Weighing Benefit of Green Tea

Can green tea spur weight loss? A growing number of dieters are latching on to supplements containing green tea as an alternative to the popular ephedra pills, which will be banned in April due to their health risks.

Sales of green-tea nutritional supplements have grown steadily to $74 million in 2002 from $14 million in 1997, according to San Diego-based Nutrition Business Journal.

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Green tea has been valued in Chinese folk medicine for helping people maintain their weight. To sort out such claims, scientists in recent years have begun exploring the issue.

Some studies suggest that catechin polyphenols -- antioxidants found in all types of tea -- may help with weight loss by boosting metabolic rates and speeding up fat oxidation. But while many experts agree that green-tea supplements won't hurt you, any real weight-loss benefit is up for debate.

A small 1999 Swiss study found that six out of 10 healthy men taking capsules of green tea extract burned, on average, about 80 additional calories a day compared with days they were taking a placebo. In comparison, only two of the 10 men, when given caffeine pills, burned extra calories. Another study conducted by the U.S. Agriculture Department found that 12 men who were assigned to drink about five cups of Oolong tea each day burned an extra 67 calories a day on average, compared to when they weren't taking the tea.

Those studies have been pooh-poohed, however, for being so small and for their inclusion of healthy, lean people. In addition, caffeine by itself is a mild appetite suppressant.

Even if those extra burned calories are real, doctors and nutritionists point out that a 30-minute walk can use more than 100 calories, providing cardiovascular benefits at the same time.

Such doubts haven't stopped manufacturers in the $19 billion-a-year nutritional supplement industry from heavily marketing pills containing green-tea extract as an effective way of "controlling" weight. Some ads use recognizable celebrities as spokesmodels, such as Anna Nicole Smith, heightening the public's interest in ephedra-free products. The Food and Drug Administration doesn't regulate nutritional supplements anywhere near as closely as pharmaceuticals, leaving consumers to sort through the advertising claims.

Figuring out whether the green-tea supplements are effective can be complicated. Many products have other ingredients, such as cocoa extract, vanadium, bitter orange and chromium, a necessary nutrient that can be toxic at high levels. And those ingredients haven't been proved valuable for weight loss. Generally, green-tea supplements cost $5 to $40 a bottle.

Better and less-advertised evidence shows green tea can be useful in reducing the risk of heart disease and lowering cholesterol levels, due to those beneficial catechin polyphenols, which are a type of flavonoid, chemicals that act as antioxidants and are also found in beverages such as grape juice and beer.

Supplement makers claim the green-tea extract is more concentrated than the brewed version, so simply drinking green tea won't render the same results. You might have to consume more cups of the green-tea beverage for a similar effect, scientists say.

While green tea is a healthy drink, high amounts of its caffeinated extract may cause anxiety and insomnia. And high consumption of green tea in combination with other caffeine sources could raise your heart rate and blood pressure -- similar to the effects that made ephedra unsafe.