Biological evidence to define a vitamin A deficiency cutoff using total liver vitamin A reserves

Persistent Challenges of Micronutrient Deficiencies in Latin America Need Action

Micronutrient deficiencies affect growth and development and are critical for maintaining health at all ages. Their critical role in exacerbating complications of infections and chronic diseases continues to impact morbidity, mortality, and quality of life for many. Raising awareness and advocating for micronutrient deficiencies in Latin America is urgent to reduce this preventable burden. Globally, an estimated 372 million preschool-aged children and 1.2 billion non-pregnant women of reproductive age suffer deficiency from 1 or more micronutrient. Data is limited and often old, and the true burden of problem in the region remains unclear. There are also limited data on dietary intake and on the double burden of malnutrition. Latin America has been a leader in the design and implementation of innovative and effective actions to reduce excess energy intake and curb the consumption of unhealthy Actions to address deficiency have been implemented in many countries in the region over the years, but current evidence suggests that micronutrient deficiencies have fallen off the public health agenda in Latin America. Effective programming can be developed / appropriately adapted only with knowledge of the current burden. Such data can also help guide and predict future areas of risk and priorities to missing upcoming nutrition issues in the population. Renewed commitment to quantify and monitor micronutrient deficiencies in the region is essential. Abundant evidence and guidance exist to inform effective program selection, design and implementation to address this public health problem.

A Landscape of Micronutrient Dietary Intake by 15- to 65-Years-Old Urban Population in 8 Latin American Countries: Results From the Latin American Study of Health and Nutrition

BACKGROUND

Latin American countries have shifted from traditional diets rich in micronutrients to a Westernized diet rich in high energy-dense foods and low in micronutrients.

OBJECTIVE

This study aimed to determine the prevalence of adequate micronutrient intakes in urban populations of 8 Latin American countries.

METHOD

Micronutrient dietary intake data were collected from September 2014 to August 2015 from 9216 men and women aged 15.0 to 65.0 years living in urban populations of 8 Latin American countries. Dietary intake was collected using two 24-hour recalls on nonconsecutive days. Micronutrient adequacy of intake was calculated using the Estimated Average Requirement cut-off method.

RESULTS

In general terms, the prevalence of inadequate intake of thiamine, riboflavin, niacin, folate, cobalamin, iron, phosphorus, copper, and selenium ranged from 0.4% to 9.9%. In contrast, the prevalence of inadequacy of pyridoxine, zinc, vitamin C, and vitamin A ranged from 15.7% to 51.5%. The nutrients with a critical prevalence of inadequacy were magnesium (80.5%), calcium (85.7%), and vitamin D (98.2%). The highest prevalence of inadequate intakes was observed in the low educational level, participants with overweight/obesity, in men, and varies according to socioeconomic status.

CONCLUSIONS

There is an urgent need to define direct regional actions and strategies in Latin America aimed at improving micronutrient adequacy, either through staple food fortification programs, agronomic biofortification, or food policies that facilitate economic access to micronutrient-rich foods.

Repeated High-Dose Vitamin A Supplements, Standard of Care for Treating Xerophthalmia, Leads to Hypervitaminosis A in Piglets

BACKGROUND

Vitamin A (VA) deficiency and excess negatively affect development, growth, and bone health. The World Health Organization's standard of care for xerophthalmia due to VA deficiency, is 3 high-dose VA supplements of 50,000-200,000 IU, based on age, which may cause hypervitaminosis A in some individuals.

OBJECTIVES

This study measured VA status following 3 VA doses in 2 piglet studies.

METHODS

In Study 1, 5 groups of piglets (n = 10/group) were weaned 10 d postbirth to VA-free feed and orally administered 0; 25,000; 50,000; 100,000; or 200,000 IU VA ester on days 0, 1, and 7. On days 14 and 15, the piglets underwent the modified relative dose-response (MRDR) test for VA deficiency, and were killed. Tissues were collected for high-pressure liquid chromatography analysis. Study 2 used the same design in 3 groups (n = 13/group) weaned at 16 d and administered 0; 25,000; and 200,000 IU doses.

RESULTS

In Study 1 (final weight: 3.6 ± 0.7 kg), liver VA concentration was hypervitaminotic in 40%, 90%, and 100% of 50,000; 100,000; and 200,000 IU groups, respectively. The 25,000 IU group was 100% adequate, and the placebo group was 40% deficient. In Study 2 (final weight: 8.7 ± 0.8 kg), where 200,000 IU could be prescribed to infants with a similar body weight, 31% of the piglets were hypervitaminotic, the 25,000 IU group was 100% VA adequate, and the placebo group was 100% deficient. The MRDR test measured deficiency in 50% and 70% of the placebo group in each study but had 3 false positives among hypervitaminotic piglets in Study 1.

CONCLUSIONS

Repeated high-dose VA may cause hypervitaminosis, indicating dose sizes may need reduction. The MRDR resulted in false positives in a hypervitaminotic state during malnutrition and should be paired with serum retinyl ester evaluation to enhance VA status assessment in populations with overlapping interventions.

The association between serum vitamin A concentrations and virus hepatitis among U.S. adults from the NHANES database: a cross-sectional study

Objective

According to the present study, the relationship between vitamin A (VA) levels and hepatitis virus carriage has been unclear and controversial. This study aimed to determine the potential relationship between serum VA levels and viral hepatitis and to provide ideas for future clinical treatments.

Methods

A cross-sectional study was performed using the 2005-2006 and 2017-2018 National Health and Nutrition Examination Survey (NHANES) datasets. Multiple linear regression and logistic regression were adopted to analyze the association between serological hepatitis B surface antigen (HBsAg) or hepatitis C RNA (HCV-RNA) positivity and VA levels. There were 5,351 HBsAg-related responders and 242 HCV-RNA-related responders, including 52 HBsAg (+) and 104 HCV-RNA (+) responders.

Results

Compared with HBsAg (-) and HCV-RNA (-) respondents, HBsAg (+) and HCV-RNA (+) respondents tended to have lower serum VA levels, respectively [1.63 (1.33 ~ 2.01) vs. 1.92 (1.57 ~ 2.34), P < 0.001; 1.54 (1.25 ~ 1.83) vs. 1.78 (1.46 ~ 2.26), P < 0.001]. A greater percentage of responders in the subclinical VA deficiency (SVAD) group were HBsAg (+) and HCV-RNA (+) than were those in the normal VA (VAN) group [2.4% (9/374) vs. 0.9% (43/4977), p = 0.003; 61.5% (16/26) vs. 40.7% (88/215), p = 0.043]. According to the results of the multiple regression analyses of the different models, the serum VA concentration was negatively correlated with HBsAg (+) and HCV-RNA (+) status (β = -0.14, 95% CI = -0.30 to -0.01, p = 0.066; β = -0.29, 95% CI = -0.50 ~ -0.09, p = 0.005, respectively). Compared to those with SVAD, patients with VAN were less likely to be serologically HBsAg (+) or HCV-RNA (+) (OR = 0.53, 95% CI = 0.25 ~ 1.10, p = 0.089; OR = 0.39, 95% CI = 0.18 ~ 0.84, p = 0.016, respectively).

Conclusion

Our study provides evidence that patients who are HBsAg (+) or HCV-RNA (+) have a high incidence of SVAD. Moreover, HBsAg and HCV-RNA positivity are negatively correlated with VA levels, and patients with SVAD are more likely to carry HBsAg (+) or HCV-RNA (+). These findings suggest that the relationship between hepatitis viruses and vitamin A needs to be validated by more basic studies and clinical large-sample randomized controlled trials to provide ideas for new therapeutic targets.

An intense 60-day weight-loss course leads to an 18 kg body weight reduction and metabolic reprogramming of soldiers with obesity

Soldiers of the Mexican Army with obesity were subjected to an intense 60-day weight-loss course consisting of a controlled diet, daily physical training, and psychological sessions. The nutritional treatment followed the European Society of Cardiology (ESC) recommendations, incorporating elements of the traditional milpa diet in the nutritional intervention. The total energy intake was reduced by 200 kcal every 20 days, starting with 1,800 kcal and ending with 1,400 kcal daily. On average, the participants reduced their body weight by 18 kg. We employed an innovative approach to monitor the progress of the twelve soldiers who completed the entire program. We compared the untargeted metabolomics profiles of their urine samples, taken before and after the course. The data obtained through liquid chromatography and high-resolution mass spectrometry (LC-MS) provided insightful results. Classification models perfectly separated the profiles pre and post-course, indicating a significant reprogramming of the participants' metabolism. The changes were observed in the C1-, vitamin, amino acid, and energy metabolism pathways, primarily affecting the liver, biliary system, and mitochondria. This study not only demonstrates the potential of rapid weight loss and metabolic pathway modification but also introduces a non-invasive method for monitoring the metabolic state of individuals through urine mass spectrometry data.

Scientific opinion on the tolerable upper intake level for preformed vitamin A and β-carotene

Following two requests from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the revision of the tolerable upper intake level (UL) for preformed vitamin A and β-carotene. Systematic reviews of the literature were conducted for priority adverse health effects of excess vitamin A intake, namely teratogenicity, hepatotoxicity and endpoints related to bone health. Available data did not allow to address whether β-carotene could potentiate preformed vitamin A toxicity. Teratogenicity was selected as the critical effect on which to base the UL for preformed vitamin A. The Panel proposes to retain the UL for preformed vitamin A of 3000 μg RE/day for adults. This UL applies to men and women, including women of child-bearing age, pregnant and lactating women and post-menopausal women. This value was scaled down to other population groups using allometric scaling (body weight0.75), leading to ULs between 600 μg RE/day (infants 4-11 months) and 2600 μg RE/day (adolescents 15-17 years). Based on available intake data, European populations are unlikely to exceed the UL for preformed vitamin A if consumption of liver, offal and products thereof is limited to once per month or less. Women who are planning to become pregnant or who are pregnant are advised not to consume liver products. Lung cancer risk was selected as the critical effect of excess supplemental β-carotene. The available data were not sufficient and suitable to characterise a dose-response relationship and identify a reference point; therefore, no UL could be established. There is no indication that β-carotene intake from the background diet is associated with adverse health effects. Smokers should avoid consuming food supplements containing β-carotene. The use of supplemental β-carotene by the general population should be limited to the purpose of meeting vitamin A requirements.

Hepatic Vitamin A Concentrations and Association with Infectious Causes of Child Death

OBJECTIVES

To assess postmortem vitamin A (VA) concentrations in children under 5 years of age and evaluate the association between VA deficiency (VAD) and infectious causes of death (CoD).

STUDY DESIGN

In this cross-sectional study from the Child Health and Mortality Prevention Surveillance (CHAMPS) Network, liver biopsies collected within 72 hours of death were analyzed from 405 stillbirths and children under 5 years in Kenya and South Africa. Total liver VA (TLVA) concentrations were quantified using ultra-performance liquid chromatography, and cutoffs of ≤0.1 μmol/g, >0.1 to <0.7 μmol/g, ≥0.7 to <1.0 μmol/g, and ≥1.0 μmol/g were used to define VAD, adequate VA status, high VA, and hypervitaminosis A, respectively. CoD were determined by expert panel review.

RESULTS

Among 366 liver samples with viable extraction, pooled prevalences of VAD, adequacy, high VA, and hypervitaminosis were 34.2%, 51.1%, 6.0%, and 8.7%, respectively. VAD was more common among neonates compared with stillbirths, infants, or children, and among those with low birthweight (LBW), underweight, or stunting (P < .05). When adjusting for site, age, and sex, there was no significant association of VAD with increased infectious CoD (OR 1.9, 95% confidence interval [CI] 0.9, 3.8, P = .073). In stratified analyses, VA deficient boys, but not girls, had an increased risk of infectious CoD (OR 3.4, 95% CI 1.3, 10.3, P = .013).

CONCLUSIONS

Definitive postmortem assessment of VA status identified both VAD and VA excess among children under 5 years of age in Kenya and South Africa. VAD in boys was associated with increased risk of infectious mortality. Our findings may inform a transition from universal VA supplementation (VAS) to targeted strategies in certain countries.

Reducing dietary intake of added sugars could affect the nutritional adequacy of vitamin A in adolescents: the Costa Rica case

BACKGROUND

In countries where sugar fortification with vitamin A is mandatory, strategies to reduce the prevalence of overweight/obesity in adolescents that involve lowering added sugar intake could lead to vitamin A inadequate intakes, since vitamin A-fortified sugar for home consumption contributes to a high proportion of this vitamin intake in the adolescent diet.

METHODS

The study employed a hierarchical linear model to perform a mediation analysis on a cross-sectional sample of adolescents (13-18 years old) in the province of San José, Costa Rica.

RESULTS

Lowering the total energy intake derived from added sugars to less than 10% significantly increases the prevalence of vitamin A inadequate intake in adolescents by 12.1% (from 29.6% to 41.7%). This is explained by the mediation model in which, the reduced adequacy of vitamin A intake is mediated by a reduction in total energy intake derived from added sugars fortified with vitamin A.

CONCLUSIONS

The vitamin A fortification of sugar for household consumption should be reassessed according to the current epidemiological profile in Costa Rica to promote strategies that reduce the prevalence of overweight/obesity in adolescents by lowering the consumption of added sugars without affecting vitamin A intake.

Contribution of Different Food Types to Vitamin A Intake in the Chinese Diet

Vitamin A is a fat-soluble micronutrient that is essential for human health. In this study, the daily vitamin A intake of Chinese residents was evaluated by investigating the vitamin A content of various foods. The results show that the dietary intake of vitamin A in common foods was 460.56 ugRAE/day, which is significantly lower than the recommended dietary reference intake of vitamin A (800 ugRAE/day for adult men and 700 ugRAE/day for adult women). Vegetables contributed the most to daily vitamin A dietary intake, accounting for 54.94% of vitamin A intake (253.03 ugRAE/day), followed by eggs, milk, aquatic products, meat, fruit, legumes, coarse cereals, and potatoes. Therefore, an increase in the vitamin A content of vegetables and the fortification of vegetable oils with vitamin A are effective ways to increase vitamin A intake to meet the recommended dietary guidelines in China. The assessment results support the design of fortified foods.

Use of Compartmental Modeling and Retinol Isotope Dilution to Determine Vitamin A Stores in Young People with Sickle Cell Disease Before and After Vitamin A Supplementation

BACKGROUND

Suboptimal plasma retinol concentrations have been documented in US children with sickle cell disease (SCD) hemoglobin SS type (SCD-HbSS), but little is known about vitamin A kinetics and stores in SCD.

OBJECTIVES

The objectives were to quantify vitamin A total body stores (TBS) and whole-body retinol kinetics in young people with SCD-HbSS and use retinol isotope dilution (RID) to predict TBS in SCD-HbSS and healthy peers as well as after vitamin A supplementation in SCD-HbSS subjects.

METHODS

Composite plasma [13C10]retinol response data collected from 22 subjects with SCD-HbSS for 28 d after isotope ingestion were analyzed using population-based compartmental modeling ("super-subject" approach); TBS and retinol kinetics were quantified for the group. TBS was also calculated for the same individuals using RID, as well as for healthy peers (n = 20) and for the subjects with SCD-HbSS after 8 wk of daily vitamin A supplements (3.15 or 6.29 μmol retinol/d [900 or 1800 μg retinol activity equivalents/d]).

RESULTS

Model-predicted group mean TBS for subjects with SCD-HbSS was 428 μmol, equivalent to ∼11 mo of stored vitamin A; vitamin A disposal rate was 1.3 μmol/d. Model-predicted TBS was similar to that predicted by RID at 3 d postdosing (mean, 389 μmol; ∼0.3 μmol/g liver); TBS predictions at 3 compared with 28 d were not significantly different. Mean TBS in healthy peers was similar (406 μmol). RID-predicted TBS for subjects with SCD-HbSS was not significantly affected by vitamin A supplementation at either dose.

CONCLUSIONS

Despite differences in plasma retinol concentrations, TBS was the same in subjects with SCD-HbSS compared with healthy peers. Because 56 d of vitamin A supplementation at levels 1.2 to 2.6 times the Recommended Dietary Allowance did not increase TBS in these subjects with SCD-HbSS, further work will be needed to understand the effects of SCD on retinol metabolism. This trial was registered as NCT03632876 at clinicaltrials.gov.

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.

Total Liver Vitamin A Reserves, Determined With 13C2-Retinol Isotope Dilution, are Similar Among Tanzanian Preschool Children in Areas With Low and High Vitamin A Exposure

BACKGROUND

In Tanzania, some districts have single vitamin A (VA) interventions and others have multiple interventions. There is limited information on total liver VA reserves (TLRs) among preschool children (PSC) in Tanzania.

OBJECTIVES

We assessed total body VA stores (TBSs) and TLRs among PSC living in 2 districts with low and high exposures to VA interventions using 13C-retinol isotope dilution.

METHODS

A cross-sectional, health facility-based study was conducted in 2 districts with access to VA supplementation only (low exposure to VA interventions) or multiple interventions (high exposure to VA interventions) to determine TLRs in 120 PSC aged 36-59 months. A questionnaire was used to collect data. Height and weight were measured, and the prevalence of undernutrition was based on z-scores. Blood samples were collected for measurement of TBSs, TLRs, retinol, biomarkers of infection and inflammation, and hemoglobin. 13C2-retinyl acetate (1.0 μmol) was administered to each child after blood collection, and the second sample was taken 14 days later. Serum was analyzed with HPLC and gas chromatography-combustion-isotope ratio mass spectrometry. Mann-Whitney U test was used to compare medians of nonnormally distributed variables. Pearson χ2 test was used to assess associations between 2 categorical variables.

RESULTS

Median TBSs differed between PSC from low-exposure (196 μmol; IQR, 120 μmol) and high-exposure (231 μmol; IQR, 162 μmol) intervention areas (P = 0.015). Median TLRs were 0.23 μmol/g liver (IQR, 0.14 μmol/g liver) and 0.26 μmol/g liver (IQR, 0.16 μmol/g liver) from low- and high-exposure areas, respectively, which did not significantly differ (P = 0.12). Prevalences of VA deficiency (VAD; ≤0.1 μmol/g liver) were 6.3% and 1.7% for PSC from low- and high-exposure areas, respectively. There was no significant difference in VAD (P = 0.25). No child had hypervitaminosis A (≥1.0 μmol/g liver).

CONCLUSIONS

TLRs in Tanzanian PSC from 2 districts did not differ between low and high exposures to VA interventions. The majority had adequate VA stores. VAD in the study area presented a mild public health problem.

Breast Milk Retinol Concentrations Reflect Total Liver Vitamin A Reserves and Dietary Exposure in Thai Lactating Women from Urban and Rural Areas

BACKGROUND

Measuring vitamin A (VA) status during lactation is required to inform dietary recommendations. Limited data exist on VA stores in women.

OBJECTIVES

Our objective was to assess VA status in lactating Thai women by measuring total body VA stores (TBSs), serum and breast milk retinol concentrations, and dietary intake.

METHODS

Lactating women (n = 94), 6-8 wk postpartum, were enrolled from rural (Ayutthaya) and urban (Bangkok) areas. TBSs were measured by the 13C-retinol isotope dilution (RID) technique using 2.0 μmol 13C-retinyl acetate and a single blood sample 14 d post-dose. Natural 13C-enrichment was determined in nonenrolled women (n = 11). Estimated total liver VA reserves (TLRs) were determined using assumptions for lactation. Serum, foremilk, and hindmilk samples were analyzed for retinol by HPLC. Dietary VA intake was assessed by FFQ and 24-h dietary recalls for 3 d. Multiple regression and Pearson correlation were used to evaluate relations.

RESULTS

Median VA intakes were 51.8% of 2003 Thai daily recommendations for lactating women, with the majority from animal-source foods. Many women in Ayutthaya consumed liver weekly. Considering TLRs as 50% TBS, 20% and 11% of mothers in Ayutthaya and Bangkok, respectively, showed deficient reserves (≤0.10 μmol retinol/g). Median (quartile 1, quartile 3) serum [1.58 (1.34, 1.91) and 1.52 (1.30, 1.70) μmol/L] and milk [1.88 (1.29, 2.95) and 1.74 (0.96, 2.26) μmol/L] retinol in Ayutthaya and Bangkok, respectively, were normal. Women with deficient TLRs showed low milk retinol concentrations (≤1.0 μmol/L) and consumed less dietary VA, especially from animal-source foods. Breast milk retinol concentrations, especially hindmilk, demonstrated strong correlation with TBSs and TLRs estimated from the RID test.

CONCLUSIONS

Approximately 15% of Thai lactating women had deficient TLRs. Breast milk retinol concentrations in conjunction with dietary intake records show potential to screen mothers at risk of VA deficiency to guide interventions.The Thai Clinical Trials Registry number is TCTR20160824001 for the work in Thailand.

Anthocyanin and Lycopene Contents Do Not Affect β-Carotene Bioefficacy from Multicolored Carrots (Daucus carota L.) in Male Mongolian Gerbils

BACKGROUND

Anthocyanins and carotenoids are phytochemicals that may benefit health through provitamin A carotenoid (PAC), antioxidant, and anti-inflammatory activities. These bioactives may mitigate chronic diseases. Consumption of multiple phytochemicals may impact bioactivity in synergistic or antagonistic manners.

OBJECTIVES

Two studies in weanling male Mongolian gerbils assessed the relative bioefficacy of β-carotene equivalents (BCEs) to vitamin A (VA) with simultaneous consumption of the non-PAC lycopene or anthocyanins from multicolored carrots.

METHODS

After 3-wk VA depletion, 5-6 gerbils were killed as baseline groups. The remaining gerbils were divided into 4 carrot treatment groups; the positive control group received retinyl acetate and the negative control group was given vehicle soybean oil (n = 10/group; n = 60/study). In the lycopene study, gerbils consumed feed varying in lycopene sourced from red carrots. In the anthocyanin study, gerbils consumed feed varying in anthocyanin content sourced from purple-red carrots, and positive controls received lycopene. Treatment feeds had equalized BCEs: 5.59 ± 0.96 μg/g (lycopene study) and 7.02 ± 0.39 μg/g (anthocyanin study). Controls consumed feeds without pigments. Serum, liver, and lung samples were analyzed for retinol and carotenoid concentrations using HPLC. Data were analyzed by ANOVA and Tukey's studentized range test.

RESULTS

In the lycopene study, liver VA did not differ between groups (0.11 ± 0.07 μmol/g) indicating no effect of varying lycopene content. In the anthocyanin study, liver VA concentrations in the medium-to-high (0.22 ± 0.14 μmol/g) and medium-to-low anthocyanin (0.25 ± 0.07 μmol/g) groups were higher than the negative control (0.11 ± 0.07 μmol/g) (P < 0.05). All treatment groups maintained baseline VA concentrations (0.23 ± 0.06 μmol/g). Combining studies, serum retinol had 12% sensitivity to predict VA deficiency, defined as 0.7 μmol/L.

CONCLUSIONS

These gerbil studies suggested that simultaneous consumption of carotenoids and anthocyanins does not impact relative BCE bioefficacy. Breeding carrots for enhanced pigments to improve dietary intake should continue.

Time Since Dose and Dietary Vitamin A Intake Affect Tracer Mixing in the 13C-Retinol Isotope Dilution Test in Male Rats

BACKGROUND

Retinol isotope dilution (RID) estimates total liver vitamin A reserves (TLRs), the gold-standard vitamin A (VA) biomarker. RID equation assumptions are based on limited data.

OBJECTIVES

We measured the impact of tracer choice, mixing period, and VA intake on tracer mixing [ratio of tracer enrichment in serum to that in liver stores (S)] in VA-deficient, -adequate, and hypervitaminotic rats.

METHODS

Study 1 was a 3 × 2 × 3 design (18 groups, n = 5/group). Male Sprague-Dawley rats (21 d old) received 50, 100, or 3500 nmol VA/d for 21 d, were administered 52 nmol 13C2- or 13C10-retinyl acetate orally, and killed 5, 10, or 15 d later. Unlabeled VA (50 nmol/d) was given on days 11-14. Study 2 used 100 nmol VA/d for 21 d with 3 groups (n = 6-7): 52 nmol 13C2- or 13C10-retinyl acetate and 100 nmol VA/d throughout 14-d mixing, or 13C2-retinyl acetate without VA. Repeated-measures, 1-factor, and 3-factor ANOVAs were used for analysis.

RESULTS

Mean ± SD TLRs (μmol/g liver) reflected intake: 0.11 ± 0.04 (50 nmol VA/d), 0.16 ± 0.04 (100 nmol VA/d), and 5.07 ± 1.58 (3500 nmol VA/d) in Study 1 and 0.24 ± 0.08 (100 nmol VA/d) in Study 2. In Study 1, mean ± SD S was 1.65 ± 0.26 (5 d), 1.16 ± 0.09 (10 d), and 0.92 ± 0.08 (15 d). The interactions tracer*VA intake and time*VA intake were significant between days 10 and 15 (P < 0.05). In Study 2, mean ± SD S was 1.07 ± 0.02 without VA during mixing, and 0.81 ± 0.04 (13C2) and 0.79 ± 0.03 (13C10) with VA intake throughout. Estimated:measured TLRs varied by VA intake and time in Study 1 but not between groups in Study 2.

CONCLUSIONS

The 13C-content effect on RID through S is inconsistent. S is highly variable at 5 d, contraindicating early-time point RID. VA intake effects on S vary with timing and quantity. Assuming S = 0.8 at 14 d with consistent VA intake in human studies is likely appropriate.