Heart Health Gets a Jolt from a Cup of Joe
Go ahead ... have that second cup of java.
Research has found that coffee offers a long list of potential health benefits, including possibly reducing the risk of diabetes, heart disease, Parkinson’s disease, cirrhosis of the liver and even Alzheimer’s.
Why? The answer may lie in the army of antioxidants coffee contains.
“Many people do not realize that coffee is the largest source of antioxidants in their diet,” said Dr. Donald Hensrud, chair of preventive, occupational and aerospace medicine at the Mayo Clinic in Rochester, Minnesota.
The Research
Numerous studies have shown that coffee is good for the heart. The Iowa Women’s Health Study, an ongoing study as of May 2011, followed 27,000 women from age 55 to 69. In that study, researchers from the University of Minnesota found that women who drink one to three cups of coffee a day reduce their risk of heart disease by 24 percent compared with those who abstain from drinking coffee.
In a study conducted at Spain's Autonomous University of Madrid, researchers tracked 129,000 men and women over 20 years and found that study participants who consumed several cups of coffee a day were less likely to die of heart disease than those who drank none. Among women taking part in the study, those who drank four to five cups a day were 34 percent less likely to die of heart disease than those women who drank no coffee. Men who drank five cups were 44 percent less likely to die of heart disease than men who drank no coffee.
Of apparent wider significance, however, was an overarching decrease in the mortality rate of the coffee-drinking participants.
According to an article published by NewScientist.com, the researchers noted that the same group of coffee-drinking women experienced 26 percent fewer deaths from any cause during the period of the study, and there were 35 percent fewer deaths from any cause among the same group of coffee-drinking men.
Reports of the study's conclusions appeared during the summer of 2008. At that time, Esther Lopez-Garcia, an epidemiologist at Autonomous University and the leader of the study, cautioned against acting on the findings until additional research was conducted.
Researchers are still trying to determine exactly why coffee might be beneficial, but it appears that antioxidants may help block inflammation and limit cell damage, both of which are associated with cardiovascular disease, Hensrud said.
The antioxidants in coffee are known as polyphenols and they are also found in fruits, vegetables, red wine and chocolate. A 2005 study found that Americans get far more antioxidants from coffee than from any other source.
Potential Research Caveats
Coffee has been researched for years, mostly through observational studies, which means researchers ask people about their coffee-drinking habits, study data over the years and look for patterns.
These studies may show strong statistical associations, researchers say, but they do not prove cause and effect. For example, previous studies that linked coffee to certain cancers may not have taken into account other lifestyle factors, such as drinking and smoking, Hensrud said.
Also, coffee drinkers who are encouraged about the recent flurry of good news might eat more healthy foods or get more exercise than abstainers.
Last, there's no guarantee that people in observational studies accurately report the amount of coffee they consume.
How Much?
A magic number does not exist, doctors say, but the benefits of drinking coffee appear to taper off after six cups. That does not mean everyone should guzzle six cups a day, said Dr. John P. Higgins, a cardiologist and assistant professor of medicine at the University of Texas Medical School in Houston. In a recent study, Higgins found more than 200 milligrams of caffeine, the amount found in about two cups of coffee, can cause the heart rate to quicken and blood pressure to rise.
“There is nothing wrong with coffee in moderation,” Higgins said. “But excessive caffeine can have adverse effects even on young, healthy people.”
Caffeine can disrupt sleep because it blocks the release of adenosine, a chemical believed to induce sleepiness, said Dr. Richard Castriotta, medical director of the Sleep Disorders Center at Houston’s Memorial Hermann Hospital. Some are affected more than others, with the half-life of the effect of a cup of coffee averaging three to seven hours. Some people are affected for up to 14 hours.
“We see people who suffer insomnia get stuck in a vicious cycle,” said Castriotta, who is also a professor of medicine at the University of Texas Health Science Center in Houston. “They need caffeine to function during the day, but it’s disrupting their sleep cycle at night.”
Castriotta recommends that patients who suffer from insomnia avoid all caffeine. Once the problem is resolved, slowly reintroduce caffeine, he advises, to determine if it caused the insomnia.
Teenagers form another group that could be more susceptible to the negative effects of caffeine, such as irritability or sleeplessness. “If kids are drinking coffee all the time rather than milk and water,” Hensrud said, “that could be a problem.”
Changing Science
If you have a hard time keeping up with the newest verdict on java, you are not alone. For years, coffee was linked to increased rates of pancreatic cancer, heart disease and high blood pressure.
Why the sudden change? Doctors and researchers cite a few reasons.
“Medicine, especially nutrition science, is constantly changing as we learn more,” Hensrud said.
Coffee is particularly complex, he said, containing hundreds of different compounds, some of which — such as antioxidants — are beneficial. Some, however, are not. And different people metabolize the same substance differently. Also, Hensrud added, earlier research didn't always take into account high-risk behaviors, such as drinking and smoking, which often go hand in hand with heavy coffee drinking.