Bioconversion of plant carotenoids to vitamin A in Filipino school-aged children varies inversely with vitamin A status

Supplementation of red palm olein-enriched biscuits improves levels of provitamin A carotenes, iron, and erythropoiesis in vitamin A-deficient primary schoolchildren: a double-blinded randomised controlled trial

PURPOSE

Vitamin A deficiency (VAD) remains a significant contributor to childhood morbidity and mortality in developing countries; therefore, the implementation of sustainable and cost-effective approaches to control VAD is of utmost pertinence. This study aims to investigate the efficacy of red palm olein (RPO)-enriched biscuit supplementation in improving vitamin A, haematological, iron, and inflammatory status among vitamin A-deficient schoolchildren.

METHODS

We conducted a double-blinded, randomised controlled trial involving 651 rural primary schoolchildren (8-12 years) with VAD in Malaysia. The schoolchildren were randomised to receive either RPO-enriched biscuits (experimental group, n = 334) or palm olein-enriched biscuits (control group, n = 317) for 6-month duration.

RESULTS

Significant improvements in retinol and retinol-binding protein 4 levels were observed in both groups after supplementation (P < 0.001). The improvement in retinol levels were similar across groups among subjects with confirmed VAD (P = 0.40). Among those with marginal VAD, greater improvement in retinol levels was recorded in the control group (P < 0.001) but lacked clinical significance. The levels of α- and β-carotenes, haematological parameters (haemoglobin, packed cell volume, mean corpuscular volume and mean corpuscular haemoglobin) and iron enhanced more significantly in the experimental group (P < 0.05). The significant reduction in the prevalence of microcytic anaemia (- 21.8%) and high inflammation (- 8.1%) was only observed in the experimental group.

CONCLUSION

The supplementation of RPO-enriched biscuits enhanced levels of provitamin A carotenes, iron, and erythropoiesis, and exhibited anti-inflammatory effects. Therefore, the incorporation of RPO into National Nutritional Intervention Programs may be a potential measure to improve the health status of vitamin A-deficient children, among various other interventions.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (NCT03256123).

The Bioactive Compounds and Fatty Acid Profile of Bitter Apple Seed Oil Obtained in Hot, Arid Environments

Bitter apple or tumba (Citrullus colocynthis L.) is a prostrate annual herb belonging to the Cucurbitaceae family. It is highly tolerant against multiple abiotic stresses like drought, heat, and soil salinity and can easily grow on very marginal soil, even on sand dunes in hot, arid regions. Tumba fruit is a fleshy berry 5–10 cm in diameter and of a pale yellow color at ripening. The tumba fruit used in this research was harvested from the ICAR-CIAH, Bikaner research farm. The seeds were separated, and their oil was extracted to analyze its physical characteristics and composition (phytochemical compounds, fatty acid profile, etc.). The seeds of the tumba fruit contained 23–25% golden-yellow-colored oil with a specific gravity of 0.92 g/mL. The extracted oil contained appreciable amounts of phytochemical (bioactive) compounds like phenolics (5.39 mg GAE/100 g), flavonoids (938 mg catechin eq./100 g), carotenoids (79.5 mg/kg), oryzanol (0.066%), and lignans (0.012%), along with 70–122 mg AAE/100 g total antioxidant activity (depending on the determination method). The results of fatty acid profiling carried out by GC-MS/MS demonstrated that tumba seed oil contained about 70% unsaturated fatty acids with more than 51% polyunsaturated fatty acids. It mainly contained linoleic acid (C18:2n6; 50.3%), followed by oleic acid (C18:1n9; 18.0%), stearic acid (C18:0; 15.2%), and palmitic acid (C16:0; 12.4%). Therefore, this oil can be considered as a very good source of essential fatty acids like omega-6 fatty acid (linoleic acid), whereas it contains a lower concentration of omega-3 fatty acids (α-linolenic acid) and hydroxy polyunsaturated fatty acids. In addition, it also contains some odd chain fatty acids like pentadecanoic and heptadecanoic acid (C15:0 and C17:0, respectively), which have recently been demonstrated to be bioactive compounds in reducing the risk of cardiometabolic diseases. The results of this study suggest that tumba seed oil contains several health-promoting bioactive compounds with nutraceutical properties; hence, it can be an excellent dietary source.

Genotype Effects on β-Carotene Conversion to Vitamin A: Implications on Reducing Vitamin A Deficiency in the Philippines

BACKGROUND

The study aimed to identify two beta-carotene 15,15'-monooxygenase (BCMO1) mutations, namely R267S and A379V, and determine their association with vitamin A status among Filipinos 6 to 19 years old respondents of the 2013 Philippine National Nutrition Survey living in the National Capital Region.

MATERIALS AND METHODS

This study followed cross-sectional design. Whole blood specimen was collected in the morning and was used as source of genomic DNA and serum for retinol concentration determination. Fisher exact test was performed to determine whether genotype frequencies were associated to retinol concentrations/vitamin A deficiency status. A level of P < .05 was identified as significant.

RESULTS

A total of 693 Filipino children and adolescents were included. Of the 693, there were at least 7.6% who bears the combined mutations for R267S + A379V. Association analysis showed that an inverse relationship exists between the A379V TT variant and vitamin A status. Although the exact role of these identified polymorphisms on retinol/carotenoid metabolism need to be confirmed in dedicated functional studies.

CONCLUSION

This study has identified for the first time the presence of 2 nonsynonymous genetic variants/mutations in the coding region of BCMO1 gene. Interestingly, one of these two variants, the A379V T, was found to be associated with vitamin A status. It is, therefore, warranted to investigate the role of BCMO1 variants for the success of supplementation programs and fortification efforts among vulnerable populations in this region. Genetic variability should be considered for future provitamin A supplementation recommendations among children and adolescents in the Philippines.

Findings in 3 clinical trials challenge the accuracy of the Institute of Medicine's estimated average requirements for vitamin A in children and women

BACKGROUND

Vitamin A (VA) estimated average requirements (EARs) for women and children are extrapolated from rats and adult males. The retinol isotope dilution (RID) test can sensitively characterize VA status and intake requirements.

OBJECTIVES

These studies evaluated current EARs for children 4-8 y and women 19-30 y old.

METHODS

Zambian children (n = 133, ages 5-7 y), US women (n = 51, ages 19-27 y), and Indonesian women (n = 29, ages 19-30 y) were provided diets or supplements containing 30%-155% of VA EARs for 42-90 d. RID was performed before and after the intervention to quantify changes in total body VA stores (TBSs) and total liver VA reserves (TLRs). Linear regression was performed between VA intake and change in TBSs or TLRs.

RESULTS

Baseline mean ± SD TLRs were hypervitaminotic in Zambian children (1.13 ± 0.41 μmol VA/g liver), optimal in US women (0.46 ± 0.32 μmol/g VA/g liver), and deficient to marginal in Indonesian women (0.10 ± 0.08 μmol VA/g liver). VA intakes, resulting in no change in TBSs or TLRs, were 185 (95% CI: 18, 288) or 257 (95% CI: 124, 411) and 285 or 330 (CIs undefined) μg retinol activity equivalents (RAE)/d in the Zambian and US trials, respectively, but inconclusive in Indonesian women. The regression was not significant in either group of women.

CONCLUSIONS

Point estimates of VA intakes to maintain stores were below the current EARs of 275 (children) and 500 (women) μg RAE/d despite the TLRs being higher than the EARs were formulated to maintain (i.e., 0.07 μmol VA/g liver). Interventions based on these EARs may need to be scaled back. Lack of change in VA stores in women taking lower doses may result from physiological adaptation resulting in lower VA utilization. Longer, larger, and controlled studies are needed to accurately define EARs for VA.These trials were registered at Clinicaltrials.gov as NCT04123210 and NCT01814891.

Which blood cutoff value should be used for vitamin A deficiency in children aged 3-10 years? A systematic review

CONTEXT

Blood cutoff values for vitamin A deficiency in children aged 3-10 years have not been addressed in the literature.

OBJECTIVE

To identify blood retinol concentrations for determining severe vitamin A deficiency in children aged 3-10 years.

DATA SOURCES

The MEDLINE, Web of Science, Embase, and Scopus databases were searched.

DATA EXTRACTION

Two reviewers independently extracted article data and assessed quality.

DATA ANALYSIS

The hierarchical summary receiver operating characteristic models were applied for the diagnostic accuracy meta-analysis. This review is registered at PROSPERO (identifier: CRD42020149367).

RESULTS

A total of 15 articles met the eligibility criteria, and 9 were included in the diagnostic accuracy meta-analysis. The summary estimates (95%CI) were: Sensitivity, 0.39 (0.20-0.62); specificity, 0.79 (0.65-0.88); positive likelihood ratio, 1.85 (1.33-2.57); and negative likelihood ratio, 0.77 (0.60-0.99). The area under the curve of the overall analysis was 0.68 (95%CI 0.63-0.72).

CONCLUSIONS

Blood retinol concentrations have low diagnostic accuracy for severe vitamin A deficiency in children aged 3-10 years. Therefore, there is unclear evidence about the preferable cutoff point for determining severe vitamin A deficiency in children in this age group.

Association between serum β-carotene-to-retinol ratio and severity of hepatic steatosis in non-alcoholic fatty liver disease in Japan: A cross-sectional study

OBJECTIVES

Retinol and β-carotene have been reported to be involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, clinical studies are limited. The aim of this study was to investigate the relationship between serum the ratio of β-carotene to retinol (SC/SR) and hepatic steatosis in NAFLD diagnosed by ultrasonography.

METHODS

The participants were 606 Japanese adults who were enrolled in a health survey. Clinical profile, dietary nutrition intake, blood biochemistry, serum retinol, and carotenoids were analyzed. NAFLD was defined as fatty liver on ultrasonography in the absence of other causes of steatosis.

RESULTS

Women had higher daily intake of α- and β-carotene, although there were no differences in daily retinol and carotenoid intake between participants with or without NAFLD in both men and women. Women had a higher SC/SR ratio than men regardless of the presence or absence of NAFLD, and the SC/SR ratio in women decreased with exacerbation of hepatic steatosis, whereas the SC/SR ratio in men did not change despite exacerbation of hepatic steatosis. After adjusting for confounding factors, the likelihood of NAFLD among participants in the highest quartile of SC/SR ratio decreased by two-thirds compared with participants in the lowest quartile (adjusted odds ratio, 0.64; 95% confidence interval, 0.21-1.92; P = 0.041). The SC/SR ratio was positively correlated with serum high-density lipoprotein cholesterol level, and negatively correlated with serum triacylglycerol level.

CONCLUSIONS

The SC/SR ratio was lower in NAFLD with sex differences, and was associated with the severity of hepatic steatosis and lipid profile. Future studies are needed to expand on these findings.

SNP rs6564851 in the BCO1 Gene Is Associated with Varying Provitamin a Plasma Concentrations but Not with Retinol Concentrations among Adolescents from Rural Ghana

In sub-Saharan Africa, vitamin A deficiency constitutes a severe health problem despite various supplementation and food fortification programs. Given that the intake of preformed vitamin A from animal products remains low in these countries, an efficient metabolization of plant-based provitamin A carotenoids is essential. Previously, adolescents in rural Ghana have shown high total plasma carotenoid concentrations, while 36% had a vitamin A deficiency (defined as plasma retinol < 0.7 µmol/L). Hence, the aim of this cross-sectional study was to identify the relationships between variants in the β-carotene 15,15'-oxygenase (BCO1) gene and plasma carotenoid concentrations among 189 15-year-old girls and boys in rural Ghana. BCO1 rs6564851, rs7500996, rs10048138 and PKD1L2 rs6420424, and rs8044334 were typed, and carotenoid concentrations were compared among the different genotypes. G allele carriers of rs6564851 (53%) showed higher plasma carotenoid concentrations than T allele carriers (median (interquartile range): 3.07 (2.17-4.02) vs. 2.59 (2.21-3.50) µmol/L, p-value = 0.0424). This was not explained by differences in socio-demographic or dietary factors. In contrast, no differences in plasma retinol concentrations were observed between these genotypes. Pending verification in independent populations, the low conversion efficiency of provitamin A carotenoids among rs6564851 G allele carriers may undermine existing fortification and supplementation programs to improve the vitamin A status in sub-Saharan Africa.

The "Super-Child" Approach Is Applied To Estimate Retinol Kinetics and Vitamin A Total Body Stores in Mexican Preschoolers

BACKGROUND

Retinol isotope dilution (RID) and model-based compartmental analysis are recognized techniques for assessing vitamin A (VA) status. Recent studies have shown that RID predictions of VA total body stores (TBS) can be improved by using modeling and that VA kinetics and TBS in children can be effectively studied by applying population modeling ("super-child" approach) to a composite data set.

OBJECTIVES

The objectives were to model whole-body retinol kinetics and predict VA TBS in a group of Mexican preschoolers using the super-child approach and to use model predictions of RID coefficients to estimate TBS by RID in individuals.

METHODS

Twenty-four healthy Mexican children (aged 3-6 y) received an oral dose (2.96 μmol) of [13C10]retinyl acetate in corn oil. Blood samples were collected from 8 h to 21 d after dosing, with each child sampled at 4 d and at 1 other time. Composite data for plasma labeled retinol compared with time were analyzed using a 6-component model to obtain group retinol kinetic parameters and pool sizes. Model-predicted TBS was compared with mean RID predictions at 4 d; RID estimates at 4 d were compared with those calculated at 7-21 d.

RESULTS

Model-predicted TBS was 1097 μmol, equivalent to ∼2.4 y-worth of VA; using model-derived coefficients, group mean RID-predicted TBS was 1096 μmol (IQR: 836-1492 μmol). TBS at 4 d compared with a later time was similar (P = 0.33). The model predicted that retinol spent 1.5 h in plasma during each transit and recycled to plasma 13 times before utilization.

CONCLUSIONS

The super-child modeling approach provides information on whole-body VA kinetics and can be used with RID to estimate TBS at any time between 4 and 21 d postdose. The high TBS predicted for these children suggests positive VA balance, likely due to large-dose VA supplements, and warrants further investigation.

Perspective: Integration to Implementation (I-to-I) and the Micronutrient Forum-Addressing the Safety and Effectiveness of Vitamin A Supplementation

An ongoing challenge to our ability to address the role of food and nutrition in health promotion and disease prevention is how to design and implement context-specific interventions and guidance that are safe, efficacious, and avoid unintended consequences. The integration to effective implementation (I-to-I) concept is intended to address the complexities of the global health context through engagement of the continuum of stakeholders involved in the generation, translation, and implementation of evidence to public health guidance/programs. The I-to-I approach was developed under the auspices of the Micronutrient Forum and has been previously applied to the question of safety and effectiveness of interventions to prevent and treat nutritional iron deficiency. The present article applies the I-to-I approach to questions regarding the safety and utility of large-dose vitamin A supplementation programs, and presents the authors' perspective on key aspects of the topic, including coverage of the basic and applied biology of vitamin A nutrition and assessment, clinical implications, and an overview of the extant data with regard to both the justification for and utility of available intervention strategies. The article includes some practical considerations based on specific country experiences regarding the challenges of implementing vitamin A-related programs. This is followed by an overview of some challenges associated with engagement of the enabling communities that play a critical role in the implementation of these types of public health interventions. The article concludes with suggestions for potential approaches to move this important agenda forward.

Impact of Crude Palm Oil Fortified Cookies Supplementation on Anthropometry, Vitamin A and Hematological Status of School Children in India

Abstract. Objectives: Food-based strategies remain the most sustainable solutions for combating micronutrient deficiencies. Crude palm oil being the richest natural source of β-carotene, the study aimed to assess the impact of crude palm oil fortified cookies supplementation on anthropometry, vitamin A and hematological status of school children.

Methods: 444 children (boys-226, girls-218), aged 5-13 years from two Municipal Corporation of Delhi primary schools were enrolled. By draw of lot, children from one of the schools formed the experimental (n = 224; boys-119, girls-105) while other formed the placebo group (n = 220; boys-107; girls-113). Children from the experimental group received six crude palm oil fortified cookies providing 2152 μg of β-carotene while the placebo group received similar but non-fortified cookies each day for 50 school days. Anthropometry, vitamin A, and hematological status were assessed at baseline and post supplementation.

Results: Post supplementation, the number of stunted subjects reduced significantly (p < 0.05) in the experimental group. There was a significant increase in plasma retinol (170.9%; mean change: 1.55 ± 1.30 μmol/L - experimental group vs. 0.45 ± 0.99 μmol/L - placebo group) and β-carotene (p < 0.01; median change from 0.55 to 0.76 μmol/L - experimental group vs. 0.59 to 0.55 μmol/L -placebo group) concentrations of the experimental group. The increase in hematological parameters (mean change in Hemoglobin: 1.64 g/dL in experimental group vs. 2.10 g/dL in placebo group) of both the groups were however, comparable.

Conclusion: To address micronutrient deficiencies particularly in developing nations, the use of crude palm oil should be encouraged through supplementary feeding programs by way of ready-to-eat snacks.

Hesperetin and Hesperidin Improved β-Carotene Incorporation Efficiency, Intestinal Cell Uptake, and Retinoid Concentrations in Tissues

Dietary constituents can influence the bioavailability of carotenoids. This study investigated the effect of citrus flavanones on β-carotene (Bc) bioavailability using four experimental models: in vitro digestion procedure, synthetic mixed micelles, Caco-2 cell monolayers, and gavage experiments in mice. The addition of hesperetin (Hes, 25 μM) and hesperidin (Hes-G, 25 μM) standards significantly increased the incorporation efficiency of the Bc standard to 68.7 ± 3.6 and 75.2 ± 7.5% ( p < 0.05), respectively. However, the addition of naringenin (Nar, 25 μM) and naringin (Nar-G, 25 μM) standards significantly reduced the incorporation efficiency of Bc by 23.8 and 26.4%, respectively ( p < 0.05). The increases in scavenger receptor class B type I (SR-BI) expression promoted by citrus flavanones played an important role in Bc cellular absorption in the Caco-2 cell model. Furthermore, after 3 days of gavage, four citrus flavanones (7.5 mg kg^-1 day^-1) increased the retinoid concentrations in tissues; in contrast, after 7 days of gavage, Nar and Nar-G significantly decreased hepatic retinoid concentrations ( p < 0.05). This finding suggested that the incorporation efficiency into micelles was the main step governing carotenoid bioavailability.

Application of Isotope Dilution Technique in Vitamin A Nutrition

The isotope dilution technique involving deuterated retinol has been developed to quantitatively estimate total body reserves of vitamin A in humans. The technique provided good estimates in comparison to hepatic vitamin A concentrations in Bangladeshi surgical patients. Kinetic studies in the United States, Bangladesh, and Guatemala indicated the mean equilibration time of 17 to 20 days irrespective of the size of hepatic reserves. Due to the controversy surrounding the efficacy of a carotene-rich diet on improvement of vitamin A status, the isotope dilution technique was proposed to pursue this research question further (IAEA's coordinated research program). In the Philippines, schoolchildren with low serum retinol concentrations showed significant improvement in total body vitamin A stores following intake of carotene-rich foods (orange fruits and vegetables), using a three-day deuterated-retinol-dilution procedure. When Chinese kindergarten children were fed green and yellow vegetables during the winter, their total body vitamin A stores were sustained as compared to a steady decline of vitamin A stores in the control children. Likewise, daily consumption of purified beta-carotene or a diet rich in provitamin A carotenoids were shown to prevent a loss in total body vitamin A stores among Thai lactating women during the rice-planting season. These studies demonstrate potentials of the isotope dilution technique to evaluate the impact of provitamin A carotenoid intervention programs.

Use of Stable Isotopes to Evaluate Bioefficacy of Provitamin A Carotenoids, Vitamin A Status, and Bioavailability of Iron and Zinc

The ability of nutrition scientists to measure the status, bioavailability, and bioefficacy of micronutrients is affected by lack of access to the parts of the body through which a nutrient may travel before appearing in accessible body compartments (typically blood or urine). Stable isotope-labeled tracers function as safe, nonradioactive tools to follow micronutrients in a quantitative manner because the absorption, distribution, metabolism, and excretion of the tracer are assumed to be similar to the unlabeled vitamin or mineral. The International Atomic Energy Agency (IAEA) supports research on the safe use of stable isotopes in global health and nutrition. This review focuses on IAEA's contributions to vitamin A, iron, and zinc research. These micronutrients are specifically targeted by the WHO because of their importance in health and worldwide prevalence of deficiency. These 3 micronutrients are included in food fortification and biofortification efforts in low- and middle-income regions of the world. Vitamin A isotopic techniques can be used to evaluate the efficacy and effectiveness of interventions. For example, total body retinol stores were estimated by using 13C2-retinol isotope dilution before and after feeding Zambian children maize biofortified with β-carotene to determine if vitamin A reserves were improved by the intervention. Stable isotopes of iron and zinc have been used to determine mineral bioavailability. In Thailand, ferrous sulfate was better absorbed from fish sauce than was ferrous lactate or ferric ammonium citrate, determined with the use of different iron isotopes in each compound. Comparisons of one zinc isotope injected intravenously with another isotope taken orally from a micronutrient powder proved that the powder increased total absorbed zinc from a meal in Pakistani infants. Capacity building by the IAEA with appropriate collaborations in low- and middle-income countries to use stable isotopes has resulted in many advancements in human nutrition.

Host-related factors explaining interindividual variability of carotenoid bioavailability and tissue concentrations in humans

Carotenoid dietary intake and their endogenous levels have been associated with a decreased risk of several chronic diseases. There are indications that carotenoid bioavailability depends, in addition to the food matrix, on host factors. These include diseases (e.g. colitis), life-style habits (e.g. smoking), gender and age, as well as genetic variations including single nucleotide polymorphisms that govern carotenoid metabolism. These are expected to explain interindividual differences that contribute to carotenoid uptake, distribution, metabolism and excretion, and therefore possibly also their association with disease risk. For instance, digestion enzymes fostering micellization (PNLIP, CES), expression of uptake/efflux transporters (SR-BI, CD36, NPC1L1), cleavage enzymes (BCO1/2), intracellular transporters (FABP2), secretion into chylomicrons (APOB, MTTP), carotenoid metabolism in the blood and liver (LPL, APO C/E, LDLR), and distribution to target tissues such as adipose tissue or macula (GSTP1, StARD3) depend on the activity of these proteins. In addition, human microbiota, e.g. via altering bile-acid concentrations, may play a role in carotenoid bioavailability. In order to comprehend individual, variable responses to these compounds, an improved knowledge on intra-/interindividual factors determining carotenoid bioavailability, including tissue distribution, is required. Here, we highlight the current knowledge on factors that may explain such intra-/interindividual differences.

Promotion of Orange-Fleshed Sweet Potato Increased Vitamin A Intakes and Reduced the Odds of Low Retinol-Binding Protein among Postpartum Kenyan Women

Background: Orange-fleshed sweet potato (OFSP) improves vitamin A (VA) status of young children; research with pregnant and lactating women is limited.Objective: We examined the effectiveness of the Mama SASHA (Sweetpotato Action for Security and Health in Africa) program to improve nutrition knowledge, diets, and nutritional status of pregnant and lactating women (PLW) in Western Kenya.Methods: Eight health facilities were allocated to the Mama SASHA intervention or comparison arms. PLW in intervention facilities received enhanced nutrition counseling at health clinics, were linked with community-based maternal support groups, and received vouchers for OFSP vine cuttings. Control PLW received clinic-based nutrition counseling only. A total of 505 women in early and midpregnancy, attending their first antenatal care visit, and with no previous engagement in project activities were enrolled from the 8 facilities. Nutrition and health-seeking knowledge, food security, dietary patterns, and anthropometric measurements were collected at 4 time points at ≤9 mo postpartum. VA intakes were assessed with multipass 24-h recalls in a subsample of 206 mothers at 8-10 mo postpartum. VA status was assessed by using serum retinol-binding protein (RBP). Impacts were estimated with multilevel mixed models adjusted for clustering and differences at enrollment.Results: At enrollment, 22.9% of women had RBP <1.17 μmol/L. By 9 mo postpartum, intervention women had significantly higher intakes of VA [adjusted difference = 297.0 retinol activity equivalent (RAE) units; 95% CI: 82, 513 RAE units; P = 0.01; n = 206], greater consumption of VA-rich fruit and vegetables in the previous 7 d (difference-in-difference estimate: 0.40 d; 95% CI: 0.23, 0.56 d; P < 0.01), and a 45% reduction in the odds of RBP <1.17 μmol/L (OR: 0.55; 95% CI: 0.33, 0.92; P = 0.01).Conclusion: Promotion of OFSP to PLW through health services is a feasible strategy to improve women's nutrition knowledge, VA intakes, and maternal RBP.

Meeting the Vitamin A Requirement: The Efficacy and Importance of β-Carotene in Animal Species

Vitamin A is essential for life in all vertebrate animals. Vitamin A requirement can be met from dietary preformed vitamin A or provitamin A carotenoids, the most important of which is β-carotene. The metabolism of β-carotene, including its intestinal absorption, accumulation in tissues, and conversion to vitamin A, varies widely across animal species and determines the role that β-carotene plays in meeting vitamin A requirement. This review begins with a brief discussion of vitamin A, with an emphasis on species differences in metabolism. A more detailed discussion of β-carotene follows, with a focus on factors impacting bioavailability and its conversion to vitamin A. Finally, the literature on how animals utilize β-carotene is reviewed individually for several species and classes of animals. We conclude that β-carotene conversion to vitamin A is variable and dependent on a number of factors, which are important to consider in the formulation and assessment of diets. Omnivores and herbivores are more efficient at converting β-carotene to vitamin A than carnivores. Absorption and accumulation of β-carotene in tissues vary with species and are poorly understood. More comparative and mechanistic studies are required in this area to improve the understanding of β-carotene metabolism.

A Retinol Isotope Dilution Equation Predicts Both Group and Individual Total Body Vitamin A Stores in Adults Based on Data from an Early Postdosing Blood Sample

BACKGROUND

Retinol isotope dilution (RID) is used to determine vitamin A total body stores (TBS) after an oral dose of a vitamin A stable isotope. The generally accepted prediction equation proposed by Olson's group in 1989 (Furr et al. Am J Clin Nutr 1989;49:713-6) includes factors related to dose absorption and retention, isotope equilibration in plasma compared with stores, catabolism during the mixing period, and the optimal time for measuring plasma isotope enrichment.

OBJECTIVES

The objectives were 1) to develop a modified RID equation and identify an earlier sampling time for predicting TBS and 2) to improve prediction in individuals as well as groups.

METHODS

To develop a modified RID equation, we used results of model-based compartmental analysis [the Simulation, Analysis and Modeling software (WinSAAM version 3.0.8; http://www.WinSAAM.org)] of plasma [¹³C₁₀]retinol kinetic data from 32 previously studied, healthy young adults of European ancestry who had moderate vitamin A intakes and who ingested 2.95 μmol [¹³C₁₀]retinyl acetate.

RESULTS

We examined the time dependence of factors in the prediction equation related to absorption/retention (Fa) and isotope equilibration (S) and determined that 4 or 5 d postdosing was the optimal sampling time. TBS calculated by the equation TBS = Fa x S x (1/SA_p), where SA_p is plasma retinol specific activity (fraction of dose/μmol), were highly correlated with model-predicted TBS (r = 0.95 and 0.96 for 4 and 5 d, respectively; P < 0.001); predictions for individuals were also highly correlated (R_s = 0.94 and 0.94; P < 0.001).

CONCLUSION

The equation TBS ≈ 0.5 × (1/SA_p) accurately predicted vitamin A TBS in this group of 32 healthy young adults and its individual members with the use of data from 1 blood sample taken 4 d after isotope administration.

Biomarkers of Nutrition for Development (BOND)-Vitamin A Review

The Biomarkers of Nutrition for Development (BOND) project is designed to provide evidence-informed advice to anyone with an interest in the role of nutrition in health. The BOND program provides information with regard to selection, use, and interpretation of biomarkers of nutrient exposure, status, function, and effect, which will be especially useful for readers who want to assess nutrient status. To accomplish this objective, expert panels are recruited to evaluate the literature and to draft comprehensive reports on the current state of the art with regard to specific nutrient biology and available biomarkers for assessing nutritional status at the individual and population levels. Phase I of the BOND project includes the evaluation of biomarkers for 6 nutrients: iodine, folate, zinc, iron, vitamin A, and vitamin B-12. This review of vitamin A is the current article in this series. Although the vitamin was discovered >100 y ago, vitamin A status assessment is not trivial. Serum retinol concentrations are under homeostatic control due in part to vitamin A's use in the body for growth and cellular differentiation and because of its toxic properties at high concentrations. Furthermore, serum retinol concentrations are depressed during infection and inflammation because retinol-binding protein (RBP) is a negative acute-phase reactant, which makes status assessment challenging. Thus, this review describes the clinical and functional indicators related to eye health and biochemical biomarkers of vitamin A status (i.e., serum retinol, RBP, breast-milk retinol, dose-response tests, isotope dilution methodology, and serum retinyl esters). These biomarkers are then related to liver vitamin A concentrations, which are usually considered the gold standard for vitamin A status. With regard to biomarkers, future research questions and gaps in our current understanding as well as limitations of the methods are described.

Short-Term Daily Consumption of Provitamin A Carotenoid-Biofortified Maize Has Limited Impact on Breast Milk Retinol Concentrations in Zambian Women Enrolled in a Randomized Controlled Feeding Trial

BACKGROUND

Provitamin A carotenoid-biofortified maize is a conventionally bred staple crop designed to help prevent vitamin A deficiency. Lactating women are a potential target group, because regularly eating biofortified maize may increase vitamin A in breast milk-a critical source of vitamin A for breastfeeding infants.

OBJECTIVE

We assessed whether daily consumption of biofortified orange maize would increase the retinol concentration in the breast milk of Zambian women.

METHODS

Lactating women (n = 149) were randomly assigned to receive orange maize delivering 600 μg retinol equivalents (REs)/d as carotenoid plus placebo (OM), low-carotenoid white maize plus 600 μg REs/d as retinyl palmitate (VA), or white maize plus placebo (WM). Boiled maize (287 g dry weight/d) was served as 2 meals/d, 6 d/wk for 3 wk. We measured initial and final breast milk plasma retinol and β-carotene concentrations, and plasma inflammatory protein concentrations.

RESULTS

Groups were comparable at enrollment, with an overall geometric mean milk retinol concentration of 0.95 μmol/L (95% CI: 0.86, 1.05 μmol/L); 56% of samples had milk retinol <1.05 μmol/L. Median capsule and maize intake was 97% and 258 g dry weight/d, respectively. Final milk β-carotene did not vary across groups (P = 0.76). Geometric mean (95% CI) milk retinol concentration tended to be higher in the OM [1.15 μmol/L (0.96, 1.39 μmol/L)] and VA [1.17 μmol/L (0.99, 1.38 μmol/L)] groups than in the WM group [0.91 μmol/L (0.72, 1.14 μmol/L); P = 0.13], and the proportion of women with milk retinol <1.05 μmol/L was 52.1%, 42.9%, and 36.7% in the WM, OM, and VA groups, respectively (P-trend = 0.16).

CONCLUSIONS

Daily biofortified maize consumption did not increase mean milk retinol concentration in lactating Zambian women; however, there was a plausible downward trend in the risk of low milk retinol across intervention groups. This trial was registered at clinicaltrials.gov as NCT01922713.

Provitamin A-biofortified maize increases serum β-carotene, but not retinol, in marginally nourished children: a cluster-randomized trial in rural Zambia

BACKGROUND

Vitamin A deficiency remains a nutritional concern in sub-Saharan Africa. Conventionally bred maize hybrids with high provitamin A carotenoid concentrations may have the potential to improve vitamin A status in maize-consuming populations.

OBJECTIVE

We evaluated the efficacy of regular provitamin A carotenoid-biofortified "orange" maizemeal (∼15 μg β-carotene/g) consumption in improving vitamin A status and reducing vitamin A deficiency in children.

DESIGN

This was a cluster-randomized controlled trial in the rural farming district of Mkushi, Zambia. All 4- to 8-y-old children in an ∼400-km(2) area were identified and grouped by proximity into clusters of ∼15-25 children. We randomly assigned clusters to 1) orange maizemeal (n = 25), 2) white maizemeal (n = 25), or 3) a parallel, nonintervention group (n = 14). Children in intervention clusters (n = 1024) received 200 g maizemeal for 6 d/wk over 6 mo; the maizemeal was prepared according to standardized recipes and served in cluster-level kitchens. Staff recorded attendance and leftovers. We collected venous blood before and after the intervention to measure serum retinol, β-carotene, C-reactive protein, and α1-acid glycoprotein.

RESULTS

Intervention groups were comparable at baseline, and vitamin A status was better than anticipated (12.1% deficient on the basis of serum retinol <0.7 μmol/L). Although attendance at meals did not differ (85%), median daily maize intake was higher in white (154 g/d) than in orange (142 g/d) maizemeal clusters. At follow-up, mean serum β-carotene was 0.14 μmol/L (95% CI: 0.09, 0.20 μmol/L) higher in orange maizemeal clusters (P < 0.001), but mean serum retinol (1.00 ± 0.33 μmol/L overall) and deficiency prevalence (17.1% overall) did not differ between arms.

CONCLUSION

In this marginally nourished population, regular biofortified maizemeal consumption increased serum β-carotene concentrations but did not improve serum retinol. This trial was registered at clinicaltrials.gov as NCT01695148.

Current Capabilities and Limitations of Stable Isotope Techniques and Applied Mathematical Equations in Determining Whole-Body Vitamin A Status

BACKGROUND

Retinol isotope dilution (RID) methodology provides a quantitative estimate of total body vitamin A (VA) stores and is the best method currently available for assessing VA status in adults and children. The methodology has also been used to test the efficacy of VA interventions in a number of low-income countries. Infections, micronutrient deficiencies (eg, iron and zinc), liver disease, physiological age, pregnancy, and lactation are known or hypothesized to influence the accuracy of estimating total body VA stores using the isotope dilution technique.

OBJECTIVE

Our objectives were to review the strengths and limitations of RID methods, to discuss what is known about the impact of various factors on results, and to summarize contributions of model-based compartmental analysis to assessing VA status.

METHODS

Relevant published literature is reviewed and discussed.

RESULTS

Various equations and compartmental modeling have been used to estimate the total body VA stores using stable isotopes, including a newer 3-day equation that provides an estimate of total body VA stores in healthy adults. At present, there is insufficient information on absorption of the isotope tracer, and there is a need to further investigate how various factors impact the application of RID techniques in field studies.

CONCLUSIONS

Isotope dilution methodology can provide useful estimates of total body VA stores in apparently healthy populations under controlled study conditions. However, more research is needed to determine whether the method is suitable for use in settings where there is a high prevalence of infection, iron deficiency, and/or liver disease.

Toward food analytics: fast estimation of lycopene and β-carotene content in tomatoes based on surface enhanced Raman spectroscopy (SERS)

The application of SERS toward the differentiation of two carotenoid molecules (namely, lycopene and β-carotene) in tomato samples is introduced.

Association of dietary consumption and serum levels of vitamin A and β-carotene with bone mineral density in Chinese adults

BACKGROUND

Former studies suggested an adverse effect of hypervitaminosis A on bone health, while the effects of retinol and its precursor (β-carotene) remain uncertain in populations consuming vitamin A (VA) mainly from plant sources.

OBJECTIVE

We investigated the association of serum, dietary retinol, and β-carotene with bone mineral density (BMD) in Chinese adults.

METHODS

We recruited 2101 women and 1053 men (aged 40-75 years) in Guangzhou, China. Dietary intake was assessed through face-to-face interviews with food-frequency questionnaires at baseline and 3 years later. Serum levels of retinol and β-carotene were determined by HPLC using a baseline specimen, and the BMD for the whole body (WB), lumbar spine (LS), total hip (TH), and femur neck (FN) were measured using dual energy X-ray absorptiometry at follow-up.

RESULTS

In general, greater levels of serum retinol, β-carotene, and the β-carotene-to-retinol ratio were associated with a higher BMD after adjustment for potential covariates in the total sample. BMD values in the top (vs. bottom) quartile were increased by 2.06% (TH) for retinol; 2.87% (WB), 2.51% (LS), 3.10% (FN) for β-carotene; 2.21% (WB) and 2.05% (FN) for the β-carotene-to-retinol ratio in the total sample (all p<0.05). A significant positive association with BMD was observed for dietary intake of β-carotene and total VA in retinol equivalents at the hip sites in the total sample.

CONCLUSION

Higher circulating and dietary levels of VA and β-carotene and higher serum β-carotene-to-retinol ratios were positively associated with BMD in Chinese adults consuming relatively low levels of VA, mainly from plant foods.

High provitamin A carotenoid serum concentrations, elevated retinyl esters, and saturated retinol-binding protein in Zambian preschool children are consistent with the presence of high liver vitamin A stores

BACKGROUND

Biomarkers of micronutrient status are needed to best define deficiencies and excesses of essential nutrients.

OBJECTIVE

We evaluated several supporting biomarkers of vitamin A status in Zambian children to determine whether any of the biomarkers were consistent with high liver retinol stores determined by using retinol isotope dilution (RID).

DESIGN

A randomized, placebo-controlled, biofortified maize efficacy trial was conducted in 140 rural Zambian children from 4 villages. A series of biomarkers were investigated to better define the vitamin A status of these children. In addition to the assessment of total-body retinol stores (TBSs) by using RID, tests included analyses of serum carotenoids, retinyl esters, and pyridoxal-5'-phosphate (PLP) by using high-pressure liquid chromatography, retinol-binding protein by using ELISA, and alanine aminotransferase (ALT) activity by using a colorimetric assay.

RESULTS

Children (n = 133) were analyzed quantitatively for TBSs by using RID. TBSs, retinyl esters, some carotenoids, and PLP differed by village site. Serum carotenoids were elevated above most nonintervened reference values for children. α-Carotene, β-carotene, and lutein values were >95th percentile from children in the US NHANES III, and 13% of children had hypercarotenemia (defined as total carotenoid concentration >3.7 μmol/L). Although only 2% of children had serum retinyl esters >10% of total retinol plus retinyl esters, 16% of children had >5% as esters, which was consistent with high liver retinol stores. Ratios of serum retinol to retinol-binding protein did not deviate from 1.0, which indicated full saturation. ALT activity was low, which was likely due to underlying vitamin B-6 deficiency, which was confirmed by very low serum PLP concentrations.

CONCLUSIONS

The finding of hypervitaminosis A in Zambian children was supported by high circulating concentrations of carotenoids and mildly elevated serum retinyl esters. ALT-activity assays may be compromised with co-existing vitamin B-6 deficiency. Nutrition education to improve intakes of whole grains and animal-source foods may enhance vitamin B-6 status in Zambians.

A Review of the Structure, Biosynthesis, Absorption of Carotenoids-Analysis and Properties of their Common Natural Extracts

Carotenoids are a class of natural pigments familiar to all through the orange-red colours of popular foods like oranges, tomatoes and carrots and the yellow colour of many flowers. They have been studied for a number of years because of their diverse roles in photobiology, photochemistry and photo medicine. Carotenoids are also added as colorants to many manufactured foods, drinks, and animal feeds, either in the forms of natural extracts (e.g annatto, paprika or marigold extracts) or as pure compounds manufactured by chemical synthesis. Carotenoids are often described as provitamins A, as this particular vitamin is a product of carotenoid metabolism. The distribution of carotenoids among the different plant groups shows no obvious pattern. b-Carotene is the most abundant in leafy vegetables, though the colour is masked by its co-existence with chlorophyll, and this carotenoid has the highest vitamin A activity. Zeaxanthin, a-carotene and antheraxanthin are also present in small amounts. In the tomato, lycopene is the major carotenoid, while fruits contain varying proportions of cryptoxanthin, lutein and antheraxanthin. In this review paper the natural occurrence of carotenoids (with focus on certain natural extracts) is described along with its structure and physicochemical properties. The biosynthesis - industrial synthesis and absorption of carotenoids is also discussed. Finally, a brief overview of analysis and properties of commonly available natural carotenoid extracts (annato, paprika, xanthophylls, lycopene) are also reported.

Biofortified orange maize is as efficacious as a vitamin A supplement in Zambian children even in the presence of high liver reserves of vitamin A: a community-based, randomized placebo-controlled trial

BACKGROUND

Biofortification is a strategy to relieve vitamin A (VA) deficiency. Biofortified maize contains enhanced provitamin A concentrations and has been bioefficacious in animal and small human studies.

OBJECTIVE

The study sought to determine changes in total body reserves (TBRs) of vitamin A with consumption of biofortified maize.

DESIGN

A randomized, placebo-controlled biofortified maize efficacy trial was conducted in 140 rural Zambian children. The paired (13)C-retinol isotope dilution test, a sensitive biomarker for VA status, was used to measure TBRs before and after a 90-d intervention. Treatments were white maize with placebo oil (VA-), orange maize with placebo (orange), and white maize with VA in oil [400 μg retinol activity equivalents (RAEs) in 214 μL daily] (VA+).

RESULTS

In total, 133 children completed the trial and were analyzed for TBRs (n = 44 or 45/group). Change in TBR residuals were not normally distributed (P < 0.0001); median changes (95% CI) were as follows: VA-, 13 (-19, 44) μmol; orange, 84 (21, 146) μmol; and VA+, 98 (24, 171) μmol. Nonparametric analysis showed no statistical difference between VA+ and orange (P = 0.34); both were higher than VA- (P = 0.0034). Median (95% CI) calculated liver reserves at baseline were 1.04 (0.97, 1.12) μmol/g liver, with 59% >1 μmol/g, the subtoxicity cutoff; none were <0.1 μmol/g, the deficiency cutoff. The calculated bioconversion factor was 10.4 μg β-carotene equivalents/1 μg retinol by using the middle 3 quintiles of change in TBRs from each group. Serum retinol did not change in response to intervention (P = 0.16) but was reduced with elevated C-reactive protein (P = 0.0029) and α-1-acid glycoprotein (P = 0.0023) at baseline.

CONCLUSIONS

β-Carotene from maize was efficacious when consumed as a staple food in this population and could avoid the potential for hypervitaminosis A that was observed with the use of preformed VA from supplementation and fortification. Use of more sensitive methods other than serum retinol alone, such as isotope dilution, is required to accurately assess VA status, evaluate interventions, and investigate the interaction of VA status and infection. This trial was registered at clinicaltrials.gov as NCT01814891.

Tomato and tomato byproducts. Human health benefits of lycopene and its application to meat products: a review

During recent decades, the food industry, consumers, and regulatory authorities have developed a significant interest in functional foods because of their potential benefits for human health over and above their basic nutritional value. Tomato is the second most important vegetable crop in the world. The amount of the related wastes is estimated at up to 50,000 tons per year, representing a serious disposal problem with a consequent negative impact on the environment. Tomato byproducts contain a great variety of biologically active substances, principally lycopene, which have been demonstrated by in vitro and in vivo studies to possess antioxidant, hypolipidemic, and anticarcinogenic activities. The aim of this review is to present an overview of the functional and physiological properties of the principal bioactive compound present in tomato and tomato byproducts, lycopene, its addition to meat, and meat products.

Relative vitamin A values of 9-cis- and 13-cis-β-carotene do not differ when fed at physiological levels during vitamin A depletion in Mongolian gerbils (Meriones unguiculatus)

Provitamin A biofortification of staple crops may decrease the prevalence of vitamin A (VA) deficiency if widely adopted in target countries. To assess the impact of processing methods on the VA value of plant foods, the unique bioefficacies of cis-βC isomers (formed during cooking) compared with all-trans (at) β-carotene (βC) must be determined. The bioefficacies of 9-cis (9c)- and 13-cis (13c)-βC isomers were compared with those of the at-βC isomer and VA positive (VA+) and negative (VA - ) controls in VA-depleted Mongolian gerbils (Meriones unguiculatus) in two experimental studies (study 1, n 56; study 2, n 57). A 3- or 4-week depletion period was followed by a 3- or 4-week treatment period in which the groups received oral doses of the 9c-, 13c- or at-βC isomers in cottonseed oil (study 1, 15 nmol/d; study 2, 30 nmol/d). In study 1, the βC isomers did not maintain baseline liver VA stores in all groups (0.69 (SD 0.20) μmol/liver) except in the VA+group (0.56 (SD 0.10) μmol/liver) (P= 0.0026). The βC groups were similar to the VA+group, but the 9c- and 13c-βC groups did not differ from the VA - group (0.39 (SD 0.09) μmol/liver). In study 2, the βC isomers maintained baseline liver VA stores in all the βC groups (0.35 (SD 0.13) μmol/liver), and in the VA+group, the VA supplement (0.54 (SD 0.19) μmol/liver) exceeded the baseline VA status (0.38 (SD 0.15) μmol/liver) (P< 0.0001); however, the 9c-βC group did not differ from the VA - group (0.20 (SD 0.07) μmol/liver). In vivo isomerisation of βC was confirmed in both experimental studies. Lower VA bioconversion factor values were obtained for the cis-βC isomers in study 2 when compared with study 1, but higher values were obtained for the at-βC isomer. Dose and VA status clearly affect bioconversion factors. In conclusion, the cis-βC isomers yielded similar liver VA stores to the at-βC isomer in Mongolian gerbils, and liver VA stores of the 9c- and 13c-βC groups did not differ when the doses were provided at physiological levels over time in two studies.

Spirulina can increase total-body vitamin A stores of Chinese school-age children as determined by a paired isotope dilution technique

Spirulina is an alga rich in high-quality protein and carotenoids. It is unclear whether spirulina can improve the total-body vitamin A stores of school-age children in China with a high prevalence of vitamin A malnutrition. We aimed to evaluate the efficacy of spirulina in improving the total-body vitamin A stores of school-age children in rural areas of China when they consumed spirulina in their daily meals. A total of 228 children (6–11 years) were recruited and randomly divided into three groups supplemented with 4 g (containing 4·18 µg β-carotene), 2 g (containing 2·54 µg β-carotene) or 0 g spirulina 5 d/week for 10 weeks, respectively. Before and after the intervention period, each child was given 0·5 mg [²H₄]retinyl acetate and [²H₈]retinyl acetate, respectively. To assess vitamin A stores, blood samples (3 ml) were collected on the third and the twenty-first day after each labelled retinyl acetate dose for a retinol enrichment analysis using a GC mass spectrometer. The concentrations of retinol and β-carotene in serum samples were also determined by using HPLC. After the 10-week intervention, serum β-carotene concentrations of children with 2 or 4 g spirulina supplement increased by 0·160 and 0·389 µmmol/l, respectively. Total-body vitamin A stores increased significantly, with a median increase of 0·160 mmol in children taking 2 g spirulina and of 0·279 mmol in children taking 4 g spirulina. Spirulina is a good dietary source of β-carotene, which may effectively increase the total-body vitamin A stores of Chinese school-age children.

The challenge to reach nutritional adequacy for vitamin A: β-carotene bioavailability and conversion--evidence in humans

β-Carotene is an important dietary source of vitamin A for humans. However, the bioavailability and vitamin A equivalency of β-carotene are highly variable and can be affected by food- and diet-related factors, including the food matrix, food-processing techniques, size of the dose of β-carotene, and the amounts of dietary fat, fiber, vitamin A, and other carotenoids in the diet as well as by characteristics of the target population, such as vitamin A status, nutrient deficiencies, gut integrity, and genetic polymorphisms associated with β-carotene metabolism. The absorption of β-carotene from plant sources ranges from 5% to 65% in humans. Vitamin A equivalency ratios for β-carotene to vitamin A from plant sources range from 3.8:1 to 28:1, by weight. Vitamin A equivalency ratios for β-carotene from biofortified Golden Rice or biofortified maize are 3.8:1 and 6.5:1, respectively, and are lower than ratios for vegetables that have more complex food matrices (10:1 to 28:1). The vitamin A equivalency of β-carotene is likely to be context-specific and dependent on specific food- and diet-related factors and the health, nutritional, and genetic characteristics of human populations. Although the vitamin A equivalency of β-carotene is highly variable, the provision of vegetable and fruit sources of β-carotene has significantly increased vitamin A status in women and children in community settings in developing countries; these results support the inclusion of dietary interventions with plant sources of β-carotene as a strategy for increasing vitamin A status in populations at risk of deficiency.

Daily consumption of orange-fleshed sweet potato for 60 days increased plasma β-carotene concentration but did not increase total body vitamin A pool size in Bangladeshi women

We assessed the effect of daily consumption of orange-fleshed sweet potatoes (OFSP), with or without added fat, on the vitamin A (VA) status of Bangladeshi women with low initial VA status. Women (n = 30/group) received one of the following for 6 d/wk over 10 wk: 1) 0 μg retinol activity equivalents (RAE)/d as boiled white-fleshed sweet potatoes (WFSP) and a corn oil capsule, 2) 600 μg RAE/d as boiled OFSP and a corn oil capsule, 3) fried OFSP and a corn oil capsule, or 4) boiled WFSP and a retinyl palmitate capsule in addition to their home diets. Plasma concentrations of retinol and β-carotene and total body VA pool size were assessed before and after the 60-d intervention. Initial and final plasma retinol concentrations (mean ± SD) were 0.75 ± 0.18 μmol/L and 0.84 ± 0.19 μmol/L, respectively (P = 0.31); final means did not differ by group. Initial and final plasma β-carotene concentrations were 0.10 ± 00 μmol/L and 0.18 ± 0.09 μmol/L, respectively (P < 0.0001); final mean plasma β-carotene concentrations were higher in groups that received OFSP (P < 0.0001), and final mean plasma β-carotene was marginally higher in the group that received fried OFSP compared with boiled OFSP (P = 0.07). Initial and final total body VA pool sizes were 0.060 ± 0.047 mmol and 0.091 ± 0.070 mmol, respectively (P = 0.05, n = 110) and did not differ by group. Despite an increase in plasma β-carotene concentration, the impact of OFSP on VA status appears to be limited in Bangladeshi women residing in a resource-poor community.

Kidney function and retinol status in type 2 diabetes mellitus patients

Kidneys play an important role in retinol turnover. We postulated that retinol homeostasis is disturbed in diabetic nephropathy. The aim of this research was to study the effect of kidney impairment on urinary excretion and on serum concentrations of retinol in type 2 diabetes mellitus patients. For this purpose, 41 type 2 diabetes patients and 9 sex -and age-matched healthy subjects were enrolled. Serum and urinary retinol and retinol-binding protein (RBP) were assessed by high-pressure liquid chromatography and enzyme-linked immunosorbent assay, respectively. The study showed that 17 out of 41 diabetic patients (41.5%) and none of the controls excreted retinol in urine (P < 0.02). Retinol excretion in the urine in these patients was 1.5-fold more prevalent than hypercreatininemia. Urinary retinol significantly correlated with clinically diagnosed nephropathy (P = 0.02). All but one of the patients with hypercreatininemia excreted retinol in the urine. Serum retinol and RBP in patients with hypercreatininemia were higher than in controls (P < 0.002). Values of urinary retinol, unlike urinary RBP, albumin and total protein, did not overlap between patients and controls. Our results indicate that (i) urinary retinol is a specific sign of tubular damage in type 2 diabetic patients and (ii) urinary retinol enables a more clear-cut identification of proximal tubule dysfunction in type 2 diabetes patients than urinary RBP or albumin.

The effect of β-carotene supplementation on the pharmacokinetics of nelfinavir and its active metabolite M8 in HIV-1-infected patients

β-Carotene supplements are often taken by individuals living with HIV-1. Contradictory results from in vitro studies suggest that β-carotene may inhibit or induce cytochrome P450 enzymes and transporters. The study objective was to investigate the effect of β-carotene on the steady-state pharmacokinetics of nelfinavir and its active metabolite M8 in HIV-1 infected individuals. Twelve hour nelfinavir pharmacokinetic analysis was conducted at baseline and after 28 days of β-carotene supplementation (25,000 IU twice daily). Nelfinavir and M8 concentrations were measured with validated assays. Non-compartmental methods were used to calculate the pharmacokinetic parameters. Geometric mean ratios comparing day 28 to day 1 area under the plasma concentration-time curve (AUC(0-12 h)), maximum (C(max)) and minimum (C(min)) concentrations of nelfinavir and M8 are presented with 90% confidence intervals. Eleven subjects completed the study and were included in the analysis. There were no significant differences in nelfinavir AUC(0-12 h) and C(min) (-10%, +4%) after β-carotene supplementation. The M8 C(min) was increased by 31% while the M8 AUC(0-12 h) and C(max) were unchanged. During the 28 day period, mean CD4+ % and CD4+:CD8+ ratio increased significantly (p < 0.01). β-carotene supplementation increased serum carotene levels but did not cause any clinically significant difference in the nelfinavir and M8 exposure.

New frontiers in science and technology: nuclear techniques in nutrition

The use of nuclear techniques in nutrition adds value by the increased specificity and sensitivity of measures compared with conventional techniques in a wide range of applications. This article provides a brief overview of well-established stable-isotope techniques to evaluate micronutrient bioavailability and assess human-milk intake in breastfed infants to monitor the transfer of micronutrients from the mother to the infant. Recent developments are highlighted in the use of nuclear techniques to evaluate biological interactions between food, nutrition, and health to move the agenda forward.

Bioavailability of micronutrients: stable isotope techniques to develop effective food-based strategies to combat micronutrient deficiencies

BACKGROUND

The prevalence of micronutrient deficiencies, in particular those of iron, vitamin A, iodine, and zinc, is unacceptably high, especially among infants, children, and women of childbearing age in developing countries. Effective food-based strategies to combat these public health problems are therefore urgently needed.

OBJECTIVE

As only a fraction of dietary iron, zinc, and provitamin A carotenoids is absorbed and utilized, i.e., bioavailable, access to information on micronutrient bioavailability is crucial in the development of food fortification strategies and interventions based on dietary diversification.

METHODS

Review of literature.

RESULTS AND CONCLUSIONS

This overview highlights the usefulness of stable isotope techniques to assess the bioavailability of nonheme iron and provitamin A carotenoids and the importance of generating data on micronutrient bioavailability to move the agenda forward.

Beta-carotene is an important vitamin A source for humans

Experts in the field of carotenoids met at the Hohenheim consensus conference in July 2009 to elucidate the current status of β-carotene research and to summarize the current knowledge with respect to the chemical properties, physiological function, and intake of β-carotene. The experts discussed 17 questions and reached an agreement formulated in a consensus answer in each case. These consensus answers are based on published valid data, which were carefully reviewed by the individual experts and are justified here by background statements. Ascertaining the impact of β-carotene on the total dietary intake of vitamin A is complicated, because the efficiency of conversion of β-carotene to retinol is not a single ratio and different conversion factors have been used in various surveys and following governmental recommendations within different countries. However, a role of β-carotene in fulfilling the recommended intake for vitamin A is apparent from a variety of studies. Thus, besides elucidating the various functions, distribution, and uptake of β-carotene, the consensus conference placed special emphasis on the provitamin A function of β-carotene and the role of β-carotene in the realization of the required/recommended total vitamin A intake in both developed and developing countries. There was consensus that β-carotene is a safe source of vitamin A and that the provitamin A function of β-carotene contributes to vitamin A intake.

Carotenoid profiles in provitamin A-containing fruits and vegetables affect the bioefficacy in Mongolian gerbils

Fruits and vegetables are rich sources of provitamin A carotenoids. We evaluated the vitamin A (VA) bioefficacy of a whole foods supplement (WFS) and its constituent green vegetables (Study 1) and a variety of fruits with varying ratios of provitamin A carotenoids (Study 2) in VA-depleted Mongolian gerbils ( n = 77/study). After feeding a VA-deficient diet for 4 and 6 weeks in Studies 1 and 2, respectively, customized diets, equalized for VA, were fed for 4 and 3 weeks, respectively. Both studies utilized negative and VA-positive control groups. In Study 1, liver VA was highest in the VA group (0.82 ± 0.16 μmol/liver, P < 0.05), followed by brussels sprouts (0.50 ± 0.15 μmol/liver), Betanat® ( β-carotene from Blakeslea trispora) (0.50 ± 0.12 μmol/liver) and spinach (0.47 ± 0.09 μmol/liver) groups, which did not differ from baseline. The WFS (0.44 ± 0.06 μmol/liver) and kale (0.43 ± 0.14 μmol/liver) groups had lower liver VA than the baseline group ( P < 0.05), but did not differ from the brussels sprouts, Betanat® and spinach groups. In Study 2, liver VA was highest in the orange (0.67 ± 0.18 μmol/liver), papaya (0.67 ± 0.15 μmol/liver) and VA (0.66 ± 0.14 μmol/liver) groups, followed by the mango (0.58 ± 0.09 μmol/liver) and tangerine (0.55 ± 0.15 μmol/liver) groups. These groups did not differ from baseline. The banana group (0.47 ± 0.15 μmol/liver) was unable to maintain baseline stores of VA and did not differ from the control (0.46 ± 0.13 μmol/liver). These fruits (except banana), vegetables and the WFS were able to prevent VA deficiency in Mongolian gerbils and could be an effective part of food-based interventions to support VA nutrition in developing countries and worldwide.

beta-Carotene conversion products and their effects on adipose tissue

Recent epidemiological data suggest that beta-carotene may be protective against metabolic diseases in which adipose tissue plays a key role. Adipose tissue constitutes the major beta-carotene storage tissue and its functions have been shown to be modulated in response to beta-carotene breakdown products, especially retinal produced after cleavage by beta-carotene 15,15'-monooxygenase (BCMO1), and retinoic acid arising from oxidation of retinal. However, the possibility exists that beta-carotene in its intact form can also affect adipocyte function. Development of a knock out model and identification of a loss-of-function mutation have pointed out BCMO1 as being probably the sole enzyme responsible for provitamin A conversion into retinal in mammals. The utilisation of BCMO1(-/-)mice should provide insights on beta-carotene effect on its own in the future. In humans, intervention studies have highlighted the huge interindividual variation of beta-carotene conversion efficiency, possibly due to genetic polymorphisms, which might impact on response to beta-carotene. This brief review discusses the processes involved in beta-carotene conversion and the effect of cleavage products on body fat and adipose tissue function.

Uncultivated Brazilian Green Leaves are Richer Sources of Carotenoids than are Commercially Produced Leafy Vegetables

Background

With the continuing problem of vitamin A deficiency, the recognition of the role of carotenoids in disease prevention, and international programs promoting biodiversity, determination of the carotenoid content of indigenous Brazilian foods is needed.

Objective

To determine the principal carotenoids in native leaves and compare the levels with those in commercially produced leafy vegetables.

Methods

The indigenous Brazilian leafy vegetables caruru, mentruz, taioba, serralha, and beldroega were analyzed with the use of a previously developed and validated high-performance liquid chromatography (HPLC) method. Parsley and coriander leaves, which were previously shown to be the richest in carotenoids among commercially produced leaves, were analyzed for comparison. Five sample lots of each vegetable collected at different times during the year were analyzed immediately after harvest.

Results

Lutein concentrations were 119 ± 21, 111 ± 48, 104 ± 44, 87 ± 7, and 34 ± 14 μg/g, and β-carotene contents were 114 ± 22, 97 ± 40, 66 ± 18, 72 ± 9, and 32 ± 14 μg/g for caruru, mentruz, taioba, serralha, and beldroega, respectively. Except for beldroega, these values were higher than those for commercial leaves. Parsley had 88 ± 18 μg/g of lutein and 65 ± 13 μg/g of β-carotene. Coriander leaves contained 74 ± 6 μg/g of lutein and 55 ± 5 μg/g of β-carotene. The violaxanthin and neoxanthin concentrations were also higher in the native leaves. Comparison with values for previously analyzed commercial leafy vegetables confirmed the higher carotenoid levels of the native leaves.

Conclusions

The indigenous leaves investigated are richer sources of carotenoids than are commercially produced leafy vegetables.

Biofortified carrot intake enhances liver antioxidant capacity and vitamin a status in mongolian gerbils

Biofortification efforts have increased concentrations of bioactive compounds in carrots. We measured the antioxidant potential and vitamin A bioefficacy of 4 biofortified carrot varieties [purple/orange, purple/orange/red, orange/red, and orange] in Mongolian gerbils (n = 73). Following a 4-wk vitamin A depletion period and baseline kill (n = 7), freeze-dried carrot powders were mixed into purified feeds and fed to 6 groups (n = 11/group) for 4 wk. White carrot-fed control and vitamin A-supplemented groups were used to calculate carrot provitamin A bioefficacy. Antioxidant capacities of carrot powders, sera, and livers were determined using the 2, 2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization assay and carotenoid and retinol concentrations were determined by HPLC. Antioxidant capacity of liver extracts from the 4 colored carrot-fed groups [10.1 +/- 1.2 mumol Trolox equivalent antioxidant capacity (TEAC)/g] was significantly higher than the white carrot-fed control group (9.3 +/- 0.9 mumol TEAC/g) and vitamin A-supplemented group (8.8 +/- 1.4 mumol TEAC/g) (P < 0.05). Liver retinol stores in the colored carrot-fed groups (0.62 +/- 0.13 to 0.67 +/- 0.08 mumol retinol/liver) did not differ and were higher than the white carrot-fed control group (0.32 +/- 0.08 mumol retinol/g) (P < 0.0001). Serum antioxidant capacity and retinol did not differ among treatment groups. Liver antioxidant capacity and vitamin A stores were higher in gerbils fed colored carrots than in those fed white carrots. Antioxidant activity is one of several proposed mechanisms by which plant foods, like biofortified carrots, may provide additional health benefits beyond maintenance of vitamin A status.

In vitro activity of vitamins, flavonoids, and natural phenolic antioxidants against the oxidative deterioration of oil-based systems

It is well-known, that lipid antioxidants can retard the oxidative rancidity of foods caused by atmospheric oxidation, and thus protect oils, fats, and fat-soluble components from their quality degradation. In the last few years, much emphasis has been put on the promotion and use of natural antioxidants, commonly occurring in many fruits and vegetables and thereby produced from various natural extracts. This review gives a summary of previously reported work together with more recent trends in the field of natural antioxidants. Focus is given on the mechanism of actions and the inhibitory effect of certain vitamins against the oxidative degradation of oil-based systems. Moreover, the use of natural phenolics (flavonoids, olive-oil penolics, herb extracts etc.) as antioxidants in numerous lipid food applications is discussed.

beta-Cryptoxanthin from supplements or carotenoid-enhanced maize maintains liver vitamin A in Mongolian gerbils ( Meriones unguiculatus) better than or equal to beta-carotene supplements

Maize with enhanced provitamin A carotenoids (biofortified), accomplished through conventional plant breeding, maintains vitamin A (VA) status in Mongolian gerbils (Meriones unguiculatus). Two studies in gerbils compared the VA value of beta-cryptoxanthin with beta-carotene. Study 1 (n 47)examined oil supplements and study 2 (n 46) used maize with enhanced beta-cryptoxanthin and beta-carotene. After 4 weeks' depletion, seven or six gerbils were killed; remaining gerbils were placed into weight-matched groups of 10. In study 1, daily supplements were cottonseed oil, and 35, 35 or 17.5 nmol VA (retinyl acetate), beta-cryptoxanthin or beta-carotene, respectively, for 3 weeks. In study 2, one group of gerbils was fed a 50% biofortified maize diet which contained 2.9 nmol beta-cryptoxanthin and 3.2 nmol beta-carotene/g feed. Other groups were given equivalent b-carotene or VA supplements based on prior-day intake from the biofortified maize or oil only for 4 weeks. In study 1, liver retinol was higher in the VA (0.74 (SD 0.11) micromol) and beta-cryptoxanthin (0.5 (SD 0.10) micromol) groups than in the beta-carotene (0.49 (SD 0.13) micromol) and control (0.41 (SD 0.16) micromol)groups (P<0.05). In study 2, the VA (1.17 (SD 0.19) micromol) and maize (0.71 (SD 0.18) micromol) groups had higher liver retinol than the control (0.42 (SD 0.16) micromol) group (P<0.05), whereas the beta-carotene (0.57 (SD 0.21) micromol) group did not. Bioconversion factors (i.e. 2.74 microg beta-cryptoxanthin and 2.4 microg beta-carotene equivalents in maize to 1 microg retinol) were lower than the Institute of Medicine values.

Carotene-rich plant foods ingested with minimal dietary fat enhance the total-body vitamin A pool size in Filipino schoolchildren as assessed by stable-isotope-dilution methodology

BACKGROUND

Strategies for improving the vitamin A status of vulnerable populations are needed.

OBJECTIVE

We studied the influence of the amounts of dietary fat on the effectiveness of carotene-rich plant foods in improving vitamin A status.

DESIGN

Schoolchildren aged 9-12 y were fed standardized meals 3 times/d, 5 d/wk, for 9 wk. The meals provided 4.2 mg provitamin A carotenoids/d (mainly beta-carotene) from yellow and green leafy vegetables [carrots, pechay (bok choy), squash, and kangkong (swamp cabbage)] and 7, 15, or 29 g fat/d (2.4, 5, or 10 g fat/meal) in groups A, B, and C (n = 39, 39, and 38, respectively). Other self-selected foods eaten were recorded daily. Before and after the intervention, total-body vitamin A pool sizes and liver vitamin A concentrations were measured with the deuterated-retinol-dilution method; serum retinol and carotenoid concentrations were measured by HPLC.

RESULTS

Similar increases in mean serum beta-carotene (5-fold), alpha-carotene (19-fold), and beta-cryptoxanthin (2-fold) concentrations; total-body vitamin A pool size (2-fold); and liver vitamin A (2-fold) concentrations were observed after 9 wk in the 3 study groups; mean serum retinol concentrations did not change significantly. The total daily beta-carotene intake from study meals plus self-selected foods was similar between the 3 groups and was 14 times the usual intake; total fat intake was 0.9, 1.4, or 2.0 times the usual intake in groups A, B, and C, respectively. The overall prevalence of low liver vitamin A (<0.07 mumol/g) decreased from 35% to 7%.

CONCLUSIONS

Carotene-rich yellow and green leafy vegetables, when ingested with minimal fat, enhance serum carotenoids and the total-body vitamin A pool size and can restore low liver vitamin A concentrations to normal concentrations.

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

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.

Studies on the bioavailability of the provitamin A carotenoid, β-carotene, using human exfoliated colonic epithelial cells

The possibility of using exfoliated colonic epithelial cells for assessing the bioavailability of β-carotene was examined. Analysis of exfoliated colonic epithelial cells showed the presence of β-carotene and vitamin A. The β-carotene content was significantly lower in cells from stool samples of subjects on a β-carotene-poor diet than those receiving a single dose of a β-carotene supplement. Colonic epithelial cells isolated from stool samples collected daily during a wash-out period while the subjects were on a β-carotene-poor diet showed a steady decrease in β-carotene content, reaching the lowest value on day 7. Kinetic analysis showed that a single dose of a β-carotene supplement in the form of spirulina (Spirulina platensis) or agathi (Sesbania grandiflora) after the wash-out period caused an increase in the β-carotene content after a lag period of 5–7 d, but the vitamin A levels during these periods were not significantly affected. Analysis of plasma β-carotene concentration also showed similar changes, which correlated with those of exfoliated colonic cells. A relationship between the β-carotene content of the diet and that of the colonic epithelial cells suggests that analysis of the β-carotene content in exfoliated human colonic epithelial cells is a useful non-invasive method to assess the bioavailability of provitamin A β-carotene.