https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(02)08761-5.pdf

Diagnosis of osteoporosis and assessment of fracture risk

Increasing interest in the health benefits of tea has led to the inclusion of tea extracts in dietary supplements and functional foods. However, epidemiologic evidence regarding the effects of tea consumption on cancer and cardiovascular disease risk is conflicting. While tea contains a number of bioactive chemicals, it is particularly rich in catechins, of which epigallocatechin gallate (EGCG) is the most abundant. Catechins and their derivatives are thought to contribute to the beneficial effects ascribed to tea. Tea catechins and polyphenols are effective scavengers of reactive oxygen species in vitro and may also function indirectly as antioxidants through their effects on transcription factors and enzyme activities. The fact that catechins are rapidly and extensively metabolized emphasizes the importance of demonstrating their antioxidant activity in vivo. In humans, modest transient increases in plasma antioxidant capacity have been demonstrated following the consumption of tea and green tea catechins. The effects of tea and green tea catechins on biomarkers of oxidative stress, especially oxidative DNA damage, appear very promising in animal models, but data on biomarkers of in vivo oxidative stress in humans are limited. Larger human studies examining the effects of tea and tea catechin intake on biomarkers of oxidative damage to lipids, proteins, and DNA are needed.

Tea catechins and polyphenols: health effects, metabolism, and antioxidant functions.

Low body mass index (BMI) is a well-documented risk factor for future fracture. The aim of this study was to quantify this effect and to explore the association of BMI with fracture risk in relation to age, gender and bone mineral density (BMD) from an international perspective using worldwide data. We studied individual participant data from almost 60,000 men and women from 12 prospective population-based cohorts comprising Rotterdam, EVOS/EPOS, CaMos, Rochester, Sheffield, Dubbo, EPIDOS, OFELY, Kuopio, Hiroshima, and two cohorts from Gothenburg, with a total follow-up of over 250,000 person years. The effects of BMI, BMD, age and gender on the risk of any fracture, any osteoporotic fracture, and hip fracture alone was examined using a Poisson regression model in each cohort separately. The results of the different studies were then merged. Without information on BMD, the age-adjusted risk for any type of fracture increased significantly with lower BMI. Overall, the risk ratio (RR) per unit higher BMI was 0.98 (95% confidence interval [CI], 0.97–0.99) for any fracture, 0.97 (95% CI, 0.96–0.98) for osteoporotic fracture and 0.93 (95% CI, 0.91–0.94) for hip fracture (all p 0.30). After adjusting for BMD, these RR became 1 for any fracture or osteoporotic fracture and 0.98 for hip fracture (significant in women). The gradient of fracture risk without adjustment for BMD was not linearly distributed across values for BMI. Instead, the contribution to fracture risk was much more marked at low values of BMI than at values above the median. This nonlinear relation of risk with BMI was most evident for hip fracture risk. When compared with a BMI of 25 kg/m2, a BMI of 20 kg/m2 was associated with a nearly twofold increase in risk ratio (RR=1.95; 95% CI, 1.71–2.22) for hip fracture. In contrast, a BMI of 30 kg/m2, when compared with a BMI of 25 kg/m2, was associated with only a 17% reduction in hip fracture risk (RR=0.83; 95% CI, 0.69–0.99). We conclude that low BMI confers a risk of substantial importance for all fractures that is largely independent of age and sex, but dependent on BMD. The significance of BMI as a risk factor varies according to the level of BMI. Its validation on an international basis permits the use of this risk factor in case-finding strategies.

Body mass index as a predictor of fracture risk: A meta-analysis

The diagnosis of osteoporosis is based on the measurement of bone mineral density (BMD). There are a number of clinical risk factors that provide information on fracture risk over and above that given by BMD. The assessment of fracture risk thus needs to be distinguished from diagnosis to take account of the independent value of the clinical risk factors. These include age, a prior fragility fracture, a parental history of hip fracture, smoking, use of systemic corticosteroids, excess alcohol intake and rheumatoid arthritis. The independent contribution of these risk factors can be integrated by the calculation of fracture probability with or without the use of BMD. Treatment can then be offered to those identified to have a fracture probability greater than an intervention threshold.

Assessment of fracture risk.

R. P. Heaney, S. Abrams, B. Dawson-Hughes, A. Looker, R. Marcus, V. Matkovic and C. Weaver Creighton University, Omaha, NE; Children’s Nutrition Research Center, Houston, TX; Tufts University, Boston, MA; National Osteoporosis Foundation, Washington, DC; National Center for Health Statistics, Hyattsville, MD; Stanford University, Palo Alto, CA; Ohio State University, Columbus, OH; and Purdue University, West Lafayette, IN, USA

Peak bone mass

The aims of this study were to determine common international risk factors for hip fracture in women aged 50 years or more. We studied women aged 50 years or more who sustained a hip fracture in 14 centers from Portugal, Spain, France, Italy, Greece, and Turkey over a 1-year period. Women aged 50 years or more selected from the neighborhood or population registers served as controls. Cases and controls were interviewed using a structured questionnaire on work, physical activity, exposure to sunlight, reproductive, history and gynecologic status, height, weight, mental score, and consumption of tobacco, alcohol, calcium, coffee, and tea. Significant risk factors identified by univariate analysis included low body mass index (BMI), short fertile period, low physical activity. lack of sunlight exposure, low milk consumption, no consumption of tea, and a poor mental score. No significant adverse effects of coffee or smoking were observed. Moderate intake of spirits was a protective factor in young adulthood, but otherwise no significant effect of alcohol intake was observed. For some risks, a threshold effect was observed. A low BMI and milk consumption were significant risks only in the lowest 50% and 10% of the population, respectively. A late menarche, poor mental score, low BMI and physical activity, low exposure to sunlight, and a low consumption of calcium and tea remained independent risk factors after multivariate analysis, accounting for 70% of hip fractures. Excluding mental score and age at menarche (not potentially reversible), the attributable risk was 56%. Thus, about half of the hip fractures could be explained on the basis of the potentially reversible risk factors sought. In contrast, the use of risk factors to "predict" hip fractures had moderate sensitivity and specificity. We conclude that variations in lifestyle factors are associated with significant differences in the risk of hip fracture, account for a large component of the total risk, and may be of some value in selecting individuals at high risk.

Lopes Antonio Vaz

Papers

Risk factors for hip fracture in European women: the MEDOS Study. Mediterranean Osteoporosis Study.