The effects of β-carotene on osteoporosis: a systematic review and meta-analysis of observational studies

Purpose The aim is to evaluate the effect of beta-carotene for osteoporosis and provide quantitative evidence. Method PubMed, Embase, Web of Science, and Cochrane Library were searched for eligible studies. Fifteen studies were included. Random-effect model was applied to pool the odds ratio (OR). The risk of osteoporosis and fracture were compared between low beta-carotene intake group and high beta-carotene intake group. Result The intake of beta-carotene was unassociated with the overall risk of osteoporosis [OR = 0.733, 95% Cl (0.528, 1.018), p = 0.064]. Subgroup analysis showed that the intake of beta-carotene was negatively associated with the risk of osteoporosis in both male subgroup [OR = 0.7, 95% Cl (0.549, 0.893), I-2 = 40.40%, p = 0.004] and female subgroup [OR = 0.684, 95% Cl (0.487, 0.960), I-2 = 86.40%, p = 0.028]. There was also a negative association between beta-carotene intake and osteoporosis in Asia subgroup [OR = 0.512, 95% Cl (0.403, 0.650), I-2 = 0.00%, p = 0], whereas no association was observed in Western subgroup [OR = 1.107, 95% Cl (0.908, 1.350), I-2 = 2.30%, p = 0.314]. In addition, random-effect model was adopted to pool the standard mean difference (SMD), and the results showed that beta-carotene intake was positively associated with overall bone mineral density (BMD) [SMD = - 0.213, 95% Cl (- 0.391, - 0.034), I-2 = 87.30%, p = 0.019]. Subgroup analysis showed that beta-carotene intake was positively associated with BMD in Asian participants [SMD = - 0.394, 95% Cl (- 0.461, - 0.328), I-2 = 0, p = 0], while unassociated in Western participants [SMD = - 0.047, 95% Cl (- 0.314, 0.219), I-2 = 78.9%, p = 0.727]. Conclusion beta-carotene may improve BMD and reduce the risk of osteoporosis and fracture. However, these effects could vary by gender and race and need to be further validated by longitudinal studies.