Tony Lambert delphine@videotron.ca

14/102007

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."

Healthway Health Promotion Foundation of Western Australia and the National Health and Medical Research Council of Australia supported this study. The authors have disclosed no relevant financial relationships.

Am J Clin Nutr. 2007;86:1243-1247.

Other than age, the most important risk factor for hip fractures in older women is low aBMD measured by DXA. Lifestyle factors, including dietary intake of calcium, protein, and sodium, affect aBMD and the risk for hip fracture. In earlier research, tea drinking has been linked to higher aBMD and lower risk for hip fracture.

The present study aims to determine the relationship of tea consumption with measures of hip structure measured by DXA in a randomly selected, population-based sample of elderly women. A cross-sectional analysis looked at the relationship between tea intake and aBMD, and a prospective analysis examined the relationship between tea intake and change in aBMD during a 4-year follow-up period.

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• In a 5-year, prospective, randomized controlled trial to determine whether oral calcium supplements prevent osteoporotic fractures, 1500 randomly selected women aged 70 to 85 years in Western Australia had DXA measurement of aBMD at the hip at years 1 and 5.
• Women with medical conditions likely to affect 5-year survival were excluded. The study population was weighted in favor of women in higher socioeconomic categories, but participants did not differ from the whole population in terms of health resource utilization.
• At 5 years, cross-sectional analysis of 1027 of these women using a questionnaire evaluated the relationship of customary tea intake with aBMD; 83% of these women were tea drinkers.
• Compared with non–tea drinkers, tea drinkers in the cross-sectional analysis had higher energy and calcium intakes, higher alcohol intake, and less coffee intake; and those who smoked did so for fewer years.
• 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.
• In the prospective analysis, 75% of participants were tea drinkers. Fewer tea drinkers had ever smoked, and tea drinkers reported less coffee consumption. Intakes of energy, calcium, and alcohol were similar between tea drinkers and non–tea drinkers.
• 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).
• Compared with non–tea drinkers, tea drinkers had a significantly higher aBMD at the total hip and trochanter sites but not at the femoral neck and intertrochanter sites.
• In the cross-sectional study, age-adjusted and fully adjusted linear regression models revealed no linear relationship between tea intake in cups per day and BMD of the total hip, femoral neck, trochanter, or intertrochanter.
• 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%.
• The dose-relationship between the amount of tea intake (cups per day) and the loss of BMD during 4 years was studied in age-adjusted and fully adjusted linear regression models in the prospective study. There was a significant negative relationship observed at the trochanter site (P < .05) but not at the total hip, femoral neck, or intertrochanter sites.
• Adjustment for covariates did not affect this pattern of findings. Dietary calcium and coffee intake, physical activity, and smoking did not appear to be important confounders of the relationship between tea intake and aBMD.
• The authors concluded that tea consumption has beneficial effects on the skeleton.
• 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.

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• A cross-sectional analysis revealed that mean total hip aBMD was 2.8% greater in elderly women tea drinkers than in non–tea drinkers.
• A prospective analysis revealed that tea drinkers lost an average of 1.6% of total hip aBMD during 4 years, whereas non–tea drinkers lost 4.0%