摘要：We examined the relationship between serum 25-hydroxyvitamin D (25[OH]D) and all-cause mortality. We searched biomedical databases for articles that assessed 2 or more categories of 25(OH)D from January 1, 1966, to January 15, 2013. We identified 32 studies and pooled the data. The hazard ratio for all-cause mortality comparing the lowest (0–9 nanograms per milliliter [ng/mL]) to the highest (> 30 ng/mL) category of 25(OH)D was 1.9 (95% confidence interval = 1.6, 2.2; P < .001). Serum 25(OH)D concentrations less than or equal to 30 ng/mL were associated with higher all-cause mortality than concentrations greater than 30 ng/mL ( P < .01). Our findings agree with a National Academy of Sciences report, except the cutoff point for all-cause mortality reduction in this analysis was greater than 30 ng/mL rather than greater than 20 ng/mL. An inverse association was proposed between solar irradiance and incidence of colon and breast cancer, based on a mechanism involving insufficient vitamin D. Individuals with lower serum 25-hydroxyvitamin D (25[OH]D) have higher risk of breast 1–3 and colon cancer, 4–6 other specific cancers, 7 all invasive cancers combined, 8 and coronary heart disease. 9,10 Physiological mechanisms for the inverse association of 25(OH)D with cancer have been reported. 11 Despite research on the association between low vitamin D status and many diseases, 12 no consensus has emerged on the optimal serum 25(OH)D concentration. The concern is whether it is safe to maintain serum 25(OH)D concentrations in the range high enough to prevent some types of cancers 13–15 and coronary heart disease. 9,10 We decided to analyze the strength and consistency of the inverse association between levels of serum 25(OH)D and age-adjusted mortality hazard ratios in a rapidly expanding field of public health. A previous meta-analysis summarized 12 studies, 16 another summarized 14, 17 and another summarized a broader range. 18 We hypothesized that lower serum 25(OH)D was associated with higher all-cause mortality hazard ratios, and defined the age-adjusted hazard ratio for death from any cause as the outcome addressed by the meta-analysis. This analysis includes all studies of all-cause mortality hazard ratios by categories of serum 25(OH)D in healthy or general medical clinic cohorts that met the eligibility criteria. Twenty new studies of serum 25(OH)D and all-cause mortality entered the literature since the Zittermann et al. review, 17 for a total of 32 in this review. 19–50 Two studies in the review by Zittermann et al. did not meet the stringent inclusion criterion of the present study, and were not included.
