scholarly journals Retinol isotope dilution accurately predicts liver reserves in piglets but overestimates reserves in lactating sows

2019 ◽  
Vol 244 (7) ◽  
pp. 579-587 ◽  
Author(s):  
Jesse Sheftel ◽  
Rebecca L Surles ◽  
Sherry A Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Isotope Dilution ◽  
Equilibration Time ◽  
Serum Retinol ◽  
Retinyl Acetate ◽  
Hypervitaminosis A ◽  
Post Dose ◽  
Human Infants ◽  
Lactating Women ◽  
Lactating Sows

Retinol isotope dilution (RID) is used to estimate total body vitamin A (VA) stores in groups to assess VA status. Metabolic differences during lactation may affect RID calculations as currently applied. We evaluated the time required for isotopic equilibration between serum and liver retinol in piglets, and the utility of milk retinol isotopic enrichment as a proxy for serum in lactating sows. Piglets ( n = 24) and sows ( n = 6) were fed 1.75 or 20 µmol 13 C2-retinyl acetate, respectively. Piglets ( n = 5 or 7) were killed on d 0, 4, 7, or 14. Blood and milk were collected at d 0, 0.5, 1, 2, 4, 7, 10, 14, and 21 before the sows were killed to collect liver. Retinol 13 C-enrichment was determined by gas chromatography-combustion-isotope ratio mass spectrometry. Equilibration time and RID-predicted liver VA reserves were calculated. In piglets, serum and liver retinol 13 C-enrichment differed significantly in individuals at d 4 and 7 ( P = 0.008, 0.03) but not d 14 ( P = 0.06); however, mean values were not different by d 4 ( P = 0.62). Current RID equations accurately predicted VA deficiency (means ≤0.027 µmol/g liver) in the piglets. In sows, milk and serum retinol 13 C-enrichment reached equilibrium between 2 and 7 d post-dose. After correcting for dose lost to milk, RID equations predicted higher liver stores than measured values even though the serum to liver atom % was 1.00 ± 0.01 at kill. In VA deficient infants, a shorter period may be accurate in population-level RID studies when using appropriate assumptions. In lactating women, the RID may have decreased accuracy due to variable losses of tracer in milk. Furthermore, assumptions about storage and loss of the dose in milk must be evaluated in lactating women considering the observed discrepancy between predicted and measured stores. Impact statement Vitamin A (VA) deficiency and hypervitaminosis A have been reported in groups of people worldwide. Conventional biomarkers of VA deficiency (e.g. serum retinol concentration, dose response tests) are not able to distinguish between sufficiency and hypervitaminosis A. Retinol isotope dilution (RID) predictions of VA status have been validated in humans and animal models from deficiency through toxicity; however, RID during life stages with unique issues related to isotopic tracing, such as infancy and lactation, requires further evaluation. This study investigated RID in piglets and lactating sows as models for human infants and women. In piglets, RID successfully determined VA deficiency (confirmed with liver analysis), and that the tracer mixes quickly. Conversely, in lactating sows, although serum and milk enrichments were similar, traditional RID equations overestimated VA stores, likely due to losses of tracer and higher extrahepatic VA storage than predictions. These data inform researchers about the challenges of using RID during lactation.

scholarly journals Breast Milk–Derived Retinol Is a Potential Surrogate for Serum in the 13C-Retinol Isotope Dilution Test in Zambian Lactating Women with Vitamin A Deficient and Adequate Status

2020 ◽  
Vol 151 (1) ◽  
pp. 255-263
Author(s):  
Chisela Kaliwile ◽  
Charles Michelo ◽  
Jesse Sheftel ◽  
Christopher R Davis ◽  
Michael Grahn ◽  
...  
Keyword(s):  
Breast Milk ◽  
Vitamin A ◽  
Isotope Dilution ◽  
Policy Development ◽  
Demographic Data ◽  
Reproductive Age ◽  
Serum Retinol ◽  
Women Of Reproductive Age ◽  
Retinyl Acetate ◽  
Lactating Women

ABSTRACT Background Vitamin A (VA) deficiency (VAD) affects ∼19 million pregnant women worldwide. The extent of VAD in Zambian women of reproductive age is unknown owing to lack of survey inclusion or the use of static serum retinol concentrations, a low-sensitivity biomarker. Objectives This cross-sectional study employed isotopic techniques to determine VA status with serum and milk among women aged 18–49 y (n = 197) either lactating with infants aged 0–24 mo or nonlactating with or without infants. Methods Assistants were trained and piloted data collection. Demographic data, anthropometry, and relevant histories were obtained including malaria and anemia. For retinol isotope dilution (RID), baseline fasting blood and casual breast milk samples were collected before administration of 2.0 μmol 13C2-retinyl acetate and 24-h dietary recalls. On day 14, blood (n = 144) and milk (n = 66) were collected. Prevalence of total liver VA reserves (TLR) ≤0.10 μmol/g was defined as VAD with comparison to the DRI assumption of 0.07 μmol/g as minimally acceptable for North Americans. Results When a 20% adjustment for dose lost to milk was made in the RID equation for lactation, mean total body VA stores (TBS) for lactating women were 25% lower than for nonlactating women (P < 0.01), which was not the case without adjustment (P = 0.3). Mean ± SD TLR for all women were 0.15 ± 0.11 μmol/g liver. Using retinol purified from breast milk instead of serum for RID analysis yielded similar TBS and TLR, which were highly correlated between methods (P < 0.0001). Serum retinol ≤0.70 μmol/L had 0% sensitivity using either VAD liver cutoff and milk retinol ≤1.0 μmol/L had 42% sensitivity for VAD at 0.10 μmol/g. Conclusions Determining accurate VA status among women of reproductive age, especially lactating women, forms a basis for extrapolation to the general population and informing policy development and program implementation.

scholarly journals Modified relative dose response values differ between lactating women in the United States and Indonesia

2020 ◽  
Vol 245 (9) ◽  
pp. 797-804 ◽  
Author(s):  
Jesse Sheftel ◽  
Kara A Bresnahan ◽  
Tetra Fadjarwati ◽  
Sherry A Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Dose Response ◽  
The United States ◽  
Molar Ratio ◽  
Secondary Outcome ◽  
Population Surveys ◽  
Post Dose ◽  
Lactating Women ◽  
Lactating Sows ◽  
Modified Relative Dose Response

The modified relative dose response (MRDR) test distinguishes between vitamin A (VA) deficiency and sufficiency using the molar ratio of 3,4-didehydroretinol to retinol (DR:R) in serum 4–6 h after administering 3,4-didehydroretinyl acetate (DRA). Research in sows demonstrated that serum and milk DR:R are correlated. Two studies determined VA status in lactating women and investigated breast milk as a surrogate for serum in the MRDR test in VA-adequate women. A secondary outcome compared serum with milk carotenoids in US women. Lactating US (24–40 years old, n =  25) and Indonesian (22–40 years old, n =  18) women were given 8.8 µmol DRA. Subjects were allocated to three collections (3–48 h post-dose) for blood and milk ( n =  4–10/time point). DR, retinol, and carotenoids were determined by HPLC. Serum DR:R time-courses were evaluated in all women and DR kinetics analyzed by noncompartmental modeling in the US and VA-deficient Indonesian women. Indonesian women had a higher proportion of VA deficiency by MRDR (61%) than US women (0%). Milk DR concentration was higher than serum. In US women, serum and milk DR:R were correlated at 5 h ( r =  0.86, P <  0.01) but not at 6 or 7 h. Serum DR kinetics ( tmax = 8, t1/2 = 15.3 h) were similar to those in VA-adequate lactating sows ( tmax = 7.5 ± 1.9, t1/2 = 17.4 ± 4.5 h) but varied in milk (human: tmax = 12, t1/2 = 22.4 h; sow: tmax = 14.4 ± 9.8, t1/2 = 71.8 ± 51.2 h). Carotenoids in milk differed from serum ( P <  0.001), with β-cryptoxanthin enrichment. Serum but not milk VA kinetics were similar between women and sows. Milk DR:R may represent a simpler VA biomarker in lactating women vulnerable to VA deficiency, but requires further validation. Impact statement Vitamin A (VA) deficiency is a major health issue globally, and lactating women are particularly vulnerable due to increased needs for milk production. Accurate detection of VA deficiency is important; however, most population surveys measure VA status using serum retinol, which is affected by inflammation and lacks sensitivity. The modified relative dose response (MRDR) test qualitatively distinguishes between VA deficiency and sufficiency and could improve population surveys if completed in a randomly selected subsample of individuals in surveys. The original relative dose response test required two blood samples, while MRDR requires only one, a significant improvement in accessibility of the technique by decreasing burden on subjects and investigators. This work demonstrates significant deficiency in Indonesian women compared with US women. In combination with previous research using lactating sows, these human data support milk as a surrogate for blood in the MRDR, which may be less invasive, but requires further validation.

scholarly journals Comparisons among Equations Used for Retinol Isotope Dilution in the Assessment of Total Body Stores and Total Liver Reserves

2015 ◽  
Vol 145 (5) ◽  
pp. 847-854 ◽  
Author(s):  
Bryan M Gannon ◽  
Sherry A Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Isotope Dilution ◽  
Vitamin A Deficiency ◽  
Storage Site ◽  
Serum Retinol ◽  
Negative Effects ◽  
Hypervitaminosis A ◽  
Major Drawback ◽  
Vitamin A Status ◽  
Wide Range

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.

scholarly journals International Experiences in Assessing Vitamin A Status and Applying the Vitamin A-Labeled Isotope Dilution Method

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 40-51 ◽  
Author(s):  
Veronica Lopez-Teros ◽  
Justin Chileshe ◽  
Nicole Idohou-Dossou ◽  
Tetra Fajarwati ◽  
Gabriel Medoua Nama ◽  
...  
Keyword(s):  
Vitamin A ◽  
Dose Response ◽  
Isotope Dilution ◽  
Qualitative Assessment ◽  
Isotope Dilution Method ◽  
Dilution Method ◽  
Serum Retinol ◽  
Retinyl Acetate ◽  
Positive Effects ◽  
Vitamin A Status

Inadequate vitamin A (VA) nutrition continues to be a major problem worldwide, and many interventions being implemented to improve VA status in various populations need to be evaluated. The interpretation of results after an intervention depends greatly on the method selected to assess VA status. To evaluate the effect of an intervention on VA status, researchers in Cameroon, India, Indonesia, Mexico, Senegal and Zambia have used serum retinol as an indicator, and have not always found improvement in response to supplementation. One problem is that homeostatic control of serum retinol may mask positive effects of treatment in that changes in concentration are observed only when status is either moderately to severely depleted or excessive. Because VA is stored mainly in the liver, measurements of hepatic VA stores are the “gold standard” for assessing VA status. Dose response tests such as the relative dose response (RDR) and the modified relative dose response (MRDR), allow a qualitative assessment of VA liver stores. On the other hand, the use of the vitamin A-labeled isotope dilution (VALID) technique, (using 13C or 2H-labeled retinyl acetate) serves as an indirect method to quantitatively estimate total body and liver VA stores. Countries including Cameroon, China, Ghana, Mexico, Thailand and Zambia are now applying the VALID method to sensitively assess changes in VA status during interventions, or to estimate a population’s dietary requirement for VA. Transition to the use of more sensitive biochemical indicators of VA status such as the VALID technique is needed to effectively assess interventions in populations where mild to moderate VA deficiency is more prevalent than severe deficiency.

scholarly journals South African preschool children habitually consuming sheep liver and exposed to vitamin A supplementation and fortification have hypervitaminotic A liver stores: a cohort study

2019 ◽  
Vol 110 (1) ◽  
pp. 91-101 ◽  
Author(s):  
Martha E van Stuijvenberg ◽  
Muhammad A Dhansay ◽  
Jana Nel ◽  
Devika Suri ◽  
Michael Grahn ◽  
...  
Keyword(s):  
South Africa ◽  
Preschool Children ◽  
Vitamin A ◽  
Total Serum ◽  
High Dose ◽  
Serum Retinol ◽  
Hypervitaminosis A ◽  
Total Liver ◽  
Before And After ◽  
Retinyl Esters

ABSTRACT Background In some regions, multiple vitamin A (VA) interventions occur in the same target groups, which may lead to excessive stores. Retinol isotope dilution (RID) is a more sensitive technique than serum retinol to measure VA status. Objective We evaluated VA status before and after a high-dose supplement in preschool children living in a region in South Africa with habitual liver consumption and exposed to VA supplementation and fortification. Methods After baseline blood samples, subjects (46.7 ± 8.4 mo; n = 94) were administered 1.0 μmol [14,15]-13C2-retinyl acetate to estimate total liver retinol reserves by RID with a follow-up 14-d blood sample. Liver intake was assessed with a frequency questionnaire. In line with current practice, a routine 200,000 IU VA capsule was administered after the RID test. RID was repeated 1 mo later. Serum retinyl esters were evaluated using ultra-performance liquid chromatography. Results At baseline, 63.6% of these children had hypervitaminosis A defined as total liver retinol reserves ≥1.0 μmol/g liver, which increased to 71.6% after supplementation (1.13 ± 0.43 to 1.29 ± 0.46 μmol/g; P < 0.001). Total serum VA as retinyl esters was elevated in 4.8% and 6.1% of children before and after supplementation. The odds of having hypervitaminosis A at baseline were higher in children consuming liver ≥1/mo (ratio 3.70 [95% CI: 1.08, 12.6]) and in children receiving 2 (4.28 [1.03, 17.9]) or 3 (6.45 [0.64, 65.41]) supplements in the past 12 mo. Total body stores decreased after the supplement in children in the highest quartile at baseline compared with children with lower stores, who showed an increase (P = 0.007). Conclusions In children, such as this cohort in South Africa, with adequate VA intake through diet, and overlapping VA fortification and supplementation, preschool VA capsule distribution should be re-evaluated. This trial was registered at https://clinicaltrials.gov/ct2/show/NCT02915731 as NCT02915731.

scholarly journals Vitamin A-fortified cooking oil reduces vitamin A deficiency in infants, young children and women: results from a programme evaluation in Indonesia

2015 ◽  
Vol 18 (14) ◽  
pp. 2511-2522 ◽  
Author(s):  
Sandjaja ◽  
Idrus Jus’at ◽  
Abas B Jahari ◽  
Ifrad ◽  
Min Kyaw Htet ◽  
...  
Keyword(s):  
Vitamin A ◽  
Nutrient Intake ◽  
Vitamin A Deficiency ◽  
Retinyl Palmitate ◽  
Oil Consumption ◽  
Serum Retinol ◽  
Cross Sectional ◽  
Lactating Women ◽  
Dietary Recall ◽  
Poor Households

AbstractObjectiveTo assess oil consumption, vitamin A intake and retinol status before and a year after the fortification of unbranded palm oil with retinyl palmitate.DesignPre–post evaluation between two surveys.SettingTwenty-four villages in West Java.SubjectsPoor households were randomly sampled. Serum retinol (adjusted for subclinical infection) was analysed in cross-sectional samples of lactating mothers (baselinen324/endlinen349), their infants aged 6–11 months (n318/n335) and children aged 12–59 months (n469/477), and cohorts of children aged 5–9 years (n186) and women aged 15–29 years (n171), alongside food and oil consumption from dietary recall.ResultsFortified oil improved vitamin A intakes, contributing on average 26 %, 40 %, 38 %, 29 % and 35 % of the daily Recommended Nutrient Intake for children aged 12–23 months, 24–59 months, 5–9 years, lactating and non-lactating women, respectively. Serum retinol was 2–19 % higher at endline than baseline (P<0·001 in infants aged 6–11 months, children aged 5–9 years, lactating and non-lactating women; non-significant in children aged 12–23 months;P=0·057 in children aged 24–59 months). Retinol in breast milk averaged 20·5 μg/dl at baseline and 32·5 μg/dl at endline (P<0·01). Deficiency prevalence (serum retinol <20 μg/dl) was 6·5–18 % across groups at baseline, and 0·6–6 % at endline (P≤0·011). In multivariate regressions adjusting for socio-economic differences, vitamin A intake from fortified oil predicted improved retinol status for children aged 6–59 months (P=0·003) and 5–9 years (P=0·03).ConclusionsAlthough this evaluation without a comparison group cannot prove causality, retinyl contents in oil, Recommended Nutrient Intake contributions and relationships between vitamin intake and serum retinol provide strong plausibility of oil fortification impacting vitamin A status in Indonesian women and children.

Usefulness of Vitamin A Isotope Methods for Status Assessment: From Deficiency through Excess

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 16-24 ◽  
Author(s):  
Sherry A. Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Isotope Dilution ◽  
Clinical Signs ◽  
Provitamin A ◽  
Serum Retinol ◽  
Vitamin A Status ◽  
Status Assessment ◽  
Indirect Indicator ◽  
Staple Foods ◽  
Retinol Concentration

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.

scholarly journals β-Carotene–vitamin A equivalence in Chinese adults assessed by an isotope dilution technique

2004 ◽  
Vol 91 (1) ◽  
pp. 121-131 ◽  
Author(s):  
Zhixu Wang ◽  
Shian Yin ◽  
Xianfeng Zhao ◽  
Robert M. Russell ◽  
Guangwen Tang
Keyword(s):  
Vitamin A ◽  
Isotope Dilution ◽  
Dilution Technique ◽  
Chinese Adults ◽  
Retinyl Acetate ◽  
Conversion Factors ◽  
Isotope Dilution Technique ◽  
Molar Basis ◽  
Β Carotene ◽  
Chemical Ionisation

The present study was carried out to determine the conversion factor of synthetic2H-labelled β-carotene to vitamin A in Chinese adults by using a stable-isotope dilution technique. Fifteen healthy volunteers aged 50–60 years were recruited for a 55 d experiment. The volunteers (nine males and six females) were each given a physiological dose of [2H8]β-carotene (6 mg) in oil on the first day of the experiment, and a reference dose of [2H8]retinyl acetate (3 mg) in oil was given on the fourth day. Serum samples were collected at 0, 3, 5, 7, 9, 11, and 13 h on the first and the fourth days of the study, daily for 10 d, and then weekly from days 14 to 56. β-Carotene and retinol were extracted from serum and isolated by HPLC, and their enrichments were respectively determined by using GC–electron capture negative chemical ionisation-MS and LC–atmospheric pressure chemical ionisation interface-MS. Four of the subjects exhibited β-carotene to vitamin A conversion factors of >29·0:1 on a molar basis and were termed ‘poor converters’. In the eleven normal converters (seven males and four females), the calculated conversion factors of β-carotene to retinol ranged from 2·0:1 to 12·2:1 with an average of 4·8 (sd 2·8):1 on a molar basis, and from 3·8:1 to 22·8:1 with an average of 9·1 (sd 5·3):1 on a weight basis. The 52 d post-intestinal absorption conversion was estimated to be about 30 % of the total converted retinol.

scholarly journals Serum retinyl esters are positively correlated with analyzed total liver vitamin A reserves collected from US adults at time of death

2018 ◽  
Vol 108 (5) ◽  
pp. 997-1005 ◽  
Author(s):  
Kiersten Olsen ◽  
Devika J Suri ◽  
Christopher Davis ◽  
Jesse Sheftel ◽  
Kohei Nishimoto ◽  
...  
Keyword(s):  
Vitamin A ◽  
Ultra Performance Liquid Chromatography ◽  
Total Serum ◽  
Serum Retinol ◽  
Hypervitaminosis A ◽  
Individual Level ◽  
Total Liver ◽  
Retinyl Esters ◽  
The Individual ◽  
Liver Vitamin

ABSTRACT Background Minimal human data exist on liver vitamin A (VA) compared with serum biomarkers. Cutoffs of 5% and 10% total serum VA as retinyl esters (REs) suggest a VA intoxication diagnosis. Objectives We compared total liver VA reserves (TLRs) with the percentage of total serum VA as REs to evaluate hypervitaminosis with the use of US adult autopsy samples. Secondary objectives evaluated serum retinol sensitivity, TLRs among lobes, and hepatic α-retinol concentrations, an α-carotene cleavage product. Design Matched serum and liver samples were procured from cadavers (n = 27; mean ± SD age: 70.7 ± 14.9 y; range: 49–101 y). TLRs and α-REs were quantified by ultra-performance liquid chromatography. Pearson correlations showed liver and serum associations. Sensitivity and specificity were calculated for >5%, 7.5%, and 10% total serum VA as REs to predict TLRs and for serum retinol <0.7 and 1 μmol/L to predict deficiency. Results Serum RE concentrations were correlated with TLRs (r = 0.497, P < 0.001). Nine subjects (33%) had hypervitaminosis A (≥1.0 μmol VA/g liver), 2 of whom had >7.5% total serum VA as REs; histologic indicators corroborated toxicity at 3 μmol/g liver. No subject had >10% total serum VA as REs. Serum retinol sensitivity to determine deficiency (TLRs <0.1 μmol VA/g) was 83% at 0.7 and 1 μmol/L. Hepatic α-retinol was positively correlated with age (P = 0.047), but removing an outlier nullified significance. Conclusions This study evaluated serum REs as a biomarker of VA status against TLRs (gold standard), and abnormal histology suggested that 7.5% total serum VA as REs is diagnostic for toxicity at the individual level in adults. The long-term impact of VA supplements and fortificants on VA status is currently unknown. Considering the high prevalence of hypervitaminotic TLRs in this cohort, and given that many countries are adding preformed VA to processed products, population biomarkers diagnosing hypervitaminosis before toxicity are urgently needed. This trial was registered at clinicaltrials.govas NCT03305042.

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