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National Hot Tea Month: Your questions about tea and health answered with Dr. Jeff Blumberg

The Tea Council gave me a heads up that January is National Hot Tea Month...perfect timing because I've been super curious about tea lately! I'm not a tea fanatic but I now drink some every day. A year ago I started sipping about 16 ounces of green tea in the morning and truly believe it's made a difference in my immune function. I have no scientific comparison and it could have been a lighter year for viruses, but I'm usually a magnet for cold bugs and last year (despite being a very stressful work year and getting less sleep) I remained sniffle-free. When I felt that familiar sore throat, it went away in about a day. But who isn't overwhelmed by the endless types of tea and deciding which is best: white, green, black? Does green tea really promote weight loss? How much should one drink?

I had the awesome chance to throw some Q&A at Dr. Jeff Blumberg, the director of the Antioxidants Research Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. He and a host of other top tea experts around the world presented the latest on tea at the Fifth International Scientific Symposium on Tea & Human Health. This infographic shows a summary of the results, and then be sure to check out my exclusive Q&A with Dr. Blumberg below.

Q:  Do health benefits vary among black, green, and white teas? Recently white tea has been touted as being even better than green; is this true?

A:  There are relatively few studies that have tested different types of tea ‘head-to-head’ against one another. However, in general, all the varieties of tea (which are all derived from the same plant species, Camellia sinensis L.) show similar benefits on major outcomes (e.g., cancer, heart disease, stroke) when the different studies are compared with one another. White tea (made from the youngest buds and processed somewhat less than green tea) has more catechins (the main class of flavonoids in tea) than green tea; however, it is also much more expensive and has a different flavor/aroma than green tea. If your goal is to obtain more of the antioxidant catechins, then you can quite simply drink a stronger brew or have a second cup.

Q:  Does it matter how long you steep the tea and if you use loose-leaf tea vs. tea bags? Are there particular brands that you prefer?

A:  The longer you steep tea, the more catechins and other phytochemicals you extract from the tea (and, thus, the more antioxidants you consume). I’m not familiar with any study that has tested the relative extraction of loose-leaf vs. bagged tea but have no reason to believe there is a significant difference between the two. I personally choose widely from the vast array of teas available. I seek out and greatly appreciate the remarkable diversity of teas and find that different ones complement different foods (and different moods). But, that’s just me…

Q:  Is there any health benefit from drinking iced tea "drinks," like the bottled Lipton iced green teas? I'm guessing they may not contain enough tea catechins to be beneficial?

A:  Ready-to-drink teas often contain lower concentrations of tea phytochemicals than freshly brewed tea, partly because of how they are formulated and partly because these compounds (mostly flavonoids) degrade over time. Some tea drinks are now fortified with tea flavonoids to address this matter; however, I have little information on this topic as it is largely proprietary data.

Q:  I've read that tea decaffeinated by effervescence is preferable to preserve the catechins over chemical decaffeination. Is this true?

A:  I don’t know the answer to this question. Generally, decaffeination reduces tea flavonoids by about 10-15%. As noted earlier, you can ‘remedy’ this loss by simply brewing a stronger cup or drinking more tea.

Q:  There's so much hype about green tea for weight loss. Do you believe that drinking green tea is useful to boost metabolism for weight management? If so, how much tea do you recommend drinking daily?

A:  There is good evidence supporting the efficacy of green tea in very modestly increasing energy expenditure (burning calories) via increased thermogenesis and increased oxidation of fat by about 100 calories per day. This is a small number of calories but, in the context of a low calorie weight loss diet or a dedicated weight maintenance plan, even 100 calories per day adds up over time.

However, this increase in basal metabolism by itself without reducing calorie intake and increasing physical activity will not make you lose body weight. Achieving this modest degree of energy expenditure requires 2-3 cups of green tea daily.

Q:  How many cups of tea do you recommend drinking daily for general optimal health benefits? In your opinion, what diseases do you feel are the most promising to benefit from tea drinking?

A:  Observational studies and clinical trials show a dose-response effect of tea up to ~5 cups daily, so drinking 1 cup is more healthful than drinking none, drinking 2 is better than 1, drinking 3 is better than 2, etc. The strongest and most consistent evidence of a health benefit for tea is lowering the risk of cardiovascular disease and stroke. The evidence (in humans) on preventing cancer is mixed. Exciting new evidence is emerging about potential benefits of tea on arthritis, cognitive performance and neurodegenerative diseases, dental caries, bone health and osteoporosis, immune responsiveness, and more.

My advice is that if you don’t drink tea, drink a cup; if you drink a cup now, drink 2; and so on. Also, drink whatever kind of tea(s) you like best and drink it freshly brewed, preferably stronger than weaker (to obtain a higher concentration of tea flavonoids).