25-hydroxyvitamin D concentration, vitamin D intake and joint symptoms in postmenopausal women.

INTRODUCTION: Low 25-hydroxyvitamin D (25(OH) D) concentrations have been associated with radiologic worsening of osteoarthritis in some reports. However, the results are mixed and few studies have evaluated associations between 25(OH) D concentrations and both total vitamin D intake and clinical joint symptoms. STUDY DESIGN: Cross-sectional analyses of information from a subset of 1993 postmenopausal women obtained at baseline entry in the Women's Health Initiative Calcium plus Vitamin D clinical trial. MAIN OUTCOME MEASURES: 25(OH) D concentration, total vitamin D intake (diet plus supplements), presence and severity of joint pain and joint swelling. RESULTS: The 25(OH) D levels were commonly low with 53% having deficient (<50 nmol/L) and only 17% having sufficient (>72 nmol/L) levels. Joint pain (reported by 74%) and joint swelling (reported by 34%) were also commonly reported. 25(OH) D concentrations were modestly correlated with total vitamin D intake (R=0.29, p<0.0001); however, considerable variability in 25(OH) D concentrations for a given vitamin D intake was seen. In adjusted linear regression models, lower serum 25(OH) D concentrations were associated with higher average joint pain score (P=0.01 for trend) with differences most apparent in the lowest 25(OH) D levels sextile. CONCLUSIONS: Relatively low 25(OH) D levels and a high frequency of joint symptoms were common in this population of postmenopausal women. Total vitamin D intake was only modestly associated with 25(OH) D. Low serum 25(OH) D concentrations were associated with higher joint pain scores. These findings can inform the design of future intervention trials.

A longitudinal study of the metabolic syndrome and risk of postmenopausal breast cancer.

The metabolic syndrome, characterized by abdominal obesity, high blood glucose levels, impaired glucose tolerance, dyslipidemia, and hypertension, is associated with increased risk of type 2 diabetes and coronary heart disease. Several studies have examined the association of the individual components of the metabolic syndrome with breast cancer; to date, however, no study has assessed the metabolic syndrome per se in relation to breast cancer risk. Furthermore, previous studies have relied only on baseline assessment of components of the syndrome. Therefore, we assessed the association of the metabolic syndrome with the risk of postmenopausal breast cancer among women in the 6% sample of subjects in the Women's Health Initiative clinical trial and the 1% sample of women in the observational study who had repeated measurements of the components of the syndrome during follow-up. We used Cox proportional hazards models to estimate hazard ratios and 95% confidence intervals for the association of breast cancer risk with the presence of the metabolic syndrome, as well as its components, at baseline and in time-dependent analyses. After exclusion of women with diabetes, among 4,888 women with baseline measurements, 165 incident cases of breast cancer were ascertained over a median of 8 years of follow-up. The presence of the metabolic syndrome at baseline was not associated with altered risk. Of the individual components measured at baseline, diastolic blood pressure showed a borderline positive association with breast cancer. In time-dependent covariate analyses, however, certain scenarios indicated a positive association between the metabolic syndrome and breast cancer, due primarily to positive associations with serum glucose, serum triglycerides, and diastolic blood pressure.

Calcium plus vitamin D supplementation and the risk of breast cancer.

BACKGROUND: Although some observational studies have associated higher calcium intake and especially higher vitamin D intake and 25-hydroxyvitamin D levels with lower breast cancer risk, no randomized trial has evaluated these relationships. METHODS: Postmenopausal women (N = 36 282) who were enrolled in a Women's Health Initiative clinical trial were randomly assigned to 1000 mg of elemental calcium with 400 IU of vitamin D(3) daily or placebo for a mean of 7.0 years to determine the effects of supplement use on incidence of hip fracture. Mammograms and breast exams were serially conducted. Invasive breast cancer was a secondary outcome. Baseline serum 25-hydroxyvitamin D levels were assessed in a nested case-control study of 1067 case patients and 1067 control subjects. A Cox proportional hazards model was used to estimate the risk of breast cancer associated with random assignment to calcium with vitamin D(3). Associations between 25-hydroxyvitamin D serum levels and total vitamin D intake, body mass index (BMI), recreational physical activity, and breast cancer risks were evaluated using logistic regression models. Statistical tests were two-sided. RESULTS: Invasive breast cancer incidence was similar in the two groups (528 supplement vs 546 placebo; hazard ratio = 0.96; 95% confidence interval = 0.85 to 1.09). In the nested case-control study, no effect of supplement group assignment on breast cancer risk was seen. Baseline 25-hydroxyvitamin D levels were modestly correlated with total vitamin D intake (diet and supplements) (r = 0.19, P < .001) and were higher among women with lower BMI and higher recreational physical activity (both P < .001). Baseline 25-hydroxyvitamin D levels were not associated with breast cancer risk in analyses that were adjusted for BMI and physical activity (P(trend) = .20). CONCLUSIONS: Calcium and vitamin D supplementation did not reduce invasive breast cancer incidence in postmenopausal women. In addition, 25-hydroxyvitamin D levels were not associated with subsequent breast cancer risk. These findings do not support a relationship between total vitamin D intake and 25-hydroxyvitamin D levels with breast cancer risk.