Most studies find drinking coffee brings health benefits, but old myths persist.
So far this year, the findings are enough to perk up coffee drinkers beyond what they get with their morning jolt.
In just the last five months, studies have found that coffee may protect against dementia, stroke and skin cancer.
This follows previous research—among some 20,000 studies to date exploring the health impact of America’s most popular beverage—that suggests regular coffee consumption may reduce the risk of Parkinson’s, type 2 diabetes, several types of cancer, suicide and some mood disorders, gallstones, liver cirrhosis and even cavities.
Coffee has long been known as an effective emergency treatment for an asthma attack and a go-to headache remedy, and, more recently, as an aid to help alcoholics quit drinking. It may even extend a person’s lifespan, researchers say. It’s the second most studied substance after cigarettes, and the studies keep percolating along.
In January, Finnish researchers reported in the Journal of Alzheimer’s Disease that after tracking 1,400 adults for 20 years and controlling for their other lifestyle and dietary habits, those drinking three to five cups per day were two-thirds less likely to develop dementia than non-imbibers.
In February came two studies—one by Harvard University School of Public Health and Spanish researchers tracking 83,000 middle-aged women since 1980, and the other by University of California, Los Angeles and University of Southern California scientists analyzing data on 9,400 adults older than 40—that showed a lower risk of stroke among coffee drinkers, with rates decreasing with the more cups consumed each day. Then there was also research in the Journal of Investigative Dermatology suggesting that consuming caffeine may protect against skin cancer by disrupting a protein that causes sun-damaged skin cells to self-destruct.
March was quiet on the java front, but with April came two more findings: Researchers at Roswell Park Cancer Institute in Buffalo, N.Y., reported that among 1,100 women studied for 16 years, those who regularly drank coffee or tea had a lower risk of endometrial cancer compared with nondrinkers. The more coffee the women consumed, the lower the disease rates. And in the International Journal of Sport Nutrition and Exercise Metabolism, scientists from the University of Iceland and the University of Illinois-Urbana found that drinking coffee seems to help relieve the pain of exercise.
Coffee shakes bad reputation
There seems to be a new coffee study published in medical journals every few weeks, for several reasons. It’s readily available, inexpensive and popular. Some 400 billion cups are consumed every year worldwide. It’s not fattening, with zero calories when served black or with artificial sweeteners. And, researchers say, it may just be one of the healthiest substances you can get.
But it wasn’t always regarded that way. Even today, some folks (typically, those not doing the research) still avoid this virtuous vice—believing coffee causes ailments ranging from bone loss and heart problems to stomach and pancreatic cancer and “the shakes.”
“When I was in medical school, we were taught that coffee was bad,” says Peter R. Martin, M.D., director of Vanderbilt University’s Institute for Coffee Studies. “But that was because early studies in the 1960s and 1970s were not well done, not taking into effect other lifestyle factors, such as that people who drank coffee also tended to smoke. And they developed health problems.” (Researchers have now realized that in those early studies, coffee-drinking smokers tended to under-report how much they smoked.)
Today, however, epidemiological studies are done more carefully, tracking various factors affecting health and illness in large groups for many years or decades. Most, say leading researchers, reach the same conclusion: For those not prone to its effect on sleep problems (decaf solves that) or indigestion, and not worried that it can slightly raise “bad” cholesterol, coffee is healthy and may even help prevent many age-related conditions.
“Coffee is most famous for being the best source of caffeine—there’s three times as much in a cup of coffee compared to an equal amount of cola—and despite its bad reputation, caffeine has some health benefits. But coffee is a very complex substance with as many as 2,000 different chemical components, including many powerful antioxidants and phytochemicals,” notes James Coughlin, a food and chemical toxicologist who has studied coffee’s health effects for more than three decades and has personally conducted or analyzed data from some 10,000 studies.
What’s more, roasting coffee beans causes a chemical reaction that makes some of these disease-fighting antioxidants even more powerful, adds Coughlin, past president of the Association for Science and Information on Coffee, a Paris-based organization of scientists who conduct coffee-related research and are funded in part by the coffee industry. This may explain why, measure for measure, coffee has been documented as the richest source of antioxidants in the American diet.
Beyond caffeine, benefits of the bean
On its own, caffeine reacts with certain brain receptors—one explanation why studies have shown it protects against Alzheimer’s and Parkinson’s, boosts mood and lowers suicide risk, and reduces pain. But an additional brain-boosting benefit comes from coffee’s abundance of chlorogenic acids, a family of antioxidants that also protect the brain and other body systems, adds Martin. “Chlorogenic acids improve the capacity of the body to metabolize sugar and glucose, which is perhaps the reason why it may be protective against type 2 diabetes and liver disease.”
In one notable study that analyzed data on 126,000 people over a period of 18 years, Harvard researchers found that, all else being equal, those drinking one to three cups of caffeinated coffee each day were slightly less likely than nondrinkers to develop type 2 diabetes. But among those drinking six or more cups daily, men’s risk was slashed by 54 percent and women’s by 30 percent compared with nondrinkers. Since then, other studies have found that regularly drinking decaf also lowers the risk of diabetes.
“Whether you drink regular or decaf coffee, you’re getting chlorogenic acids,” notes Frank Hu, M.D., professor of nutrition and epidemiology at Harvard’s School of Public Health, who led that January 2004 diabetes study published in Annals of Internal Medicine and participated in the recent February report indicating a lower risk of stroke among coffee drinkers. “These substances have a powerful, positive effect on cardiovascular health and in preventing gallstones, which, similarly to diabetes, is related to insulin resistance.”
Antioxidants in coffee may also play a role in reducing the risk of certain cancers. “There really seems to be a strong, consistent protective effect against liver and endometrial cancer, with the benefit coming with at least two cups per day,” says Lenore Arab, a researcher at UCLA’s David Geffen School of Medicine who analyzed more than 500 previous coffee studies for a study soon to be published in Nutrition & Cancer. “There is increasing evidence that coffee is protective against colorectal cancer.” Her research indicates that coffee has little impact—positive or negative—on cancers of the breast, pancreas, kidney, ovaries, prostate or stomach. And in one of the first studies of its kind, a recent study from Japan finds lower rates of oral cancers among coffee drinkers.
However, more than six cups a day is linked with a higher risk of bladder cancer in men, but not women, adds Arab. And higher rates of leukemia occur in people whose mothers drank more than two cups a day during pregnancy.
What about bone loss leading to osteoporosis, a common concern from drinking coffee? “There is very little risk in drinking up to four cups per day,” Coughlin says.
Even many patients with heart arrhythmias—long told to avoid coffee—can drink it with their doctor’s approval. In fact, mounting evidence suggests that coffee may be heart-healthy. A study last year that tracked nearly 128,000 adults for 18 year or longer indicated that, all else considered, coffee drinkers have a longer lifespan than nondrinkers. Why might that java habit help people live longer? Coffee is rich in magnesium—important for heart health—and its bounty of antioxidants helps reduce inflammation and protect the inner lining of blood vessels, says lead researcher Esther Lopez-Garcia of the Universidad Autónoma de Madrid in Spain.
The bottom line: “For most people in their 50s, 60s or older,” says Harvard’s Hu, “there is no reason to worry about coffee. Just don’t add too much sugar or cream.”