Harris Susan S, Dawson-Hughes Bess
Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, Massachusetts 02111, USA.
J Clin Endocrinol Metab. 2007 Aug;92(8):3155-7. doi: 10.1210/jc.2007-0722. Epub 2007 May 29.
Greater adiposity is associated with lower blood levels of 25-hydroxyvitamin D [25(OH)D]. The extent to which this results from reduced sun exposure among heavier individuals is unknown.
This analysis was conducted to determine whether sun exposure habits differ according to percent body fat (%FAT) in older adults and to what extent they explain the inverse association of adiposity with 25(OH)D in that population.
We performed a cross-sectional analysis of baseline data from a randomized trial of calcium and vitamin D supplementation to prevent bone loss.
The study was performed at the Metabolic Research Unit at the Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging at Tufts University.
A total of 381 generally healthy male and female volunteers age 65 and older participated in the study. Exclusion criteria included vitamin D and calcium supplement use, and medical conditions and medications known to affect bone metabolism.
There were no interventions. Measurements for this analysis were made before participants received trial supplements.
Plasma 25(OH)D, an indicator of vitamin D status, was measured.
Sunscreen use, hours spent outside per week, and percent of skin exposed did not differ across quartiles of %FAT (P > 0.43). 25(OH)D decreased across %FAT quartiles (P < 0.05) and was about 20% lower in the highest compared with the lowest quartile of %FAT after adjustments for age, sex, season, and vitamin D intake. Further adjustment for sun exposure habits had little effect on estimates of 25(OH)D.
In older adults, sun exposure habits do not vary according to adiposity and do not appear to explain lower 25(OH)D concentrations with increasing adiposity.
更高的肥胖程度与较低的25-羟基维生素D[25(OH)D]血液水平相关。体重较重者阳光照射减少在多大程度上导致了这种情况尚不清楚。
进行该分析以确定老年人的阳光照射习惯是否因体脂百分比(%FAT)而异，以及它们在多大程度上解释了该人群中肥胖与25(OH)D的负相关关系。
我们对一项关于补充钙和维生素D以预防骨质流失的随机试验的基线数据进行了横断面分析。
该研究在塔夫茨大学让·迈耶美国农业部人类营养研究中心衰老代谢研究室进行。
共有381名65岁及以上的一般健康男性和女性志愿者参与了该研究。排除标准包括使用维生素D和钙补充剂，以及已知会影响骨代谢的医疗状况和药物。
未进行干预。本次分析的测量是在参与者接受试验补充剂之前进行的。
测量了血浆25(OH)D，这是维生素D状态的一个指标。
防晒霜使用情况、每周户外活动时间和皮肤暴露百分比在%FAT四分位数间无差异(P>0.43)。25(OH)D随%FAT四分位数增加而降低(P<0.05)，在对年龄、性别、季节和维生素D摄入量进行调整后，最高%FAT四分位数组的25(OH)D比最低四分位数组低约20%。对阳光照射习惯进行进一步调整对25(OH)D的估计值影响不大。
在老年人中，阳光照射习惯不会因肥胖程度而有所不同，似乎也无法解释随着肥胖程度增加25(OH)D浓度降低的现象。
