With voluminous scientific evidence now showing that it protects the heart, helps stave off diabetes and provides other significant health benefits, it’s no surprise that green tea is among the most popular health foods in the US.

The disease-fighting punch of green tea is largely due to its high concentration of epigallocatechin gallate (EGCG), a substance with more antioxidant activity than vitamins C and E and other nutritional heavyweights.

The other side of the green tea story: Even if you are consuming green tea, the truth is that you might not be getting what you pay for.

Some bottled green teas and even green tea supplements contain only trace amounts of EGCG. Meanwhile, the amount of EGCG in other green tea–based products can vary by more than 240%. These and other findings, from the scientists at ConsumerLab.com, an independent laboratory that evaluates supplements and other products, show just how important it is to shop wisely for green tea products.

WHY GREEN TEA?

Both green and black teas (they come from the leaves of the same plant) contain catechins, a group of antioxidants that includes EGCG. Green tea is particularly rich in these compounds, with about four times more EGCG than black tea.

Multiple large studies suggest that green tea is good for cardiovascular health. For example, people who drink five or more cups daily are about 20% less likely to develop heart disease than those who don’t drink green tea. Green tea drinkers also have lower cholesterol and a lower risk for stroke.

One large analysis, which pooled data from 20 previous studies, found that people who drank three or more cups of green or black tea daily were 16% less likely to develop diabetes. Green tea has also been linked to reduced risk for stomach, lung, breast and other cancers.

While these studies did not examine the brand or exact source of the green teas that were consumed, it stands to reason that if you want to get the health benefits, you want a green tea with a good amount of EGCG.

LABELS THAT LIE

The FDA doesn’t test tea or tea-based supplements. Without testing, it’s impossible to know how much EGCG is in a particular product. And even when this information is included on the label, it may not be accurate.

ConsumerLab.com purchased dozens of commonly available tea products, including tea leaves, tea bags, bottled beverages and supplements. The products were tested for levels of EGCG, lead contamination and amounts of caffeine, which naturally occurs in green tea. They were also analyzed for cost—how much you have to pay to get 200 mg of EGCG, which is the daily amount that’s recommended by many experts. Key findings…

TEA LEAVES/TEA BAGS

Labels may or may not include the amount of EGCG per serving. You will obviously get more if you drink more tea or if you increase the strength of the tea by using more than the recommended amount.

Don’t forget that green tea does contain caffeine—the amounts range widely from about 20 mg per cup to as much as 85 mg. If caffeine is a problem for you, decaffeinated green tea may be a good option. Some reports have suggested that decaffeinated green tea has less EGCG due to processing than the caffeinated version, but that was not shown to be the case in ConsumerLab.com’s analysis.

A variety of products were tested using the serving amounts recommended on the labels. The amounts of EGCG varied widely. A brand of loose-leaf tea, Teavana Green Tea Gyokuro, provided the most EGCG, with 86 mg per one-teaspoon serving. Bigelow Green Tea had the least, with 25 mg per tea bag.

Important: When you brew loose-leaf or bagged teas, steep them for three to five minutes. That’s how long it takes to extract the EGCG. Longer steeping times won’t extract more EGCG and may make the tea more bitter tasting.

Cost: Lipton Green Tea was the least expensive way to get EGCG due to its low cost (10 cents per bag) and relatively high level of EGCG (71 mg per bag). The most expensive was Teavana Green Tea Gyokuro at 94 cents per serving, despite its high level of EGCG (86 mg).

BOTTLED TEAS

If you are drinking tea mainly for the health benefits (rather than taste), bottled teas may not be the best choice. They are expensive…often contain little EGCG…and tend to be high in sweeteners.

None of the bottled green teas that were tested listed the amount of EGCG on the label, but Honest Honey Green Tea listed the amount of catechins. However, it had only 63% of the catechins listed on the label.

When tested, Harney & Sons Organic Green was found to contain 46.8 mg of EGCG per eight-ounce serving, which is comparable to some brewed teas. Honest Green Tea had 27.2 mg of EGCG, and AriZona Green Tea—Ginseng & Honey had only 5.4 mg. Snapple Diet Green Tea had even less—just 3.5 mg.

Cost: To get 200 mg of EGCG from bottled teas, you would have to spend a lot more per serving than with tea leaves/tea bags. The least expensive was Harney & Sons Organic Green at $4.45. The most expensive by far was Snapple Diet Green Tea. To obtain 200 mg of EGCG, you would have to spend more than $70 and drink 28 16-ounce bottles.

TEA SUPPLEMENTS

Supplements can be an effective way to get large amounts of EGCG. You would have to drink two or more cups of green tea to get the amount that’s included in a few supplement capsules. Also, supplements (in terms of their EGCG content) may be less expensive than other forms of green tea.

Here’s the problem: Most supplements list the amount of EGCG on the label, but you can’t always trust the numbers. For example, Omega Sports Green Tea contained only 38% of the EGCG listed on the label. The amounts of EGCG in other products averaged 188 mg per daily serving (that’s typically two capsules).

Cost: Trunature (Costco) Green Tea and NOW EGCG Green Tea Extract were the best value, with a cost of approximately 10 cents for 200 mg of EGCG. One of the more expensive supplements (which ConsumerLab.com didn’t approve in its report because of incorrect label information) would cost $3.41 for the same amount of EGCG.

BEWARE OF LEAD

In four tea-leaf products that were tested, small amounts of lead (2 mcg to 5 mcg per serving) were detected. Exposure to lead can lead to brain, nerve and kidney damage, particularly in children, who shouldn’t be exposed to more than 6 mcg per day from all sources. Adults can handle more (25 mcg to 70 mcg per day), but it’s best to avoid unnecessary lead exposure—it accumulates in the body.

All plants can absorb lead from the environment, but tea absorbs it more readily than other plants. In China, tea that’s grown near roadways or industrial areas can accumulate high levels of lead within the leaf and on the leaf surfaces. Fortunately, only about 10% to 20% of the lead that’s in tea gets into the liquid portion—most stays trapped within the leaves. If you don’t swallow the leaves, your lead exposure will be minimal.

My advice: When brewing tea, use tea bags or a fine strainer to help prevent leaf fragments from getting into the liquid.

Also: Check where the tea originated. When comparing the largest producers of green tea, the teas from Japan are less likely to contain lead than Chinese teas.

Free for Bottom Line/Health readers: For a complimentary, 24-hour pass to read ConsumerLab’s full green tea report plus reports on fish oil and iron supplements, go to ConsumerLab.com/BottomLine.