We'd never get between a java lover and her favorite pick-me-up. But for all the potential benefits of coffee—from decreasing your diabetes risk to protecting against Parkinson's—research shows that the brew isn't without its dangers. Luckily, there are simple ways to avoid them. Read this before you pour your next cup.
If you have high cholesterol...use a paper filter. Every cup of unfiltered coffee (think French press) contains cafestol—"the most potent cholesterol-elevating substance we know of in the human diet," according to researcher Marie-Louise Ricketts, PhD, of the University of Nevada, Reno. One study found that drinking roughly four eight-ounce cups of French press coffee every day for four weeks could increase your cholesterol by about 8 percent. To remove most of the cafestol, brew your coffee with paper filters (single-serve options, like Keurig K-Cups, already have them built in), because they're more effective at removing the compound than permanent metal filters.
If you're at risk for developing heart disease...switch to decaf. Caffeinated coffee may increase your odds of having a heart attack if you already have three or more heart disease risk factors (such as being overweight, smoking, or having high blood pressure). In a study that evaluated the coffee intake of more than 500 people in the 24 hours prior to their first heart attack, those with three or more risk factors were twice as likely to have suffered their attack within an hour of getting their fix. "Caffeine will cause your blood pressure to briefly spike, and when you already have plaque buildup in your arteries, this can loosen and block blood flow, leading to a heart attack," explains study coauthor Ana Baylin, MD, associate professor of epidemiology at the University of Michigan School of Public Health. Light coffee drinkers should be especially cautious: The same study found that people at risk for heart disease who sipped only small amounts (one cup or less a day) were four times as likely to have a heart attack, possibly because the jolts of caffeine had a stronger effect.
Next: The best brew for avoiding acid reflux (it's not what you think)If you experience acid reflux...brew a darker roast. Dark coffees may taste stronger, but according to one study, they're gentler on your stomach. The roasting process produces a compound that slows the production of stomach-irritating acid, according to researcher Veronika Somoza, PhD, a professor in the University of Vienna's department of nutritional and physiological chemistry; because darker brews are roasted longer, they produce more of the compound than their lighter counterparts. Another plus: Dark roasts tend to contain lower amounts of caffeine, which can also trigger acid reflux.
If you suffer from insomnia...know when to say when. Caffeine sensitivity can vary widely: Its half-life in adults—the time it takes for half of the stimulant to leave your body—is between four and seven hours, says researcher Frank Ritter, PhD, of the Applied Cognitive Science Lab at Penn State University. If your half-life is six hours and you drink an eight-ounce coffee at 4 p.m., half the caffeine will likely still be in your system at 10 p.m.—blocking the action of a snooze-inducing chemical in the brain and making it harder to wind down. Time your last cup so you can get a good night's rest by using an app like Caffeine Zone 2, developed by Ritter's lab. Just enter how much coffee you drink and how fast you drink it, and the app will predict how long your buzz should last.