Research Recommendations for Applying Vitamin A-Labelled Isotope Dilution Techniques to Improve Human Vitamin A Nutrition

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 52-59 ◽  
Author(s):  
Sherry A. Tanumihardjo ◽  
Anura V. Kurpad ◽  
Janet R. Hunt

The current use of serum retinol concentrations as a measurement of subclinical vitamin A deficiency is unsatisfactory for many reasons. The best technique available for vitamin A status assessment in humans is the measurement of total body pool size. Pool size is measured by the administration of retinol labelled with stable isotopes of carbon or hydrogen that are safe for human subjects, with subsequent measurement of the dilution of the labelled retinol within the body pool. However, the isotope techniques are time-consuming, technically challenging, and relatively expensive. There is also a need to assess different types of tracers and doses, and to establish clear guidelines for the use and interpretation of this method in different populations. Field-friendly improvements are desirable to encourage the application of this technique in developing countries where the need is greatest for monitoring the risk of vitamin A deficiency, the effectiveness of public health interventions, and the potential of hypervitaminosis due to combined supplement and fortification programs. These techniques should be applied to validate other less technical methods of assessing vitamin A deficiency. Another area of public health relevance for this technique is to understand the bioconversion of β-carotene to vitamin A, and its relation to existing vitamin A status, for future dietary diversification programs.

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1851-1851
Author(s):  
Rui Wang ◽  
Chen Jing ◽  
Yichun Hu ◽  
Xiaoguang Yang ◽  
Lichen Yang

Abstract Objectives Vitamin A deficiency is recognized as a major public health nutrition issue in developing countries including China. It is one of the most common micronutrient deficiencies, yet vitamin A status of the elderly in China paucity of data since 2002. We sought to evaluate Chinese elderly aged 60 years and above in vitamin A status, and to compare vitamin A insufficiency between year 2002 and 2012. Methods We compared serum retinol concentrations from the China National Nutrition and Health Survey 2002 (CNNHS 2002), with CNNHS data collected during 2010 through 2012 (CNNHS 2010–2012). Complete data were available for 4933 elderly participants in CNNHS 2002 and 5613 elderly participants in CNNHS 2010–2012. Results The mean serum retinol concentration was 1.69 (95% confidence interval (CI): 1.68–1.71) μmol/L during CNNHS 2002 and increase to 1.98 (1.96–2.00) μmol/L during CNNHS 2010–2012. Compared with 2002, the vitamin A levels in the elderly across all region, gender and age groups showed an upward trend, with the difference being statistically significant (all P < 0.05). In 2012, the incidence of VAD in the elderly participants was higher than in 2002 (3.39vs1.46) (P < 0.001). However, the incidence of marginal VAD was lower than in 2002 (7.38vs8.62) (P = 0.019). VAD in those being large cities, small and medium-sized cities, rural area, male and female, aged 60–69 or 70–79 were higher than in 2002 (all P < 0.05), poor rural areas was significantly lower than in 2002 (P < 0.001). The prevalence of marginal VAD among the urban elderly in 2012 was higher than in 2002 (P < 0.05), whereas the prevalence was lower than that in 2002 among the rural elderly (P < 0.001). The prevalence of marginal VAD in the male elderly (P < 0.001) and in the 60–69 age group (P = 0.014) were lower than in 2002. Conclusions Our findings showed that vitamin A status among elderly was greatly improved by 10 years, but VAD remains a public health problem in the Chinese elderly population. Therefore, reducing the incidence of VAD is crucial to the health of the elderly in China. In particular, attention needs to be paid to the nutrition and health status of urban and ≥80 year elderly. Funding Sources This research was supported by the Special Fund for Health-scientific Research in the Public Interest (No. 20,120,212) from the National Health and Family Planning Commission of the People's Republic of China.


2009 ◽  
Vol 102 (3) ◽  
pp. 342-349 ◽  
Author(s):  
Julie A. Howe ◽  
Bussie Maziya-Dixon ◽  
Sherry A. Tanumihardjo

Efforts to increase β-carotene in cassava have been successful, but the ability of high-β-carotene cassava to prevent vitamin A deficiency has not been determined. Two studies investigated the bioefficacy of provitamin A in cassava and compared the effects of carotenoid content and variety on vitamin A status in vitamin A-depleted Mongolian gerbils (Meriones unguiculatus). Gerbils were fed a vitamin A-free diet 4 weeks prior to treatment. In Expt 1, treatments (ten gerbils per group) included 45 % high-β-carotene cassava, β-carotene and vitamin A supplements (intake matched to high-β-carotene cassava group), and oil control. In Expt 2, gerbils were fed cassava feeds with 1·8 or 4·3 nmol provitamin A/g prepared with two varieties. Gerbils were killed after 4 weeks. For Expt 1, liver vitamin A was higher (P < 0·05) in the vitamin A (1·45 (sd 0·23) μmol/liver), lower in the control (0·43 (sd 0·10) μmol/liver), but did not differ from the β-carotene group (0·77 (sd 0·12) μmol/liver) when compared with the high-β-carotene cassava group (0·69 (sd 0·20) μmol/liver). The bioconversion factor was 3·7 μg β-carotene to 1 μg retinol (2 mol:1 mol), despite 48 % cis-β-carotene [(Z)-β-carotene] composition in cassava. In Expt 2, cassava feed with 4·3 nmol provitamin A/g maintained vitamin A status. No effect of cassava variety was observed. Serum retinol concentrations did not differ. β-Carotene was detected in livers of gerbils receiving cassava and supplements, but the cis-to-trans ratio in liver differed from intake. Biofortified cassava adequately maintained vitamin A status and was as efficacious as β-carotene supplementation in the gerbil model.


2000 ◽  
Vol 83 (5) ◽  
pp. 513-520 ◽  
Author(s):  
Suzanne M. Filteau ◽  
Juana F. Willumsen ◽  
Keith Sullivan ◽  
Karin Simmank ◽  
Mary Gamble

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.


2008 ◽  
Vol 11 (7) ◽  
pp. 720-728 ◽  
Author(s):  
Andrew Seal ◽  
Emmanuel Kafwembe ◽  
Ismail AR Kassim ◽  
Mei Hong ◽  
Annie Wesley ◽  
...  

AbstractObjectiveTo assess changes in the Fe and vitamin A status of the population of Nangweshi refugee camp associated with the introduction of maize meal fortification.DesignPre- and post-intervention study using a longitudinal cohort.SettingNangweshi refugee camp, Zambia.SubjectsTwo hundred and twelve adolescents (10–19 years), 157 children (6–59 months) and 118 women (20–49 years) were selected at random by household survey in July 2003 and followed up after 12 months.ResultsMaize grain was milled and fortified in two custom-designed mills installed at a central location in the camp and a daily ration of 400 g per person was distributed twice monthly to households as part of the routine food aid ration. During the intervention period mean Hb increased in children (0·87 g/dl;P< 0·001) and adolescents (0·24 g/dl;P= 0·043) but did not increase in women. Anaemia decreased in children by 23·4 % (P< 0·001) but there was no significant change in adolescents or women. Serum transferrin receptor (log10-transformed) decreased by −0·082 μg/ml (P= 0·036) indicating an improvement in the Fe status of adolescents but there was no significant decrease in the prevalence of deficiency (−8·5 %;P= 0·079). In adolescents, serum retinol increased by 0·16 μmol/l (P< 0·001) and vitamin A deficiency decreased by 26·1 % (P< 0·001).ConclusionsThe introduction of fortified maize meal led to a decrease in anaemia in children and a decrease in vitamin A deficiency in adolescents. Centralised, camp-level milling and fortification of maize meal is a feasible and pertinent intervention in food aid operations.


1999 ◽  
Vol 2 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Faruk Ahmed

AbstractObjective:This article provides a comprehensive review of the change in vitamin A status and the extent of vitamin A deficiency among different population groups in Bangladesh up to the present time. The result of experience with different strategies and interventions designed to improve vitamin A status are then reviewed, leading to a discussion of key options for action, as well as important areas for research and evaluation.Design and setting:All the available data have been examined in detail, including data from nationally representative samples and nationwide surveys, as well as small studies in different population groups. Reports on the effectiveness of different intervention programmes have been used.Results:Over the past three decades a number of studies, which include national nutrition surveys, have been carried out to investigate the prevalence of vitamin A deficiency among different population groups in Bangladesh, and they have demonstrated a significant public health problem. Studies have shown that the prevalence of severe deficiency, based on the prevalence of night blindness in preschool children, decreased from 3.6% in 1982–83 to 1.78% in 1989 and 0.6% in 1996. However, there is still a high prevalence of subclinical vitamin A deficiency, based on the biochemical assessment of serum retinol levels in preschool children, estimated mainly from hospital-based groups. Night blindness and Bitot's spot are also found to exist among school-age children and adolescents. Recent reports indicate that night blindness among rural mothers is as high as 1.4%. Only a limited number of studies, with small sample sizes, are available where serum retinol has been reported for school-age children, adolescents and pregnant women. Nevertheless, these studies confirm the presence of low levels of serum retinol and hence, the existence of subclinical vitamin A deficiency. Furthermore, the dietary intake of vitamin A in each population group has been found to be less than the Recommended Daily Allowance (RDA), indicating a significant risk of deficient intakes of vitamin A.To address the problem of vitamin A deficiency, the government of Bangladesh started the Nutritional Blindness Programme in 1973. The main activities of the programme include vitamin A capsule (VAC) supplementation to children of 6 months to 6 years old, nutrition education to increase the production and consumption of vitamin A rich foods, and training of primary health-care workers on the clinical diagnosis and treatment of vitamin A deficiency, VAC distribution and nutrition education. Since 1988, as a long-term strategy, Helen Keller International has been implementing community home gardening promotion projects. To date, the possibility that foods may be fortified with vitamin A, has not been explored as a possible approach in Bangladesh.Conclusion:Although short- to long-term prevention and control programmes are to some extent in place, to improve the situation of vitamin A deficiency, Bangladesh needs a more appropriate mix of interventions for the entire population. More operational research and evaluation are needed if a fully effective programme to alleviate the problem of vitamin A deficiency is to be developed. Finally, to achieve the goal of virtual elimination of vitamin A deficiency will require an integrated approach which brings together appropriate actions at every level, within and across the many sectors of society.


2010 ◽  
Vol 4 (6) ◽  
pp. 255 ◽  
Author(s):  
Endang Achadi ◽  
Siti Arifah ◽  
Siti Muslimatun ◽  
Trisari Anggondowati ◽  
Asih Setiarini

Di Indonesia, kekurangan Vitamin A masih menjadi masalah kesehatan masyarakat yang penting seperti terlihat pada balita penderita vitamin A defisiensi subklinis yang tinggi (50%). Hal tersebut akan berpengaruh terhadap berbagai fungsi tubuh yang antara lain meliputi sistem imun, penglihatan, sistem reproduksi dan diferensiasi sel. Tujuan dari penelitian ini adalah untuk mengetahui kontribusi konsumsi minyak yang diperkaya vitamin A dalam memperbaiki status vitamin A dan hemoglobin balita. Penelitian dengan disain studi intervensi Before-After ini dilaksanakan pada anak sehat berusia 7-10 tahun yang diberi obat cacing sebelum intervensi dilakukan. Pengukuran serum retinol dan hemoglobin dilakukan sebelum dan 3 bulan setelah intervensi . Minyak yang difortifikasi vitamin A telah disediakan di warung/ toko di sekitar tempat tinggal responden. Untuk meningkatkan demand, penelitian ini dilengkapi dengan pendekatan pemasaran sosial yang dilakukan pihak lain. Secara umum tidak terlihat perubahan status gizi, tetapi prevalensi anemia turun dari 21,8% menjadi 11,6%. Sementara, prevalens vitamin A defisiensi ditemukan lebih rendah pada anak yang mengkonsumsi ³12 minggu (26,6%) daripada yang mengkonsumsi < 12 minggu (42%) . Hasil tersebut dapat dijadikan pertimbangan untuk merekomendasikan agar minyak difortifikasi vitamin A.Kata kunci: Defisiensi vitamin A, anak sekolah, minyak fortifikasiAbstractVitamin A deficiency (VAD) remains as one of significant public health problems in Indonesia. Around 50% of under five children are suffering from subclinical VAD. Deficiency of vitamin A will affect several important role in the body, such as immune system, vision, reproductive system and cell differentiation. Therefore, guarding Indonesian children to be free from VAD is crucial for their quality as Human Resources. We assessed the impact of the consumption of vitamin A fortified cooking oil on the improvement of vitamin A and hemoglobin status among school children in urban slum area in Makassar City. The study was an intervention design Before-After. Healthy school children 7-10 years were selected from schools and de-wormed before the intervention. Serum retinol and hemoglobin was measured at baseline and at 3 months after. Fortified oil was made available through distribution at shops and accompanied with social marketing. Eventhough overall there was no change in VAD prevalence, the VAD prevalence is lower among children who consumedfortified oil ³12 weeks (26.6%) compared to those who consumed <12 weeks (42%). Prevalence of anemia decreased from 21.8% to 11.6%. We recommended that fortified oil is made mandatory.Key words: Vitamin A deficiency, school children, fortified oil


2015 ◽  
Vol 145 (5) ◽  
pp. 847-854 ◽  
Author(s):  
Bryan M Gannon ◽  
Sherry A Tanumihardjo

Abstract Vitamin A plays an essential role in animal biology and has negative effects associated with both hypo- and hypervitaminosis A. Many notable interventions are being done globally to eliminate vitamin A deficiency, including supplementation, fortification, and biofortification. At the same time, it is important to monitor vitamin A status in nations where preformed vitamin A intake is high because of consumption of animal source foods (e.g., liver, dairy, eggs), fortified foods (e.g., milk, cereals, oil, sugar, margarine), or vitamin supplements (e.g., one-a-day multivitamins) to ensure the population does not reach hypervitaminosis A. To accurately assess population status and evaluate interventions aimed at improving vitamin A status, accurate assessment methods are needed. The primary storage site of vitamin A is the liver; however, routinely obtaining liver samples from humans is impractical and unethical. Isotope dilution using deuterium- or 13C-labeled retinol is currently the most sensitive indirect biomarker of vitamin A status across a wide range of liver reserves. The major drawback to its application is the increased technicality in sample analysis and data calculations when compared to less sensitive methodology, such as serum retinol concentrations and dose response tests. Two main equations have emerged for calculating vitamin A body pool size or liver concentrations from isotope dilution data: the “Olson equation” and the “mass balance equation.” Different applications of these equations can lead to confusion and lack of consistency if the underlying principles and assumptions used are not clarified. The purpose of this focused review is to describe the evolution of the equations used in retinol stable-isotope work and the assumptions appropriate to different applications of the test. Ultimately, the 2 main equations are shown to be fundamentally the same and differ only in assumptions made for each specific research application.


2020 ◽  
Author(s):  
Masako Suzuki ◽  
Tao Wang ◽  
Diana J Garretto ◽  
Carmen R. Isasi ◽  
Wellington V Cardoso ◽  
...  

Abstract Vitamin A is an essential micronutrient that plays critical roles in many biological functions of the body. Limited access to vitamin A-rich food or supplements severely affects tissue and blood levels of vitamin A. Therefore, low serum vitamin A and poverty levels are strongly associated in vitamin A deficiency (VAD) studies that have focused mainly on developing countries. The current national prevalence rate of vitamin A deficiency in the United States is reported to be very low (<1%). However, several studies, including ours, have suggested that people from certain ethnic groups still face a higher proportion of vitamin A deficiency. We hypothesize that the genetic variations between ethnic groups may associate to the VAD proportional differences between women of different ancestries. To assess the associations, we re-analyzed two independent datasets of serum retinol levels of pregnant women in the United States and three datasets of genotypic information of different ancestries. We found that pregnant women with non-Hispanic Black and with Latin American/Afro-Caribbean ancestry have strikingly high proportions of VAD compared to non-Hispanic White and Latin American/Mexican ancestry. Genotypic analyses showed that the minor allele frequencis of genetic variants that associate to serum retinol levels have significantly higher variations between these different ancestries. Our study revealed that VAD rates in the pregnant women differ between different ancestries and that ancestry-dependent genetic variations might contribute to the differences.


2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 16-24 ◽  
Author(s):  
Sherry A. Tanumihardjo

A variety of methods exist to assess vitamin A status of groups and populations. Vitamin A status is usually defined by the liver retinol concentration. Most indicators of status do not measure or estimate liver stores of retinol. Clinical signs only have utility when liver reserves are almost exhausted, and serum retinol concentrations have utility in the zone of overt deficiency. Dose response tests offer more coverage, but cannot distinguish among liver vitamin A stores in the adequate through toxic range. Different countries continue, or are beginning, to add preformed vitamin A to a variety of staple foods through fortification, and vitamin A supplements are still being distributed in many countries, especially to preschool children. Further, provitamin A biofortified crops are currently being released in several countries. Assessing population vitamin A status in response to these interventions needs to move beyond serum retinol concentrations. Indicators that work in the excessive to toxic range of liver reserves are needed. To date, the only indirect indicator that has been validated in this range of liver reserves in animals and humans is the retinol isotope dilution test using deuterium or 13C, which spans the entire liver reserve continuum from deficiency through excess.


Nutrients ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 849
Author(s):  
Blessings H. Likoswe ◽  
Edward J. M. Joy ◽  
Fanny Sandalinas ◽  
Suzanne Filteau ◽  
Kenneth Maleta ◽  
...  

Retinol Binding Protein (RBP) is responsible for the transport of serum retinol (SR) to target tissue in the body. Since RBP is relatively easy and cheap to measure, it is widely used in national Micronutrient Surveys (MNS) as a proxy for SR to determine vitamin A status. By regressing RBP concentration against SR concentration measured in a subset of the survey population, one can define a population-specific threshold concentration of RBP that indicates vitamin A deficiency (VAD). However, the relationship between RBP and SR concentrations is affected by various factors including inflammation. This study, therefore, aimed to re-define the population-specific cut-off for VAD by examining the influence of inflammation on RBP and SR, among pre-school children (PSC) from the 2015–16 Malawi MNS. The initial association between RBP and SR concentrations was poor, and this remained the case despite applying various methods to correct for inflammation. The World Health Organization (WHO) recommends the threshold of 0.7 µmol/L to define VAD for SR concentrations. Applying this threshold to the RBP concentrations gave a VAD prevalence of 24%, which reduced to 10% after inflammation adjustments following methods developed by the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA). Further research is required to identify why SR and RBP were poorly associated in this population. Future MNS will need to account for the effect of inflammation on RBP to measure the prevalence of VAD in Malawi.


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