Influence of morbidity on serum retinol of children in a community-based study in northern Ghana

A comparative study on indicators of vitamin A status and risk factors for sensitivity and specificity of the methods to detect vitamin A deficiency

BACKGROUND

Serum retinol (SR) and retinol-binding protein (RBP) are commonly used indicators, but they are affected by infections and inflammation. This study aimed to assess the sensitivity and specificity of VA indicators to detect vitamin A deficiency (VAD) in 36-59-month-old children living in a rural area in Burkina Faso.

METHODS

In a community-based study, two cross-sectional surveys were carried out from November 2016 to September 2017 in the health district of Dandé in Burkina Faso. The surveys included 115 children 36-59 months old. Indicators of VA and inflammation assessed in all children included SR, RBP and total liver VA reserves (TLR) estimated by retinol isotope dilution, and inflammation markers (C-reactive protein (CRP) and alpha 1-acid glycoprotein (AGP)). We calculated the sensitivity, specificity, positive and negative predictive values. In addition, the effects of inflammation, helminth infection, and season on sensitivity and specificity were assessed.

RESULTS

The prevalence of VAD assessed by SR (< 0.7 µmol/L), RBP (< 0.7 µmol/L), and TLR (< 0.1 µmol/g liver) were, respectively, 30.9%, 33.3%, and 0%. Compared to TLR, the specificity, positive predictive value, and negative predictive value of SR were 71.1%, 0%, and 100%, and of RBP, were 68.9%, 0%, and 100%, respectively. The sensitivity was indeterminable for SR and RBP. The specificity of SR and RBP was lower during the dry season. Elevated CRP (> 5.0 mg/L) and AGP (> 1.0 g/L) were detected in 1.9% and 28.6% of children, respectively. The adjustment of VA indicators for inflammation improved SR's specificity to 75.9% and decreased RBP's specificity to 67.8%.

CONCLUSION

No cases of VAD were identified by TLR. However, (inflammation-adjusted) SR and RBP had varying accuracy in the estimation of VAD.

TRIAL REGISTRATION

The study was registered, retrospectively, on 22 March 2018 as a clinical trial with the Pan African Clinical Trials Registry under the number Cochrane South Africa; PACTR201803002999356.

Association between Biomarkers of Inflammation and Total Liver Vitamin A Reserves Estimated by 13C-Retinol Isotope Dilution among Preschool Children in 5 African Countries

BACKGROUND

Vitamin A (VA) assessment is important for targeting public health programs. Retinol isotope dilution (RID) is a sensitive method to estimate total body VA stores (TBSs) and total liver reserves (TLRs), but the impact of subclinical inflammation on RID is unclear.

OBJECTIVE

We determined the association between TBSs and TLRs, estimated by RID, and inflammation among preschool children without clinical infection in Burkina Faso, Cameroon, Ethiopia, South Africa, and Tanzania.

METHODS

Five studies (n = 532; 47.9 ± 8.3 mo; 49.0% male) included ¹³C-RID and measurement of inflammation markers, CRP, and α₁-acid glycoprotein (AGP). Spearman correlations were used to evaluate TBSs and TLRs with inflammation biomarkers. Wilcoxon and Kruskal-Wallis tests were used to compare TBSs and TLRs by inflammation categories [normal vs. elevated CRP (>5 mg/L) or AGP (>1 g/L)] and inflammation stage [reference, incubation (elevated CRP), early convalescence (elevated CRP and AGP), and late convalescence (elevated AGP)].

RESULTS

Complete data were available for 439 children. Median (Q1, Q3) TLRs ranged from 0.12 (0.07, 0.18) μmol/g in Ethiopia to 1.10 (0.88, 1.38) μmol/g in South Africa. Elevated CRP ranged from 4% in Burkina Faso to 42% in Cameroon, and elevated AGP from 20% in Tanzania to 58% in Cameroon. Pooled analysis (excluding Cameroon) showed a negative correlation between TBSs and AGP (ρ = -0.131, P = 0.01). Children with elevated AGP had higher probability of having lower TBSs (probability = 0.61, P = 0.002). TBSs differed among infection stages (P = 0.020). Correlations between TLRs and CRP or AGP were not significant.

CONCLUSIONS

No indication of systematic bias in RID-estimated TLRs was found due to subclinical inflammation among preschool children. The inverse relationship between TBSs and AGP may reflect decreased stores after infection or an effect of inflammation on isotope partitioning. Further research should investigate potential confounding variables to improve TBS-estimate validity.

Measuring the impact of malaria infection on indicators of iron and vitamin A status: a systematic literature review and meta-analysis

Inflammation and infections such as malaria affect estimates of micronutrient status. Medline, Embase, Web of Science, Scopus and the Cochrane library were searched to identify studies reporting mean concentrations of ferritin, hepcidin, retinol or retinol binding protein in individuals with asymptomatic or clinical malaria and healthy controls. Study quality was assessed using the US National Institute of Health tool. Random effects meta-analyses were used to generate summary mean differences. In total, forty-four studies were included. Mean ferritin concentrations were elevated by: 28·2 µg/l (95 % CI 15·6, 40·9) in children with asymptomatic malaria; 28·5 µg/l (95 % CI 8·1, 48·8) in adults with asymptomatic malaria; and 366 µg/l (95 % CI 162, 570) in children with clinical malaria compared with individuals without malaria infection. Mean hepcidin concentrations were elevated by 1·52 nmol/l (95 % CI 0·92, 2·11) in children with asymptomatic malaria. Mean retinol concentrations were reduced by: 0·11 µmol/l (95 % CI -0·22, -0·01) in children with asymptomatic malaria; 0·43 µmol/l (95 % CI -0·71, -0·16) in children with clinical malaria and 0·73 µmol/l (95 % CI -1·11, -0·36) in adults with clinical malaria. Most of these results were stable in sensitivity analyses. In children with clinical malaria and pregnant women, difference in ferritin concentrations were greater in areas with higher transmission intensity. We conclude that biomarkers of iron and vitamin A status should be statistically adjusted for malaria and the severity of infection. Several studies analysing asymptomatic infections reported elevated ferritin concentrations without noticeable elevation of inflammation markers, indicating a need to adjust for malaria status in addition to inflammation adjustments.

Association between infection and nutritional status among infants in a cohort study of vitamin A in western Kenya

Background

Infection is associated with impaired nutritional status, especially for infants younger than 5 years.

Objectives

We assessed the impact of infection indicated by both acute phase proteins (APP), C-reactive protein (CRP), and α-1-acid-glycoprotein (AGP), and as reported by maternal recall on the nutritional status of infants.

Materials and methods

A total of 505 pregnant women were enrolled in a nested longitudinal cohort study of vitamin A (VA). Data from 385 children are reported here. The incidence and severity of respiratory infection and diarrhea (previous 14 days) were assessed by maternal recall; infant/child feeding practices were collected. Infant weight, recumbent length, and heel-prick capillary blood were taken at 9 months postpartum. Indicators of the VA status [retinol binding protein (RBP)], iron status (Hb, ferritin), and subclinical inflammation APP, CRP (>5 mg/L), and AGP (>1 g/L) were determined. Impacts of infection on the infant nutritional status were estimated using logistic regression models.

Results

Infection prevalence, based on elevated CRP and AGP levels, was 36.7%. For diarrhea reported symptoms, 42.4% of infants at 9 months had no indication of infection as indicated by CRP and AGP; for acute respiratory reported symptoms, 42.6% had no indication of infection. There was a significant positive association with infection among VA-deficient (RBP < 0.83 μmol/L) infants based on maternal reported symptoms but not with iron deficiency (ferritin < 12 μg/L). The odds of having infection, based on increased CRP and AGP, in underweight infants was 3.7 times higher (OR: 3.7; 95% CI: 2.3, 4.5; P = 0.019). Infants with iron deficiency were less likely (OR: 0.40; 95% CI: 0.1, 0.7; P = 0.001) to have infection based on CRP and AGP, while infants with VA deficiency were five times more likely (OR: 5.06; 95% CI: 3.2, 7.1; P = 0.0001) to have infection.

Conclusion

Acute phase proteins are more useful in defining infection in a population than reported symptoms of illness. Not controlling for inflammation in a population while assessing the nutritional status might result in inaccurate prevalence estimation.

Inflammation Adjustments to Serum Retinol and Retinol-Binding Protein Improve Specificity but Reduce Sensitivity when Estimating Vitamin A Deficiency Compared with the Modified Relative Dose-Response Test in Ghanaian Children

BACKGROUND

Serum retinol and retinol-binding protein (RBP) concentrations are commonly used biomarkers of vitamin A deficiency (VAD); however, evidence indicates that they are not always accurate, especially in populations with high exposure to inflammation.

OBJECTIVE

The aim was to assess sensitivity and specificity of serum retinol and RBP concentrations to predict VAD, with and without adjustment for inflammation (using categorical and regression-adjusted approaches), using the modified relative dose-response (MRDR) as the reference standard for liver reserves.

METHODS

This secondary analysis of diagnostic accuracy used inflammation and RBP data and analyzed serum retinol and MRDR from a subsample of women of reproductive age (n = 178) and preschool children (n = 166) in the cross-sectional 2017 Ghana Micronutrient Survey.

RESULTS

Inflammation (elevated C-reactive protein and/or α1-acid glycoprotein) was present in 41% of children and 16% of women. Among children, estimates of VAD prevalence were as follows: 7% (MRDR), 40% (serum retinol), 29% (categorical-adjusted serum retinol), 24% (RBP), 13% (categorical-adjusted RBP), and 7% (regression-adjusted RBP). Sensitivity (95% CI) ranged from 22.2% (2.81%, 60.0%; both adjusted RBPs) to 80.0% (44.4%, 97.5%; serum retinol), whereas specificity ranged from 63.3% (54.7%, 71.3%; serum retinol) to 93.5% (88.0%, 97.0%; regression-adjusted RBP). Among women, VAD prevalence ranged from 1% (RBP) to 4% (all others); sensitivity was 0% and specificity was >96% for all indicators.

CONCLUSIONS

Serum retinol and RBP had varying accuracy in estimating VAD, especially in children; adjustment for inflammation increased accuracy by increasing specificity at the expense of sensitivity. Effects of inflammation adjustment in the context of high inflammation and VAD prevalence need to be further explored. Especially in populations with high inflammation, the MRDR test should accompany serum retinol or RBP measurements in a subsample of subjects in population-based surveys. This trial was registered with the Open Science Framework registry (doi: 10.17605/OSF.IO/J7BP9).

Low plasma vitamin A concentration is associated with tuberculosis in Moroccan population: a preliminary case control study

BACKGROUND

Vitamin A plays numerous roles in immune system. Its deficiency alters both the innate and adaptive immunity. Previous results reported that the micronutrients deficiency, particularly vitamin A, is observed in patients with tuberculosis. Thus, we aimed in this study to assess vitamin A concentrations in Moroccan patients with tuberculosis to set up a large efficacy study of vitamin A supplementation for TB infected patients. Plasma retinol concentration was measured by HPLC in 44 recently diagnosed TB patients and 40 healthy controls.

RESULTS

We showed that plasma vitamin A is significantly lower in tuberculosis patients as compared to healthy controls (p < 0.0001). Moreover, no significant association was found between vitamin A deficiency and, TB severity and patients' ages.

CONCLUSION

Our study confirms the association between low vitamin A levels and tuberculosis disease.

Iron Fortification: Its Efficacy and Safety in Relation to Infections

Iron-fortification programs are efficacious and effective provided recent guidelines are followed: the iron compound is carefully chosen and its level in the food is based on target population requirements, the amount lacking in the diet, and the iron bioavailability of the diet and the compound. For monitoring, serum ferritin and transferrin receptor should be included in addition to hemoglobin. Thus, recent studies of provision of iron-fortified salt to children in Morocco, rice to children in India, wheat flour to women in Thailand, and fish sauce in Vietnam have demonstrated efficacy and effectiveness. All were in nonmalarious areas, and intestinal parasites were uncommon except in India, where the children were dewormed. C-reactive protein was used to eliminate high ferritin values due to infection. An efficacy study of iron-fortified salt in dewormed school-aged children in Côte d'Ivoire, where the prevalence of malaria parasitemia was 55%, found no change in hemoglobin after 6 months, but serum ferritin increased and transferrin receptor decreased significantly, and the increase in body iron and estimated iron absorbed compared favorably with the results of a study of similar design in Morocco, where the prevalence of iron-deficiency anemia decreased from 30% to 5% after 10 months. Hence, iron-fortification programs in malarious areas may not decrease anemia prevalence but will improve iron status and, presumably, iron-dependent health outcomes. Eight studies in nonmalarious areas, all but one in infants receiving iron-fortified formula, have found no evidence of increase in infections and some evidence of a decrease in respiratory infection. There have been no studies in malarious areas.

The Relationship between Vitamin A Deficiency and Hiv Infection: Review of Scientific Studies

Review of the literature shows that in adults there are variations in the association of hyporetinemia with disease progression as well as variations in the response to supplementation. Populations that are likely to be deficient in vitamin A show the biggest responses. Additional vitamin A supplementation may not be necessary, and may even be harmful, in adults who already have a good dietary intake of vitamin A and who take many other vitamin supplements. Vitamin A supplementation does not appear to have any impact on mother-to-child transmission of HIV; nevertheless, vitamin A supplementation of pregnant women in the third trimester may be useful to reduce the incidence of low-birthweight and premature infants. the impact of vitamin A on mother-to-child transmission of HIV in preterm infants is awaiting further investigation. Vitamin A supplementation of HIV-infected children appears to be beneficial to reduce the incidence and severity of diarrhea in particular. Randomized, placebo-controlled trials in pregnant women and adults have shown that the association between vitamin A and HIV is probably an association of reverse causality.

Vitamin A supplementation for postpartum women

BACKGROUND

In areas where vitamin A deficiency (VAD) is a public health concern, the maternal dietary intake of vitamin A may be not sufficient to meet either the maternal nutritional requirements, or those of the breastfed infant, due the low retinol concentrations in breast milk.

OBJECTIVES

To evaluate the effects of vitamin A supplementation for postpartum women on maternal and infant health.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (8 February 2016), LILACS (1982 to December 2015), Web of Science (1945 to December 2015), and the reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or cluster-randomised trials that assessed the effects of vitamin A supplementation for postpartum women on maternal and infant health (morbidity, mortality and vitamin A nutritional status).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, conducted data extraction, assessed risk of bias and checked for accuracy. We assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

Fourteen trials of mainly low or unclear risk of bias, enrolling 25,758 women and infant pairs were included. The supplementation schemes included high, single or double doses of vitamin A (200,000 to 400,000 internation units (IU)), or 7.8 mg daily beta-carotene compared with placebo, no treatment, other (iron); or higher (400,000 IU) versus lower dose (200,000 IU). In all trials, a considerable proportion of infants were at least partially breastfed until six months. Supplement (vitamin A as retinyl, water-miscible or beta-carotene) 200,000 to 400,000 IU versus control (placebo or no treatment) Maternal: We did not find evidence that vitamin A supplementation reduced maternal mortality at 12 months (hazard ratio (HR) 1.01, 95% confidence interval (CI) 0.44 to 2.21; 8577 participants; 1 RCT, moderate-quality evidence). Effects were less certain at six months (risk ratio (RR) 0.50, 95% CI 0.09 to 2.71; 564 participants; 1 RCT; low-quality evidence). The effect on maternal morbidity (diarrhoea, respiratory infections, fever) was uncertain because the quality of evidence was very low (50 participants, 1 RCT). We found insufficient evidence that vitamin A increases abdominal pain (RR 1.28, 95% CI 0.95 to 1.73; 786 participants; 1 RCT; low-quality evidence). We found low-quality evidence that vitamin A supplementation increased breast milk retinol concentrations by 0.20 µmol/L at three to three and a half months (mean difference (MD) 0.20 µmol/L, 95% CI 0.08 to 0.31; 837 participants; 6 RCTs). Infant: We did not find evidence that vitamin A supplementation reduced infant mortality at two to 12 months (RR 1.08, 95% CI 0.77 to 1.52; 6090 participants; 5 RCTs; low-quality evidence). Effects on morbidity (gastroenteritis at three months) was uncertain (RR 6.03, 95% CI 0.30 to 121.82; 84 participants; 1 RCT; very low-quality evidence). There was low-quality evidence for the effect on infant adverse outcomes (bulging fontanelle at 24 to 48 hours) (RR 2.00, 95% CI 0.61 to 6.55; 444 participants; 1 RCT). Supplement (vitamin A as retinyl) 400,000 IU versus 200,000 IUThree studies (1312 participants) were included in this comparison. None of the studies assessed maternal mortality, maternal morbidity or infant mortality. Findings from one study showed that there may be little or no difference in infant morbidity between the doses (diarrhoea, respiratory illnesses, and febrile illnesses) (312 participants, data not pooled). No firm conclusion could be drawn on the impact on maternal and infant adverse outcomes (limited data available).The effect on breast milk retinol was also uncertain due to the small amount of information available.

AUTHORS' CONCLUSIONS

There was no evidence of benefit from different doses of vitamin A supplementation for postpartum women on maternal and infant mortality and morbidity, compared with other doses or placebo. Although maternal breast milk retinol concentrations improved with supplementation, this did not translate to health benefits for either women or infants. Few studies reported on maternal and infant mortality and morbidity. Future studies should include these important outcomes.

Accounting for the influence of inflammation on retinol-binding protein in a population survey of Liberian preschool-age children

Vitamin A deficiency (VAD) is an important contributor to child morbidity and mortality. The prevalence of VAD, measured by retinol-binding protein (RBP) or retinol, is overestimated in populations with a high prevalence of inflammation. We aimed to quantify and adjust for the effect of inflammation on VAD prevalence in a nationally representative survey of Liberian children 6 to 35 months of age. We compared five approaches to adjust RBP for inflammation and estimate VAD prevalence (defined as RBP < 0.7 µmol/L): (1) ignoring inflammation; (2) excluding individuals with inflammation (C-reactive protein (CRP) >5 mg/L or alpha1-acid glycoprotein (AGP) >1 g/)L; (3) multiplying each individual's RBP by an internal correction factor; (4) by an external correction factor; and (5) using regression (corrected RBP = exp(InRBP - β₁ (lnCRP_obs -lnCRP_ref ) - β₂ (lnAGP_obs -lnAGP_ref )). Corrected RBP was based on a regression model where reference lnCRP and lnAGP were set to the maximum of the lowest decile. The unadjusted prevalence of VAD was 24.7%. Children with elevated CRP and/or AGP had significantly lower RBP concentrations than their apparently healthy peers (geometric mean RBP 0.79 µmol/L (95% CI: 0.76, 0.82) vs. 0.95 µmol/L (95% CI: 0.92, 0.97), P < 0.001). Using approaches 2-5 resulted in a prevalence of VAD of 11.6%, 14.3%, 13.5% and 7.3%, respectively. Depending on the approach, the VAD prevalence is reduced 10-17 percentage points when inflammation is taken into account. Further quantification of the influence of inflammation on biomarkers of vitamin A status from other national surveys is needed to compare and recommend the preferred adjustment approach across populations.

Late-Pregnancy Salivary Cortisol Concentrations of Ghanaian Women Participating in a Randomized Controlled Trial of Prenatal Lipid-Based Nutrient Supplements

BACKGROUND

High circulating cortisol is associated with miscarriage, preterm birth, and low birth weight. Research in nonpregnant individuals suggests that improved nutrition may lower cortisol concentrations. It is unknown whether nutritional supplementation during pregnancy lowers cortisol.

OBJECTIVE

Our objective was to determine whether women receiving a lipid-based nutrient supplement (LNS) throughout pregnancy would have lower salivary cortisol at 36 wk gestation compared with women receiving other nutrient supplements.

METHODS

We conducted a randomized controlled trial in 1320 pregnant Ghanaian women at ≤20 wk gestation who were assigned to receive daily throughout pregnancy: 1) 60 mg iron + 400 μg folic acid (IFA), 2) multiple micronutrients (MMNs), or 3) 20 g LNS (containing 118 kcal, 22 micronutrients, and protein). Morning salivary cortisol was collected from a subsample at baseline and at 28 and 36 wk gestation.

RESULTS

A total of 758 women had cortisol measurements at 28 or 36 wk gestation. Salivary cortisol at 36 wk gestation did not differ between groups and was (mean ± SE) 7.97 ± 0.199 in the IFA group, 7.84 ± 0.191 in the MMN group, and 7.77 ± 0.199 nmol/L in the LNS group, when adjusted for baseline cortisol, time of waking, and time between waking and saliva collection (P = 0.67). There was an interaction between supplementation group and women's age (continuous variable, P-interaction = 0.03); and when age was dichotomized by the median, significant differences in salivary cortisol concentrations between groups were seen in women ≤26 y of age (IFA = 8.23 ± 0.284 nmol/L, MMN = 8.20 ± 0.274 nmol/L, and LNS = 7.44 ± 0.284 nmol/L; P = 0.03) but not in women >26 y old (IFA = 7.71 ± 0.281 nmol/L, MMN = 7.50 ± 0.274 nmol/L, and LNS = 8.08 ± 0.281 nmol/L; P = 0.13).

CONCLUSIONS

We conclude that supplementation with LNSs or MMNs during pregnancy did not affect the cortisol concentration in the study population as a whole, in comparison with IFA, but that LNS consumption among younger women may lead to lower cortisol at 36 wk gestation. This trial was registered at clinicaltrials.gov as NCT00970866.

Serum retinol concentrations demonstrate high specificity after correcting for inflammation but questionable sensitivity compared with liver stores calculated from isotope dilution in determining vitamin A deficiency in Thai and Zambian children

BACKGROUND

The WHO estimates that 190 million preschool children have vitamin A deficiency (VAD). Serum retinol (SR) concentration is a common indicator of vitamin A (VA) status, but SR is homeostatically controlled and suppressed during inflammation, which may lead to misdiagnosis.

OBJECTIVE

The sensitivity and specificity of SR compared with VA total liver reserves (TLRs) were evaluated for VAD in children from Thailand (n = 37) and Zambia (n = 128). SR was adjusted for inflammation in the Zambian children.

DESIGN

Each child was classified as VA-deficient or not based on cutoffs of <0.1 μmol VA/g liver with the use of retinol isotope dilution and <0.7 μmol/L for SR concentrations. Four categories of infection status in the Zambian children were based on elevated C-reactive protein (CRP) and α1-acid glycoprotein (AGP). Sensitivity and specificity were calculated with the use of unadjusted and inflammation marker-adjusted SR cutoffs.

RESULTS

VAD was 65% and 0% according to TLRs and SR, respectively, in Thai children and 0% and 17%, respectively, in Zambian children. No true positive VAD cases occurred; thus, sensitivity was 0% and indeterminable, respectively; specificity was 100% and 82.8%, respectively. CRP was elevated in 26.6% of Zambian children, whereas 97.7% had elevated AGP, categorizing them as having no infection (2.3%) or in early (26.6%) or late (58.6%) convalescence. With the use of marker-adjusted SR cutoffs of 0.6 μmol/L for late convalescence and 0.5 μmol/L for early convalescence, the adjusted prevalence of SR deficiency was 2.3%, increasing specificity to 97.3%.

CONCLUSIONS

No cases of VAD were identified by both TLRs and SR (true positives) in Thai or Zambian children. Specificity of SR to evaluate VAD was high, but additional research is needed to investigate sensitivity. Adjusting SR cutoffs for inflammation improved specificity by reducing false positives. SR as a VAD indicator may depend on infection rates, which should be taken into consideration. These studies were registered at clinicaltrials.gov as NCT01061307 (for Thailand) and NCT01814891 (for Zambia).

Asymptomatic malaria infection affects the interpretation of biomarkers of iron and vitamin A status, even after adjusting for systemic inflammation, but does not affect plasma zinc concentrations among young children in Burkina Faso

BACKGROUND

Biomarkers of iron [plasma ferritin (pF)], vitamin A [retinol binding protein (RBP)], and zinc status [plasma zinc (pZn)] are affected by the acute phase response, independent of micronutrient status.

OBJECTIVE

The objective of these analyses was to assess how asymptomatic malaria infection affects the interpretation of these biomarkers after adjustment for elevated acute phase proteins (APPs).

METHODS

Soluble transferrin receptor (sTfR), pF, RBP, and pZn concentrations were measured among 451 asymptomatic children aged 6-23 mo in Burkina Faso and adjusted for elevated APP (C-reactive protein ≥5 mg/L and/or α-1-acid-glycoprotein ≥1 g/L) based on a 4-group categorical model. Plasma histidine-rich protein II (HRP2) concentrations ≥0.75 μg/L were considered indicative of current or recent malaria parasitemia.

RESULTS

Of the children in the study, 57.4% had at least 1 elevated APP, and 48.5% had elevated HRP2. After adjusting for APP, children with elevated HRP2 had higher pF (23.5 ± 1.5 μg/L vs. 11.1 ± 0.8 μg/L; P < 0.001) and lower RBP (0.79 ± 0.01 μmol/L vs. 0.92 ± 0.01 μmol/L; P < 0.001) than those without, but there were no differences in pZn among those with and without elevated HRP2 (64.9 ± 12.7 μg/dL vs. 64.9 ± 11.1 μg/dL; P = 0.98). Children with elevated HRP2 had higher sTfR than those without (17.6 ± 0.5 mg/L vs. 12.3 ± 0.4 mg/L; P < 0.0001). After adjusting for HRP2, along with APP, the estimated prevalence of iron deficiency (pF < 12 μg/L) increased from 38.7% to 50.6% and vitamin A deficiency (RBP < 0.84 μmol/L) decreased from 33.4% to 27.7%.

CONCLUSIONS

Asymptomatic malaria is associated with indicators of micronutrient status, even after adjusting for APP. Adjusting indicators of iron and vitamin A status based only on APP may inaccurately estimate the prevalence of micronutrient deficiencies in settings with a high prevalence of malaria and inflammation. This trial was registered at clinicaltrials.gov as NCT00944853.

Diagnostic utility of zinc protoporphyrin to detect iron deficiency in Kenyan pregnant women

BACKGROUND

Iron-deficient erythropoiesis results in excess formation of zinc protoporphyrin (ZPP), which can be measured instantly and at low assay cost using portable haematofluorometers. ZPP is used as a screening marker of iron deficiency in individual pregnant women and children, but also to assess population iron status in combination with haemoglobin concentration. We examined associations between ZPP and disorders that are common in Africa. In addition, we assessed the diagnostic utility of ZPP (measured in whole blood and erythrocytes), alone or in combination with haemoglobin concentration, in detecting iron deficiency (plasma ferritin concentration <15 μg/L).

METHODS

Single blood samples were collected from a population sample of 470 rural Kenyan women with singleton pregnancies, gestational age 13 to 23 weeks, and haemoglobin concentration ≥90 g/L. We used linear regression analysis to assess associations between ZPP and iron markers (including anaemia), factors known or suspected to be associated with iron status, inflammation markers (plasma concentrations of C-reactive protein and α 1-acid glycoprotein), infections (Plasmodium infection, HIV infection), and other disorders (α(+)-thalassaemia, plasma concentrations of total bilirubin, and lactate dehydrogenase). Subsequently, in those without inflammation, Plasmodium infection, or HIV infection, we used logistic discriminant analysis and examined receiver operating characteristics curves with corresponding area-under-the-curve to assess diagnostic performance of ZPP, alone and in combination with haemoglobin concentration.

RESULTS

Individually, whole blood ZPP, erythrocyte ZPP, and erythrocyte protoporphyrin had limited ability to discriminate between women with and without iron deficiency. Combining each of these markers with haemoglobin concentration had no additional diagnostic value. Conventional cut off points for whole blood ZPP (>70 μmol/mol haem) resulted in gross overestimates of the prevalence of iron deficiency.

CONCLUSIONS

Erythrocyte ZPP has limited value to rule out iron deficiency when used for screening in conditions with a low prevalence (e.g., 10%). ZPP is of unreliable diagnostic utility when discriminating between pregnant women with and without iron deficiency. Based on these findings, guidelines on the use of ZPP to assess iron status in individuals or populations of pregnant women need review.

TRIAL REGISTRATION

NCT01308112 (2 March 2011).

Undernutrition, the acute phase response to infection, and its effects on micronutrient status indicators

Infection and undernutrition are prevalent in developing countries and demonstrate a synergistic relation. Undernutrition increases infection-related morbidity and mortality. The acute phase response (APR) is an innate, systemic inflammatory reaction to a wide array of disruptions in a host's homeostasis, including infection. Released from immune cells in response to deleterious stimuli, proinflammatory cytokines act on distant tissues to induce behavioral (e.g., anorexia, weakness, and fatigue) and systemic effects of the APR. Cytokines act to increase energy and protein requirements to manifest fever and support hepatic acute phase protein (APP) production. Blood concentrations of glucose and lipid are augmented to provide energy to immune cells in response to cytokines. Additionally, infection decreases intestinal absorption of nutrients and can cause direct loss of micronutrients. Traditional indicators of iron, zinc, and vitamin A status are altered during the APR, leading to inaccurate estimations of deficiency in populations with a high or unknown prevalence of infection. Blood concentrations of APPs can be measured in nutrition interventions to assess the time stage and severity of infection and correct for the APR; however, standardized cutoffs for nutrition applications are needed. Protein-energy malnutrition leads to increased gut permeability to pathogens, abnormal immune cell populations, and impaired APP response. Micronutrient deficiencies cause specific immune impairments that affect both innate and adaptive responses. This review describes the antagonistic interaction between the APR and nutritional status and emphasizes the need for integrated interventions to address undernutrition and to reduce disease burden in developing countries.

The acute phase response affected traditional measures of micronutrient status in rural Zambian children during a randomized, controlled feeding trial

The acute phase response (APR) to infection can alter blood-based indicators of micronutrient status. Data from a 3-mo randomized, controlled feeding trial in rural Zambian children (n = 181, aged 3-5 y) were used to determine the impact of the APR on indicators of vitamin A and iron status using baseline and final blood samples. Concentrations of acute phase proteins were categorized as raised C-reactive protein (CRP; >5 and >10 mg/L) only, both raised CRP and α1-acid glycoprotein (AGP; >1.2 g/L), raised AGP only, and neither CRP nor AGP raised to identify the respective stages of infection: incubation, early convalescence, convalescence, and healthy state. Data were insufficient to examine the incubation stage of infection. A CRP concentration of >5 mg/L was an effective elevation cutoff point in this population to show impact on micronutrient markers. Time did not affect hemoglobin, serum ferritin, or serum retinol concentrations (P > 0.05). During early convalescence, hemoglobin decreased (14-16%; P ≤ 0.05), serum ferritin increased (279-356%; P ≤ 0.05), and serum retinol decreased (20-30%; P ≤ 0.05). Serum retinol concentrations did not change during convalescence; however, hemoglobin remained depressed (4-9%) and serum ferritin was elevated (67-132%) (both P ≤ 0.05). Modified relative dose response values were unaffected by the APR (P > 0.05) but increased between time points (16%; P ≤ 0.05), indicating a decrease in liver vitamin A reserves on the background of a semiannual vitamin A supplementation program. The observed prevalence of anemia and vitamin A deficiency assessed by serum retinol concentration was higher during the APR (P ≤ 0.05). It is important to consider the impact of infection on dietary interventions and to adjust for acute phase proteins when assessing iron status or vitamin A status by serum retinol concentration alone in children.

Quantification of food and nutrient intakes in Zambian children with and without malaria under controlled feeding conditions

Vitamin A supplementation improves status, which may protect against malarial infection. Provitamin A carotenoid biofortified staple crops may provide a more sustainable approach to alleviate vitamin A deficiency than supplementation, but the impact of febrile illness on food intake must be considered in malaria endemic regions. Morbidity data and food logs from a three-month efficacy trial on provitamin A biofortified (orange) maize in preschool Zambian children (n = 181, age 3-5 years) were systematically analyzed over time to determine the impact of malaria on food intake. Nutrients examined included macronutrients, iron, zinc, and vitamin A. Comparisons based on individual intakes in healthy and malarial states over three-day intervals were made including children from both the orange and white maize groups (n = 100). Malaria prevalence did not differ overall or between treatment groups over time (all P > 0.05). Lower nutrient intakes were observed for all variables during malaria outbreaks (food 289 ± 412 g; energy 248 ± 346 kcal; carbohydrate 42 ± 62 g; protein 8 ± 12 g; fat 5 ± 7 g; iron 1 ± 2 mg; zinc 1 ± 1 mg; vitamin A 58 ± 100 retinol activity equivalents; all P < 0.05). No differences were observed between nutrient decreases in orange and white maize groups (P > 0.05). Considering the impact of malaria on food and nutrient intakes and increased vitamin A utilization and excretion due to the acute phase response, biofortification targets for provitamin A carotenoids may need to be elevated in malaria endemic regions.

Plasma and cerebrospinal proteomes from children with cerebral malaria differ from those of children with other encephalopathies

Clinical signs and symptoms of cerebral malaria in children are nonspecific and are seen in other common encephalopathies in malaria-endemic areas. This makes accurate diagnosis difficult in resource-poor settings. Novel malaria-specific diagnostic and prognostic methods are needed. We have used 2 proteomic strategies to identify differentially expressed proteins in plasma and cerebrospinal fluid from children with a diagnosis of cerebral malaria, compared with those with a diagnosis of malaria-slide-negative acute bacterial meningitis and other nonspecific encephalopathies. Here we report the presence of differentially expressed proteins in cerebral malaria in both plasma and cerebrospinal fluid that could be used to better understand pathogenesis and help develop more-specific diagnostic methods. In particular, we report the expression of 2 spectrin proteins that have known Plasmodium falciparum–binding partners involved in the stability of the infected red blood cell, suppressing further invasion and possibly enhancing the red blood cell's ability to sequester in microvasculature.

Nutritional supplements and plasma antioxidants in childhood asthma

OBJECTIVE

This study investigated the relationship of plasma antioxidants to airway inflammation and systemic oxidative stress in children suffering from atopic asthma with consideration of the intake of nutritional supplements.

SUBJECTS AND RESEARCH METHODS

A total of 35 asthmatic children (AG) and 21 healthy controls (CG) participated in this study. Plasma levels of vitamins A and E, β-carotene, coenzyme Q10 and malondialdehyde (MDA) were analyzed with high-performance liquid chromatography (HPLC); the total antioxidant capacity (TAC) was measured photometrically, and selenium was determined by atomic absorption spectroscopy (AAS). The volume of fractionated exhaled nitric oxide (FeNO) was measured with the NIOX nitric oxide monitoring system.

RESULTS

The plasma antioxidants vitamins A and E, selenium, and coenzyme Q10 but not β-carotene were significantly (p < 0.05) lower in asthmatics than in controls. Further, asthmatic children had significantly reduced plasma concentrations of TAC (p < 0.01), significantly enhanced levels of MDA (p < 0.001), and exhaled a significantly (p < 0.001) higher mean volume of FENO than healthy children. Regular intake of supplements had a significant positive influence on plasma vitamin E (p < 0.01), selenium (p < 0.01), TAC (p < 0.05), MDA (p < 0.01), and FENO (p < 0.01) in asthmatics but not in controls. Additionally, significant negative associations of vitamin E and MDA (AG: p < 0.01; CG: p < 0.05), and vitamin E and FENO (AG: p < 0.05; CG: p > 0.05) were identified.

CONCLUSION

These results indicate that nutritional supplements beneficially modulate plasma antioxidants and thus might have a positive influence on systemic redox balance and subsequently, pulmonary inflammation in asthmatic children.

The importance of controlling for the acute-phase response in the population-based assessment of vitamin A status: a study in children of pre-school age in Uganda

OBJECTIVE

To improve estimates of vitamin A deficiency in children of pre-school age in the 2006 Uganda Demographic and Health Survey (UDHS 2006).

DESIGN

A cross-sectional study in which dried blood spot samples were analysed for C-reactive protein (CRP). Retinol-binding protein (RBP) had previously been analysed using a commercial enzyme immunoassay.

SETTING

A population-based study in Uganda.

SUBJECTS

A systematically selected subset of the dried blood spot samples collected from children aged 6–59 months for UDHS 2006. Children were categorized into ‘normal CRP’ (Group A) and ‘raised CRP’ (Group B) using a CRP cut-off of 5mg/l. A correction factor was calculated to adjust the Group B RBP values for the influence of the acute-phase response.

RESULTS

Geometric mean CRP was 6.2 (95% CI 5.5, 7.0) mg/l, 1.6 (95% CI 1.5, 1.8) mg/l and 17.9 (95% CI 16.4, 19.6) mg/l in all children, in Group A and in Group B, respectively. Geometric mean RBP in all children, in Group A and in Group B was 1.18 (95% CI 1.14, 1.22)mmol/l, 1.26 (95% CI 1.20, 1.33)mmol/l and 1.12 (95% CI 1.07, 1.17)mmol/l, respectively, before correction. Correction increased mean RBP in Group B to 1.26 (95% CI 1.21, 1.31)mmol/l. The prevalence of vitamin A deficiency (RBP,0.825mmol/l) reduced from 18.4% (95% CI 17.2, 23.0%) to 13.9% (95% CI 11.3, 16.5%).

CONCLUSIONS

Correcting for the acute-phase response significantly reduced the prevalence of vitamin A deficiency; thus, the acute-phase response should be considered when vitamin A status is assessed using RBP in order to improve population-level estimates of vitamin A deficiency.

Sensitivity and specificity of C-reactive protein and α(1) -acid glycoprotein for episodes of acute infection among children in Kilimanjaro, Tanzania

OBJECTIVES

Biomarkers of inflammation, including C-reactive protein (CRP) and α(1) -acid glycoprotein (AGP), have tremendous potential in anthropological, public health, and nutrition research as objective indicators of acute infection; however, their usage is limited by the lack of widely agreed upon, reliable cutpoints to define infection. We assessed the sensitivity and specificity of CRP and AGP for identifying acute infectious disease (ID) episodes among children in the Kilimanjaro region of Tanzania.

METHODS

Data were available from 43 3- to 5-year-old children. CRP and AGP were measured in capillary whole dried blood spots (DBS). Two-week morbidity history interviews with children's primary caregivers were used to detect recent episodes of acute ID. Specimens and morbidity history interviews were collected from each child on one (n = 13) or two (n = 30) occasions for 73 paired interviews and specimens.

RESULTS

We evaluated CRP and AGP for identifying acute infection (report of fever, diarrhea, or vomiting in the last week): CRP ≥ 1.1 mg/l had sensitivity of 57.14% and specificity of 86.44%; AGP ≥ 0.76 g/l had sensitivity of 57.14% and specificity of 72.41%. The combined definition (AGP ≥ 0.76 g/l or CRP ≥ 1.1 mg/l) had sensitivity of 71.43% and specificity of 70.69%.

CONCLUSIONS

Among children in Kilimanjaro, Tanzania, assessed in whole blood stored as DBS, AGP ≥ 0.76 g/l or CRP ≥ 1.1 mg/l provided the best definition of acute infection. Whether this definition is appropriate for use in other populations remains to be determined.

Serum retinol and xerophthalmia among a prison population in Papua New Guinea

PURPOSE

To estimate the prevalence of vitamin A deficiency (VAD) and one of its clinical manifestations, xerophthalmia, and examine the predictive value of nyctalopia and ocular signs for serum retinol concentrations among a prison population in Papua New Guinea.

METHODS

A cross-sectional study of 148 prisoners and 9 guards; all males aged ≥18 years. Interview-based questionnaire; ocular examination; serum retinol concentration determination.

RESULTS

Two guards had marginal (retinol <1.05-≥0.70 µmol/L) VAD. For prisoners: mean retinol was 0.84 ± 0.49 µmol/L; 43.9% (95% CI 35.9, 52.2) had VAD (retinol <0.70 µmol/L); 9.6% (95% CI 5.1, 17.0) self-reported nyctalopia prior to, and 36.1% (95% CI 27.7, 45.5) after incarceration; 10.9% (95% CI 6.7, 17.0) exhibited at least one sign of xerophthalmia (2 had fundus changes; all 4 with more than conjunctival xerosis alone had severe [<0.35 µmol/L] retinol deficiency). Prisoners with ocular signs were more likely than those without to have VAD (OR 10.4; 95% CI 2.5, 70.3; P < 0.001) and severe retinol deficiency (OR 19.1; 95% CI 5.5, 77.2; P < 0.001). Positive (PPV) and Negative (NPV) Predictive Values: of nyctalopia for any (PPV 62.9%; NPV 32.8%) and severe (PPV 25.7%; NPV 85.9%) retinol deficiency; of ocular signs for any (PPV 93.3%; NPV 38.2%) and severe (PPV 73.1%; NPV 87.8%) retinol deficiency, and VAD (PPV 86.5%, NPV 38.2%).

CONCLUSIONS

VAD and xerophthalmia were present in this prison population. There may be VAD in the wider community. The former needs remedy and the latter deserves investigation. Self-reported nyctalopia was not a useful indicator of retinol deficiency. Absence of ocular signs was unhelpful for ruling out VAD.

Field-friendly techniques for assessment of biomarkers of nutrition for development

Whereas cost-effective interventions exist for the control of micronutrient malnutrition (MN), in low-resource settings field-friendly tools to assess the effect of these interventions are underutilized or not readily available where they are most needed. Conventional approaches for MN measurement are expensive and require relatively sophisticated laboratory instrumentation, skilled technicians, good infrastructure, and reliable sources of clean water and electricity. Consequently, there is a need to develop and introduce innovative tools that are appropriate for MN assessment in low-resource settings. These diagnostics should be cost-effective, simple to perform, robust, accurate, and capable of being performed with basic laboratory equipment. Currently, such technologies either do not exist or have been applied to the assessment of a few micronutrients. In the Demographic and Health Surveys (DHS), a few such examples for which "biomarkers" of nutrition development have been assessed in low-resource settings using field-friendly approaches are hemoglobin (anemia), retinol-binding protein (vitamin A), and iron (transferrin receptor). In all of these examples, samples were collected mainly by nonmedical staff and analyses were conducted in the survey country by technicians from the local health or research facilities. This article provides information on how the DHS has been able to successfully adapt field-friendly techniques in challenging environments in population-based surveys for the assessment of micronutrient deficiencies. Special emphasis is placed on sample collection, processing, and testing in relation to the availability of local technology, resources, and capacity.

Global proteomic analysis of plasma from mice infected with Plasmodium berghei ANKA using two dimensional gel electrophoresis and matrix assisted laser desorption ionization-time of flight mass spectrometry

BACKGROUND

A global proteomic strategy was used to identify proteins, which are differentially expressed in the murine model of severe malaria in the hope of facilitating future development of novel diagnostic, disease monitoring and treatment strategies.

METHODS

Mice (4-week-old CD1 male mice) were infected with Plasmodium berghei ANKA strain, and infection allowed to establish until a parasitaemia of 30% was attained. Total plasma and albumin depleted plasma samples from infected and control (non-infected) mice were separated by two-dimensional gel electrophoresis (2-DE). After staining, the gels were imaged and differential protein expression patterns were interrogated using image analysis software. Spots of interest were then digested using trypsin and the proteins identified using matrix-assisted laser desorption and ionization-time of flight (MALDI-TOF) mass spectrometry (MS) and peptide mass fingerprinting software.

RESULTS

Master gels of control and infected mice, and the corresponding albumin depleted fractions exhibited distinctly different 2D patterns comparing control and infected plasma, respectively. A wide range of proteins demonstrated altered expression including; acute inflammatory proteins, transporters, binding proteins, protease inhibitors, enzymes, cytokines, hormones, and channel/receptor-derived proteins.

CONCLUSIONS

Malaria-infection in mice results in a wide perturbation of the host serum proteome involving a range of proteins and functions. Of particular interest is the increased secretion of anti-inflammatory and anti apoptotic proteins.

Supplementation with vitamin A early in life and subsequent risk of asthma

Animal models suggest that vitamin A deficiency affects lung development adversely and promotes airway hyperresponsiveness, and may predispose to an increased risk of asthma. We examined the long-term effects of vitamin A supplementation early in life on later asthma risk. In 2006-2008, we revisited participants from two cohorts in rural Nepal who were enrolled in randomised trials of vitamin A supplementation. The first cohort received vitamin A or placebo for <16 months during their pre-school years (1989-1991). The second cohort was born to mothers who received vitamin A, β-carotene or placebo before, during and after pregnancy (1994-1997). At follow-up, we asked about asthma symptoms and performed spirometry. Out of 6,421 subjects eligible to participate, 5,430 (85%) responded to our respiratory survey. Wheezing prevalence during the previous year was 4.8% in participants aged 9-13 yrs and 6.6% in participants aged 14-23 yrs. We found no differences between the vitamin A supplemented and placebo groups from either trial in the prevalence of lifetime or current asthma and wheeze or in spirometric indices of obstruction (p ≥ 0.12 for all comparisons). Vitamin A supplementation early in life was not associated with a decreased risk of asthma in an area with chronic vitamin A deficiency.

Short communication: predicting adverse HIV-related outcomes in a resource-limited setting: use of the inflammation marker α(1)-acid glycoprotein

Limited data exist on the use of acute-phase proteins as predictors of HIV-related outcomes. We examined the relationship between postpartum α(1)-acid glycoprotein (AGP) concentrations and HIV-related maternal mortality, mother-to-child transmission, and HIV-free survival among 643 Zimbabwean women. Elevated AGP was significantly associated with a 5.74-fold (p = 0.001) increased risk of maternal death, a 2.39-fold (p = 0.033) increased risk of postnatal transmission, and a marginally significant 1.85-fold (p = 0.087) increased risk of infant infection or death. In a resource-limited setting, AGP may be of utility as an inexpensive prognostic tool for HIV-infected individuals.

Vitamin A supplementation for postpartum women

BACKGROUND

In vitamin A deficient populations, the amount of vitamin A may be insufficient for maintenance of maternal health and levels in breast milk may be insufficient for breastfeeding infants' needs.

OBJECTIVES

To assess the effects of postpartum maternal vitamin A supplementation on maternal and infant health.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 July 2010), LILACS (1982 to July 2010), Web of Science (1945 to July 2010) and Biological Abstracts (1998 to July 2010).

SELECTION CRITERIA

Randomised controlled trials evaluating the effects of postpartum maternal vitamin A supplementation.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the studies independently.

MAIN RESULTS

We included 12 trials at moderate risk of bias, enrolling 25,465 mother-baby pairs and comparing several postpartum doses (200,000-400,000 IU) of vitamin A or 7.8 mg daily beta-carotene, with placebo, iron or no supplement; or higher (400,000 IU) versus lower dose (200,000 IU). The majority of infants in all studies were at least partially breastfed for six months.Maternal: we observed no impact of vitamin A on maternal mortality (two trials of 9,126 women), morbidity (one trial of 50 women) or adverse effects (subset of 786 women in one trial). Vitamin A enhanced serum and breast milk retinol at three months in five trials, but these improvements were generally not sustained.Infant: we observed no significant differences for infant mortality RR 1.14 95% CI 0.84 to 1.57 (five trials (6,170 infants) or morbidity (three trials) except for fewer episodes of fever with vitamin A in one small trial. No significant differences in infant vitamin A status were seen with maternal vitamin A supplementation (five trials).No beneficial effects for maternal or infant health were associated with higher compared to lower doses of vitamin A in two trials.

AUTHORS' CONCLUSIONS

The lack of effect on maternal and infant mortality and morbidity, with exception of some improved infant morbidity in one small study, and the improvement in maternal vitamin A status, suggest that maternal postpartum vitamin A supplementation offers limited benefits.

Adjusting for the acute phase response is essential to interpret iron status indicators among young Zanzibari children prone to chronic malaria and helminth infections

The extent to which the acute phase response (APR) influences iron status indicators in chronic infections is not well documented. We investigated this relationship using reported recent fever and 2 acute phase proteins (APP), C-reactive protein (CRP), and alpha-1-acid glycoprotein (AGP). In a sample of 690 children matched on age and helminth infection status at baseline, we measured plasma for AGP, CRP, ferritin, transferrin receptor (TfR), and erythropoietin (EPO) and whole blood for hemoglobin (Hb) concentration, zinc protoporphyrin (ZPP), and malaria parasite density, and we obtained maternal reports of recent fever. We then examined the influence of the APR on each iron status indicator using regression analysis with Hb as the outcome variable. Ferritin was inversely related to Hb in the APR-unadjusted model. Adjusting for the APR using reported recent fever alone was not sufficient to reverse the inverse Hb-ferritin relationship. However, using CRP and/or AGP resulted in the expected positive relationship. The best fit model included reported recent fever, AGP and CRP (R(2) = 0.241; P < 0.001). The best fit Hb-ZPP, Hb-TfR, and Hb-EPO models included reported recent fever and AGP but not CRP (R(2) = 0.253, 0.310, and 0.292, respectively; P < 0.001). ZPP, TfR, and EPO were minimally influenced by the APR, whereas ferritin was immensely affected. Reported recent fever alone cannot be used as a marker for the APR. Either AGP or CRP is useful for adjusting if only 1 APP can be measured. However, AGP best predicted the APR in this population.

Malaria and vitamin A deficiency in African children: a vicious circle?

Vitamin A deficiency and malaria are both highly prevalent health problems in Africa. Vitamin A deficiency affects over 30 million children, most of whom are in the age-group (under five years) most affected by malaria. Vitamin A deficiency increases all-cause mortality in this part of the population, and malaria is an important cause of death in children at this age. A low serum retinol concentration (a marker of vitamin A deficiency) is commonly found in children suffering from malaria, but it is not certain whether this represents pre-existing vitamin A deficiency, a contribution of malaria to vitamin A deficiency, or merely an acute effect of malaria on retinol metabolism or binding. In this paper, available evidence in support of a causal relationship in each direction between vitamin A deficiency and malaria is reviewed. If such a relationship exists, and especially if this is bidirectional, interventions against either disease may convey an amplified benefit for health.

Concentrações de vitamina A no leite humano e características socioeconômicas e nutricionais maternas: resultados de estudos brasileiros

OBJETIVOS: agregar e discutir os resultados de estudos realizados no Brasil que avaliaram a concentração de vitamina A no leite materno. FONTES DOS DADOS: foram pesquisadas as bases LILACS, Banco de Teses da Capes, SciELO (Scientific Electronic Library), e Plataforma Lattes -seção de produção científica. As palavras-chaves utilizadas foram: gestantes, lactante, concentração de vitamina A no leite humano, Brasil. As buscas foram realizadas em 2006 e atualizadas em março de 2008. Foram incluídos todos os estudos localizados. SÍNTESE DOS DADOS: foram localizados 14 estudos, publicados entre 1988 e 2008, heterogêneos quanto ao tamanho da amostra, fase do leite, período do dia da coleta e método de determinação das concentrações de vitamina A. Foram descritas concentrações médias de vitamina A no leite humano entre 0,62 e 4,50 µmol/L. CONCLUSÕES: não houve consenso sobre a relação entre concentração de vitamina A no leite humano e vitamina A dietética, estado nutricional materno, características obstétricas e demográficas e duração da gestação. Sugere-se que estudos futuros utilizem, amostras de leite maduro, coletadas aleatoriamente ao longo dos diferentes períodos do dia, e a utilização do high performance liquid chromatography - HPLC - como método de determinação de vitamina A.

Application of Retinol-Binding Protein Enzyme Immunoassay to Dried Blood Spots to Assess Vitamin A Deficiency in a Population-Based Survey: The Uganda Demographic and Health Survey 2006

Background

Vitamin A deficiency is a public health problem in most developing countries. The technological challenges associated with the measurement of serum retinol have limited the epidemiologic assessment of vitamin A deficiency. The combination of retinol-binding protein (RBP) enzyme immunoassay and dried blood spots offers a rapid, inexpensive, and reliable tool for the population-level assessment of vitamin A deficiency in resource-poor settings.

Objective

To report on the application of RBP enzyme immunoassay and dried blood spots to assess serum retinol concentrations as an indicator of vitamin A status in the Uganda Demographic and Health Survey 2006.

Methods

A total of 5,642 capillary blood spot samples were collected by fingerprick onto filter paper cards from women (15–49 years) and children (6–59 months) in a representative probability sample of 9,864 households between May and October 2006. The cards were dried, packed individually with desiccant, and kept at 4°C in a portable refrigerator in the field and at –20°C in the laboratory. Prior to analysis, the RBP enzyme immunoassay was optimized with the use of matched serum and dried blood spots.

Results

The correlation between RBP values determined by matching serum and dried blood spots was excellent ( r = 0.79, p < .00001). The prevalence of vitamin A deficiency in women (RBP < 1.24 μmol/L) and children (RBP < 0.825 μmol/L) was 19.4% and 20.4%, respectively.

Conclusions

The combination of RBP enzyme immunoassay and dried blood spots is a simple, reliable, and cost-effective tool for the estimation of vitamin A deficiency in population-level surveys in resource-poor settings.

Elevated iron stores are associated with HIV disease severity and mortality among postpartum women in Zimbabwe

OBJECTIVES

The relationship between Fe status and HIV infection is complex and poorly understood. While anaemia is a major complication of HIV infection, higher Fe stores may be associated with disease progression. There is limited and conflicting data available from Africa.

DESIGN

Cross-sectional and prospective cohort study. SETTING, SUBJECTS AND METHODS: We examined the association between postpartum Fe status (Hb, serum ferritin (SF) and transferrin receptor (TfR)) and viral load (VL) and HIV-related mortality in 643 HIV-positive Zimbabwean women over a period of 12 months.

RESULTS

In non-anaemic women a log10 increase in SF was associated with a 2.3-fold increase in VL (P = 0.019); this association was absent in anaemic women. In prospective analyses, a log10 increase in SF was associated with a 4-fold increase in mortality by 12 months (P = 0.002). Hb was negatively associated with VL (P = 0.001) and mortality (P = 0.047). The adverse associations between SF and both VL and mortality were found at SF concentrations > 45 microg/l (P < 0.05). Controlling for alpha1 acid glycoprotein, a marker of inflammation, attenuated the association between both SF and VL and mortality, but these remained significant.

CONCLUSIONS

These results are consistent with the hypothesis that high Fe stores have adverse consequences in HIV infection. If adverse consequences are real, our data suggest that they occur at SF concentrations exceeding those consistent with adequate Fe nutriture.

Plasma lycopene and antioxidant vitamins in asthma: the PLAVA study

OBJECTIVE

Scientific evidence suggests that lycopene and antioxidant vitamins have significant antioxidant and protective effects.

METHODS

This case-control study included 96 subjects (40 asthmatics, 56 healthy control subjects). Baseline blood samples, pulmonary function tests, and clinical and alimentary histories were collected. All subjects were grouped by age, sex, cigarette smoking habit, body mass index, alimentary intake, and atopic status.

RESULTS

Serum lycopene concentration was significantly lower in asthmatic subjects than in healthy control subjects (0.10+/-0.7 micromoL/L vs. 0.16+/-0.8 micromoL/L--p<0.001). Serum vitamin A concentration was significantly lower in asthmatics (2.38+/-0.37 micromoL/L) in respect to control subjects (3.06+/-0.56 micromoL/L) (p<0.01). Plasma serum concentration of vitamin E and beta-carotene were not found to be different in the two groups.

CONCLUSIONS

Dietary supplementation or adequate intake of lycopene and vitamin A rich foods may be beneficial in asthmatic subjects.

The importance of β-carotene as a source of vitamin A with special regard to pregnant and breastfeeding women

Vitamin A is essential for growth and differentiation of a number of cells and tissues. Notably during pregnancy and throughout the breastfeeding period, vitamin A has an important role in the healthy development of the fetus and the newborn, with lung development and maturation being particularly important. The German Nutrition Society (DGE) recommends a 40% increase in vitamin A intake for pregnant women and a 90% increase for breastfeeding women. However, pregnant women or those considering becoming pregnant are generally advised to avoid the intake of vitamin A rich liver and liver foods, based upon unsupported scientific findings. As a result, the provitamin A carotenoid beta-carotene remains their essential source of vitamin A. Basic sources of provitamin A are orange and dark green vegetables, followed by fortified beverages which represent between 20% and 40% of the daily supply. The average intake of beta-carotene in Germany is about 1.5-2 mg a day. Assuming a vitamin A conversion rate for beta-carotene for juices of 4:1, and fruit and vegetables between 12:1 and 26:1; the total vitamin A contribution from beta-carotene intake represents 10-15% of the RDA. The American Pediatrics Association cites vitamin A as one of the most critical vitamins during pregnancy and the breastfeeding period, especially in terms of lung function and maturation. If the vitamin A supply of the mother is inadequate, her supply to the fetus will also be inadequate, as will later be her milk. These inadequacies cannot be compensated by postnatal supplementation. A clinical study in pregnant women with short birth intervals or multiple births showed that almost 1/3 of the women had plasma retinol levels below 1.4 micromol/l corresponding to a borderline deficiency. Despite the fact that vitamin A and beta-carotene rich food is generally available, risk groups for low vitamin A supply exist in the western world. It is therefore highly critical to restrict the beta-carotene supply from diet, particularly from sources of beta-carotene with high consumer acceptance such as fortified juices (e.g. "ACE juices") or dietary supplements (e.g. multivitamins for pregnant women). For the part of the population unable to meet vitamin A requirements according to the DACH recommendations, sufficient intake of beta-carotene may be crucial to help improve and maintain adequate vitamin A status and prevention of developmental disorders. At this time it has to be urgently advised against restricting the beta-carotene supply or putting warning labels on beta-carotene fortified products. It is, however, highly recommended to improve the available data on nutrient intakes in Germany, especially for pregnant and breastfeeding women. For them, recommendations to be aware of potential nutrient intake inadequacies might prove useful.

Maternal reports of child illness and the biochemical status of the child: the use of morbidity interviews in rural Bangladesh

In a longitudinal study of child growth and nutritional status in Bangladesh, child morbidity was recorded using health interviews with the mother. The aim of the present study was to establish whether maternal reports of child illness were associated with the biochemical health status of the child. Children aged 2–5 years (n 117) took part in the study and their mothers were interviewed every fortnight by Bangladeshi fieldworkers. Maternal reports of diarrhoea were associated with significantly lower plasma albumin concentrations (P < 0·001), poorer intestinal permeability (P < 0·001), higher plasma immunoglobulin A levels (P < 0·005) and higher α-1-antichymotrypsin (ACT) levels (P < 0·05) compared with children reported to be healthy. Children with fever had significantly higher ACT (P < 0·001) and lower albumin (P < 0·05) levels compared with their healthy counterparts. Respiratory infections (RI) were not associated with any significant changes; however, reports of RI with fever were associated with significantly higher levels of ACT than either illness individually (interaction P < 0·05). These highly significant associations between maternal reports of illness and biochemical profiles of child health support the use of health interviews in developing countries.

Use of the retinol-binding protein : transthyretin ratio for assessment of vitamin A status during the acute-phase response

The ratio plasma retinol-binding protein (RBP) : transthyretin (TTR) has been proposed as a means to improve the assessment of vitamin A status of individuals with concurrent infection or inflammation. We have measured RBP and TTR in stored sera from South African children who had accidentally ingested kerosene. Samples were collected from these children in hospital when suffering acute inflammation and respiratory distress, and from them and neighbourhood control children 3 months later. Vitamin A status was defined by modified relative dose response (MRDR) tests of liver retinol stores at 3 months and by serum retinol concentration both when children were ill and when they were well. Illness was defined as either being in hospital or, at follow-up, as having a raised plasma α1-acid glycoprotein (AGP) level. The RBP : TTR value was significantly decreased by both illness and low liver retinol stores. When the effects on RBP : TTR of illness and vitamin A stores were considered together for the 3-month follow-up samples, only vitamin A status significantly decreased the value. We calculated sensitivity and specificity of the RBP : TTR ratio against established measures of vitamin A status using a cut-off value of 0·3 for RBP : TTR and standard cut-off values for MRDR (0·06) and plasma retinol (0·7 μmol/l). Compared with MRDR, RBP : TTR had sensitivities of 76 % and 43 % and specificities of 22 % and 81 % to detect vitamin A deficiency in hospitalized and well children respectively. Compared with plasma retinol, sensitivities were 88 % and 44 % and specificities were 55 % and 64 % in hospitalized and well children respectively. Only for the case of clinically well children with biochemical evidence of subclinical inflammation did sensitivity (62 % and 100 % against MRDR and plasma retinol respectively) and specificity (100 % and 60 % against MRDR and retinol) approach useful levels for an assessment tool. Overall, although a trend supporting the theory behind the use of the RBP : TTR for assessment of vitamin A status in infection was observed in the current study, the ratio did not provide adequate sensitivity and specificity to be a useful assessment tool.

Feeding difficulties in disabled children leads to malnutrition: experience in an Indian slum

The aim of the present study was to explore the nature, extent and probable causes of nutritional deficiencies among children with disabilities living in Dharavi, a slum in Mumbai, India. A cross-sectional study was conducted to investigate whether the nutritional status of children with disabilities, aged 2–6 years (n141), was worse than that of non-disabled sibling controls (n122) and neighbour controls (n162). Data on food patterns, anthropometry, micronutrient status and feeding difficulties reported by parents were collected. The mean weight for age of the children with disabilities (−2·44 (sd 1·39)Zscores;n120) was significantly lower (P<0·05) compared with the sibling (−1·70 (sd 1·20)Zscores;n109) and neighbour (−1·83 (sd 1·290)Zscores;n162) control groups. The children with disabilities had significantly lower (P<0·05) mean haemoglobin levels (92 (sd 23) g/l;n134) compared with siblings (102 (sd 18) g/l;n103) and neighbours (99 (sd 18) g/l;n153). Relative risk (RR) analysis indicated that the disabled children with feeding difficulties were significantly more likely (P<0·05) to be malnourished, by the indicator of weight for age (RR 1·1; 95 % CI 1·08, 1·20) compared with the disabled children without a feeding difficulty. They were also significantly more likely to be malnourished using the indicators of height for age (RR 1·3; 95 % CI 1·19, 1·43) and weight for height (RR 2·4; 95 % CI 1·78, 3·23) compared with the disabled children without a feeding difficulty. Feeding difficulties were identified as a risk factor for vulnerability to inadequate nutritional status among children with disabilities.

Maternal micronutrient status and decreased growth of Zambian infants born during and after the maize price increases resulting from the southern African drought of 2001–2002

Objective

To investigate the effects on maternal micronutrient status and infant growth of the increased maize prices that resulted from the southern African drought of 2001–2002.

Design

Longitudinal cohort study.

Setting

A maternal and child health clinic in Lusaka, Zambia.

Subjects

Maternal and infant health and nutrition data and maternal plasma were being collected for a study of breast-feeding and postpartum health. Samples and data were analysed according to whether they were collected before (June to December 2001), during (January 2002 to April 2003) or after (May 2003 to January 2004) the period of increased maize price. Season and maternal HIV status were controlled for in analyses.

Results

Maize price increases were associated with decreased maternal plasma vitamin A during pregnancy (P = 0.028) and vitamin E postpartum (P = 0.042), with the lowest values among samples collected after May 2003 (vitamin A: 0.96 μmol l−1, 95% confidence interval (CI) 0.84–1.09, n = 38; vitamin E: 30.8 μmol mmol−1 triglycerides, 95% CI 27.2–34.8, n = 64) compared with before January 2002 (vitamin A: 1.03 μmol l−1, 95% CI 0.93–1.12, n = 104; vitamin E: 38.9 μmol mmol−1 triglycerides, 95% CI 34.5–43.8, n = 47). There were no significant effects of sampling date on maternal weight, haemoglobin or acute-phase proteins and only marginal effects on infant weight. Infant length at 6 and 16 weeks of age decreased progressively throughout the study (P-values for time of data collection were 0.51 at birth, 0.051 at 6 weeks and 0.026 at 16 weeks).

Conclusions

The results show modest effects of the maize price increases on maternal micronutrient status. The most serious consequence of the price increases is likely to be the increased stunting among infants whose mothers experienced high maize prices while pregnant. During periods of food shortages it might be advisable to provide micronutrient supplements even to those who are less food-insecure.

Effects of vitamins, including vitamin A, on HIV/AIDS patients

An estimated 25 million lives have been lost to acquired immune-deficiency syndrome (AIDS) since the immunodeficiency syndrome was first described in 1981. The progress made in the field of treatment in the form of antiretroviral therapy (ART) for HIV disease/AIDS has prolonged as well as improved the quality of life of HIV-infected individuals. However, access to such treatment remains a major concern in most parts of the world, especially in the developing countries. Hence, there is a constant need to find low-cost interventions to complement the role of ART in prevention of HIV infection and slowing clinical disease progression. Nutritional interventions, particularly vitamin supplementation, have the potential to be a low-cost method for being such an intervention by virtue of their modulation of the immune system. Among all the vitamins, the role of vitamin A has been studied most extensively; most observational studies have found that low vitamin A levels are associated with increased risk of transmission of HIV from mother to child. This finding has not been supported by large randomized trials of vitamin A supplementation; on the contrary, these trials have found that vitamin A supplementation increases the risk of mother-to-child transmission (MTCT). There are a number of potential mechanisms that might explain these contradictory findings. One is the issue of reverse causality in observational studies-for instance, advanced HIV disease may suppress release of vitamin A from the liver. This would lead to low levels of vitamin A in the plasma despite the body having enough vitamin A liver stores. Further, advanced HIV disease is likely to increase the risk of MTCT, and hence it would appear that low serum vitamin A levels are associated with increased MTCT. The HIV genome also has a retinoic acid receptor element-hence, vitamin A may increase HIV replication via interacting with this element, thus increasing risk of MTCT. Finally, vitamin A is known to increase lymphoid cell differentiation, which leads to an increase in CCR5 receptors. These receptors are essential for attachment of HIV to the lymphocytes and therefore, an increase in their number is likely to increase HIV replication. Vitamin A supplementation in HIV-infected children, on the other hand, has been associated with protective effects against mortality and morbidity, similar to that seen in HIV-negative children. The risk for lower respiratory tract infection and severe watery diarrhea has been shown to be lower in HIV-infected children supplemented with vitamin A. All-cause mortality and AIDS-related deaths have also been found to be lower in vitamin A-supplemented HIV-infected children. The benefits of multivitamin supplementation, particularly vitamins B, C, and E, have been more consistent across studies. Multivitamin supplementation in HIV-infected pregnant mothers has been shown to reduce the incidence of adverse pregnancy outcomes such as fetal loss and low birth weight. It also has been shown to decrease rates of MTCT among women who have poor nutritional or immunologic status. Further, multivitamin supplementation reduces the rate of HIV disease progression among patients in early stage of disease, thus delaying the need for ART by prolonging the pre-ART stage. In brief, there is no evidence to recommend vitamin A supplementation of HIV-infected pregnant women; however, periodic vitamin A supplementation of HIV-infected infants and children is beneficial in reducing all-cause mortality and morbidity and is recommended. Similarly, multivitamin supplementation of people infected with HIV, particularly pregnant women, is strongly suggested.

Effect of multiple micronutrient supplementation during pregnancy on inflammatory markers in Nepalese women

BACKGROUND

Multiple micronutrient supplementation of Nepalese women during pregnancy is associated with a significant increase in birth weight.

OBJECTIVE

We tested the hypothesis that improved birth weight in infants of mothers supplemented with micronutrients is associated with a decrease in inflammatory responses and an increase in the production of T helper 1 cells and T helper 2 cells.

DESIGN

The study was embedded in a randomized controlled trial of 15 micronutrients, compared with iron-folate supplementation (control), given during pregnancy with the aim of increasing birth weight. Blood samples were collected at 32 wk of gestation, 12-20 wk after supplementation began, for the measurement of inflammatory markers. Breast-milk samples were collected 1 mo after delivery for the measurement of the ratio of milk sodium to potassium (milk Na:K). In an opportunistically selected subgroup of 70 women, mitogen-stimulated cytokine production was measured ex vivo in whole blood.

RESULTS

Blood eosinophils; plasma concentrations of the acute phase reactants C-reactive protein, alpha(1)-acid glycoprotein (AGP), neopterin, and ferritin; milk Na:K; and the production of interleukin (IL) 10, IL-4, interferon gamma, and tumor necrosis factor alpha in whole blood did not differ significantly between the supplemented and control groups. Plasma C-reactive protein and AGP were higher in women who had a preterm delivery, and AGP was higher in women who delivered a low-birth-weight term infant than in women who delivered a normal-birth-weight term infant.

CONCLUSIONS

The results indicate an association between systemic inflammation in late pregnancy and compromised delivery outcome in Nepalese women but do not support the hypothesis that multiple micronutrient supplementation changes cytokine production or inflammatory markers.

Mortality and morbidity among postpartum HIV-positive and HIV-negative women in Zimbabwe: risk factors, causes, and impact of single-dose postpartum vitamin A supplementation

BACKGROUND

Vitamin A deficiency is common among women in resource-poor countries and is associated with greater mortality during HIV.

METHODS

Fourteen thousand one hundred ten mothers were tested for HIV and randomly administered 400,000 IU vitamin A or placebo at less than 96 hours postpartum. The effects of vitamin A and HIV status on mortality, health care utilization, and serum retinol were evaluated.

RESULTS

Four thousand four hundred ninety-five (31.9%) mothers tested HIV positive. Mortality at 24 months was 2.3 per 1000 person-years and 38.3 per 1000 person-years in HIV-negative and HIV-positive women, respectively. Vitamin A had no effect on mortality. Tuberculosis was the most common cause of death, and nearly all tuberculosis-associated deaths were among HIV-positive women. Among HIV-positive women, vitamin A had no effect on rates of hospitalization or overall sick clinic visits, but did reduce clinic visits for malaria, cracked and bleeding nipples, pelvic inflammatory disease, and vaginal infection. Among HIV-negative women, serum retinol was responsive to vitamin A, but low serum retinol was rare. Among HIV-positive women, serum retinol was largely unresponsive to vitamin A, and regardless of treatment group, the entire serum retinol distribution was shifted 25% less than that of HIV-negative women 6 weeks after dosing.

CONCLUSIONS

Single-dose postpartum vitamin A supplementation had no effect on maternal mortality, perhaps because vitamin A status was adequate in HIV-negative women and apparently unresponsive to supplementation in HIV-positive women.

Risk factors for subclinical mastitis among HIV-infected and uninfected women in Lusaka, Zambia

Subclinical mastitis, defined as raised milk sodium/potassium (Na/K) ratio, is associated with poor infant growth and, among HIV-infected women, with increased milk HIV viral load. We conducted a longitudinal cohort study in Lusaka, Zambia, in order to investigate the relative importance of several potential causes of subclinical mastitis: maternal infection, micronutrient deficiencies and poor lactation practice. Women (198 HIV-infected, 189 HIV-uninfected) were recruited at 34 weeks' gestation and followed up to 16 weeks postpartum for collection of information on their health, their infant's health, infant growth and infant feeding practices. Milk samples were collected from each breast at 11 postpartum visits and blood at recruitment and 6 weeks postpartum. The geometric mean milk Na/K ratio and the proportion of women with Na/K ratio > 1.0 in one or both breasts were significantly higher among HIV-infected than among uninfected women. Other factors associated with the higher mean Na/K ratio in univariable analyses were primiparity, high maternal alpha(1)-acid glycoprotein (AGP) at 6 weeks, maternal overall morbidity and specific breast symptoms, preterm delivery, low infant weight or length, infant thrush and non-exclusive breast feeding. In multivariable analyses, primiparity, preterm delivery, breast symptoms, HIV status and raised AGP were associated with the raised Na/K ratio. Thus the main factors associated with subclinical mastitis that are amenable to intervention are poor maternal overall health and breast health. The impact of improved postpartum health care, especially management of maternal infections and especially in primiparous women, on the prevalence of subclinical mastitis and its consequences requires investigation.

The positive impact of red palm oil in school meals on vitamin A status: study in Burkina Faso

Background

Vitamin A (VA) deficiency is widespread in sub-Saharan Africa and school-age children are a vulnerable group. In Burkina Faso, the production and consumption of red palm oil (RPO) is being promoted as a food supplement for VA. The objective of the study was to assess the impact on serum retinol of adding RPO to school lunch in two test zones of Burkina Faso.

Methods

Over one school year, 15 ml RPO was added to individual meals 3 times a week in selected primary schools in two sites. Serum retinol was measured with HPLC at baseline and exactly 12 months later to take account of seasonality. A simple pre-post test design was used in the Kaya area (north-central Burkina), where 239 pupils from 15 intervention schools were randomly selected for the evaluation. In Bogandé (eastern Burkina), 24 schools were randomised for the controlled intervention trial: 8 negative controls (G1) with only the regular school lunch; 8 positive controls (G2) where the pupils received a single VA capsule (60 mg) at the end of the school year; and 8 schools with RPO through the school year (G3). A random sample of 128 pupils in each school group took part in the evaluation.

Results

In Kaya, serum retinol went from 0.77 ± 0.37 μmol/L at baseline to 1.07 ± 0.40 μmol/L one year later (p < 0.001). The rate of low serum retinol (<0.7 μmol/L) declined from 47.2% to 13.1%. In Bogandé, serum retinol increased significantly (p < 0.001) only in the capsule and RPO groups, going from 0.77 ± 0.28 to 0.98 ± 0.33 μmol/L in the former, and from 0.82 ± 0.3 to 0.98 ± 0.33 μmol/L in the latter. The rate of low serum retinol went from 46.1 to 17.1% in the VA capsule group and from 40.4% to 14.9% in the RPO group. VA-deficient children benefited the most from the capsule or RPO. Female sex, age and height-for-age were positively associated with the response to VA capsules or RPO.

Conclusion

RPO given regularly in small amounts appears highly effective in the reduction of VA deficiency. RPO deserves more attention as a food supplement for VA and as a potential source of rural income in Sahelian countries.

Plasma alpha1-acid glycoprotein can be used to adjust inflammation-induced hyporetinolemia in vitamin A-sufficient, but not vitamin A-deficient or -supplemented rats

We examined the association between alpha(1)-acid glycoprotein (AGP), all-trans-retinol (retinol), and albumin concentrations in a longitudinal animal model of IL-6-induced inflammation. Vitamin A-sufficient (VAS) male Sprague-Dawley rats were administered recombinant human IL-6 [n = 4, 65 mug/(kg.d)] or PBS (n = 4) continuously for 7 d via osmotic minipumps. Plasma samples were obtained daily and concentrations of retinol, AGP, albumin, and total protein were measured. Compared with both baseline and controls, retinol and albumin decreased (P < 0.05), AGP increased (P < 0.05), and total protein concentrations were unaffected in IL-6-treated rats. In vitamin A-deficient (VAD) rats, AGP concentrations were significantly lower at all time points and increased only to one-third of that in VAS rats. The AGP cut-off value indicative of inflammation was 0.11 g/L (i.e., 95% upper limit of baseline concentrations). After 20.5 h, there was an inverse linear correlation between AGP concentrations and the relative change in retinol to baseline (y = -0.18x + 0.48, r = -0.84, P < 0.001). However, changes in AGP and albumin were not correlated (P = 0.94). The application of this function to retinol concentrations in rats from separate experiments showed that hyporetinolemia cannot be adjusted using plasma AGP in VAD or vitamin A-supplemented rats. In conclusion, correcting inflammation-induced hyporetinolemia using an acute-phase protein requires longitudinally derived data, knowledge of vitamin A status, and a common underlying mechanism of change.

Factors influencing breast milk HIV RNA viral load among Zambian women

In a longitudinal cohort study we investigated factors contributing to breast milk HIV RNA viral load among lactating women in Lusaka, Zambia. Detailed data from 135 HIV-infected women were collected by questionnaires concerning postpartum maternal and infant health and infant feeding practice. Maternal blood was collected during pregnancy and at 6 weeks postpartum. Milk samples collected from each breast at 10 days and 6 weeks postpartum plus a subset collected at other time points were analyzed for HIV RNA viral load. Increased milk viral load was associated in univariate analyses with maternal symptoms of poor health, raised plasma alpha(1)-acid glycoprotein (AGP) at week 6, raised milk sodium/potassium (Na/K) ratio, postpartum need for antibiotics, preterm delivery, and low birth weight infants. In a multiple regression 49% of variability in mean milk viral load was explained by milk Na/K ratio and need for antibiotics, with borderline contributions from plasma AGP and plasma viral load. Maternal blood hemoglobin or receipt of iron supplements and infant feeding variables such as changing the infant's diet by moving from exclusive to nonexclusive breastfeeding or adding solid foods were not associated with milk viral load. Thus maternal health was the main factor contributing to milk viral load. The lack of effect of feeding practices on milk viral load and the previously determined association of poor maternal health with reduced duration of exclusive breastfeeding in this cohort suggest the relation between exclusive breastfeeding and decreased HIV transmission may be secondary to poor maternal health.