Cancer fighter, weight loss aid, and all-around super food? Time to tee up the evidence.
Cancer fighter, weight loss aid, and all-around super food? Time to tee up the evidence.
Nutrition Diva is hosted by Monica Reinagel. A transcript is available at Simplecast.
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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.
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.
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.
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.
I doubt that green tea will turn out to be the magic bullet against all disease. But I think the evidence will ultimately confirm that drinking green tea is a really healthy habit, just like eating your vegetables, flossing, and wearing your seat belt.
In the meantime, the market has been flooded with products by people trying to make as much money as possible from the health halo surrounding green tea before we all lose interest and move on to the next health craze.
In particular, a lot is being made of research showing that green tea can help you lose weight. While there is some evidence that EGCG could promote weight loss, you really have to read the fine print.
For example, one study found that people who drank green tea and engaged in moderate intensity exercise for three hours a week lost slightly more weight than those who exercised the same amount but didn’t drink green tea. In a different study, however, researchers found that giving green tea extracts to overweight people who weren’t dieting or exercising had no effect whatsoever.
In other words, if you are dieting and exercising enough to lose weight, drinking some green tea might give you a little incremental boost. But simply drinking green tea or taking green tea extracts is not going to magically melt off the fat. Sorry, Garrison.
Finally, to answer some of Martin’s questions, you get the biggest dose of EGCG in green tea that is brewed from tea bags or loose tea leaves. Decaffeinated and flavored green teas have quite a bit less EGCG, and those bottled, sweetened green teas that are so popular now contain the lowest amounts. In fact, I’d say the nutritional downside of the sugar in these beverages far outweighs any benefits you might get from the remaining antioxidants.
And what about these capsules that are supposed to provide the benefits of several cups of green tea in a single pill? Well, we don’t yet know how green tea extracts might affect your health over the long term. But if the past is any guide, I’m not all that optimistic.
We have this tendency to take whatever we think is the healthiest part of a food and put it into a pill. I guess this is meant to save everyone the trouble of actually eating healthy foods. But that never seems to work as well as we hope it will. For one thing, whenever we set out to extract the magic compound from a food, we inevitably leave out some other compound that turns out to be just as important.
Also, just because something is good for you, it doesn’t necessarily follow that taking a super concentrated form of it is better for you. And finally, when we actually eat healthy foods, instead of trying to take them in pill form, there’s a greater likelihood that we eat these foods instead of less healthy foods—and that may be at least half the benefit.
If you’d like to enjoy the health benefits of green tea, I suggest you buy some loose green tea or tea bags and enjoy a cup or two a day. Home-brewed iced green tea is also terrific. I’ll include some links in the show notes to more on the art of brewing and enjoying green tea, along with some of the research on green tea.
And for a Quick Tip on making green tea that tastes better (not bitter), head on over here.
This is Monica Reinagel, the Nutrition Diva, reminding you that these tips are not intended as medical advice.
If you have a nutrition question for me, send an email to nutrition@quickanddirtytips.com and include the topic of your question in the subject line of your email.
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Have a great day and eat something good for me!