Tea—black tea, green tea, white tea—is made from the tea plant. That’s different from herbal tea, which is defined as pouring hot water over any plant in the world other than this particular plant.

There are 287,655 different types of plants on the planet that we know of. Why is this one plant the most popular beverage in the world? It’s not the caffeine; the coffee plant has more caffeine, but more people drink tea than coffee. It’s probably not the taste; most people would probably prefer peppermint, or some of the fruity berry teas as better tasting. It’s a pretty enough plant, but why do we drink literally billions of cups a day of this one?

Well, we might have just figured it out. It turns out there’s something in this plant that’s basically found only two places in nature—here, and in a weird bluish mushroom called the bay bolete, which has these little holes instead of gills. Scientists figured this one might taste better with crumpets, and so they called the unique substance theanine. What does this stuff do that it has billions of people hooked on it? We weren’t quite sure, until last year.

When you hook up people to an EEG to measure their brain wave activity, you find that human beings essentially have four mental states—two while sleeping, and two while awake. Delta waves, where your whole brain is basically electrically pulsing very slowly at about a wave a second, are seen only in deep sleep. Then there’s theta wave sleep—when you’re dreaming—at about five cycles per second.

The two waking states are alpha and beta. Alpha is relaxed, aware, attentive; like when we close our eyes and meditate. And beta is more the stimulated, hustle-and-bustle state, where most of us live our lives.

Alpha is where we want to be; fully alert and focused, but calm. How do we get there? Well, if you relax in a nice peaceful place, after about 90 minutes you can start to see some significant alpha activity, which is this yellow and red. Now, practicing meditators, like Buddhist monks, can achieve this state earlier, and maintain it even with their eyes open.

So, you can meditate every day for a few years, or just drink some tea. This is the amount of theanine that enters your brain after you drink about two cups of tea. Look closely, compare, and see if you can detect a difference. That is why people drink tea from the tea plant.

But are there side effects to so dramatically altering our brain on a daily basis? Well, if you’ve seen my previous years’ lectures, you know that the side effects of daily tea consumption include things like less breast cancer risk, and living a significantly longer life.

Here are the new side-effects we just learned about in the last 12 months. Drinking tea from the tea plant halves our risk of getting ovarian cancer. Halves our risk of getting endometrial cancer. Can lower our cholesterol, our blood sugars, and our weight. Protect our liver. And protect our brain. Drink green tea every day.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by veganmontreal.

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