Monday, October 15, 2007

Tea Drinking and Hip Structure in Elderly Women

October 12, 2007 — Tea drinking is associated with preservation of hip structure in elderly women, according to the results of a cross-sectional and longitudinal study reported in the October issue of the American Journal of Clinical Nutrition.

"Impaired hip structure assessed by dual-energy X-ray absorptiometry (DXA) areal bone mineral density (aBMD) is an independent predictor for osteoporotic hip fracture," write Amanda Devine, from the University of Western Australia in Perth, and colleagues. "Previous studies have shown that drinking tea has been associated with a higher aBMD and a reduced risk of hip fracture."

In a 5-year prospective trial to determine whether oral calcium supplements prevent osteoporotic fractures, 1500 randomly selected women aged 70 to 85 years had measurement of aBMD at the hip with DXA at years 1 and 5. At 5 years, cross-sectional analysis of 1027 of these women using a questionnaire evaluated the relationship of customary tea intake with aBMD. A prospective analysis of 164 women evaluated the relationship of tea intake at baseline, measured with a 24-hour dietary recall, with change in aBMD from years 1 to 5.

The cross-sectional analysis revealed that mean total hip aBMD was 2.8% greater in tea drinkers (806; 95% confidence interval [CI], 797 - 815 mg/cm2) than in non–tea drinkers (784; 95% CI, 764 - 803 mg/cm2; P < .05). During the 4-year period of the prospective analysis, tea drinkers lost an average of 1.6% of total hip aBMD, whereas non–tea drinkers lost 4.0%. Adjustment for covariates did not affect this pattern of findings.

Study limitations include the small sample size in the prospective study because of limited data on beverage intake collected at baseline; 2 different methods used to assess tea drinking; and measurement error associated with the self-administered beverage questionnaire.

"Tea drinking is associated with preservation of hip structure in elderly women," the authors write. "This finding provides further evidence of the beneficial effects of tea consumption on the skeleton.... Dietary calcium and coffee intake, physical activity, and smoking did not appear to be important confounders of the relation between tea and BMD."