Green Tea

Cancer fighter, weight loss aid, and all-around super food? Time to tee up the evidence.

Monica Reinagel, M.S.,L.D./N,
April 8, 2009
Episode #038

I’ve accumulated a small stack of listener questions about tea, green tea in particular. Tori wants to know about the antioxidants it contains. Garrison wants to know if it can help you lose weight. And Martin is wondering whether it matters if the tea is loose leaf, in tea bags, pre-made in bottles, or in pill form.

What Is Tea?

We commonly refer to any beverage that’s made by steeping leaves, flowers, roots, or bark in water as “tea.” There are literally thousands of things you can brew this way: everything from chamomile to licorice root to rosehips to mint leaves. But, strictly speaking, it’s only tea if it’s made from the leaves of a plant known as Camellia sinensis. Everything else is properly called a “tisane.” Herbal tisanes have a wide range of health benefits, but today we’ll focus on the benefits of the Camellia sinensis, or tea, plant.

Tea is actually a type of evergreen shrub that grows in tropical and subtropical climates. When the leaves (or needles) are very young and immature, they can be collected and dried as white tea. Later in the season, once they’ve greened up a bit, they are harvested and preserved as green tea. Black and oolong teas are made by fermenting the green leaves, which turns them black.

Tea: What’s In It For You?

So, what can drinking tea do for you? First off, tea contains caffeine and, as I talked about a couple of weeks ago, drinking caffeinated beverages seems to have some protective benefits for your brain. The amount of caffeine in tea and coffee can vary a LOT, depending on how you brew them. But in general, coffee has two or three times more caffeine than black tea, which has about twice as much caffeine as white or green tea.

Tea is also very high in disease-fighting antioxidants called polyphenols and catechins. These compounds, which are found in other healthy foods as well, appear to protect against both cancer and heart disease. And, in fact, people who drink more tea do seem to have lower rates of these diseases.

Benefits of Green Tea

Now, all forms of tea—white, green, and black—are high in antioxidants. But the most potent antioxidants seem to be found in green tea. In particular, green tea contains a compound called epigallocatechin-3-gallate (or EGCG, for short) which seems to have some very special properties. Black tea doesn’t contain much EGCG because the fermentation process converts this chemical to a different antioxidant compound.

EGCG has gotten a lot of attention over the last several years, fueling green tea’s reputation as a super food. Researchers have observed, for example, that people who drink two or three cups of green tea every day appear to have a lower risk of heart disease, many types of cancer, osteoporosis, and even gum disease.

That suggests that you could lower your risk of these diseases by drinking green tea. But these findings are still preliminary. Most of the data on the effect of green tea in humans (as opposed to animals or test tubes) have been collected in Asia, so it’s still unclear whether those benefits would apply equally to those eating a Western diet, for example.