Tuesday, September 30, 2008

Coffee and Tea Are Good for Us? Yes! (First in a Series)

You'll be pleased to learn that many of the foods and drinks you love are not just "okay" as an occasional indulgence—they're good for you! Let's begin with coffee and tea…and I invite you to read my related articles on wine and beer, and on chocolate.
Coffee is made from the roasted and ground seeds of several tropical trees or shrubs of the genus Coffea.
An Arabian legend tells of a goatherd who made a beverage from berries growing on strange shrubs, and after drinking it experienced extraordinary lucidity and wakefulness. The shrubs were said to have been planted by the descendants of the Queen of Sheba, who came from Ethiopia, where Coffea arabica originates.
Nearly 20,000 scientific studies to date have been conducted on coffee or caffeine. Here, in a nutshell, are the results: not only is drinking coffee in moderation no threat to health, it actually can be a boon. It is harmless even during pregnancy, and children are no more sensitive to caffeine than adults.
"Moderate" consumption is generally defined as 300 mg daily—two to five cups of coffee, or four to eight cups of hot tea, depending on the size of the cup. The average American consumes about 200 milligrams of caffeine daily, roughly the equivalent of two cups of coffee (a figure that of course includes those who drink none at all).
Dark-roasted coffees may contain less caffeine than more lightly roasted beans; arabica beans tend to have less caffeine and milder flavor than robusta. There are also significant variations in the variety of coffee or tea and the brewing method used. But because less tea is required to make a cup of tea, generally a cup of coffee has more caffeine—approximately twice as much. On a pound-for-pound basis, tea has more.

It depends. Which has more caffeine, coffee or tea?
"Decaffeinated" coffee and tea contain about 5 mg per cup.
(Now, that's good news for those of us who prefer coffee but feel obligated to switch to herbal tea with the onset of a sore throat or stuffy nose!) This alertness-enhancing effect also can relieve the malaise associated with the common cold. All this has important implications especially for night shift workers and for drivers, as well as for anyone wanting to remain productive on the job after lunch. Caffeine can increase the speed of rapid information processing, alertness, energy, endurance, motivation, and concentration. While individuals vary in their sensitivity to caffeine, some generalizations apply.

Caffeine is a central nervous system stimulant.
So it's no surprise that it's an active ingredient in headache relievers. Caffeine soothes headaches by constricting blood vessels in the brain, which in turn reduces cranial pressure.
Some studies have linked caffeine consumption to a decline in levels of depression and anxiety.
Caffeine has long been known to help asthmatics, many of whom have found regular consumption of coffee to have a moderating effect on attacks. That's no surprise, either, thanks to the ingredient theophylline—a drug prescribed for symptomatic relief of bronchial asthma.
Higher caffeine intake is associated with a significantly lower incidence of Parkinson's disease. That's because caffeine intake reduces the amount of dopamine depletion, one of the characteristics of Parkinson's.
Last but not least, caffeine stimulates metabolism.
Flavonoids are particularly widespread in plants and likewise important in disease protection. A characteristic of many plants is the abundance of compounds with antioxidant properties, and coffee is no exception. Caffeine aside, coffee has a complex chemical composition.
Antioxidants reduce the risk of cancer and prevent good (HDL) cholesterol from turning into bad (LDL) cholesterol, a cause of heart disease. Antioxidants neutralize the effect of "free radicals," highly reactive molecules that travel around the body causing chemical chain reactions that can damage cells, by binding with the extra electrons. Free radicals also have been implicated in strokes, cancer, and the aging process. Substances with antioxidant activity are found to be generated in the roasting process.
Coffee is a good dietary source of potassium. That makes coffee a good choice as a diuretic; potassium loss is an undesirable side effect of most diuretics. Coffee can reduce the risk of cirrhosis of the liver.
Tea is made from the leaves of a shrub of the Camellia genus.
The Chinese first gathered tea leaves in the wild, and have cultivated the tea plant at least as far back as 350 AD. The court of England's Charles II in the 17th century established tea as a fashionable drink for the elite.
The firing, fermenting, and/or oxidizing that is done to the leaves determines whether the tea will be green, black, or oolong.
Tea is a source of vitamins A and B6, thiamin, and riboflavin; nicotinic, pantothenic, ascorbic, and folic acids; manganese, potassium, and fluoride.
Flavonoids are found in all types of tea; green tea has the highest concentration. Tea is being studied for its benefits in enhancing immune function, lowering LDL and raising HDL levels, reducing blood pressure, thinning blood, reducing the risk of heart attack, stroke, and cancer, increasing longevity, aiding digestion, and promoting dental health.
There is convincing evidence for a protective effect of both coffee and tea against colorectal cancers, the second leading cause of cancer-related deaths in the United States. High coffee intake decreases the excretion of bile acids, which are suspected carcinogens to the colon. Because of its diuretic properties, caffeine may help lower the risk of bladder cancer.
(A slight advantage was found in caffeine-containing coffee over decaffeinated.) Interestingly, increased consumption of apple and grapefruit juices correlated with increased risk of stone formation. Greater intakes of coffee and tea, both regular and decaffeinated, were associated with a decreased risk of kidney stone formation, significantly more so than water.
This may not, however, be a straight cause-and-effect relationship: possibly people who choose to drink coffee have more youthful/healthful lifestyles in other respects. One study has found that people who drink coffee are less likely to suffer heart disease than are tea drinkers.
Science has debunked the dark myths that caffeine contributes to breast cancer, bladder cancer, ulcers, indigestion, and osteoporosis.
In some patients, caffeine is associated with temporary rises in blood pressure, so people with high blood pressure might be advised to avoid caffeine during high-stress times. Is there any reason not to consume caffeine?
Moreover, those more sensitive to caffeine may not be able to drink coffee or tea late in the day because caffeine delays the onset of sleep. Worse, some people may not be aware that they are not as rested the following day as they should be, and thus may be more prone to fatigue-related accidents.
Is it possible to become addicted to caffeine? Coffee drinkers do not exhibit the behaviors that define addiction—severe withdrawal symptoms, tolerance, the need to consume the addictive substance at all costs, and antisocial behavior including crimes. Neither coffee nor other products containing caffeine are classified by drug dependence experts as addictive.
Weaning oneself gradually—say, over a week—should minimize the discomfort. The most common withdrawal symptoms include headaches, fatigue, drowsiness, irritability, depression, and flu-like feelings. Nevertheless, giving up caffeine suddenly can be unpleasant.
So drink up—without the guilt.


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