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Tea Drinkers Have Stronger Bones

This study evaluated whether compounds found in tea such as caffeine, phytoestrogens, flavonoids and fluoride affected bone mineral density (BMD).

More than 1,000 Chinese men and women (497 men and 540 women, 30 years and older) were questioned about their habits of drinking green, black, or oolong tea, and other lifestyle characteristics. Measurements of bone mineral density of the total body, low back, and hip taken using DEXA scans (the gold standard for bone mineral density evaluation) were recorded.

Among the study participants, 502 subjects (48.4%) were habitual tea drinkers, with a mean duration of tea consumption of approximately 10 years. Compared to those who did not frequently drink tea, subjects who had habitually consumed any kind of tea for 6 to 10 years had higher lumbar spine BMDs, while those whose tea consumption had continued for more than 10 years had the highest BMDs of all measured regions.

The average tea drinker drank 3.5 cups of tea per day, but the authors found that in relation to BMD, how long the individuals had been regularly drinking tea was more important than how much tea was consumed daily. No significant differences in BMD were found among green, black, or oolong teas.

Tea's protective effect of tea against bone loss may appear surprising since other studies have shown that caffeine consumption is associated with increased bone loss, particularly in women whose intake of caffeine is greater than 300 mg/d (the amount found in approximately 514 g, or 18 oz, brewed coffee), and who carry the tt genetic variant of VDR (Vitamin D receptor) genotype. Studies suggest that these women appear to be at greater risk for caffeine's deleterious effect on bone.

In tea drinkers, however, it appears that any negative effect of the caffeine is more than overcome by other components of tea. Those wishing to limit their intake of caffeine might wish to choose green, rather than black tea, since green tea contains less caffeine than black tea, although even black tea contains about one-quarter of the amount found in regular coffee.

References: Wu C, Yang Y, Yao W, et al. Epidemiological evidence of increased bone mineral density in habitual tea drinkers. Arch Intern Med2002;162:1001-6. Rapuri PB, Gallagher JC, Kinyamu HK, Ryschon KL. Caffeine intake increases the rate of bone loss in elderly women and interacts with vitamin D receptor genotypes. Am J Clin Nutr2001;74:694-700. Laz Bannock, PhD., HumanNutrition.com, Technical Newsletter, June 15, 2002.