Impacts of vitamin A deficiency on biological rhythms: Insights from the literature

Abstract

Vitamin A is essential for brain function, in addition to its important roles in vision, immunity, and reproduction. Previous studies have shown that retinoic acid (RA), the bioactive form of vitamin A, is involved in the regulation of various intracellular responses related to biological rhythms. RA is reported to affect the circadian rhythm by binding to RA receptors, such as receptors in the circadian feedback loops in the mammalian suprachiasmatic nucleus. However, evidence of the impacts of vitamin A deficiency (VAD) on biological rhythms is limited, and most of the related studies were conducted on animals. In this review, we described the physiological functions of biological rhythms and physiological pathways/molecular mechanisms regulating the biological rhythms. We then discussed the current understanding of the associations of VAD with biological rhythm disorders/diseases (sleep disorders, impairments in learning/memory, emotional disorders, and other immune or metabolism diseases) and summarized the currently proposed mechanisms (mainly by retinoid nuclear receptors and related proteins) for the associations. This review may help recognize the role of VAD in biological rhythm disorders and stimulate clinical or epidemiological studies to confirm the findings of related animal studies.

Advancing Endocrine Disruptors via In Vitro Evaluation: Recognizing the Significance of the Organization for Economic Co-Operation and Development and United States Environmental Protection Agency Guidelines, Embracing New Assessment Methods, and the Urgent Need for a Comprehensive Battery of Tests

“…The retinoid system is involved in many functions, such as reproduction, differentiation, development, and sight [ 72 , 73 , 74 ]. The effect of retinoids is mediated via nuclear receptors, RAR (alpha, beta, and gamma) and RXR (alpha, beta, and gamma) [ 75 ].…”

The role and impact of abnormal vitamin levels in autism spectrum disorders

“…VA and its active metabolite RA are necessary for the development of the central nervous system (CNS), including early brain development, neuronal proliferation, neuronal differentiation, synaptic growth, and synaptogenesis. [53][54][55] The hippocampus, a crucial component of the brain, is associated with both cognition and emotion. 56 The hippocampus has high levels of VA receptor expression, which is linked to the emergence of ASD, and that continuous postnatal VAD suppresses retinoic acid receptor (RAR)-α expression, which then inhibits Ca 2+ excitability in hippocampal neurons, thereby leading to functional deficits in the hippocampus.…”

Association between circulating antioxidants and sleep disorders: comprehensive results from NHANES 2017–2018

“…15,20,22 Vitamin A and retinoids participate in regulation of biological rhythms and sleep regulation by use of the retinoid signaling pathways. 27,28 Similarly, vitamin E can induce oxidative stress and reduce the ROS levels, 29,30 and has been reported to provide neuroprotective effects in memory impairment caused by chronic sleep disorders. 31 Despite these findings, comprehensive studies investigating the relationship between circulating antioxidants and the risk of sleep disorders on a general population level are still lacking.…”