Coffee does more than help you get started and keep going. It also keeps you healthy. Over the past two decades, close to 20,000 studies have closely examined the effect of coffee on health and almost all conclude that a few cups a day lower the risk of several diseases, including diabetes, heart disease, colon cancer, liver cirrhosis and Parkinson's.
Last week, US researchers identified how coffee helps you lose weight and lower diabetes risk. A compound called chlorogenic acid (CGA) in coffee beans lowered insulin resistance and fat accumulation in the liver, they report in the journal Pharmaceutical Research. The compound is a powerful antioxidant that reduces inflammation, a risk factor for heart attacks and stroke.
Apart from coffee beans, CGA is found in lower amounts in fruits and vegetables, such as apples, pears, tomatoes and blueberries. Other antioxidants found in coffee beans include phenols, volatile aroma compounds and oxazoles, all of which prevent cell damage that slow disease development and ageing.
Drinking one to three cups of caffeinated coffee each day reduced diabetes risk by several percentage points, compared with not drinking coffee at all. More significantly, having six cups or more a day slashed men's diabetes risk by 54% and women's risk by 30% over those who avoided coffee, wrote researchers from Harvard in The Annals of Internal Medicine. The study does make you wonder, though, whether the participants slept at all during the duration of the study.
Then, there are heart benefits. Using data on more than 27,000 women ages 55 to 69 in the Iowa Women's Health Study who were followed for 15 years, Norwegian researchers concluded that women who drank one to three cups a day reduced their risk of heart disease by 24% compared with those who drank no coffee at all.
As a stimulant, caffeine leaves some people sleepless, but most others benefit from its kick. It increases the speed of rapid information processing in the brain by 10%, and a couple of cups help to improve alertness and concentration during night shift hours, report researchers in Psychopharmacology.
According to The Journal of the American Medical Association review of six studies, people who drink coffee regularly are at an 80% lower risk of Parkinson's disease. Other studies indicate that, compared to not drinking coffee, drinking at least two cups per day led to a 25% lower risk of colon cancer, an 80% drop in the risk of liver cirrhosis, and nearly 50% reduced gallstone risk.
So, is it caffeine that is responsible for these benefits or the antioxidants found in the beans? Studies indicate that it might be both. Researchers believe that some of coffee's reported beneficial effects are a direct result of its higher caffeine content: A 250-ml cup of coffee contains about 85 mg of caffeine, about three times more than the same serving of tea or cola.
On the other hand, coffee is not for everyone. Caffeine is a temporary stimulant that can affect the central nervous and cardiovascular systems, increase heart rate and blood pressure. In excessive amounts, it can cause nervousness, jitters, and rapid heartbeat, with a study in the American Journal of Epidemiology linking it with higher cholesterol levels.
Having coffee or tea with or after meals as is usually done is not a great idea. Caffeine lowers calcium and iron absorption and also increases calcium loss through the kidneys and the intestines, so people who have a lot of coffee should make sure they take adequate amounts of calcium.
So, how much caffeine is too much?
An average person's daily caffeine intake should not exceed 300 mg- that's about three cups of coffee a day. The American Academy of Pediatrics recommends that pregnant women and nursing women should limit the caffeine-intake to 100 mg, as caffeine can enter breastmilk and make a baby wakeful and agitated. Children, too, should limit caffeine intake to 100 mg a day as it can make them hyperactive.
But before you start counting your cups of coffee, don't forget to include other sources of caffeine. Many people overdose on caffeine simply because they forget tea, colas, energy drinks and chocolates also have some amounts of caffeine.
Carbonated drinks (colas) apart, caffeine is added to medicines, including analgesics (where caffeine acts as an adjuvant), diet aids, and cold medicines. Since caffeine is a broncho-dilator (widens the airways), it is used for the treatment of neonatal apnoea (inability of the newborn to breath properly) and recommended in limited amounts for asthmatics.
While its stimulant and diuretic properties may make it difficult to label caffeine as a health food, there are no two opinions about it being a beneficial drink.