Vitamin A Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin A, including details on retinol, benefits, dosage, supplements, deficiency, information. | ||||||||
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Serum retinoids and beta-carotene as predictors of hip and other fractures in elderly women.Barker ME, McCloskey E, Saha S, Gossiel F, Charlesworth D, Powers HJ, Blumsohn A Human Nutrition Unit, Division of Clinical Sciences (North), University of Sheffield, United Kingdom. m.e.barker@sheffield.ac.uk There is debate about the possible deleterious effect of excessive vitamin A exposure on fracture risk. In this nested case control study in older women (312 cases and 934 controls), serum retinol, retinyl palmitate, and beta-carotene were not associated with fracture risk, and there was no evidence of excess risk with multivitamin or cod liver oil supplementation. INTRODUCTION: Recent studies have suggested that higher vitamin A intake may account for a component of fracture risk within the general population and that supplemental vitamin A may be harmful even within recommended limits. No studies have examined the relationship between biochemical retinol status and fracture in older women. MATERIALS AND METHODS: We examined serum retinol, retinyl palmitate, and beta-carotene as predictors of incident hip and other fractures in a large prospective study of British women over the age of 75 years (n = 2606, 312 incident osteoporotic fractures, 92 incident hip fractures; mean follow-up duration, 3.7 years). Fasting blood samples (9:00-11:00 a.m.) were collected at baseline. Using a case-control design (three controls per case), serum retinol, retinyl palmitate, and beta-carotene were assessed as univariate predictors of incident osteoporotic fracture or hip fracture. Baseline BMD at the total hip, age, 25(OH)D, serum beta Crosslaps, bone-specific alkaline phosphatase, weight, height, and smoking were considered as covariates in a multivariate model. RESULTS: Serum retinol, retinyl palmitate, and beta-carotene were not significant univariate predictors of either hip fracture or any fracture (all p > 0.05; Cox proportional hazards regression). For all osteoporotic fractures, the hazard ratio (HR) was 0.92 (95% CI, 0.81-1.05) per 1 SD increase in serum retinol. Risk of any osteoporotic fracture was slightly less in the highest quartile of serum retinol compared with the lowest quartile (HR, 0.85; 95% CI, 0.69-1.05; p = 0.132) There was a tendency for increased serum retinol to predict benefit rather than harm in terms of BMD (r = 0.09, p = 0.002). Multivitamin or cod liver oil supplementation was associated with a significantly lower risk of any fracture (HR, 0.76; 95% CI, 0.60-0.96; p = 0.021). In multivariate analysis, only age, total hip BMD, and weight were associated with fracture risk (p < 0.05). CONCLUSIONS: We found no evidence to support any skeletal harm associated with increased serum indices of retinol exposure or modest retinol supplementation in this population. Published 10 May 2005 in J Bone Miner Res, 20(6): 913-20.
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