Once believed to stunt growth, cause cancer and trigger heart attacks, recent research indicates that coffee may be a powerful elixir. Our favorite brew has been shown to prevent diabetes, liver damage and gallstones, plus it may also improve physical endurance and pump up your brain power.
"Not only is coffee not bad for our health, as once believed, coffee may actually have a healthy protective effect," says Cheryl Rock, researcher and professor of nutrition at University of California San Diego's School of Medicine.Dr. Ken Fujioka, director of nutrition and metabolic research at Scripps Clinic, isn't surprised by the reported coffee perks.
"When I see patients, I look carefully at what they eat and drink," he says. "I find that the elderly patients who are the healthiest and doing the best have always had a cup or two of coffee every morning."
While the second-most consumed beverage on the planet (after water) is best known for providing a jolt of adrenaline-raising caffeine, to assume that all of its health advantages are due to caffeine may be misleading, Rock says. (Most of the studies looked at caffeinated, not decaffeinated coffee.)
"It may be something else. The healthy benefits may come from its plant source," says Rock, who calls coffee a "very complex beverage." "In addition to caffeine, coffee also has many useful antioxidants and phytochemicals (plant chemicals ) which can reduce inflammation and counteract and prevent many diseases."
The drink isn't perfect, though. It can be addictive, and too much of it can cause sleeplessness or the jitters. A safe limit, according to the American Journal of Clinical Nutrition is around 400 milligrams or three 8-ounce cups of coffee a day. Coffee's also been associated with fertility problems. Women who are pregnant, trying to get pregnant or breast-feeding, should talk to their doctor about recommended consumption.
While the coffee/health studies that have been reported seem promising, Rock says more research is needed before everyone trades in their ubiquitous water bottle for a coffee mug.
Most of the coffee studies have been "observational," examining lifestyle and dietary factors for possible connections to the risk for disease.
"These studies are good for creating a hypothesis, but further clinical studies have to be done," Rock says.
But, even though definitive conclusions about coffee's health benefits can't always be drawn, Fujioka would still recommend it to his patients, as long as it's not laden with loads of sugar and rich cream.
"The No. 1 health problem in the U.S. besides obesity is diabetes," he says. "So, if there's something that has no calories and has been shown to reduce the risk of diabetes and be protective for other diseases, then I'm all for it."
Here's a sampling of the good news about coffee and why you no longer need to feel guilt over enjoying this simple pleasure:
- Reduces risk of type 2 diabetes. As part of the Women's Health Study (recently published in the Archives of Internal Medicine), 29,000 postmenopausal women were followed for 11 years. It was found that women who drank more than six cups of any type of coffee per day were 22 percent less likely to develop diabetes than women who drank no coffee. Women who drank more than six cups of decaffeinated coffee had a 33 percent reduced risk.
Experts suspect that coffee's phytochemicals and antioxidants deserve the credit. Coffee may stimulate the muscles to burn carbohydrates more efficiently and help promote the delivery of insulin to the tissues, so insulin resistance is less likely.
- Reduce risk of liver disease. According to researchers at Kaiser Permanente in Oakland, Calif., drinking between one and four cups of coffee a day can reduce the risk of cirrhosis and is especially good at repairing the damage done by heavy drinking sessions.
In a study of 125,000 people, the risk of developing cirrhosis (a permanent scarring damage to the liver) was cut by 20 percent in those who drank one cup of coffee a day. That figure rose to 80 percent with four cups a day, and general blood tests showed healthier liver results in those who were coffee drinkers.
- No cardiovascular risk. "We can put the coffee-cardiovascular disease connection to rest. Coffee will not cause these problems," Rock says.
As long as you don't have high blood pressure, heart arrhythmia or anxiety, drinking coffee is no problem, reports the Journal of the American Medical Association. However, if you already have a preexisting cardiovascular condition, avoid excessive intake, since coffee may exacerbate it.
In May, the American Journal of Clinical Nutrition reported on a study that followed 27,000 women ages 55 to 69 for 15 years. It found a 30 percent reduction in the risk of cardiovascular disease among those who drank two to four cups of coffee a day.
- Increases alertness and cognitive functions. In your brain, caffeine intercepts adenosine, the chemical that slows down our nerves and brain and signals the need to sleep. It also increases dopamine levels, stimulating pleasure centers. So, coffee can make you feel both alert and relaxed.
- Improves physical stamina. Coffee can stimulate you to exercise 10 percent to 15 percent longer because it keeps you from getting tired, according to a study at Ontario's University of Guelph. Drinking a cup or two of coffee one hour before exercise may reduce muscle soreness during exercise, according to a 2003 study published in the Journal of Pain. Caffeine may stimulate the release of endorphins and hormones that depress the sensation of pain or discomfort.
However, a recent Swiss study reports that drinking coffee before exercise may reduce blood flow to the heart. Anyone with any coronary risk factors should probably skip the pre-workout java.
- Helps headaches. The caffeine in coffee constricts blood vessels, which is one reason it's used in some headache medications, including Excedrin and Anacin. It also increases the speed with which headache-reducing analgesics are absorbed into the body by as much as 40 percent.
- Minimizes tooth decay. Coffee drinkers' teeth may be stained, but at least they won't be full of cavities. Coffee's antibacterial properties may slow the growth of Streptococcus mutans, the culprit in tooth decay. Coffee also contains compounds that keep bacteria from sticking to tooth enamel.
- Reduces risk of kidney stones. It's no secret that coffee makes your bladder more active. While that can be annoying, it can also help reduce the risk of kidney stones, according to the Nurses Health Study. Those in the study who drank the most coffee had the lowest risks. Caffeine increases the flow of more diluted urine, which lowers the chance of a kidney stone forming.
- Reduces risk of Parkinson's. Some research shows that just one cup of coffee a day can halve your risk of Parkinson's, a brain disease that causes tremors and affects movement. Caffeine's adenosine-blocking power may protect the brain cells typically lost to Parkinson's, according to a study at the Harvard School of Public Health. Women on hormone therapy don't seem to benefit, however. Estrogen may dilute the effectiveness of caffeine.
- Reduces risk of gallstones. The Harvard School of Public Health found that male coffee drinkers had a 45 percent lower risk of developing the condition and females a 40 percent lower risk.
Gallstones are small blobs of hardened matter that form out of liquid in the gallbladder and can block intestinal tubes, causing painful and occasionally fatal damage.
- Does not lead to bone loss. Contrary to what we believed just a few years ago, coffee does not cause thinning bones. There's evidence that calcium is lost through urine and by increasing the amount of urine you produce, you decrease your body's calcium stores. The effect, however, is negligible.