Prospective association of vitamin D concentrations with mortality in postmenopausal women: results from the Women's Health Initiative (WHI) American Journal of Clinical Nutrition, 10/31/2011

Eaton CB et al. – Body fat distribution may play an important role in the modulation of the effect of low vitamin D concentrations on health.

• A substudy in 2429 postmenopausal women within the Women's Health Initiative (WHI) with measured baseline 25–hydroxyvitamin D [25(OH)D] concentrations were followed for 10 y for death from cardiovascular disease (CVD), cancer, and all–cause mortality.
• Proportional hazards models were performed to evaluate quartiles of month–adjusted 25(OH)D concentrations, with adjustment for potential confounders.
• Sequential model building and analysis for multiplicative interaction were performed to evaluate the effects of central adiposity on the association of low 25(OH)D with all–cause mortality.

• Of the 2429 women, 224 deaths occurred, with 79 deaths from CVD and 62 deaths from cancer.
• Multivariate–adjusted HRs that compared quartiles 1 (lowest) to 4 (highest) of 25(OH)D for all–cause mortality (HR: 1.25; 95% CI: 0.80, 1.95), CVD mortality (HR: 1.27; 95% CI: 0.81, 1.99), and cancer mortality (HR: 1.39; 95% CI: 0.88, 2.19) were not significant.
• There was a potential interaction (P = 0.08) between abdominal obesity and low 25(OH)D concentrations that showed an increased risk of the lowest quartile of 25(OH)D concentrations (HR: 1.85; 95% CI: 1.00, 3.44) with increased mortality in women with a normal waist circumference but no increased risk in women with abdominal obesity (HR: 0.96; 95% CI: 0.52, 1.76).