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1.
The Role of Vitamin A in Wound Healing.
Polcz, ME, Barbul, A
Nutrition in clinical practice : official publication of the American Society for Parenteral and Enteral Nutrition. 2019;(5):695-700
Abstract
Vitamin A is an essential micronutrient that comes in multiple forms, including retinols, retinals, and retinoic acids. Dietary vitamin A is absorbed as retinol from preformed retinoids or as pro-vitamin A carotenoids that are converted into retinol in the enterocyte. These are then delivered to the liver for storage via chylomicrons and later released into the circulation and to its biologically active tissues bound to retinol-binding protein. Vitamin A is a crucial component of many important and diverse biological functions, including reproduction, embryological development, cellular differentiation, growth, immunity, and vision. Vitamin A functions mostly through nuclear retinoic acid receptors, retinoid X receptors, and peroxisome proliferator-activated receptors. Retinoids regulate the growth and differentiation of many cell types within skin, and its deficiency leads to abnormal epithelial keratinization. In wounded tissue, vitamin A stimulates epidermal turnover, increases the rate of re-epithelialization, and restores epithelial structure. Retinoids have the unique ability to reverse the inhibitory effects of anti-inflammatory steroids on wound healing. In addition to its role in the inflammatory phase of wound healing, retinoic acid has been demonstrated to enhance production of extracellular matrix components such as collagen type I and fibronectin, increase proliferation of keratinocytes and fibroblasts, and decrease levels of degrading matrix metalloproteinases.
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2.
Endometriosis Pathoetiology and Pathophysiology: Roles of Vitamin A, Estrogen, Immunity, Adipocytes, Gut Microbiome and Melatonergic Pathway on Mitochondria Regulation.
Anderson, G
Biomolecular concepts. 2019;(1):133-149
Abstract
Endometriosis is a common, often painful, condition that has significant implications for a woman's fertility. Classically, endometriosis has been conceptualized as a local estrogen-mediated uterine condition driven by retrograde menstruation. However, recent work suggests that endometriosis may be a systemic condition modulated, if not driven, by prenatal processes. Although a diverse array of factors have been associated with endometriosis pathophysiology, recent data indicate that the low body mass index and decreased adipogenesis may be indicative of an early developmental etiology with alterations in metabolic function crucial to endometriosis pathoetiology. The present article reviews the data on the pathoetiology and pathophysiology of endometriosis, suggesting key roles for alterations in mitochondria functioning across a number of cell types and body systems, including the immune system and gut microbiome. These changes are importantly regulated by decreases in vitamin A and its retinoic acid metabolites as well as increases in mitochondria estrogen receptor-beta and the N-acetylserotonin/melatonin ratio across development. This has treatment and future research implications for this still poorly managed condition, as well as for the association of endometriosis with a number of cancers.
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3.
The development and release of maize fortified with provitamin A carotenoids in developing countries.
Manjeru, P, Van Biljon, A, Labuschagne, M
Critical reviews in food science and nutrition. 2019;(8):1284-1293
Abstract
Micronutrient deficiencies have been identified as major public health problems affecting a large part of the world's population. Biofortification of staple crops like maize has been proposed as one of the most cost effective and feasible approaches to combat micronutrient deficiencies. Studies have shown that provitamin A from biofortified crops is highly bioavailable and has the capacity to improve vitamin A status of vulnerable groups. Most people in sub-Saharan Africa subsist on maize and many people may benefit from consumption of provitamin A carotenoid biofortified maize, especially women and children. With the exception of transgenic golden rice, biofortified crops have received considerable acceptance by most communities. Negative perceptions associated with yellow maize do not affect orange maize, which is, for example, well-liked in rural Zambia. With proper policy frameworks and full commercialization, provitamin A maize can address the problem of vitamin A deficiencies among poor nations with maize-based diets.
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4.
The Potential of Integrating Provitamin A-Biofortified Maize in Smallholder Farming Systems to Reduce Malnourishment in South Africa.
Zuma, MK, Kolanisi, U, Modi, AT
International journal of environmental research and public health. 2018;(4)
Abstract
Biofortification interventions have the potential to combat malnutrition. This review explored the use of provitamin A-biofortified maize (PVABM) as a vitamin A deficiency (VAD) reduction agricultural-based strategy. Maize has been identified as one of the key staple crops for biofortification to reduce hidden hunger in Africa. Most nutrition interventions have not been successful in reducing hunger because rural communities, who mainly rely on agriculture, have been indirectly excluded. The biofortification intervention proposed here aims to be an inclusive strategy, based on smallholder farming systems. Vitamin A is a micronutrient essential for growth, immune function, reproduction and vision, and its deficiency results in VAD. VAD is estimated to affect more than 250 million children in developing countries. In Africa, especially sub-Saharan Africa, maize is a staple food for rural communities, consumed by most household members. Due to carotenoids, PVABM presents an orange color. This color has been reported to lead to negative perceptions about PVABM varieties. The perceived agronomic traits of this maize by smallholder farmers have not been explored. Adoption and utilization of PVABM varieties relies on both acceptable consumer attributes and agronomic traits, including nutritional value. It is therefore important to assess farmers' perceptions of and willingness to adopt the varieties, and the potential markets for PVABM maize. It is essential to establish on-farm trials and experiments to evaluate the response of PVABM under different climatic conditions, fertilizer levels and soils, and its overall agronomic potential. For the better integration of PVABM with smallholder farming systems, farmer training and workshops about PVABM should be part of any intervention. A holistic approach would enhance farmers' knowledge about PVABM varieties and that their benefits out-compete other existing maize varieties.
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5.
Vitamin A supplements for reducing mother-to-child HIV transmission.
Wiysonge, CS, Ndze, VN, Kongnyuy, EJ, Shey, MS
The Cochrane database of systematic reviews. 2017;(9):CD003648
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Abstract
BACKGROUND Strategies to reduce the risk of mother-to-child transmission of the human immunodeficiency virus (HIV) include lifelong antiretroviral therapy (ART) for HIV-positive women, exclusive breastfeeding from birth for six weeks plus nevirapine or replacement feeding plus nevirapine from birth for four to six weeks, elective Caesarean section delivery, and avoiding giving children chewed food. In some settings, these interventions may not be practical, feasible, or affordable. Simple, inexpensive, and effective interventions (that could potentially be implemented even in the absence of prenatal HIV testing programmes) would be valuable. Vitamin A, which plays a role in immune function, is one low-cost intervention that has been suggested in such settings. OBJECTIVES To summarize the effects of giving vitamin A supplements to HIV-positive women during pregnancy and after delivery. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Embase, and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) up to 25 August 2017, and checked the reference lists of relevant articles for eligible studies. SELECTION CRITERIA We included randomized controlled trials conducted in any setting that compared vitamin A supplements to placebo or no intervention among HIV-positive women during pregnancy or after delivery, or both. DATA COLLECTION AND ANALYSIS At least two review authors independently assessed study eligibility and extracted data. We expressed study results as risk ratios (RR) or mean differences (MD) as appropriate, with their 95% confidence intervals (CI), and conducted random-effects meta-analyses. This is an update of a review last published in 2011. MAIN RESULTS Five trials met the inclusion criteria. These were conducted in Malawi, South Africa, Tanzania, and Zimbabwe between 1995 and 2005 and none of the participants received ART. Women allocated to intervention arms received vitamin A supplements at a variety of doses (daily during pregnancy; a single dose immediately after delivery, or daily doses during pregnancy plus a single dose after delivery). Women allocated to comparison arms received identical placebo (6601 women, 4 trials) or no intervention (697 women, 1 trial). Four trials (with 6995 women) had low risk of bias and one trial (with 303 women) had high risk of attrition bias.The trials show that giving vitamin A supplements to HIV-positive women during pregnancy, the immediate postpartum period, or both, probably has little or no effect on mother-to-child transmission of HIV (RR 1.07, 95% CI 0.91 to 1.26; 4428 women, 5 trials, moderate certainty evidence) and may have little or no effect on child death by two years of age (RR 1.06, 95% CI 0.92 to 1.22; 3883 women, 3 trials, low certainty evidence). However, giving vitamin A supplements during pregnancy may increase the mean birthweight (MD 34.12 g, 95% CI -12.79 to 81.02; 2181 women, 3 trials, low certainty evidence) and probably reduces the incidence of low birthweight (RR 0.78, 95% CI 0.63 to 0.97; 1819 women, 3 trials, moderate certainty evidence); but we do not know whether vitamin A supplements affect the risk of preterm delivery (1577 women, 2 trials), stillbirth (2335 women, 3 trials), or maternal death (1267 women, 2 trials). AUTHORS' CONCLUSIONS Antepartum or postpartum vitamin A supplementation, or both, probably has little or no effect on mother-to-child transmission of HIV in women living with HIV infection and not on antiretroviral drugs. The intervention has largely been superseded by ART which is widely available and effective in preventing vertical transmission.
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6.
Provitamin A biofortification of crop plants: a gold rush with many miners.
Giuliano, G
Current opinion in biotechnology. 2017;:169-180
Abstract
Carotenoids are synthesized de novo by plants, where they play fundamental physiological roles as photosynthetic pigments and precursors for signaling molecules. They are also essential components of a healthy diet, as dietary antioxidants and vitamin A precursors. Vitamin A deficiency is a public health problem in developing countries, which has prompted a series of efforts toward the biofortification of plant-derived foods with provitamin A carotenoids (mainly β-carotene), giving rise to 'golden' crops. Since the 'golden rice' exploit, a number of biofortified crops have been generated, using transgenic approaches as well as conventional breeding. Bioavailability studies have demonstrated the efficacy of several 'golden' crops in maintaining vitamin A status. This review presents the state of the art and the areas that need further experimentation.
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7.
Alterations in vitamin A/retinoic acid homeostasis in diet-induced obesity and insulin resistance.
Mody, N
The Proceedings of the Nutrition Society. 2017;(4):597-602
Abstract
Vitamin A is an essential micronutrient for life and the phytochemical β-carotene, also known as pro-vitamin A, is an important dietary source of this vitamin. Vitamin A (retinol) is the parent compound of all bioactive retinoids but it is retinoic acid (RA) that is the active metabolite of vitamin A. The plasma concentration of retinol is maintained in a narrow range and its normal biological activities strictly regulated since excessive intake can lead to toxicity and thus also be detrimental to life. The present review will give an overview of how vitamin A homeostasis is maintained and move on to focus on the link between circulating vitamin A and metabolic disease states. Finally, we will examine how pharmacological or genetic alterations in vitamin A homeostasis and RA-signalling can influence body fat and blood glucose levels including a novel link to the liver secreted hormone fibroblast growth factor 21, an important metabolic regulator.
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8.
The interrelationship between bile acid and vitamin A homeostasis.
Saeed, A, Hoekstra, M, Hoeke, MO, Heegsma, J, Faber, KN
Biochimica et biophysica acta. Molecular and cell biology of lipids. 2017;(5):496-512
Abstract
Vitamin A is a fat-soluble vitamin important for vision, reproduction, embryonic development, cell differentiation, epithelial barrier function and adequate immune responses. Efficient absorption of dietary vitamin A depends on the fat-solubilizing properties of bile acids. Bile acids are synthesized in the liver and maintained in an enterohepatic circulation. The liver is also the main storage site for vitamin A in the mammalian body, where an intimate collaboration between hepatocytes and hepatic stellate cells leads to the accumulation of retinyl esters in large cytoplasmic lipid droplet hepatic stellate cells. Chronic liver diseases are often characterized by disturbed bile acid and vitamin A homeostasis, where bile production is impaired and hepatic stellate cells lose their vitamin A in a transdifferentiation process to myofibroblasts, cells that produce excessive extracellular matrix proteins leading to fibrosis. Chronic liver diseases thus may lead to vitamin A deficiency. Recent data reveal an intricate crosstalk between vitamin A metabolites and bile acids, in part via the Retinoic Acid Receptor (RAR), Retinoid X Receptor (RXR) and the Farnesoid X Receptor (FXR), in maintaining vitamin A and bile acid homeostasis. Here, we provide an overview of the various levels of "communication" between vitamin A metabolites and bile acids and its relevance for the treatment of chronic liver diseases.
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9.
Changes in fat-soluble vitamin levels after gastrectomy for gastric cancer.
Rino, Y, Oshima, T, Yoshikawa, T
Surgery today. 2017;(2):145-150
Abstract
Several authors have reported the relationship between gastric cancer risk and vitamins. However, there are few reports on fat-soluble vitamins after gastrectomy for gastric cancer. Fat malabsorption and suppression of food intake after gastrectomy for gastric cancer have been previously documented. Because of fat malabsorption and suppression of food intake, a potential deficiency in fat-soluble vitamins, such as vitamins A, D, E, and K, has been readily suggested. In about 20 % of patients, the serum vitamin E levels were decreased. Indeed, vitamin E deficiency is a common complication after gastrectomy. Continuous vitamin E deficiency could develop from neurological symptoms, i.e., peripheral neuropathy, limb or truncal ataxia. The total cholesterol level is associated with the vitamin E levels. However, the serum vitamin A levels were decreased in only 1.8 % of patients. In total gastrectomy cases, the serum vitamin A level may readily decrease. In contrast, 1,25(OH)2 vitamin D deficiency, which is the most active vitamin D metabolite, is rare. Additionally, vitamin K deficiency after gastrectomy has not been reported thus far. Evidence that serum fat-soluble vitamin levels may decrease after gastrectomy for gastric cancer has not been established yet. Future research must explore fat-soluble vitamin deficiency after gastrectomy.
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10.
Vitamin A Supplementation for the Prevention of Bronchopulmonary Dysplasia in Preterm Infants: An Update.
Schwartz, E, Zelig, R, Parker, A, Johnson, S
Nutrition in clinical practice : official publication of the American Society for Parenteral and Enteral Nutrition. 2017;(3):346-353
Abstract
Bronchopulmonary dysplasia (BPD) is a common complication of premature birth and is associated with significant morbidity. Vitamin A supplementation has been suggested as a potential preventative measure against BPD due to its role in lung maturation and because preterm infants are particularly predisposed to vitamin A deficiency. The aim of this review was to determine whether vitamin A supplementation reduces BPD risk among preterm infants. PubMed, CINAHL, and Web of Science databases were searched with the keywords "bronchopulmonary dysplasia," "vitamin A," and "preterm infants" and with the time frame of 2006-2016, and 4 studies were selected for review per the inclusion criteria. Only 1 study found a significant reduction in BPD risk associated with vitamin A supplementation; however, 2 studies indicated a nonsignificant benefit and may have been underpowered to show statistical significance. One study revealed an increased risk of sepsis associated with vitamin A supplementation (for infants weighing >1000 g at birth), but no risk was seen with vitamin A supplementation in the other studies. Because intramuscular vitamin A has shown benefit with minimal risk, continued supplementation for preterm infants is warranted. Future studies aimed at assessing infant groups that are most likely to benefit from supplementation (based on birth weight or other conditions), as well as determining the optimal dosing while minimizing injections, would be beneficial.