Nutrition: calcium, cholesterol, and calories

A longitudinal study of bone density in midlife women

A longitudinal study of 386 healthy Black and White women aged 35-60 years was conducted to determine the effects of physical activity and other related factors on lumbar bone mineral density over 24 months. Bone mineral density of the lumbar spine, L2-L4, was measured using dual energy x-ray (Hologic 1000). Physical activity levels in three dimensions (leisure, household, and occupational) from both a lifelong and current perspective were obtained by questionnaire. Body mass index was calculated from measured weight in kilograms divided by measured height in meters squared. Calcium, caffeine, and alcohol intake was estimated using a food frequency questionnaire. Age, race, and smoking were determined by self-report. Radioimmunoassays of follicle stimulating hormone (FSH) and estradiol were used to validate self-reports of menopausal status. Multiple regression analysis revealed that race, age, weight, FSH, calcium, and years of tobacco intake formed the best model at baseline (r(2) = 0.32) and at 24 months (r(2) = 0.303). Physical activity was not a significant predictor for bone mineral density at either time point. There were cross-sectional changes of bone mineral density with race, age, and menopausal status. Black women had significantly higher bone mineral density than White women. However, an age-related decline in bone mineral density was exhibited in both Black and White women. Perimenopausal women had significantly lower bone mineral density as compared with premenopausal women. Furthermore 37 (9.6%) women at baseline and 34 (11%) at 24 months were designated at risk for fracture.

Methylxanthine consumption and the risk of ovarian malignancy

Between 1970 and 1988, reports were published about two ecological studies, six case-control studies and one cohort study that evaluated the relationship between methylxanthine consumption and the risk of ovarian cancer. Because of the limitations of ecological studies, no inferences are based on them. All of the case-control studies recruited hospital controls. Nevertheless, four of the six had risk ratios of 1.5 or less. The one cohort study, which showed no relationship between coffee drinking and ovarian cancer, has low power. From these studies, it appears that coffee and tea consumption do not increase the risk of ovarian cancer.