Tea, especially green tea, is often said to be good for your health. But if tea is good for you, how good? And why?
It turns out that tea does contain substances that have been linked to a lower risk for heart disease and even cancer. But if you just don’t like tea, take heart: Tea drinking alone will never come close to the most potent health promoter we know of—a healthy lifestyle. And coffee may also provide a similar health boost, as we discuss below.
Tea consumption, especially green tea, may not be a panacea, but it can be provide extra dividends when incorporated in an overall healthy diet with whole grains, fish, fruits and vegetables, and less red and processed meat.
WHY IS TEA BENEFICIAL?
Tea contains certain substances linked to better health, including chemicals called polyphenols, in particular catechins and epicatechins found in tea—especially green tea. The fermentation process used to make green tea boosts levels of polyphenols. Black and red teas have them, too, but in lesser amounts that are less strongly tied to improved health. Although we’re not quite sure why polyphenols are beneficial, they have “antioxidant” properties that may neutralize potentially harmful chemicals called oxidants, and elevated levels of oxidants can cause harm by attacking artery walls and contributing to cardiovascular disease. Unfortunately, in studies of antioxidants in humans, as opposed to experiments in rodents and test tubes, this effect has not been substantiated.
Polyphenols seem to provide additional help by lowering the risk of diabetes, lowering blood pressure and improving cholesterol, all of which contribute to heart disease and stroke.
WHAT’S THE EVIDENCE OF BENEFIT?
Some of the best circumstantial evidence on tea and health has come from large, long-term studies of doctors and nurses based at the Harvard School of Public Health: the female Nurses’ Health Study and the male Health Professionals Follow-up Study.
By following these groups for long periods, researchers determined that tea drinkers are less likely over time to develop diabetes, compared with people who drink less tea. That makes sense, in light of research showing that polyphenols help regulate blood sugar (glucose).
Further support is provided by a study presented at the American Heart Association’s Epidemiology/Lifestyle 2016 Scientific Sessions. In it, researchers studied available information on 6,212 adults to determine how tea drinking might be associated with coronary artery calcium progression, a marker for blood vessel disease, and heart attacks, angina (chest pain), cardiac arrest, stroke and death from other types of heart disease. They divided the participants into those who never drank tea, less than one-cup-a-day drinkers, one cup-a-day drinkers, two to three cups a day and four or more cups a day tea drinkers. The study followed patients for an average 11.1 years for major cardiovascular events and more than five years to determine changes in coronary artery calcium scores. The researchers found that adults who drank one and two to three cups of tea daily had more favorable coronary calcium scores than those who never drank tea. They also noted a graded relationship between the amount of tea a person drank and a progressively lower incidence of major heart-related events starting with the one-cup-a-day tea drinkers, versus never tea drinkers.
WHAT’S THE BOTTOM LINE?
Drinking tea of all types regularly seems to be associated with better health. However, it remains unclear whether the tea itself is the cause and, if so, how it works its magic. The studies attempt to rule out the possibility that tea drinkers simply live healthier lifestyles, but it’s difficult to be sure. Nevertheless, tea itself appears to have no harmful effects except for an occasional case of the jitters if you drink too much caffeinated brew. It fits in perfectly fine with a heart-healthy lifestyle. So if you drink tea, keep it up, but don’t take up the habit thinking it will have a dramatic impact.
But in any event, stay away from processed sugar-sweetened tea beverages. These products may be loaded with extra calories, and consuming more than the occasional sweetened tea drink may be counterproductive. If there are any health benefits to tea consumption, it’s probably completely offset by adding sugar, as I have pointed out in a previous post.
| BUT WHAT ABOUT COFFEE?
Coffee contains a complex mix of chemicals with known biological effect including polyphenols that may account for coffee’s purported health benefits. Animal studies suggest the polyphenol chlorogenic acid, which is abundant in coffee, could reduce risk of diabetes. Recent research pooled 36 studies involving over 1.2 million people and found that, when compared with coffee abstainers, people who drank three to five cups of coffee per day had a lower risk of heart attacks and strokes. Complete coverage noted on http://www.mortontavel.com/2013/10/07/