March is National Nutrition Month, when the Academy of Nutrition and Dietetics reminds everyone to return to the basics of healthy eating. It is also the time of year when the Academy celebrates expertise of registered dietitian nutritionists as the food and nutrition experts.
Across the country, restaurants, cultural venues and retail shops serve premium teas, while most supermarkets, convenience stores and vending machines are stocking bottled tea.
According to the Tea Association of the U.S.A. Inc., the number of Americans who will drink tea today is over 158 million, about half the U.S. population. And, the trend of increased consumer purchases of tea is expected to continue over the next five years.
Ever since 2737 B.C., when Chinese legend says leaves from an overhanging Camellia sinensis plant fell into Emperor Shennong's cup of boiling water, tea has been recognized by cultures around the world for its capacity to soothe, restore and refresh. Far from being a fictitious promise, tea has been lauded for an array of potential health benefits — from reducing cancer and heart disease risk to improving dental health and boosting weight loss.
Tea and Heart Health
The strongest evidence is on the side of heart health, attributed to the antioxidant effects in tea. Studies that looked at the relationship of black tea intake and heart health reported decreased incidence of heart attack, whereas drinking green tea was associated with lower total cholesterol, LDL and triglycerides, and higher HDL (the "good" cholesterol) levels.
Can Tea Prevent Cancer?
Support for tea's cancer prevention benefits is less compelling. It has been suggested that polyphenol compounds — particularly catechins — in tea may play a role in preventing cancer. However, studies related to black tea and different types of cancers have been extremely limited or conflicting.
Tea for Teeth
In 2010, Japanese researchers reported at least one cup of green tea per day was associated with significantly decreased odds for tooth loss. Other studies have suggested tea may lower the pH of the tooth surface, suppressing the growth of periodontal bacteria. A more likely reason for tea's anticariogenic effect is its fluoride content. Tea usually is brewed with fluoridated water and the tea plant naturally accumulates fluoride from the soil.
Tea and Weight Loss
Evidence supporting tea as a weight-loss aid is based mainly on studies that used tea extracts (epigallocatechin gallate and other polyphenols and caffeine). These results may not be directly applicable to brewed tea consumed in normal amounts.
Tea and Caffeine
The caffeine content of tea varies widely depending on the kind of tea used and the way in which it is brewed. Typical levels for tea are less than half that of coffee, ranging from 20 to 90 milligrams per 8 fluid ounces (compared to 50 to 120 milligrams in coffee).
This article originally appeared in the Summer 2012 edition of Food & Nutrition Magazine.