Every day, people around the world drink an estimated 2 billion cups of tea, the beverage made from the leaves of the camellia sinensis bush. Whether black, green, oolong, or white, most of those cups are downed for enjoyment or as a pick-me-up. But the many bioactives in tea—catechins, caffeine, chlorogenic acid, theaflavins, and more than 2,000 other natural chemicals—do more than deliver a satisfying brew.
Many of these natural chemicals are plant compounds called polyphenols that energize cells, improve the signaling between body systems, and rev up metabolic mechanisms like fat-burning, rejuvenating your body and reducing your risk of the chronic diseases that harm or kill millions, like cardiovascular disease, cancer, diabetes, and dementia.
In a recent 11-year study with 500,000 participants conducted by researchers at the National Institutes of Health, people who consumed two to three cups of tea a day had a 13 percent lower risk of dying from any cause, compared with people who did not drink tea. The tea drinkers also had a lower risk of dying from heart disease and stroke.
People who drink more tea are more likely to have better health outcomes.
Cardiovascular disease. Tea helps lower the risk of cardiovascular disease in several ways. It lowers high blood pressure, a major risk factor for heart attack and stroke. It improves blood flow, protecting the heart and brain. It helps healthy gut bacteria generate more short-chain fatty acids, which reduce inflammation, a key driver of cardiovascular disease. Tea also lowers LDL cholesterol and triglycerides, and it mobilizes the body’s stem cells for repair—including the repair of the lining of blood vessels.
In one study, drinking two cups of black tea daily increased endothelial stem cells by 56 percent. In another, researchers gave 20 men who had smoked for at least six years four cups of green tea every day for two weeks. Drinking green tea increased the number of circulating, reparative stem cells by 43 percent.
Cancer. Your body forms microscopic cancers all the time. Most of these mini tumors are eliminated by your immune system. They only become dangerous when they hijack normal blood vessels and redirect your blood supply to feed the cancer. This process is called tumor angiogenesis, and extensive research shows that tea can stop these abnormal blood vessels from growing.
Cancers that have been treated by chemotherapy or surgically removed often recur because cancer stem cells remain in the body, allowing the cancer to resurrect itself. For example, between 10 to 40 percent of women who are supposedly cured of breast cancer have a recurrence.
Research shows that one of the main polyphenols in green tea, epigallocatechin-3-gallate (EGCG), can kill cancer stem cells. Numerous studies bear out this cellular research, with people who drink more tea having less risk of various cancers. In a meta-analysis of 43 of those studies, researchers at Harvard Medical School reported that tea reduced the risk of oral cancer by 38 percent, and also reduced the risk of breast, liver, endometrial, and biliary tract cancers.
Type 2 diabetes. In a recent 10-year study reported at the European Association for the Study of Diabetes Annual Meeting, drinking at least four cups a day of black, green, or oolong tea reduced the risk of developing type 2 diabetes by 17 percent. And in a five-year study published in BMJ Open Diabetes Research & Care, people with type 2 diabetes who drank at least four cups of green tea had a 63 percent lower risk of death from any cause. Obesity and type 2 diabetes go hand in hand. EGCG and chlorogenic acid (another bioactive found in green tea) have been shown to activate brown fat, a useful type of fat that helps burn white fat.
Dementia. Researchers analyzed health data from more than 350,000 people ages 50 to 74 and found that those who drank three to five cups of tea daily had a 28 percent lower risk of dementia.
Tips for healthy tea-drinking
There are many simple ways to maximize the health-giving effects of drinking tea. Choose the type you like the most, whether it’s black, green, oolong, or white. All types of tea are loaded with health-giving bioactives.
- Loose-leaf, bagged, or powdered? If loose leaf tea is your choice, you can keep pouring water on the leaves for three brewings. After that, change the leaves.
If you choose a tea bag, dunk the tea bag up and down for a couple of minutes to shake the polyphenols out of the leaf. If you choose a powdered tea like matcha, put in as much powder as the instructions say—or as much as you want to have the most pleasurable cup of tea.
- Temperature. Polyphenols are present in hot and cold tea. Most laboratory-
based research on tea involves first brewing tea, then refrigerating (or even freezing) it overnight, and then thawing it out for studies later. And it’s still loaded with polyphenols. Steeping in hot water does not destroy healthful polyphenols like catechins, but don’t drink scalding tea—it has been linked to esophageal cancer. Put very hot tea in a mug and let it cool to a drinkable temperature.
- Added milk. When you add milk or cream to tea, the dairy creates fatty bubbles that entrap the polyphenols, reducing their absorption by about 20 percent. If you’re drinking tea for health, it’s better not to use dairy. Try a plant-based milk like soy, oat, or almond, which gives the tea a rounded flavor similar to dairy but doesn’t form bubbles that block polyphenols.
• Amount. The sweet spot for “a spot of tea” is two to three cups daily. But if you enjoy drinking more, no problem—there are no recorded cases of anybody overdosing on tea.