Therefore , vitamin A supplementation alone may reduce the risk of anemia , by improving hemoglobin and ferritin levels in individuals with low serum retinol levels
ABSTRACT Anemia is a worldwide public health problem that can be related to many causes , including vitamin A deficiency .
The aim of this study was to assess and estimate the effect of vitamin A supplementation ( VAS ) on iron status biomarkers and anemia in humans .
Vitamin A supplements ameliorate the adverse effect of HIV-1, malaria, and diarrheal infections on child growth.
OBJECTIVE Evidence from animal experiments and observational studies in humans suggests that vitamin A plays a fundamental role in physical growth . However , results from vitamin A supplementation trials in children are inconsistent ; whereas some did not find an overall effect on growth , others found benefits only among specific groups , including children with low concentrations of serum retinol or short duration of breastfeeding . The apparent lack of an overall effect of vitamin A on growth could be attributed to context -specific distribution of conditions that affect both growth and the response to supplementation , eg , baseline vitamin A status , deficiency of other nutrients ( fat , zinc ) , and the presence of infectious diseases . Human immunodeficiency virus ( HIV ) infection , malaria , and diarrheal disease adversely affect growth and are associated with increased prevalence of vitamin A deficiency . We hypothesize that vitamin A supplementation could ameliorate the adverse effect of these infections on child growth . METHODS We conducted a r and omized , clinical trial among 687 Tanzanian children who were 6 to 60 months of age and admitted to the hospital with pneumonia . Children were assigned to oral doses of 200 000 IU vitamin A ( half that dose if < 12 months ) or placebo on the day of admission , a second dose on the following day , and third and fourth doses at 4 and 8 months after discharge from the hospital , respectively . Anthropometric measurements were obtained at baseline and at monthly visits to the study clinics during 12 months after the initial hospitalization . Surveillance on the incidence and severity of diarrhea and respiratory infections was conducted during biweekly visits , alternately at a study clinic and the child 's home , using a pictorial diary that the mothers were trained to use . A blood specimen was drawn at baseline for determination of HIV status , malaria infection , and hemoglobin levels . We used mixed effects models to compare estimated total weight and height increases after 1 year of follow-up between treatment arms , overall and within levels of HIV status , malaria , and other possible baseline effect modifiers . We also assessed the potential modulating effect of vitamin A on the risk of stunting ( height-for-age < -2 st and ard deviations of the gender-specific National Center for Health Statistics median reference ) attributable to diarrheal and respiratory infections during follow-up , in the subset of children who were not stunted at baseline . A similar approach was followed for wasting ( weight-for-height < -2 st and ard deviations of the reference median ) . Cox regression models were used to estimate relative risks and 95 % confidence intervals ( CI ) , treating episodes of infection as time-dependent covariates . RESULTS A total of 554 children had at least 2 follow-up measurements of height or weight and constituted the study base . Baseline characteristics did not differ significantly by treatment arm . Seventy-three percent of the children were < 2 years of age , and 37 % were < 12 months ; 31 % were stunted at baseline and 9 % were wasted . Malaria ( Plasmodium falciparum ) and HIV infection were found in 24 % and 9 % of the children , respectively . Median duration of follow-up was 351 days , with 10 measurements /child , on average , irrespectively of treatment assignment . Supplementation with vitamin A among children who had HIV infection and were < 18 months of age result ed in a significant length increase . Four months after the first dose , infants who were HIV positive in the vitamin A arm had gained , on average , 2.8 cm ( 95 % CI : 1.0 - 4.6 ) more than children who received placebo , whereas no effect was observed among infants who were HIV negative ( difference at 4 months : -0.2 cm ; 95 % CI : -0.8 - 0.5 ) . Children who were < 12 months of age and had malaria at enrollment experienced a 747-g ( 95 % CI : 71 - 1423 ) higher yearly weight gain attributable to vitamin A ; among children without malaria , however , the supplements did not have a significant effect ( -57 g ; 95 % CI : -461 - 348 ) . These results remained unchanged after controlling for indicators of the socioeconomic and nutritional status at baseline . Linear growth was also improved by vitamin A among children from households with poor water supply ( 0.8 cm/year ; 95 % CI : 0 - 1.5 ) but not in children with tap water in the house or compound ( -1.0 cm/year ; 95 % CI : -1.9 - 0 ) . Weight gain was greater among children with mid-upper arm circumference below the 25th percentile of the age-specific distribution at baseline ( 458 g/year ; 95 % CI : 1 - 905 ) , but no benefit was evident among children with higher mid-upper arm circumference . The risk of stunting associated with episodes of persistent diarrhea ( lasting 14 or more days ) during follow-up was virtually eliminated by vitamin A supplements . Among children in the placebo group , the average risk of stunting associated with 1 or more episodes of persistent diarrhea between 2 consecutive visits was 5.2 times higher ( 95 % CI : 2.4 - 11.2 ) than that of children without diarrhea or with acute episodes . In contrast , among children who received vitamin A , there was virtually no risk of stunting associated with persistent diarrhea ( relative risk : 1.0 ; 95 % CI : 0.3 - 1.3 ) . This effect was slightly attenuated after controlling for the number of household possessions , gender , baseline low arm circumference , HIV infection , and presence of malaria parasites in blood . Vitamin A supplements did not modify the associations between respiratory infections and the risk of stunting or wasting . CONCLUSIONS Vitamin A supplementation improves linear and ponderal growth in infants who are infected with HIV and malaria , respectively , and decreases the risk of stunting associated with persistent diarrhea . Supplementation could constitute a low-cost , effective intervention to decrease the burden of growth retardation in setting s where infectious diseases are highly prevalent
Therefore , vitamin A supplementation alone may reduce the risk of anemia , by improving hemoglobin and ferritin levels in individuals with low serum retinol levels
ABSTRACT Anemia is a worldwide public health problem that can be related to many causes , including vitamin A deficiency .
The aim of this study was to assess and estimate the effect of vitamin A supplementation ( VAS ) on iron status biomarkers and anemia in humans .