The Effect of Vitamin A on Fracture Risk: A Meta-Analysis of Cohort Studies

Abstract

This meta-analysis evaluated the influence of dietary intake and blood level of vitamin A (total vitamin A, retinol or β-carotene) on total and hip fracture risk. Cohort studies published before July 2017 were selected through English-language literature searches in several databases. Relative risk (RR) with corresponding 95% confidence interval (CI) was used to evaluate the risk. Heterogeneity was checked by Chi-square and I2 test. Sensitivity analysis and publication bias were also performed. For the association between retinol intake and total fracture risk, we performed subgroup analysis by sex, region, case ascertainment, education level, age at menopause and vitamin D intake. R software was used to complete all statistical analyses. A total of 319,077 participants over the age of 20 years were included. Higher dietary intake of retinol and total vitamin A may slightly decrease total fracture risk (RR with 95% CI: 0.95 (0.91, 1.00) and 0.94 (0.88, 0.99), respectively), and increase hip fracture risk (RR with 95% CI: 1.40 (1.02, 1.91) and 1.29 (1.06, 1.57), respectively). Lower blood level of retinol may slightly increase total fracture risk (RR with 95% CI: 1.11 (0.94, 1.30)) and hip fracture risk (RR with 95% CI: 1.27 (1.05, 1.53)). In addition, higher β-carotene intake was weakly associated with the increased risk of total fracture (RR with 95% CI: 1.07 (0.97, 1.17)). Our data suggest that vitamin A intake and level may differentially influence the risks of total and hip fractures. Clinical trials are warranted to confirm these results and assess the clinical applicability.

Effects of β-carotene intake on the risk of fracture: A Bayesian meta-analysis

“…Our findings were consistent with the results of a previous meta-analysis published by Xu et al 11 , who found that a high intake of dietary β-carotene was significantly decreased the risk of hip fracture by 28% (OR 0.72; 95% CI: 0.54-0.95). However, our findings were contradicted with recent meta-analysis 38 , which revealed that higher β-carotene intake was weakly associated with the increased risk of total fracture (RR 1.07;…”

“…95% CI: 0.97, 1.17). The difference can be explained by a limited number of studies included for both total fracture and hip fracture risk by Zhang et al 38 , in their studies all sources of beta-carotene such as serum, plasma, and dietary intake were analyzed together.…”

Effects of β-carotene intake on the risk of fracture: A Bayesian meta-analysis

“…This may be a plausible result given hormonal differences between sexes. These results provide additional information beyond those published by the two meta-analyses [16,45] that reported a null association between β-carotene intake and fracture risk in females, but not in males. Differing conclusions in sub-analyses by geographic region for the relationship between dietary β-carotene and factures are likely due to variations in the study populations, speci cally with regard to genetics, diverse dietary habits that may be tailored to each culture, and lifestyle factors.…”

“…Our ndings were consistent with the results of a previous meta-analysis published by Xu et al [16] that concluded high intake of dietary β-carotene signi cantly decreased the risk of hip fracture by 28% (Odds Ratio [6] 0.72; 95% CI: 0.54-0.95). However, ndings from the present meta-analysis were discordant with the recently published meta-analysis published by Zhang et al [45], which observed that higher β-carotene intake was weakly associated with the increased risk of total fracture (RR 1.07; 95% CI: 0.97, 1.17), though the results were not statistically signi cant. The differences in the ndings between our study and Zhang et al's may be due to the lower number of studies included by Zhang et al [45].…”

“…However, ndings from the present meta-analysis were discordant with the recently published meta-analysis published by Zhang et al [45], which observed that higher β-carotene intake was weakly associated with the increased risk of total fracture (RR 1.07; 95% CI: 0.97, 1.17), though the results were not statistically signi cant. The differences in the ndings between our study and Zhang et al's may be due to the lower number of studies included by Zhang et al [45]. Further, Zhang et al [46] did not differentiate between the assessment measures of β-carotene, including serum, plasma, and dietary intake of β-carotene in their analysis, while our study focused solely on dietary βcarotene measures.…”