Black tea is pretty good too
Not to be out-done by its greener cousin, black tea’s many health benefits continue to be documented. 1,500 elderly Australian women participated in a five-year trial of the effect of calcium supplementation on osteoporotic hip fracture. Information on tea consumption was collected at the beginning and end of the study. Over four years, tea drinkers lost an average of only 1.6% of their total hip bone mineral density, while non-tea drinkers lost 4% percent. A dose-dependent relationship was not observed. The authors speculate that antioxidant flavonoids in the tea might account for the observed benefit, or that the weak oestrogenic effect of phytoestrogens found in tea might be beneficial to older women with low endogenous oestrogen. In addition, milk drunk in tea may add bone-building calcium to the diet. (Tea drinking is associated with benefits on bone density in older women. Am J Clin Nutr. 2007 Oct;86(4):1243-7).
UK researchers recruited 16 healthy subjects and assigned them to drink glucose dissolved in either water, water plus caffeine or water plus instant black tea. After two hours plasma glucose concentrations were significantly reduced in the group who consumed the tea drink. Tea consumption also resulted in elevated insulin concentrations compared with the control beverages, probably due to stimulation of pancreatic beta-cells by polyphenols in the tea. (The effect of consuming instant black tea on postprandial plasma glucose and insulin concentrations in healthy humans. J Am Coll Nutr. 2007 Oct;26(5):471-7).
Regular tea consumption also appears to have favourable effects on markers of coronary heart disease (CHD) risk. In a UK study, 75 healthy males (aged 18-55 years) were randomised to receive black tea (equivalent to four strong cups) or a placebo drink similar in taste and caffeine content, but without active tea constituents, for six weeks. After six weeks, platelet activation and C-reactive protein levels were significantly lower in the tea drinking group compared with the placebo group. (The effects of chronic tea intake on platelet activation and inflammation: a double-blind placebo controlled trial. Atherosclerosis. 2007 Aug;193(2):277-82).