Brewed, bottled, or instant, there is a coffee and tea that fits conveniently into anyone’s life. But do they all have the same health benefits? Jeffrey Blumberg, PhD, Senior Scientist in the Antioxidants Research Laboratory at the Jean Mayer Human Nutrition Research Center on Aging (HNRCA), who has studied the health effects of coffee and tea answer your questions.
Q. Do powdered green-tea beverage mixes contain any of the beneficial compounds found in brewed green tea?
A. Dr. Blumberg says that yes, green-tea drink mixes do contain health-promoting flavonoids, mostly compounds called catechins—but not much compared to brewed tea. Catechins have been associated with increased antioxidant activity, fat oxidation and blood vessel dilation, and some studies have found catechin intake to be linked with decreased body mass index, LDL cholesterol and blood pressure. One popular drink-mix brand, for example, says on the label, “Contains 63 milligrams catechins from green tea extract.”
By comparison, says Blumberg, “The total flavonoid content of a 200-milliliter (a little less than 7 fluid ounces) cup of green tea is approximately 267 milligrams, most of which are catechins. So the catechins in this drink mix are equivalent to those in just less than a quarter-cup of brewed green tea. On the other hand, if you want to drink four to eight glasses of this formulated beverage per day…. If you want flavonoid-rich iced tea (green, oolong or black), brew it yourself at double strength and then add ice.”
Q. Can you tell me if instant coffee confers the same health benefits as brewed coffee?
A. Dr. Blumberg answers: "Instant coffee, made by removing the water from liquid coffee, contains less caffeine, fewer antioxidant chlorogenic acids, and smaller amounts of N-methylpyridinium, a putative anti-cancer compound, than found in regular coffee. Instant coffee contains more acrylamide, a potentially harmful product generated when some foods are cooked at high temperatures, than regular coffee but the amounts in both beverages are very low and considered safe. While regular coffee is not a good source of magnesium or potassium, instant coffee contains even less of these minerals. Nonetheless, studies of large populations appear to suggest comparable benefits from both instant and regular coffee, e.g., in reducing the risk for type 2 diabetes and heart disease. So you can base your decision to drink instant or regular coffee based on aroma, taste, cost and/or convenience rather than the modest health benefits associated with coffee drinking."
Q. When studies refer to "cups" of coffee or tea, do they mean eight-ounce cups or the more typical amount found in a standard mug of coffee or tea?
A. Dr. Blumberg answers: "The 'conventional' size for a cup of coffee in the US is six ounces and for tea it can be five or six ounces (i.e., not the standard 'kitchen' cup of eight ounces). In practice, these values are partly determined by manufacturers of coffeemakers/percolators and tea kettles, which define how many 'cups' their machines make - and they vary from brand to brand.
However, the US legal cup is 8.1 fluid ounces, the customary cup is 8 fluid ounces, the Imperial cup (UK) is 9.6 fluid ounces, the metric cup is 8.45 fluid ounces, the Japanese customary cup is 6.75 fluid ounces, and the Japanese traditional Go cup is 6.1 fluid ounces. Of course, if you are a Starbucks fan, then your serving size for a cup of coffee can be short (8 ounces), tall (12 ounces), grande (16 ounces), venti (20 ounces), or trenta (31 ounces)!"
When the Dietary Guidelines Advisory Committee concluded that drinking three to five cups a day of coffee was associated with minimal health risks (see the May 2015 newsletter), it referenced eight-ounce cups totaling up to 400 milligrams of caffeine.
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These questions and answers have been adapted from the Tufts Health & Nutrition Letter, a publication of the Friedman School of Nutrition Science & Policy at Tufts University: Editor-in-Chief, Dariush Mozaffarian, MD, DrPH, and Executive Editor, Alice H Lichtenstein, DSc. It is written with your needs in mind but is not a substitute for consulting with your physician or other health care providers. The publisher and authors are not responsible for any adverse effects or consequences resulting from the use of the suggestions, products or procedures that appear in this magazine. All matters regarding your health should be supervised by a licensed health care physician.
The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy is the only graduate school of nutrition in the United States. The mission of the school is to generate trusted science, educate future leaders, and produce real world impact.