School of Population Health, The University of Western Australia, Perth, Western Australia.
Western Australian Centre for Health and Ageing, The University of Western Australia, Perth, Western Australia.
Nutrition. 2014 May;30(5):551-6. doi: 10.1016/j.nut.2013.10.007. Epub 2013 Oct 16.
Observational studies suggest that moderate intakes of retinol and increased circulating retinol levels may increase fracture risk. Easy access to supplements, combined with an aging population, makes this a potentially important association. The aim of this study was to investigate plasma retinol and total carotene concentrations in relation to fracture risk after long-term supplementation with retinol and/or beta-carotene in 998 adults between 1990 and 2007.
Participants were 663 men and 335 women in a cancer prevention program who were initially randomized to a retinol (7.5 mg RE/d) or beta-carotene (30 mg/d) supplement between 1990 and 1996. After 1996, all participants received the retinol supplement only. Plasma retinol and total carotene, medication use and various lifestyle factors were measured at annual clinic visits. Fractures were identified by self-report in 2007. The risk for any fracture or osteoporotic fracture was modeled using Cox proportional hazard models.
Over a median follow-up of 7.8 y, 123 participants with plasma samples reported an incident fracture. Although plasma retinol concentrations were markedly higher than those reported in observational studies, no association was observed between plasma retinol and risk for any fracture (hazard ratio [HR], 0.86 μmol/L; 95% confidence interval [CI], 0.65-1.14) or osteoporotic fracture (HR, 0.97 μmol/L; 95% CI, 0.66-1.43). A lower risk for any fracture was suggested with increasing plasma total carotenes (HR, 0.85 μmol/L; 95% CI, 0.71-1.01).
This study does not support earlier reports of an increased fracture risk associated with increased plasma retinol concentration. The potential for carotenes to prevent fractures deserves further investigation.
观察性研究表明，视黄醇的适度摄入和循环视黄醇水平的升高可能会增加骨折风险。补充剂的易得性，加上人口老龄化，使得这种关联变得尤为重要。本研究旨在调查 1990 年至 2007 年期间，998 名成年人长期补充视黄醇和/或β-胡萝卜素后，血浆视黄醇和总类胡萝卜素浓度与骨折风险的关系。
本研究参与者为癌症预防计划中的 663 名男性和 335 名女性，他们最初于 1990 年至 1996 年期间被随机分配到视黄醇（7.5 毫克视黄醇当量/天）或β-胡萝卜素（30 毫克/天）补充剂组。1996 年后，所有参与者仅接受视黄醇补充剂。在每年的诊所就诊时，测量血浆视黄醇和总类胡萝卜素、药物使用和各种生活方式因素。2007 年通过自我报告确定骨折情况。使用 Cox 比例风险模型对任何骨折或骨质疏松性骨折的风险进行建模。
在中位随访 7.8 年期间，123 名有血浆样本的参与者报告发生了一次骨折事件。尽管血浆视黄醇浓度明显高于观察性研究报告的浓度，但未观察到血浆视黄醇与任何骨折（风险比[HR]，0.86 μmol/L；95%置信区间[CI]，0.65-1.14）或骨质疏松性骨折（HR，0.97 μmol/L；95% CI，0.66-1.43）风险之间存在关联。随着血浆总类胡萝卜素的增加，任何骨折的风险呈下降趋势（HR，0.85 μmol/L；95% CI，0.71-1.01）。
本研究不支持先前关于血浆视黄醇浓度升高与骨折风险增加相关的报告。类胡萝卜素预防骨折的潜力值得进一步研究。
