coffee consumption is inversely associated with risk for Alzheimer's disease. Coffee drinkers experienced a 30% reduction in risk for developing AD compared to those who didn't drink coffee.

In an animal model study published in the Journal of Alzheimer's Disease, coffee provided to rodents with AD helped protect against memory loss, it helped to maintain memory and actually appears to help reverse some effects of AD in an animal model. While more research is needed to show these benefits in humans, there appears to be little downside of drinking coffee in moderation for its potential health benefits.

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Julie Upton, MS, RD, CSSD
Julie Upton is an award-winning registered dietitian and communications specialist who has written thousands of articles for national media outlets, including The New York Times, US News & World Report, and USA Today. Read more about Julie
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