Range of flavan-3-ol content in foods commonly consumed. Data based on Phenol Explorer v2.0
Nutrition researchers would like for flavan-3-ols to be included in the official Dietary Guidelines for Americans published by the United States Department of Agriculture and Health Canada’s Food Guide.
The intake recommendations, published in the journal Advances in Nutrition, state that consuming 400 to 600 milligrams of flavan-3-ols daily may reduce the risk of diabetes and cardiovascular disease.
Flavanols are abundant in fruits, such as blueberries, apples, and blackberries, but the highest concentrations are found in tea, wrote Professor Taylor C. Wallace, Ph.D. one of the authors of the recommendations. If the recommendations to add flavanols is acted on, it would become the first time that bioactive compounds are included in the USDA and Canadian guidelines.
“Flavan-3-ols are non-essential nutrients, meaning you won’t develop scurvy and die from not consuming them, as is the case with vitamin C and other essential nutrients, but flavanols may promote and maintain good health,” Taylor explains. There are thousands of bioactive compounds, including carotenoids, such as beta-carotene; flavonoids, such as isoflavones; cannabinoids, and phytosterols," Taylor noted.
Brewed tea is by far the best dietary source of flavan-3-ols, Taylor observed. “An 8-ounce cup of green tea provides about 318 mg of flavan-3-ols, while the same amount of black tea provides about 277 mg. It is worth noting that the harm of added sugar may offset the benefits of flavan-3-ols, so choose unsweetened tea,” he said.
Tea associations in the U.S. and Canada are lobbying to include tea in dietary guidelines. Tea and Herbal Association of Canada president Shabnam Weber is lobbying government officials in Ottawa. “Canada’s Food Guide should reflect how consumers eat today,” she said. “Health Canada should expand its recommendations to include flavan-3-ols considering the increase in cardiovascular disease and obesity — particularly in the past two years.”
According to Dr. Wallace, flavan-3-ols improve blood pressure, blood flow, cholesterol level and blood sugar, and “even help protect the body’s cells from damage as we age.”
The intake recommendations follow years of debate on the benefits of bioactive plant-based compounds., “The scientific community has finally decided that the evidence is sufficient to move forward with an official intake recommendation for what is arguably the most studied group of dietary bioactive compounds: The flavan-3-ols,” Wallace said.
Black tea is the largest source of flavan-3-ols in the U.S. diet, accounting for 32% of total flavonols consumed, according to the National Health and Nutrition Survey of food intake. Brewed tea (caffeinated and decaffeinated, green, black, and oolong) account for 94% of flavan-3-ols consumed in the American diet.
Wallace observed, “Flavan-3-ols aren’t just your typical 'antioxidants,' marketed by food companies. For decades, research has consistently demonstrated the ability of Flavan-3-ols to help reduce the risk of diet-related conditions.”
To calculate the intake of flavan-3-ols in tea, researchers sum the total concentration of catechin, epigallocatechin, epicatechin, epicatechin 3-gallate, epigallocatechin 3-gallate (EGCG), theaflavin, thearubigins, theaflavin-3,3-digallate, theaflavin-3-gallate, theaflavin-3'-gallate, gallocatechin, and catechin 3-gallate.