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Vitamin A intake and risk of melanoma: a meta-analysis

BACKGROUND: Mounting evidence from experimental and animal studies suggests that vitamin A may have a protective effect on melanoma, but the findings on the association of vitamin A intake with risk of melanoma have been inconsistently reported in epidemiologic studies. We attempted to elucidate the association by performing a meta-analysis.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet] - Centre for Reviews and Dissemination (UK).

Version: 2014

Vitamin A and carotenoids and the risk of Parkinson's disease: a systematic review and meta-analysis

BACKGROUND: Vitamin A and carotenoids are involved in signalling pathways regulating gene expression in many organs, including the brain. The dopaminergic system is a target of retinoic acid action in the central nervous system. The aim of this review is to assess the epidemiological evidence on the association between blood levels or dietary intakes of vitamin A and carotenoids and risk of Parkinson's disease (PD).

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet] - Centre for Reviews and Dissemination (UK).

Version: 2014

Vitamin A for acute respiratory infection in developing countries: a meta-analysis

AIM: To determine the efficacy of intervention with high-dose vitamin A as an adjunct to standard treatment on outcome in acute lower respiratory tract infection in children in developing countries.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet] - Centre for Reviews and Dissemination (UK).

Version: 2004

Review of the safety and efficacy of vitamin A supplementation in the treatment of children with severe acute malnutrition

BACKGROUND: World Health Organization (WHO) guidelines recommend for children with severe acute malnutrition (SAM), high-dose vitamin A (VA) supplements be given on day 1 of admission, and on days 2 and 14 in the case of clinical signs of vitamin A deficiency (VAD). Daily low-dose VA follows, delivered in a premix added to F-75 and F-100. This study aimed to systematically review the evidence for safety and effectiveness of high-dose VA supplementation (VAS) in treatment of children with SAM.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet] - Centre for Reviews and Dissemination (UK).

Version: 2013

Vitamin A and carotenoids during pregnancy and maternal, neonatal and infant health outcomes: a systematic review and meta-analysis

Vitamin A (VA) deficiency during pregnancy is common in low-income countries and a growing number of intervention trials have examined the effects of supplementation during pregnancy on maternal, perinatal and infant health outcomes. We systematically reviewed the literature to identify trials isolating the effects of VA or carotenoid supplementation during pregnancy on maternal, fetal, neonatal and early infant health outcomes. Meta-analysis was used to pool effect estimates for outcomes with more than one comparable study. We used GRADE criteria to assess the quality of individual studies and the level of evidence available for each outcome. We identified 23 eligible trials of which 17 had suitable quality for inclusion in meta-analyses. VA or beta-carotene (βC) supplementation during pregnancy did not have a significant overall effect on birthweight indicators, preterm birth, stillbirth, miscarriage or fetal loss. Among HIV-positive women, supplementation was protective against low birthweight (<2.5 kg) [risk ratio (RR) = 0.79 [95% confidence interval (CI) 0.64, 0.99]], but no significant effects on preterm delivery or small-for-gestational age were observed. Pooled analysis of the results of three large randomised trials found no effects of VA supplementation on neonatal/infant mortality, or pregnancy-related maternal mortality (random-effects RR = 0.86 [0.60, 1.24]) although high heterogeneity was observed in the maternal mortality estimate (I(2) = 74%, P = 0.02). VA supplementation during pregnancy was found to improve haemoglobin levels and reduce anaemia risk (<11.0 g/dL) during pregnancy (random-effects RR = 0.81 [0.69, 0.94]), also with high heterogeneity (I(2) = 52%, P = 0.04). We found no effect of VA/βC supplementation on mother-to-child HIV transmission in pooled analysis, although some evidence suggests that it may increase transmission. There is little consistent evidence of benefit of maternal supplementation with VA or βC during pregnancy on maternal or infant mortality. While there may be beneficial effects for certain outcomes, there may also be potential for harm through increased HIV transmission in some populations.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet] - Centre for Reviews and Dissemination (UK).

Version: 2012

The use of regular vitamin A preparations for children and adults with cystic fibrosis

Cystic fibrosis can lead to certain vitamins, such as vitamin A, not being properly absorbed by the body. This can result in problems caused by vitamin deficiency. A lack of vitamin A (vitamin A deficiency) can cause specific problems such as eye and skin problems. It can also be associated with poorer general and respiratory health. Therefore people with cystic fibrosis are usually given regular vitamin A preparations from a very young age. However, too much vitamin A can also cause respiratory and bone problems. The review aimed to show whether giving vitamin A regularly to people with cystic fibrosis is beneficial or not. However, the authors did not find any relevant trials to include in the review. They are therefore unable to draw any conclusions regarding the routine administration of vitamin A supplements and recommend that until further evidence is available, local guidelines are followed regarding this practice.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2014

Vitamin A creams and lotions for nappy (diaper) rash

There is not enough evidence to support the use of vitamin A to treat nappy rash. Nappy or diaper rash is a term used to describe inflammation in babies' napkin area. Whilst nappy rash does not make babies very sick, it is very common and it causes varying levels of discomfort to infants and concern to parents. Ointments that contain vitamin A have been suggested as possible treatments for napkin rash. Our review found that there is not enough evidence to say whether vitamin A is effective for treating or preventing napkin rash; more research is needed. One small trial found that applying vitamin A in the first three months of life did not prevent napkin rash.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2009

The relationship between vitamin A and risk of fracture: meta-analysis of prospective studies

Osteoporotic fracture is a significant cause of morbidity and mortality and is a challenging global health problem. Previous reports of the relation between vitamin A intake or blood retinol and risk of fracture were inconsistent. We searched Medline and Embase to assess the effects of vitamin A (or retinol or beta-carotene but not vitamin A metabolites) on risk of hip and total fracture. Only prospective studies were included. We pooled data with a random effects meta-analysis with adjusted relative risk (adj.RR) and 95% confidence interval (CI). We used Q statistic and I(2) statistic to assess heterogeneity and Egger's test to assess publication bias. Eight vitamin A (or retinol or beta-carotene) intake studies (283,930 participants) and four blood retinol level prospective studies (8725 participants) were included. High intake of vitamin A and retinol were shown to increase risk of hip fracture (adj.RR [95% CI] = 1.29 [1.07, 1.57] and 1.40 [1.03, 1.91], respectively), whereas beta-carotene intake was not found to increase the risk of hip fracture (adj.RR [95% CI] = 0.82 [0.59, 1.14]). Both high or low level of blood retinol was shown to increase the risk of hip fracture (adj.RR [95% CI] = 1.87 [1.31, 2.65] and 1.56 [1.09, 2.22], respectively). The risk of total fracture does not differ significantly by level of vitamin A (or retinol) intake or by blood retinol level. Dose-response meta-analysis shows a U-shaped relationship between serum retinol level and hip fracture risk. Our meta-analysis suggests that blood retinol level is a double-edged sword for risk of hip fracture. To avoid the risk of hip fracture caused by too low or too high a level of retinol concentration, we suggest that intake of beta-carotene (a provitamin A), which should be converted to retinol in blood, may be better than intake of retinol from meat, which is directly absorbed into blood after intake. © 2014 American Society for Bone and Mineral Research.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet] - Centre for Reviews and Dissemination (UK).

Version: 2014

Vitamin A for preventing acute lower respiratory tract infections in children up to seven years of age

Acute lower respiratory tract infections (LRTIs), especially pneumonia and bronchiolitis, are leading causes of mortality in children up to five years of age. The Global Burden of Disease 2000 project estimated that the annual number of acute respiratory tract infection (ARTI)‐related deaths in children up to five years of age was 2.1 million (excluding deaths caused by measles, whooping cough and neonatal deaths). Others estimate worldwide child deaths from ARTIs at 1.9 million in 2000, 70% of them in Africa and Southeast Asia. Vitamin A deficiency is common in low‐income countries and weakens barriers to infection.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2011

The use of retinoids (vitamin A derivatives) to prevent progression of cervical intra‐epithelial neoplasia (CIN)

Cervical cancer is preceded by cervical intra‐epithelial neoplasia (CIN). Surgery for CIN is effective in reducing the risk of subsequent invasive carcinoma. An effective chemo‐preventive agent might avoid the need for surgery and reduce the cost and morbidity of work‐up and treatment. Retinoids are natural and synthetic derivatives of naturally occurring vitamin A. Overall, the retinoids studied are not effective in causing regression of severe CIN3 but may have activity in moderate CIN2. Data are inadequate to allow assessment of whether the retinoids studied are effective in preventing progression of any grade of CIN.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2014

Impact of vitamin A supplementation on infant and childhood mortality

INTRODUCTION: Vitamin A is important for the integrity and regeneration of respiratory and gastrointestinal epithelia and is involved in regulating human immune function. It has been shown previously that vitamin A has a preventive effect on all-cause and disease specific mortality in children under five. The purpose of this paper was to get a point estimate of efficacy of vitamin A supplementation in reducing cause specific mortality by using Child Health Epidemiology Reference Group (CHERG) guidelines.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet] - Centre for Reviews and Dissemination (UK).

Version: 2011

Vitamin A supplementation for breastfeeding mothers

While the amount of vitamin A in well‐nourished mothers' breast milk is sufficient to meet the needs of their infants, this may not be the case for mothers from populations with vitamin A deficiency. Therefore, trials have tested whether giving mothers vitamin A supplements as single doses soon after birth or beta‐carotene for long periods can improve the health and survival of these mothers and their babies. Ten of the 12 trials in this review compared a single dose of vitamin A and placebo, with one trial supplementing women with beta‐carotene for nine months after birth. Two studies compared a higher dose with a lower dose of vitamin A. None of the trials was able to show an effect on infant death and only one small study showed improved infant health. None of the trials was able to show an effect on maternal death or morbidity. A significant improvement was seen for maternal serum retinol, breast milk retinol and vitamin A liver stores after single dose of vitamin A supplementation. Vitamin A did not show any adverse effects in these trials, but this may not apply for women and babies from well nourished populations.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2010

Vitamin A for non‐measles pneumonia in children

Acute respiratory infections, mostly in the form of pneumonia, are the leading cause of death in children under five years of age living in low‐income countries. Vitamin A supplementation has been found to reduce mortality and the severity of respiratory infections in children with measles. This updated review was undertaken to assess the effectiveness of vitamin A adjunctive therapy in children with non‐measles respiratory infections, particularly pneumonia.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2010

Vitamin A supplementation for preventing disease and death in children 6 months to five years of age

Vitamin A deficiency (VAD) is a major public health problem in low and middle income countries affecting 190 million children under 5 years of age. VAD pre‐disposes children to increased risk of a range of problems, including respiratory diseases, diarrhoea, measles and vision problems, and can lead to death.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2011

Vitamin A for measles in children

Measles is caused by a virus and possible complications include pneumonia. Measles is a major cause of death in children in low‐income countries and is particularly dangerous in children with vitamin A deficiency. Eight studies involving 2574 participants were included in this review and we found that there was no significant reduction in mortality in children receiving vitamin A. However, vitamin A megadoses (200,000 international units (IUs) on each day for two days) lowered the number of deaths from measles in hospitalized children under the age of two years. Two doses of vitamin A are not considered to be too expensive, and are not likely to produce adverse effects.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2011

Vitamin A supplementation to prevent mortality and short‐ and long‐term morbidity in very low birthweight infants

Vitamin A is a group of fat‐soluble compounds used by the body for regulation and promotion of growth and differentiation of many cells, including cells in the retina of the eye and the cells that line the lung. Preterm infants have low vitamin A levels at birth. This may contribute to an increased risk of developing chronic lung disease, and hence a requirement for oxygen. It is possible that additional vitamin A supplement may reduce complications of prematurity, including abnormal development of the retina (retinopathy), bleeding in the brain (intraventricular haemorrhage), and damage to the gut from inflammation (necrotising enterocolitis) as well as reducing respiratory infections. Too much vitamin A is potentially harmful as it can raise intracranial pressure and cause skin and mucous membrane changes (injury or lesions), and vomiting. Nine trials were included in this review, eight comparing vitamin A with a control (placebo or no supplementation) and one comparing different vitamin A regimens. Supplementing very low birthweight infants with vitamin A by intramuscular injection or in the milk formula was associated with a trend toward a reduced number of deaths or oxygen requirement at one month of age compared to placebo. For surviving infants with birthweight less than 1000 g (three trials, 824 infants of which at least 96% had a birthweight < 1000 g), fewer infants required oxygen at 36 weeks' postmenstrual age compared to the control; the number needed to treat for one to benefit was 13 (95% confidence interval 7 to 100). Three trials with information on retinopathy of prematurity suggested a trend towards reduced incidence in infants receiving vitamin A supplementation. The one trial that investigated neurodevelopmental status at 18 to 22 months of age correcting for prematurity found no evidence of benefit or harm associated with vitamin A supplementation compared to control. No adverse effects of vitamin A supplementation were reported, but it was noted that intramuscular injections of vitamin A were painful.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2011

Neonatal vitamin A supplementation for the prevention of mortality and morbidity in term neonates in developing countries

Vitamin A is an important micronutrient that is required for the maintenance of normal functioning of the human body. In the developing world, many pregnant women are vitamin A‐deficient. During pregnancy, additional vitamin A is required for the growth of the baby and for providing stores in the baby's liver. Deficiency of this micronutrient in the mother may also lead to its deficiency in the baby and may result in adverse effects on the baby's health. The benefits of giving vitamin A to children greater than six months of age, in reducing death and adverse effects on health, have been established but no evidence of this beneficial effect is available in infants one to five months of age. The potential benefits of vitamin A supplementation in the newborn period (during the first month of life) is under investigation and the review identified seven studies including 51,446 newborns with the intervention group supplemented with vitamin A in this period. There was a significant reduction in infant deaths at six months of age with the intervention when data for all infants were analysed. A similar reduction in the risk was observed for term neonates whose data were available from a subset of studies. These findings should be interpreted with caution because of the small number of studies used in these analyses and their estimates were close to the null effect of vitamin A. There are several large studies being conducted. The data from these, when available, will inform our analysis and help in establishing a definitive role of this intervention.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2011

Vitamin A supplementation for prophylaxis or therapy in childhood pneumonia: a systematic review of randomized controlled trials

This review concluded that there was no benefit of vitamin A supplementation for the prevention and treatment of childhood community acquired pneumonia. However, due to problems with the conduct and reporting of the review, the author's conclusion may not be reliable.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet] - Centre for Reviews and Dissemination (UK).

Version: 2010

Vitamin A supplementation given to mothers of newborn children or infants below six months of age for preventing death and illnesses in the first year of life

Vitamin A deficiency is a significant public health problem in low and middle income countries. Vitamin A supplementation (VAS) given to children between the age of six months and five years has been shown to reduce deaths in these settings. Infants below one year of age are at higher risk of developing vitamin A deficiency. There are two possible ways to enhance the vitamin A status of these infants. Firstly, VAS can be given to lactating mothers to increase the vitamin A content of their breast milk, and secondly, VAS can be given direct to young infants below six months of life. Researchers have examined the potential role of these two strategies in preventing death and illness in the first year of life.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2011

Vitamin A supplementation for reducing the risk of mother‐to‐child transmission of HIV infection

Mother‐to‐child transmission (MTCT) of HIV is the primary way that children become infected with HIV. More than 1000 children worldwide are infected in this way every day. Researchers theorized that giving vitamin A supplements to HIV‐infected pregnant or breastfeeding women might make it less likely that their children would be infected with HIV. The primary objective of this review of randomised studies is to estimate the effect of vitaminA supplementation during pregnancy and/or breastfeeding on the risk of mother‐to‐child transmission of HIV infection. The secondary objectives are to estimate the effect of vitamin A supplementation on infant and maternal mortality and morbidity, and to describe any side effects for the mother and the new baby.

Cochrane Database of Systematic Reviews: Plain Language Summaries [Internet] - John Wiley & Sons, Ltd.

Version: 2011

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