Menzies Research Institute, University of Tasmania, Hobart, Tas., Australia.
J Intern Med. 2010 Nov;268(5):501-10. doi: 10.1111/j.1365-2796.2010.02267.x.
To determine the associations between body adiposity and change in serum 25-(OH)D levels over 2.6 years, and if these associations are mediated by metabolic and inflammatory factors in older adults.
This is a longitudinal study of 859 randomly selected subjects (mean 62 years, range 51-80, 49% women). Serum 25-hydroxyvitamin D [25-(OH)D] was assessed by radioimmunoassay at baseline and 2.6 years later. Baseline serum level of leptin was assessed by radioimmunoassay and interleukin (IL)-6 by a chemiluminescent immunoassay in the first 183 subjects.
In multivariable analyses, body mass index, trunk fat percentage and waist-to-hip ratio were significant predictors of increased incident vitamin D deficiency [a 25-(OH)D < 50 nmol L⁻¹ at follow-up when ≥50 nmol L⁻¹ at baseline] and decreased recovery of vitamin D deficiency [a 25-(OH)D ≥ 50 nmol L⁻¹ at follow-up when < 50 nmol L⁻¹ at baseline]. Change in 25-(OH)D levels per annum was also independently predicted by baseline leptin (β: -0.09/unit, 95% CI: -0.17, -0.03), IL-6 (β: -0.68/quartile, 95% CI: -1.35, -0.02) and total cholesterol/high-density lipoprotein (HDL) ratio (β: -0.51, 95% CI: -0.88, -0.14). The associations between body adiposity measures and change in 25-(OH)D completely disappeared after adjustment for leptin, diminished after adjustment for IL-6, but remained unchanged after adjustment for total cholesterol/HDL ratio. All associations were independent of season and sun exposure.
Body fat is not simply a passive reservoir for 25-(OH)D. In addition to season and sun exposure, 25-(OH)D levels appear to be determined by metabolic and, to a lesser extent, inflammatory factors, and these appear to mediate the effects of adiposity on change in 25-(OH)D.
确定身体肥胖与血清 25-（OH）D 水平在 2.6 年内的变化之间的关联，以及这些关联是否通过代谢和炎症因素在老年人中发生。
这是一项对 859 名随机选择的受试者（平均年龄 62 岁，范围 51-80 岁，49%为女性）进行的纵向研究。血清 25-羟维生素 D [25-（OH）D] 通过放射免疫分析在基线和 2.6 年后进行评估。在最初的 183 名受试者中，通过放射免疫分析法评估瘦素的基线血清水平，通过化学发光免疫分析法评估白细胞介素（IL）-6。
在多变量分析中，体重指数、躯干脂肪百分比和腰围与臀围比值是维生素 D 缺乏症发病率增加[25-（OH）D 在随访时<50 nmol/L，而在基线时≥50 nmol/L]和维生素 D 缺乏症恢复减少的显著预测因素[25-（OH）D 在随访时≥50 nmol/L，而在基线时<50 nmol/L]。25-（OH）D 水平的年度变化也独立预测基线瘦素（β：-0.09/单位，95%CI：-0.17，-0.03）、IL-6（β：-0.68/四分位距，95%CI：-1.35，-0.02）和总胆固醇/高密度脂蛋白（HDL）比值（β：-0.51，95%CI：-0.88，-0.14）。在调整瘦素、减少调整 IL-6 后，身体脂肪测量值与 25-（OH）D 变化之间的关联完全消失，但在调整总胆固醇/HDL 比值后，这些关联仍然不变。所有关联均独立于季节和阳光照射。
脂肪组织不仅仅是 25-（OH）D 的被动储存库。除了季节和阳光照射之外，25-（OH）D 水平似乎还由代谢因素决定，在较小程度上由炎症因素决定，这些因素似乎介导了肥胖对 25-（OH）D 变化的影响。
