Raise Your Mugs!
Confused about whether coffee is good or bad for you? The latest research suggests it can have real perks.
More than 60% of Americans get their java fix every day, sipping 3 cups on average, according to the National Coffee Association. Yet for being such a popular hot beverage, coffee has had a tepid reputation. In the 1970s, research began suggesting that the caffeine in coffee was linked to cancer, birth defects and heart disease. And despite a smattering of positive news throughout the years, doctors still worried that its stimulant effects could raise blood pressure and cause heart palpitations—putting some patients at risk for dangerous heart arrhythmias, explains Tamara Horwich, M.D., associate clinical professor of medicine at the David Geffen School of Medicine at UCLA.
But it turns out that the early research highlighting the dark side of coffee had a common flaw: the biggest java drinkers also tended to have other risk factors for disease that weren’t adequately accounted for. Take, for example, the studies linking coffee to lung cancer. “Heavy coffee drinkers were more likely to smoke. So it was the tobacco that contributed to lung cancer—not coffee,” says coffee researcher Marilyn Cornelis, PH.D., associate professor of preventive medicine at Northwestern University in Chicago.
More recent, high-quality research suggests that coffee is not only safe, but that it may even prevent diseases like cancer, heart disease and diabetes. A 2018 meta-analysis of 30 studies that included more than a million participants found that people who drank the most coffee—about 5 cups per day—had a
29% lower risk for type 2 diabetes than those who abstained. Coffee drinking has also been associated with a reduced risk of depression as well as Alzheimer’s disease and other cognitive disorders.
And as for those risks of blood pressure and palpitations? “We now know that caffeine’s effects do not cause heart problems,” says Horwich.
Coffee beans are packed with powerful antioxidant and anti-inflammatory compounds, such as chlorogenic acid and tannins, explains Cornelis. (In fact, coffee is a major source of antioxidants in the American diet.) And each of these compounds can act uniquely on the body to protect you from a wide range of health problems. Chlorogenic acid, for one, is thought to regulate insulin and reduce body fat, two factors that may bolster metabolic function.
Current guidelines suggest that up to 400 mg of caffeine a day is safe for healthy adults. (That’s about five 8-ounce cups of coffee, although caffeine content varies widely depending on roast and brewing method.) People do differ in their ability to metabolize caffeine, so if you suspect that it’s causing unpleasant side effects—anxiety, tremors, heartburn, trouble sleeping—horwich recommends cutting back slowly. Women who are pregnant and breastfeeding are advised to limit caffeine to 200 mg per day. And be mindful of what you stir in. Flavored syrups, cream and drizzles can drown your healthy brew in saturated fat and sugar. Otherwise, go ahead and enjoy that a.m.—and 2 p.m.—cup! And know that it loves you right back.