Nutritional Deficiencies - Health Concerns
Vitamin A -
updated: 01 December 2008
Vitamin A deficiency disorders in children and women
Food Nutr Bull. 2003 Dec;24(4 Suppl):S78-90
West KP Jr.
Vitamin A deficiency is an endemic nutrition problem throughout much of the developing world, especially affecting the health and survival of infants, young children, and pregnant and lactating women. These age and life-stage groups represent periods when both nutrition stress is high and diet likely to be chronically deficient in vitamin A. Approximately 127 million preschool-aged children and 7 million pregnant women are vitamin A deficient. Health consequences of vitamin A deficiency include mild to severe systemic effects on innate and acquired mechanisms of host resistance to infection and growth, increased burden of infectious morbidity, mild to severe (blinding) stages of xerophthalmia, and increased risk of mortality. These consequences are defined as vitamin A deficiency disorders (VADD). Globally, 4.4 million preschool children have xerophthalmia and 6 million mothers suffer night blindness during pregnancy. Both conditions are associated with increased risk of morbidity and mortality. While reductions of child mortality of 19-54% following vitamin A treatment have been widely reported, more recent work suggests that dosing newborns with vitamin A may, in some settings, lower infant mortality. Among women, one large trial has so far reported a > or = 40% reduction in mortality related to pregnancy with weekly, low-dose vitamin A supplementation. Epidemiologic data on vitamin A deficiency disorders can be useful in planning, designing, and targeting interventions.
Publication Types:
Online - Abstract
Vitamin A deficiency disorders: international efforts to control a preventable "pox".
J Nutr. 2004 Jan;134(1):231S-236S
Underwood BA.
Visual symptoms (night blindness) of vitamin A deficiency (VAD) were among the earliest diet-related deficiencies documented. Knowledge of vitamin A chemistry, metabolism and deficiency consequences accrued rapidly during the first eight decades of the 20th century. A series of disorders were described in animals, including impaired growth, reproduction, epithelial integrity, and disease resistance that were relieved by consumption of both animal and plant sources of the vitamin. Identification of the intestinal beta-carotene cleavage enzyme in the laboratory of James Allen Olson was seminal to understanding the mechanism for formation of vitamin A from ingested carotenoids. WHO's 1990 estimate of about 40 million children annually with clinical eye signs of VAD was revised upward to 140-250 million at risk of vitamin A deficiency disorders (VADD) when epidemiological and clinical trials demonstrated morbidity and mortality risk even in the absence of ocular signs. Alternative methods for VAD status assessment and more reliable analytical techniques were developed, several in Dr. Olson's laboratory. The last decade has seen global progress in VADD control by expanding distribution of medicinal supplements, fortification of foods and dietary diversification through horticulture and education programs. Experience shows that achievements gained through narrowly focused interventions are fragile and vulnerable to national political and economic instability. Contextually relevant, community-centered strategies that improve household food and nutrition security and self-reliance are critical to sustaining international efforts to control the VADD "pox."
Publication Types:
Online - Article
Vitamin A deficiency disorders
J Indian Med Assoc. 1999 Aug;97(8):320-3
McLaren DS.
The major cause of blindness in children worldwide is xerophthalmia caused by vitamin A deficiency. In addition it has other adverse effects, including increased mortality and the term vitamin A deficiency disorders (VADD) has been introduced to cover the whole clinical spectrum of disease. The ocular manifestations of xerophthalmia have been classified and a set of prevalence criteria for the detection of a problem of public health magnitude has been in use for more than two decades. The global prevalence of VADD is now well documented and World Health Organisation (WHO) receives information continuously for updating its data base on the subject. The pathogenesis of the disease is still imperfectly understood, it is not at all clear precisely why certain subjects in vulnerable communities develop xerophthalmia, while the majority are spared. A schedule for treatment of the established case has been available for a long time, but at both clinic and hospital level concentrated sources of vitamin A for treatment are frequently not available. More emphasis needs to be laid on prevention and a choice of methods consisting of large dose supplementation, fortification of food, control of precipitating infections and dietary improvement. The advantages and drawbacks of each are discussed.
PIP: This article focuses on xerophthalmia, caused by vitamin A deficiency, which is the major cause of blindness among children worldwide. The term "vitamin A deficiency disorders" (VADD) has been introduced to cover the whole clinical spectrum of disease. The global prevalence of VADD is now well documented and WHO has evidence that the number of young children suffering from subclinical vitamin A deficiency is steadily increasing. Moreover, the pathogenesis of the disease is still imperfectly understood. It is not clear why certain subjects in vulnerable communities develop xerophthalmia, while the majority are spared. Oral preparations of vitamin A are well absorbed and utilized in even severely malnourished patients. A schedule of treatment is given to serve as a guide in the full treatment process. Control of VADD involves a massive dose supplementation, fortification of common foodstuffs with vitamin A, immunization, and dietary improvement. However, each of these methods has drawbacks and advantages.
Publication Types:
Online - Abstract
Vitamin A for preventing acute lower respiratory tract infections in children up to seven years of age
Cochrane Database Syst Rev. 2008 Jan 23;(1):CD006090.
Chen H, Zhuo Q, Yuan W, Wang J, Wu T.
BACKGROUND: Vitamin A supplements are effective for preventing diarrhoea. There are theoretical reasons it might also be effective for acute lower respiratory tract infections (LRTIs), also very common in children, especially in low income countries. OBJECTIVES: To assess the effectiveness and safety of vitamin A for preventing acute LRTIs in children up to seven years of age. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 2); MEDLINE (1966 to July 2007); EMBASE (1974 to July 2007); and the Chinese Biomedicine Database (CBM) (1976 to July 2007). SELECTION CRITERIA: Randomised controlled trials (RCTs) that assessed the effectiveness of vitamin A in the prevention of acute LRTI in children up to seven years of age. DATA COLLECTION AND ANALYSIS: The review authors independently extracted data and assessed trial quality. Study authors were contacted for additional information. MAIN RESULTS: Most studies found no significant effect of vitamin A on the incidence of acute LRTI, or prevalence of symptoms of acute LRTI. Vitamin A caused an increased incidence of acute LRTI in one study; an increase in cough and fever; and increased symptoms of cough and rapid breathing in two others. Three reported no differences and no protective effect of vitamin A. Two studies reported that vitamin A significantly reduced the incidence of acute LRTI with children with poor nutritional status or weight, but increased it in normal children. AUTHORS' CONCLUSIONS: This unexpected result is outside our current understanding of the use of vitamin A for preventing acute LRTIs. Accordingly, vitamin A should not be given to all children to prevent acute LRTIs. There is evidence for vitamin A supplements to prevent acute LRTIs in children with low serum retinol or those with a poor nutritional status.
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Online - Article
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