If you drink green tea for your health, be aware that the catechin and caffeine levels can vary by more than 240 percent across products. Some also contain significant amounts of lead in their tea leaves. This is according to recent tests by ConsumerLab.com, which reports on the quality of health and nutrition products. Brands of green tea reviewed were Bigelow, Celestial Seasonings, Lipton, Salada, and Teavana. The products were tea bags, a loose tea, and a K-Cup (for brewing in a Keurig machine).

Studies of large populations have found that drinking at least 2 to 3 cups of green tea daily is associated with a reduced risk of cardiovascular disease, certain cancers and type 2 diabetes. In addition, supplements containing green tea compounds may assist in weight loss and reduce the risk of prostate cancer.

ConsumerLab.com found the amount of tea leaf in a suggested serving of each product to range from 1.38 grams to 3.14 grams, with some larger tea bags actually containing less tea than some smaller bags. In terms of chemical strength, servings yielded from 25 mg to 86 mg of EGCG, one of the key "catechin" compounds in green tea and a natural phenol in the flavanol family. The amount of caffeine per serving ranged from 22.7 mg (less than in a can of cola) to 85.8 mg (similar to that in a cup of regular coffee), with decaffeinated teas containing just 5 mg.

ConsumerLab.com found the cost to get 200 mg of EGCG from the brewed teas ranged from 27 cents to $2.50. The cost to obtain the same amount of EGCG from green tea dietary supplements tested earlier by ConsumerLab.com ranged from 10 cents to $3.41, and from bottled green teas the cost was $4.45 to $71.72.

ConsumerLab.com also measured the amount of lead, a toxic heavy metal, in each product. Lead is known to be taken up into tea leaves from the environment and can occur in high amounts in tea plants grown near industrial areas and active roadways, such as in certain areas of China. Although the liquid portions of the brewed teas did not contain measurable amounts of lead (i.e., no more than 1.25 mcg per serving), when including the brewed leaves in the analysis, 2 to 5 mcg of lead was detected per serving in four different products, including an "organic" green tea. Interestingly, measurable lead was not found in decaffeinated green teas or in a Japanese green tea. Most of the teas reviewed likely originated in China.

"The bad news from our tests is that there can be significant amounts of lead contamination in some green tea sold in the U.S.," said Tod Cooperman, M.D., president of ConsumerLab.com. He continued, "The good news is that most of this lead stays within the leaves and doesn't get into the tea." His advice: Be sure to use a tea bag or other filter for your tea and don't eat the tea leaves unless you know they are not contaminated."

Test results and comparisons of all the products are found in ConsumerLab.com's report, Green Tea Supplements, Drinks, and Brewable Teas Review, which can be accessed online.