Tea is the most widely consumed beverage in the world aside from water, and in 2015 Americans alone drank roughly 3.6 billion gallons of it. More than 165 million cups of tea are consumed every day; some out of habit, others because of taste and the widely touted health benefits. But on National Tea Day, we can’t help but wonder: What exactly is it doing to our brains and bodies?

The type of tea we drink today has been around for over 350 years, but the story of tea dates back to 2737 BC, when a Chinese emperor drank boiled water with infused leaves. Since then, the tea leaves steeped in water have diverged into dozens of different flavors. The commonly claimed health benefits from tea derive from a specific plant Camellia sinensis that can be brewed into only four varieties, including green, black, white, and oolong. Infusion of a different plant may provide benefits outside of the traditional tea.

The four types of tea can attribute most of their benefits to their antioxidants. For those who enjoy sipping on green tea, they’ll consume catechins, a type of antioxidant that scientists have found to boost the body’s ability to burn fat into fuel, which increases muscle endurance. Antioxidants work by neutralizing harmful molecules, known as free radicals, in our cells. Free radicals contain unpaired electrons, which makes them highly unstable and damaging to the body in many ways. Antioxidants work to provide the molecule with its missing electron, which stops the chain reaction of harm and boosts the immune system in return by providing it with a greater amount of stable molecules.

Tea also has a high oxygen radical absorbance capacity (ORAC), which gives it the ability to destroy free radicals, which can damage DNA in the body. The human body is designed to fight off free radicals on its own but as we age it becomes more and more difficult to combat all of them. Free radicals have been linked to cancer, heart disease, and neurological degeneration. In studies, researchers have found the antioxidants in tea coupled with ORAC might be the reason why tea drinkers decrease their risk of cancer. Ultimately, any protection against damage from free radicals is likely to increase your overall health and longevity.

One of tea’s greatest benefits come from its polyphenols, which are a special type of antioxidants that are designed to get rid of cell-damaging free radicals. Tea has between 8 and 10 times more polyphenols than fruits and vegetables, making it a potent producer of free radical fighters. According to a study published in the American Society for Clinical Nutrition, green tea contains the highest concentration of them, which is why it provides the greatest benefits. All teas from the Camellia plant are rich in polyphenols, but because oolong and black teas are fermented, they have lower concentrations of polyphenols compared to green teas.

Whatever your tea type, all varieties from the Camellia plant lower levels of cortisol, which is a hormone that releases into the body during moments of stress. People who drink at least two cups of tea a day put themselves at a lower risk for heart disease, stroke, and high cholesterol, along with the ability to recover from heart attacks faster. Another powerful antioxidant found in teas are flavonoids, which also help fight against the free radicals that clog arteries and contribute to cancer risk.

When it comes to the brain, tea also provides a boost of heightened mental alertness thanks to the caffeine and the amino acid L-theanine. Higher concentrations of L-theanine are found in green tea, which studies have shown able to curb a rising heart rate, high blood pressure, and even elevated levels of anxiety. One study found anxiety-prone test-takers were more calm and focused after taking 200 milligrams of L-theanine beforehand, compared to test takers who did not.

Humans have been reaping the benefits of tea for thousands of years, making it one of nature’s most coveted concoctions. If you’re a tea drinker, know that each sip you take puts you one step closer to a healthier body and brain.