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Biochimica Et Biophysica Acta.... Nov 2020Carotenoids exert a rich variety of physiological functions in mammals and are beneficial for human health. These lipids are acquired from the diet and metabolized to... (Review)
Review
Carotenoids exert a rich variety of physiological functions in mammals and are beneficial for human health. These lipids are acquired from the diet and metabolized to apocarotenoids, including retinoids (vitamin A and its metabolites). The small intestine is a major site for their absorption and bioconversion. From here, carotenoids and their metabolites are distributed within the body in triacylglycerol-rich lipoproteins to support retinoid signaling in peripheral tissues and photoreceptor function in the eyes. In recent years, much progress has been made in identifying carotenoid metabolizing enzymes, transporters, and binding proteins. A diet-responsive regulatory network controls the activity of these components and adapts carotenoid absorption and bioconversion to the bodily requirements of these lipids. Genetic variability in the genes encoding these components alters carotenoid homeostasis and is associated with pathologies. We here summarize the advanced state of knowledge about intestinal carotenoid metabolism and its impact on carotenoid and retinoid homeostasis of other organ systems, including the eyes, liver, and immune system. The implication of the findings for science-based intake recommendations for these essential dietary lipids is discussed. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.
Topics: Animals; Carotenoids; Homeostasis; Humans; Intestinal Absorption; Lipid Metabolism; Lipids; Liver; Triglycerides; Vitamin A
PubMed: 31794861
DOI: 10.1016/j.bbalip.2019.158580 -
Nutrients Jun 2021The association between obesity and vitamin A has been studied. Some studies point to the anti-obesity activity related to this vitamin, carotenoids with provitamin A... (Review)
Review
The association between obesity and vitamin A has been studied. Some studies point to the anti-obesity activity related to this vitamin, carotenoids with provitamin A activity, and carotenoid conversion products. This performance has been evaluated in respect of adipogenesis, metabolic activity, oxidation processes, secretory function, and oxidative stress modulation, showing a new property attributed to vitamin A in preventing and treating obesity. However, vitamin A and its precursors are highly sensitive and easily degraded when subjected to heat, the presence of light, and oxygen, in addition to losses related to the processes of digestion and absorption. In this context, encapsulation presents itself as an alternative capable of increasing vitamin A's stability in the face of unfavorable conditions in the environment, which can reduce its functionality. Considering that vitamin A's status shows a strong correlation with obesity and is an innovative theme, this article addresses the associations between vitamin A's consumption and its precursors, encapsulated or not, and its physiological effects on obesity. The present narrative review points out those recent studies that demonstrate that vitamin A and its encapsulated precursors have the most preserved functionality, which guarantees better effects on obesity therapy.
Topics: Carotenoids; Drug Delivery Systems; Humans; Obesity; Vitamin A; Vitamins
PubMed: 34204998
DOI: 10.3390/nu13061921 -
Frontiers in Endocrinology 2022The terms "vitamin A" and "retinoids" encompass a group of fat-soluble compounds essential for human nutrition. Some of them (retinol, retinal, 9-cis-retinoic acid,... (Review)
Review
The terms "vitamin A" and "retinoids" encompass a group of fat-soluble compounds essential for human nutrition. Some of them (retinol, retinal, 9-cis-retinoic acid, tretinoin, and 13-cis-retinoic acid) are fully natural, while others are synthetic compounds used mostly for therapeutic purposes. Some evidence indicates that the nutritional status of these retinoids (i.e., the presence or absence of deficiency) is able to modulate thyroid gland metabolism. Vitamin A deficiency is tightly correlated with structural and functional impairment of the thyroid gland and is often associated with iodine deficiency. Furthermore, retinoids are involved in different immune functions, as well as in the process of activation, proliferation, and differentiation of regulatory T cells (Treg). This is particularly significant given the high prevalence of thyroid autoimmune disorders, whose pathogenesis seems to be related to the altered homeostasis of regulatory T cells. Retinoids are also involved in the modulation of gene expression their interaction with nuclear receptors, and they also act as cofactors in cell growth and differentiation. The ability of retinoic acid to increase iodine uptake and sodium-iodine symporter activity in human thyroid cancer cell lines suggests that some retinoids and their derivatives may be of use in the treatment of different thyroid tumors. This minireview summarizes the current knowledge on the link between nutritional intake of vitamin A and various thyroid disorders.
Topics: Humans; Vitamin A; Thyroid Gland; Retinoids; Tretinoin; Iodine; Vitamins
PubMed: 36303869
DOI: 10.3389/fendo.2022.968215 -
American Journal of Respiratory Cell... Nov 2018
Topics: Autophagy; Bacterial Infections; Humans; Tretinoin; Tuberculosis; Vitamin A
PubMed: 30095993
DOI: 10.1165/rcmb.2018-0198ED -
Methods in Molecular Biology (Clifton,... 2023Retinoic acid (RA) and the family of molecules based on vitamin A known as retinoids have remarkable effects on limb regeneration in salamanders and newts and cause...
Retinoic acid (RA) and the family of molecules based on vitamin A known as retinoids have remarkable effects on limb regeneration in salamanders and newts and cause whole limb duplications in a concentration-dependent manner. They respecify all three axes of the limb-the proximodistal, the anteroposterior, and the dorsoventral axis. As a result, complete limbs can be induced to regenerate from distal amputation planes producing two limbs in tandem. Here, we describe the basic methods for undertaking these experiments as well as the use of new synthetic retinoids which have retinoic acid receptor-selective actions. These will be valuable tools in future studies on the molecular basis of limb duplications and thus our understanding of the nature of positional information in the regenerating salamander limb.
Topics: Animals; Tretinoin; Vitamin A; Retinoids; Salamandridae; Extremities; Receptors, Retinoic Acid
PubMed: 36272081
DOI: 10.1007/978-1-0716-2659-7_17 -
Methods in Enzymology 2020Vitamin A signaling pathways are predominantly driven by the cellular concentrations of all-trans-retinoic acid (atRA), as the main mechanism of retinoid signaling is...
Vitamin A signaling pathways are predominantly driven by the cellular concentrations of all-trans-retinoic acid (atRA), as the main mechanism of retinoid signaling is via activation of retinoic acid receptors. atRA concentrations are in turn controlled by the storage of vitamin A and enzymatic processes that synthesize and clear atRA. This has resulted in the need for robust and highly specific analytical methods to accurately quantify retinoids in diverse biological matrices. Tissue-specific differences in both the quantity of retinoids and background matrix interferences can confound the quantification of retinoids, and the bioanalysis requires high performance instrumentation, such as liquid chromatography mass-spectrometry (LC-MS). Successful bioanalysis of retinoids is further complicated by the innate structural instability of retinoids and their relatively high lipophilicity. Further, in vitro experiments with retinoids require attention to experimental design and interpretation to account for the instability of retinoids due to isomerization and degradation, sequential metabolism to numerous structurally similar metabolites, and substrate depletion during experiments. In addition, in vitro biological activity is often confounded by residual presence of retinoids in common biological reagents such as cell culture media. This chapter identifies common biological and analytical complexities in retinoid bioanalysis in diverse biological matrices, and in the use of retinoids in cell culture and metabolic incubations. In addition, this chapter highlights best practices for the successful detection and quantification of the vitamin A metabolome in a wide range of biological matrices.
Topics: Receptors, Retinoic Acid; Retinoids; Signal Transduction; Tretinoin; Vitamin A
PubMed: 32359651
DOI: 10.1016/bs.mie.2020.02.010 -
TheScientificWorldJournal 2016Vitamin A is essential for life in all vertebrate animals. Vitamin A requirement can be met from dietary preformed vitamin A or provitamin A carotenoids, the most... (Review)
Review
Vitamin A is essential for life in all vertebrate animals. Vitamin A requirement can be met from dietary preformed vitamin A or provitamin A carotenoids, the most important of which is -carotene. The metabolism of -carotene, including its intestinal absorption, accumulation in tissues, and conversion to vitamin A, varies widely across animal species and determines the role that -carotene plays in meeting vitamin A requirement. This review begins with a brief discussion of vitamin A, with an emphasis on species differences in metabolism. A more detailed discussion of -carotene follows, with a focus on factors impacting bioavailability and its conversion to vitamin A. Finally, the literature on how animals utilize -carotene is reviewed individually for several species and classes of animals. We conclude that -carotene conversion to vitamin A is variable and dependent on a number of factors, which are important to consider in the formulation and assessment of diets. Omnivores and herbivores are more efficient at converting -carotene to vitamin A than carnivores. Absorption and accumulation of -carotene in tissues vary with species and are poorly understood. More comparative and mechanistic studies are required in this area to improve the understanding of -carotene metabolism.
Topics: Animals; Diet; Intestinal Absorption; Vitamin A; beta Carotene
PubMed: 27833936
DOI: 10.1155/2016/7393620 -
Hepatology Communications May 2023Vitamin A, a fat-soluble vitamin that includes retinol and carotenoids, is implicated in liver fibrosis, whereas its deficiency has been associated with various liver...
INTRODUCTION
Vitamin A, a fat-soluble vitamin that includes retinol and carotenoids, is implicated in liver fibrosis, whereas its deficiency has been associated with various liver diseases and higher overall mortality. This study aims to determine the relationship between levels of vitamin A species and liver fibrosis, as well as liver-related mortality in the population of the US.
METHODS
A total of 12,299 participants from the National Health and Nutrition Examination Survey III (NHANES III) were analyzed to provide nationally representative estimates of the relationship between the levels of vitamin A species and liver fibrosis measured by Fibrosis-4 (FIB-4) index and liver-related mortality.
RESULTS
A low blood level of retinol, but not other retinoid derivatives, was associated with significant liver fibrosis after adjustment for demographics, anthropometric measurements, medical history, retinol, and carotene intakes. Compared with vitamin D and E, retinol deficiency demonstrated much stronger associations with a high FIB-4 score. Individuals with known risks of chronic liver disease (CLD) and the lowest pentile of retinol levels had ORs of 3.12 (95% CI, 1.64-5.91) for possible fibrosis and 19.7 (95% CI, 5.71-67.7) for likely fibrosis, and an HR of 7.76 (95% CI, 1.19-50.5) for liver-related mortality compared with those in the highest retinol-level pentile. These relationships were more pronounced among individuals with known risks of chronic liver disease than without.
CONCLUSIONS
A low circulating retinol level is associated with liver fibrosis and liver-related mortality in chronic liver disease. This relationship is potentially driven by a mechanistic link rather than the malabsorption of fat-soluble vitamins and may be leveraged for disease prognostication and have therapeutic implications.
Topics: Humans; Vitamin A; Nutrition Surveys; Cohort Studies; Carotenoids; Liver Diseases; Liver Cirrhosis
PubMed: 37058112
DOI: 10.1097/HC9.0000000000000124 -
Frontiers in Immunology 2023Vitamin A has long been associated with bladder cancer, and many exogenous vitamin A supplements, vitamin A derivatives, and synthetic drugs have been investigated over... (Review)
Review
Vitamin A has long been associated with bladder cancer, and many exogenous vitamin A supplements, vitamin A derivatives, and synthetic drugs have been investigated over the years. However, the effectiveness of these strategies in clinical practice has not met expectations, and they have not been widely adopted. Recent medical research on intestinal flora has revealed that bladder cancer patients exhibit reduced serum vitamin A levels and an imbalance of gut microbiota. In light of the close relationship between gut microbiota and vitamin A, one can speculate that a complex regulatory mechanism exists between the two in the development and occurrence of bladder cancer. As such, further exploration of their interaction in bladder cancer may help guide the use of vitamin A for preventive purposes. During the course of this review, attention is paid to the influence of intestinal microbiota on the vitamin A metabolism and the RA signaling pathway, as well as the mutual promotion relationships between them in the prevention of bladder cancer, In addition, it emphasizes the importance of intestinal microbiota for bladder cancer prevention and treatment.
Topics: Humans; Gastrointestinal Microbiome; Vitamin A; Urinary Bladder Neoplasms; Biomedical Research; Dietary Supplements
PubMed: 37711628
DOI: 10.3389/fimmu.2023.1252616 -
Vitamin A (retinoid) metabolism and actions: What we know and what we need to know about amphibians.Zoo Biology 2014Vitamin A status is an important consideration in the health of both wild and captive amphibians. Data concerning whole body vitamin A homeostasis in amphibians are... (Review)
Review
Vitamin A status is an important consideration in the health of both wild and captive amphibians. Data concerning whole body vitamin A homeostasis in amphibians are scarce, although these animals have been used as experimental models to study the actions of vitamin A in vision, limb regeneration and embryogenesis. The available data suggest that many aspects of vitamin A biology in amphibians are similar to the canonical characteristics of vitamin A metabolism and actions established in mammals. This is consistent with the evolutionary conservation of these important biological processes. Amphibians must obtain vitamin A in their diet, with captive animals being prone to vitamin A deficiency. There is still much to be learned about vitamin A biology in amphibians that can only be achieved through rigorous scientific research. Improved understanding of amphibian vitamin A biology will aid the conservation of endangered amphibians in the wild, as well as the successful maintenance of ex situ populations.
Topics: Amphibians; Animal Husbandry; Animal Nutritional Physiological Phenomena; Animals; Conservation of Natural Resources; Species Specificity; Vitamin A
PubMed: 24958673
DOI: 10.1002/zoo.21140