Is tea good for you?

It's full of health-giving antioxidants. But what about the caffeine and tannin?

By Moira Adams

Granada Tea Market

Tea Market in Granada
Photo © Ruth Lewis

Tea is often promoted as a healthy drink - especially when compared to caffeine-laden coffee. But tea also contains caffeine (although not as much as coffee) as well as other possibly harmful ingredients such as tannin. Then again, it's also rich in beneficial antioxidants. So does the good outweigh the bad?


Countless studies have shown that drinking moderate amounts of tea is good for your health. Just two or three cups a day can reduce the risk of cancer, fight heart disease, prevent arthritis, improve your dental health, delay the effects of aging, and even reduce the risk of getting Parkinson's disease, according to these studies.

The reason is simple. Like fruit and vegetables, tea is resplendent in antioxidants. These substances, which in tea are known as flavonoids, are a vital agent in countering the damaging effects of free radicals on body tissues. There's overwhelming evidence that a diet high in antioxidants can boost your health in a variety of ways.

One particular antioxidant in tea, known as catechin, is especially valuable in strengthening your teeth and gums. Another important ingredient is fluorine, which plays an important role in improving bone density. Tea also helps keep you hydrated. And if drunk without milk or sugar, it has almost no calories.


One reason some people steer clear of tea is that it can slow down the absorption of iron in the diet. In fact, this is only a problem for people with serious iron deficiencies or who are prone to anemia.

If you are in that category, you should avoid drinking tea at meal times, and limit your intake at other times to two or three cups a day. Adding milk or lemon will also help counteract the problem. For the rest of the population, it isn't an issue.

Which kind of tea is healthiest?

Both green and black varieties of tea have similar levels of antioxidants, and offer similar health benefits. In fact, green tea and black tea are really the same thing - at least, they come from the same plant. They differ only in how they are processed.

As an exception, green tea is a better source of catechin (mentioned above).

It makes little difference whether you brew your tea from leaves or tea bags, or whether you drink it hot or cold. However, you should avoid instant tea or bottled ready-to-drink products, as the health benefits are greatly reduced in those cases.

But what about the caffeine?

Most of us need a shot of caffeine to get us started in the morning and to help us through the day. Experts agree that a moderate amount - the equivalent of two or three cups of coffee per day - is beneficial. It stimulates the nervous system, keeps us alert and wards off fatigue.

But larger amounts of caffeine can cause problems. These range from headaches and anxiety to irritability and insomnia. People vary in how they react to excess caffeine: some have those symptoms after just one strong coffee. And some people are required to reduce their caffeine intake for medical reasons, as caffeine can interfere with the workings of some medicines.

As a rough guide, black varieties of tea contain a little less than half as much caffeine as an equivalent amount of coffee. And green varieties contains about half as much as black. A large cup of strong coffee will typically contain 90 to 120 milligrams (mg) per cup. Instant coffee has around 70 mg; black tea, 40 mg; and green tea, 20 mg. By comparison, a 12-oz (360 ml) can of Coca Cola has 34 mg, and a 1-ounce (25 gm) chunk of dark chocolate has about 20 mg.

On that basis, around half a dozen cups of black tea per day will be within a safe range for most people. If you feel the need to imbibe larger quantities, switch to a green variety. (But, remember, this doesn't apply if you are particularly sensitive to caffeine or you have been advised to cut down for medical reasons.)

Of course, there's also the option of switching to decaffeinated tea. Like decaffeinated coffee, this isn't completely free of the drug, but the content is very low - typically less than 4 mg per cup. Unfortunately, there's also evidence that decaff tea is poorer in antioxidants.

And the tannin?

As well as caffeine, tea contains relatively large amounts of tannin. Some people worry that tannin causes stomach problems, as well as irritation of the bowel and possibly kidney and liver damage. However, you would have to drink large amounts of tea for those problems to occur. Even people who are particularly sensitive to tannin are not usually advised to reduce their tea intake (but that doesn't necessarily apply to tannin from other sources, such as certain herbs).

In general, green tea has less tannin than black. The longer you brew the tea, the higher the tannin content. And contrary to popular opinion, tea does not contain tannic acid (the substance that's used for tanning leather).

Herbal and fruit teas

Not surprisingly, herbal and fruit teas have become very popular in recent years, entirely on the strength of their supposed healthiness. After all, we know that fruit is full of vitamins, and all manner of therapeutic benefits are attributed to herbs. Herbal and fruit teas (which, by the way, are not really teas at all) are also naturally caffeine-free.

Unfortunately, the quantity of herb or fruit found in these products is much too low to have an effect. This is especially true if you make the brew from tea bags, most of which contain only minuscule amounts of herbs (you'll get slightly more benefit if you make the tea from fresh herbs, in the form of a tisane). As for fruit, many so-called fruit teas contain no fruit at all, only fruit "flavorings".

Green tea

Photo © Veg World

One possible exception is rooibos tea. Grown in South Africa, where it's also known as red tea or bush tea, this beverage does have high levels of antioxidants, although no studies have yet been done to support its health claims. It also has low tannin levels and is free of caffeine.

Summing up

On balance, it's safe to say that tea (real tea, that it, not the herbal or fruit varieties) offers substantial health benefits. The only significant downside is its caffeine content, but this is not likely to be a problem for the average tea drinker. So, assuming you don't drink more than about six cups per day (or fewer, if you also drink coffee), you can relax and enjoy a nice brew-up at any time.

October 2010

Please note: Neither Veg World nor its contributors are qualified to give medical or nutritional advice. If in doubt, always consult a suitably-qualified professional.

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