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This One Tea Habit Ruins Its Health Benefits, New Study Says

Approximately 60 percent of tea drinkers do this, which impacts a critical function of the body.

Some experts have reported tea is the second most popular beverage in the world, trumped only by water. (Coffee and wine lovers, it will all be OK.) Tea's timeless popularity means big payoffs for those who drink it, as many studies have pointed to the many medicinal benefits of a nice, brewed cuppa.

Now, a study published this month in the journal Cellular Physiology and Biochemistry has highlighted what seems to be an additional benefit to drinking black and green tea. Knowing that past research found that antioxidants in these teas have helped to fight cancer and promote cardiovascular health, a team of researchers at the University of California, Irvine aimed to examine whether black and green tea could trigger an expansion of blood vessels in a way that lowers blood pressure. (Related: The One Vitamin Doctors Are Urging Everyone to Take Right Now)

Indeed, the research team found that two polyphenols in black and green tea "strongly" activated a specific gene, KCNQ5, which regulates neural activity and can lead to less constriction—that is, greater expansion—of the blood vessels.

It's exciting news that could even yield a breakthrough in the development of blood pressure medications. However, the researchers were careful to factor in the notion that, as they write, "Black tea, typically consumed with milk, is preferred over green tea in many countries, such as United Kingdom"—where an estimated 60% of tea drinkers add milk. Thus, as part of the study, they examined this common addition to black tea, which resulted in a clear finding: When cow's milk is added to black tea, the milk inhibits the activation of the KCNQ5 gene that helps to open blood vessels.

In other words, if you have high blood pressure and wonder what this means for your daily habits, you'll want to take your tea plain with no milk. However, don't give up dairy just yet: the milk alone didn't produce this hindrance to activation—it was only when milk was combined with black tea that the researchers saw no significant benefit in lowering blood pressure.

How do you take your tea? However you like, you'll surely want to check out the surprising side effects tea has on your immunity, according to science. And to get breaking news on healthy eating delivered to your inbox daily, sign up for our newsletter!

Krissy Gasbarre
Krissy is a senior news editor at Eat This, Not That!, managing morning and weekend news related to nutrition, wellness, restaurants and groceries (with a focus on beverages), and more. Read more about Krissy
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