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The Indian Journal of Medical Research Jul 2022The silent epidemic of micronutrient deficiencies (MNDs) continues to be a major public health challenge in the developing world, including India. The prevalence of... (Review)
Review
The silent epidemic of micronutrient deficiencies (MNDs) continues to be a major public health challenge in the developing world, including India. The prevalence of iron, iodine, zinc, vitamin A and folate deficiencies is alarmingly high worldwide. India is additionally facing a high prevalence of vitamin D and B12 deficiencies. To combat the hidden epidemic of MNDs, various governments around the world have mostly relied on supplementation or fortification-based interventions. India launched salt iodization programme in 1962 and vitamin A and iron-folate supplementation programmes in 1970. Yet, even after decades of these programmes, MNDs are still widespread in the country. Due to slow progress in alleviating the burden of most MNDs, the Government of India aims to scale up fortification-based intervention programmes. However, there are safety and effectiveness concerns with such approaches. Hence, overdependence on supplementation and fortification alone may be counterproductive. Instead, food based dietary diversification approach can be the way forward. In this article, we list the common MNDs in India, evaluate major policy interventions, discuss concerns pertaining to fortification and suggest the need for a concurrent food-based approach, in particular dietary diversification, as a long-term and sustainable strategy to address population-based MNDs.
Topics: Humans; Micronutrients; Vitamin A; Food, Fortified; Malnutrition; Iron; Folic Acid; India
PubMed: 36510896
DOI: 10.4103/ijmr.ijmr_3314_21 -
International Journal of Molecular... May 2023Vitamin A ensures intestinal homeostasis, impacting acquired immunity and epithelial barrier function; however, its role in innate immunity is mostly unknown. Here, we...
Vitamin A ensures intestinal homeostasis, impacting acquired immunity and epithelial barrier function; however, its role in innate immunity is mostly unknown. Here, we studied the impact of vitamin A in different dextran sulfate sodium (DSS)-induced colitis animal models. Interestingly, more severe DSS-induced colitis was observed in vitamin A-deficient (VAD) mice than in vitamin A-sufficient (VAS) mice; the same was observed in VAD severe combined immunodeficient mice lacking T/B cells. Remarkably, IL-1β production, LC3B-II expression, and inflammasome activity in the lamina propria were significantly elevated in VAD mice. Electron microscopy revealed numerous swollen mitochondria with severely disrupted cristae. In vitro, non-canonical inflammasome signaling-induced pyroptosis, LC3B-II and p62 expression, and mitochondrial superoxide levels were increased in murine macrophages (RAW 264.7) pretreated with retinoic acid receptor antagonist (Ro41-5253). These findings suggest that vitamin A plays a crucial role in the efficient fusion of autophagosomes with lysosomes in colitis.
Topics: Animals; Mice; Inflammasomes; Vitamin A; Dextran Sulfate; Colitis; Lysosomes; Mice, Inbred C57BL; Disease Models, Animal
PubMed: 37240022
DOI: 10.3390/ijms24108684 -
Biomolecules Dec 2019The concentration of all--retinoic acid, the bioactive derivative of vitamin A, is critically important for the optimal performance of numerous physiological processes.... (Review)
Review
The concentration of all--retinoic acid, the bioactive derivative of vitamin A, is critically important for the optimal performance of numerous physiological processes. Either too little or too much of retinoic acid in developing or adult tissues is equally harmful. All--retinoic acid is produced by the irreversible oxidation of all--retinaldehyde. Thus, the concentration of retinaldehyde as the immediate precursor of retinoic acid has to be tightly controlled. However, the enzymes that produce all--retinaldehyde for retinoic acid biosynthesis and the mechanisms responsible for the control of retinaldehyde levels have not yet been fully defined. The goal of this review is to summarize the current state of knowledge regarding the identities of physiologically relevant retinol dehydrogenases, their enzymatic properties, and tissue distribution, and to discuss potential mechanisms for the regulation of the flux from retinol to retinaldehyde.
Topics: Animals; Biosynthetic Pathways; Humans; Retinaldehyde; Tretinoin
PubMed: 31861321
DOI: 10.3390/biom10010005 -
Frontiers in Endocrinology 2023The thyroid hormones play a pivotal role in various physiological processes, including growth, metabolism regulation, and reproduction. While non-modifiable factors are... (Review)
Review
The thyroid hormones play a pivotal role in various physiological processes, including growth, metabolism regulation, and reproduction. While non-modifiable factors are known to impact thyroid function, such as genetics and age, nutritional factors are also important. Diets rich in selenium and iodine are conventionally acknowledged to be beneficial for the production and release of thyroid hormones. Recent studies have suggested a potential link between beta-carotene, a precursor to vitamin A (retinol), and thyroid function. Beta-carotene is known for its antioxidant properties and has been shown to play a role in the prevention of various clinical conditions such as cancer and cardiovascular and neurological diseases. However, its impact on thyroid function is still unclear. Some studies have suggested a positive association between beta-carotene levels and thyroid function, while others have found no significant effect. Conversely, the hormone produced by the thyroid gland, thyroxine, enhances the conversion of beta-carotene to retinol. Furthermore, vitamin A derivatives are being explored as potential therapeutic options for thyroid malignancies. In this review, we highlight the mechanisms through which beta-carotene/retinol and thyroid hormones interact and review the findings of clinical studies examining the association between beta-carotene consumption and thyroid hormone levels. Our review underscores the need for further research to clarify the relationship between beta-carotene and thyroid function.
Topics: Thyroid Gland; beta Carotene; Vitamin A; Thyroid Hormones; Physiological Phenomena
PubMed: 37305054
DOI: 10.3389/fendo.2023.1089315 -
Pflugers Archiv : European Journal of... Dec 2023Optogenetics is a technology using light-sensitive proteins to control signaling pathways and physiological processes in cells and organs and has been applied in...
Optogenetics is a technology using light-sensitive proteins to control signaling pathways and physiological processes in cells and organs and has been applied in neuroscience, cardiovascular sciences, and many other research fields. Most commonly used optogenetic actuators are sensitive to blue and green light, but red-light activation would allow better tissue penetration and less phototoxicity. Cyp27c1 is a recently deorphanized cytochrome P450 enzyme that converts vitamin A to vitamin A, thereby red-shifting the spectral sensitivity of visual pigments and enabling near-infrared vision in some aquatic species.Here, we investigated the ability of Cyp27c1-generated vitamin A to induce a shift in spectral sensitivity of the light-gated ion channel Channelrhodopsin-2 (ChR2) and its red-shifted homolog ReaChR. We used patch clamp to measure photocurrents at specific wavelengths in HEK 293 cells expressing ChR2 or ReaChR. Vitamin A incubation red-shifted the wavelength for half-maximal currents (λ) by 6.8 nm for ChR2 and 12.4 nm for ReaChR. Overexpression of Cyp27c1 in HEK 293 cells showed mitochondrial localization, and HPLC analysis showed conversion of vitamin A to vitamin A. Notably, the λ of ChR2 photocurrents was red-shifted by 10.5 nm, and normalized photocurrents at 550 nm were about twofold larger with Cyp27c1 expression. Similarly, Cyp27c1 shifted the λ of ReaChR photocurrents by 14.3 nm and increased normalized photocurrents at 650 nm almost threefold.Since vitamin A incubation is not a realistic option for in vivo applications and expression of Cyp27c1 leads to a greater red-shift in spectral sensitivity, we propose co-expression of this enzyme as a novel strategy for red-shifted optogenetics.
Topics: Humans; Vitamin A; Optogenetics; HEK293 Cells; Heart; Channelrhodopsins
PubMed: 37987804
DOI: 10.1007/s00424-023-02880-2 -
Global Health, Science and Practice Jun 2022To identify vitamin A supplementation (VAS) trends in South Sudan and provide insights to refocus VAS programming vis a vis polio eradication campaigns recently phased... (Review)
Review
AIM
To identify vitamin A supplementation (VAS) trends in South Sudan and provide insights to refocus VAS programming vis a vis polio eradication campaigns recently phased out while access to health care, land, food, and markets remain challenging.
METHOD
Review of data from survey and coverage reports; review of policy and program documents; key informant responses; general literature search.
RESULTS
Vitamin A deficiency (VAD) is likely a severe public health problem among preschool-aged children in South Sudan based on a high under-5 mortality rate (96.2 deaths/1,000 live births) and high levels of undernutrition, infections, and food insecurity. Vitamin A capsules, with deworming tablets (VASD), have been delivered to preschool-aged children during national immunization days (NIDs) for the past decade. Although areas of South Sudan and certain populations continue to have low VAS coverage, when comparing national VAS coverage (reported in the last 6 months) between 2010 and August 2019, a large improvement is noted from 4% to 76%. In 2021, VAS coverage was more than 90% at the national level during 2 stand-alone distribution campaigns. Deworming coverage trends generally mimicked VAS coverage. VAS is provided to postpartum mothers who deliver at health facilities (approximately 12%-25%), but coverage data are not available.
CONCLUSION
Twice-yearly VAS should remain a key lifesaving intervention to address VAD, but alternative delivery strategies will be needed. Conducting events, such as child health days, supported by promotional activities or community-based VASD distribution activities for the youngest children and those missed during campaigns, should be considered. For the long term, a hybrid approach targeting underserved areas with mass distribution events while integrating VASD into community-based programs such as quarterly screening for wasting should be tested further and gradually scaled up everywhere as this has the potential to sustainably reach all vulnerable children twice yearly.
Topics: Child, Preschool; Child; Female; Humans; Infant; Vitamin A; South Sudan; Vitamin A Deficiency; Mothers; Dietary Supplements
PubMed: 36332070
DOI: 10.9745/GHSP-D-21-00660 -
Bioscience Reports Apr 2020Previous studies have demonstrated some associations between dietary vitamin A intake and ovarian cancer risk with an inconsistent relationship. We therefore performed... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Previous studies have demonstrated some associations between dietary vitamin A intake and ovarian cancer risk with an inconsistent relationship. We therefore performed the present study to further explore the association between them.
METHODS
Databases of PubMed, Embase, and Web of Science were retrieved up to September 1, 2019. Summarized relative risk (RR) with corresponding 95% confidence intervals (CI) were calculated. Stata 14.0 software was used for data analysis.
RESULTS
Fifteen articles involving 4882 cases and 443,179 participants were included in this meta-analysis. A positive association between dietary vitamin A intake and ovarian cancer risk was found (RR = 0.816, 95%CI = 0.723-0.920, I2 = 48.4%, Pfor heterogeneity = 0.019). Significant association was also found in case-control studies (RR = 0.769, 95%CI = 0.655-0.902), but not in cohort studies. When we performed the analysis between ovarian cancer risk and geographic locations, we found an inverse association in North American populations (RR = 0.825, 95%CI = 0.720-0.946), instead of other populations.
CONCLUSIONS
In summary, findings from the present study suggested that higher dietary intake of vitamin A may contribute to the lower development of ovarian cancer, especially among North Americans.
Topics: Feeding Behavior; Female; Humans; North America; Ovarian Neoplasms; Risk Factors; Vitamin A
PubMed: 32149329
DOI: 10.1042/BSR20193979 -
Journal of Lipid Research 2021Lecithin:retinol acyltransferase and retinol-binding protein enable vitamin A (VA) storage and transport, respectively, maintaining tissue homeostasis of retinoids (VA...
Lecithin:retinol acyltransferase and retinol-binding protein enable vitamin A (VA) storage and transport, respectively, maintaining tissue homeostasis of retinoids (VA derivatives). The precarious VA status of the lecithin:retinol acyltransferase-deficient (Lrat) retinol-binding protein-deficient (Rbp) mice rapidly deteriorates upon dietary VA restriction, leading to signs of severe vitamin A deficiency (VAD). As retinoids impact gut morphology and functions, VAD is often linked to intestinal pathological conditions and microbial dysbiosis. Thus, we investigated the contribution of VA storage and transport to intestinal retinoid homeostasis and functionalities. We showed the occurrence of intestinal VAD in LratRbp mice, demonstrating the critical role of both pathways in preserving gut retinoid homeostasis. Moreover, in the mutant colon, VAD resulted in a compromised intestinal barrier as manifested by reduced mucins and antimicrobial defense, leaky gut, increased inflammation and oxidative stress, and altered mucosal immunocytokine profiles. These perturbations were accompanied by fecal dysbiosis, revealing that the VA status (sufficient vs. deficient), rather than the amount of dietary VA per se, is likely a major initial discriminant of the intestinal microbiome. Our data also pointed to a specific fecal taxonomic profile and distinct microbial functionalities associated with VAD. Overall, our findings revealed the suitability of the LratRbp mice as a model to study intestinal dysfunctions and dysbiosis promoted by changes in tissue retinoid homeostasis induced by the host VA status and/or intake.
Topics: Vitamin A
PubMed: 33587919
DOI: 10.1016/j.jlr.2021.100046 -
Translational Vision Science &... Dec 2021This study aimed to evaluate the contribution of vitamin A dimerization to retinal pigment epithelium (RPE) atrophic changes. Leading causes of irreversible blindness,...
PURPOSE
This study aimed to evaluate the contribution of vitamin A dimerization to retinal pigment epithelium (RPE) atrophic changes. Leading causes of irreversible blindness, including Stargardt disease and age-related macular degeneration (AMD), occur as a result of atrophic changes in RPE. The cause of the RPE atrophic changes is not apparent. During the vitamin A cycle, vitamin A dimerizes, leading to vitamin A cycle byproducts, such as vitamin A dimers, in the RPE.
METHODS
To study the consequence of vitamin A dimerization to RPE atrophic changes, we used a rodent model with accelerated vitamin A dimerization, Abca4-/-/Rdh8-/- mice, and the vitamin A analog C20D3-vitamin A to selectively ameliorate the accelerated rate of vitamin A dimerization.
RESULTS
We show that ameliorating the rate of vitamin A dimerization with C20D3-vitamin A mitigates pathological changes observed in the prodromal phase of the most prevalent retinal degenerative diseases, including fundus autofluorescence changes, dark adaptation delays, and signature RPE atrophic changes.
CONCLUSIONS
Data demonstrate that the dimerization of vitamin A during the vitamin A cycle is sufficient alone to cause the prerequisite RPE atrophic changes thought to be responsible for the leading causes of irreversible blindness and that correcting the dimerization rate with C20D3-vitamin A may be sufficient to prevent the RPE atrophic changes.
TRANSLATIONAL RELEVANCE
Preventing the dimerization of vitamin A with the vitamin A analog C20D3-vitamin A may be sufficient to alter the clinical course of the most prevalent forms of blindness, including Stargardt disease and age-related macular degeneration (AMD).
Topics: ATP-Binding Cassette Transporters; Animals; Macular Degeneration; Mice; Retinal Degeneration; Retinal Pigment Epithelium; Stargardt Disease; Vitamin A
PubMed: 34878528
DOI: 10.1167/tvst.10.14.8 -
PLoS Pathogens Apr 2022Fatty acid-and retinol-binding proteins (FARs) belong to a unique family of excreted/secreted proteins (ESPs) found exclusively in nematodes. Much of our understanding... (Review)
Review
Fatty acid-and retinol-binding proteins (FARs) belong to a unique family of excreted/secreted proteins (ESPs) found exclusively in nematodes. Much of our understanding of these proteins, however, is limited to their in vitro binding characteristics toward various fatty acids and retinol and has provided little insight into their in vivo functions or mechanisms. Recent research, however, has shown that FARs elicit an immunomodulatory role in plant and animal model systems, likely by sequestering lipids involved in immune signaling. This alludes to the intricate relationship between parasitic nematode effectors and their hosts.
Topics: Animals; Fatty Acids; Helminth Proteins; Nematoda; Retinol-Binding Proteins; Vitamin A
PubMed: 35446920
DOI: 10.1371/journal.ppat.1010424