Background: Even though vitamin A (Vit A) is one of the essential vitamins required for bone growth and development, it is still uncertain whether its effect on bone mineral density (BMD) is beneficial or harmful. Aim: To assess Vit A's effect and its derivatives on BMD and the risk of developing osteoporosis. Data sources: PubMed, Cochrane Library, Science Direct, Embase, and Google Scholar were searched in February 2019 and updated in November 2020. Methods: Conducted following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Results: A total of 13 studies were included in this report out of 9,124 citations. Five of them were cross-sectional studies, and nine were cohort studies. Three out of five cross-sectional studies showed an increase in BMD, while two showed a decrease in BMD. Four out of eight cohort studies found an increase in BMD; two studies found no association between vitamin A level and BMD; one showed an inverse U-shape association of vitamin A with BMD, suggesting that both the increase or decrease levels of vitamin A affect BMD, while only one study showed a decrease in BMD. Conclusion: Although most of the included studies showed a favorable effect of Vit A on BMD, Vit A's role or its derivatives on BMD change remains unclear.
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