A Plasma α-Tocopherome Can Be Identified from Proteins Associated with Vitamin E Status in School-Aged Children of Nepal

Vitamin E deficiency in childhood: a narrative review

Vitamin E is an important nutrient from the earliest stages of life. It plays key roles as an antioxidant and in the maintenance of the immune system, among others. Vitamin E deficiency (VED), which occurs more frequently in children, is rarely addressed in the literature. This narrative review aims to summarise the chemistry, biology, serum indicators and clinical trials that have evaluated the impact of fortification and other relevant aspects of vitamin E, in addition to the prevalence of its deficiency, in children worldwide. Vitamin E intake in recommended amounts is essential for this nutrient to perform its functions in the body. Serum α-tocopherol is the most widely used biochemical indicator to assess the prevalence of VED. VED has been associated with symptoms secondary to fat malabsorption and may lead to peripheral neuropathy and increased erythrocyte haemolysis. Reduced concentrations of α-tocopherol may be caused by the combination of diets with low amounts of vitamin E and inadequate consumption of fats, proteins and calories. The lowest prevalence of VED was found in Asia and the highest in North America and Brazil. High proportions of VED provide evidence that this nutritional deficiency is a public health problem in children and still little addressed in the international scientific literature. The planning, evaluation and implementation of health policies aimed at combatting VED in the paediatric population are extremely important.

Identification of Protein Biomarkers of the Dietary Approaches to Stop Hypertension Diet in Randomized Feeding Studies and Validation in an Observational Study

Background The Dietary Approaches to Stop Hypertension (DASH) diet is recommended for cardiovascular disease prevention. We aimed to identify protein biomarkers of the DASH diet using data from 2 randomized feeding studies and validate them in an observational study, the ARIC (Atherosclerosis Risk in Communities) study. Methods and Results Large-scale proteomic profiling was conducted in serum specimens (SomaLogic) collected at the end of 8-week and 4-week DASH diet interventions in multicenter, randomized controlled feeding studies of the DASH trial (N=215) and the DASH-Sodium trial (N=396), respectively. Multivariable linear regression models were used to compare the relative abundance of 7241 proteins between the DASH and control diet interventions. Estimates from the 2 trials were meta-analyzed using fixed-effects models. We validated significant proteins in the ARIC study (N=10 490) using the DASH diet score. At a false discovery rate <0.05, there were 71 proteins that were different between the DASH diet and control diet in the DASH and DASH-Sodium trials. Nineteen proteins were validated in the ARIC study. The 19 proteins collectively improved the prediction of the DASH diet intervention in the feeding studies (range of difference in C statistics, 0.267-0.313; P<0.001 for both tests) and the DASH diet score in the ARIC study (difference in C statistics, 0.017; P<0.001) beyond participant characteristics. Conclusions We identified 19 proteins robustly associated with the DASH diet in 3 studies, which may serve as biomarkers of the DASH diet. These results suggest potential pathways that are impacted by consumption of the DASH diet. Registration URL: https://www.clinicaltrials.gov; Unique identifiers: NCT03403166, NCT00000608.

Systemic vitamin intake impacting tissue proteomes

The kinetics and localization of the reactions of metabolism are coordinated by the enzymes that catalyze them. These enzymes are controlled via a myriad of mechanisms including inhibition/activation by metabolites, compartmentalization, thermodynamics, and nutrient sensing-based transcriptional or post-translational regulation; all of which are influenced as a network by the activities of metabolic enzymes and have downstream potential to exert direct or indirect control over protein abundances. Considering many of these enzymes are active only when one or more vitamin cofactors are present; the availability of vitamin cofactors likely yields a systems-influence over tissue proteomes. Furthermore, vitamins may influence protein abundances as nuclear receptor agonists, antioxidants, substrates for post-translational modifications, molecular signal transducers, and regulators of electrolyte homeostasis. Herein, studies of vitamin intake are explored for their contribution to unraveling vitamin influence over protein expression. As a body of work, these studies establish vitamin intake as a regulator of protein abundance; with the most powerful demonstrations reporting regulation of proteins directly related to the vitamin of interest. However, as a whole, the field has not kept pace with advances in proteomic platforms and analytical methodologies, and has not moved to validate mechanisms of regulation or potential for clinical application.

Vitamin E status in healthy population in Asia: A review of current literature

Vitamin E is a lipid soluble antioxidant which mainly circulates as α-tocopherol in the human plasma. Its deficiency is associated with ataxia, neuropathy, anaemia and several other health conditions. Although substantial data on vitamin E status has been published worldwide, there is paucity of data on the extent of deficiency from most Asian countries, including India. Part of the problem is lack of validated biomarkers for vitamin E and no consensus on cut offs for defining deficiency and sufficiency. Thus, interpretation of the data on the vitamin E status is difficult. Limited available data from 31 studies on vitamin E status in healthy people from Asia, the most populated continent, has been collated for the purpose of this review. Broadly, the results suggest inadequate vitamin E status in most age groups, with the prevalence of deficiency reaching 67%, 80%, 56% and 72% in infants, children and adolescents, adults, elderly and pregnant women, respectively, based on varying cut offs. The findings are not surprising as both, vitamin E intakes and its status have not received too much attention in the past. Lack of conclusive data accentuates the need for more research on the vitamin E status across all age groups and to define age, gender and physiological state specific cut offs for vitamin E levels.

Rainer Gross Award Lecture 2018: The Childhood Plasma Proteome: Discovering its Applications in Public Health Nutrition

Millions of children have multiple nutritional deficiencies, threatening their optimal growth, development, and quality of life. Revealing the magnitude and underlying biology of malnutrition from a greatly expanded set of practical biomarkers will be critical for developing appropriately targeted and evaluated interventions. However, our abilities to reveal and quantify the many forms of malnutrition, other than by anthropometry and occasional use of biochemical indicators, remain limited. Plasma proteomics holds great promise as a basis for developing novel biomarkers to facilitate assessment of growth, micronutrient status, inflammation, and other health status of populations while also providing biological insight into causes and adverse consequences of malnutrition. Discovery-driven plasma proteomics has been shown to reveal functional biomarkers of nutritional and health status, identifying clusters of protein biomarkers from which field-friendly, comprehensive, and low-cost methods could be developed for assessing populations. In this brief review, we summarize several key discoveries to date and discuss potential public health applications of proteomics-based biomarkers in reporting the extent and metabolic features of undernutrition in low-resource settings.

Vitamin E Metabolic Effects and Genetic Variants: A Challenge for Precision Nutrition in Obesity and Associated Disturbances

Vitamin E (VE) has a recognized leading role as a contributor to the protection of cell constituents from oxidative damage. However, evidence suggests that the health benefits of VE go far beyond that of an antioxidant acting in lipophilic environments. In humans, VE is channeled toward pathways dealing with lipoproteins and cholesterol, underlining its relevance in lipid handling and metabolism. In this context, both VE intake and status may be relevant in physiopathological conditions associated with disturbances in lipid metabolism or concomitant with oxidative stress, such as obesity. However, dietary reference values for VE in obese populations have not yet been defined, and VE supplementation trials show contradictory results. Therefore, a better understanding of the role of genetic variants in genes involved in VE metabolism may be crucial to exert dietary recommendations with a higher degree of precision. In particular, genetic variability should be taken into account in targets concerning VE bioavailability per se or concomitant with impaired lipoprotein transport. Genetic variants associated with impaired VE liver balance, and the handling/resolution of oxidative stress might also be relevant, but the core information that exists at present is insufficient to deliver precise recommendations.

Plasma proteome correlates of lipid and lipoprotein: biomarkers of metabolic diversity and inflammation in children of rural Nepal

Proteins involved in lipoprotein metabolism can modulate cardiovascular health. While often measured to assess adult metabolic diseases, little is known about the proteomes of lipoproteins and their relation to metabolic dysregulation and underlying inflammation in undernourished child populations. The objective of this population study was to globally characterize plasma proteins systemically associated with HDL, LDL, and triglycerides in 500 Nepalese children. Abnormal lipid profiles characterized by elevated plasma triglycerides and low HDL-cholesterol (HDL-C) concentrations were common, especially in children with subclinical inflammation. Among 982 proteins analyzed, the relative abundance of 11, 12, and 52 plasma proteins was correlated with LDL-cholesterol (r = −0.43∼0.70), triglycerides (r = −0.39∼0.53), and HDL-C (r = −0.49∼0.79) concentrations, respectively. These proteins included apolipoproteins and numerous unexpected intracellular and extracellular matrix binding proteins, likely originating in hepatic and peripheral tissues. Relative abundance of two-thirds of the HDL proteome varied with inflammation, with acute phase reactants higher by 4∼40%, and proteins involved in HDL biosynthesis, cholesterol efflux, vitamin transport, angiogenesis, and tissue repair lower by 3∼20%. Untargeted plasma proteomics detects comprehensive sets of both known and novel lipoprotein-associated proteins likely reflecting systemic regulation of lipoprotein metabolism and vascular homeostasis. Inflammation-altered distributions of the HDL proteome may be predisposing undernourished populations to early chronic disease.

Novel Plasma Proteins in Nepalese School-aged Children are Associated with a Small Head Size at Birth

Fetal growth restriction increases the risk of poor childhood growth and development and chronic disease in adulthood. Yet, little is known about biological pathways that mediate the long-lasting effects of suboptimal intrauterine growth. We explored the plasma proteome in a cohort of 500 Nepalese children 6–8 years of age to identify plasma proteins associated with multiple anthropometric size indicators at birth. Among 982 proteins analyzed, no proteins differed by birth weight, length, or weight-for-length indicators. However, 25 proteins were differentially abundant in children with a small vs normal head circumference at birth (<−2 vs. ≥−2 z-scores of the WHO growth standards). Angiopoietin-like 6 was 19.4% more abundant and the other 24 proteins were 7–21% less abundant in children with a small vs normal head circumference at birth, adjusted for potential confounders. The less abundant proteins included actins, actin filament organizing proteins (α-actinin, talin, filamin, cofilin, profilin, and vinculin), proteins involved in muscle contraction, and glycolytic enzymes, which were all positively correlated with each other. A novel cluster of childhood plasma proteins involved in angiogenesis and cytoskeleton dynamics was associated with a small head size at birth. The prognostic value of an altered proteomic phenotype remains to be investigated.

Plasma proteins associated with circulating carotenoids in Nepalese school-aged children

Carotenoids are naturally occurring pigments that function as vitamin A precursors, antioxidants, anti-inflammatory agents or biomarkers of recent vegetable and fruit intake, and are thus important for population health and nutritional assessment. An assay approach that measures proteins could be more technologically feasible than chromatography, thus enabling more frequent carotenoid status assessment. We explored associations between proteomic biomarkers and concentrations of 6 common dietary carotenoids (α-carotene, β-carotene, lutein/zeaxanthin, β-cryptoxanthin, and lycopene) in plasma from 500 6-8 year old Nepalese children. Samples were depleted of 6 high-abundance proteins. Plasma proteins were quantified using tandem mass spectrometry and expressed as relative abundance. Linear mixed effects models were used to determine the carotenoid:protein associations, accepting a false discovery rate of q < 0.10. We quantified 982 plasma proteins in >10% of all child samples. Among these, relative abundance of 4 were associated with β-carotene, 11 with lutein/zeaxanthin and 51 with β-cryptoxanthin. Carotenoid-associated proteins are notably involved in lipid and vitamin A transport, antioxidant function and anti-inflammatory processes. No protein biomarkers met criteria for association with α-carotene or lycopene. Plasma proteomics may offer an approach to assess functional biomarkers of carotenoid status, intake and biological function for public health application. Original maternal micronutrient trial from which data were derived as a follow-up activity was registered at ClinicalTrials.gov: NCT00115271.

The Plasma Proteome Is Associated with Anthropometric Status of Undernourished Nepalese School-Aged Children

Background: Malnutrition affects body growth, size, and composition of children. Yet, few functional biomarkers are known to be associated with childhood morphology.

Objective: This cross-sectional study examined associations of anthropometric indicators of height, musculature, and fat mass with plasma proteins by using proteomics in a population cohort of school-aged Nepalese children.

Methods: Height, weight, midupper arm circumference (MUAC), triceps and subscapular skinfolds, upper arm muscle area (AMA), and arm fat area (AFA) were assessed in 500 children 6–8 y of age. Height-for-age z scores (HAZs), weight-for-age z scores (WAZs), and body mass index–for-age z scores (BAZs) were derived from the WHO growth reference. Relative protein abundance was quantified by using tandem mass spectrometry. Protein-anthropometry associations were evaluated by linear mixed-effects models and identified as having a false discovery rate (q) <5%.

Results: Among 982 proteins, 1, 10, 14, and 17 proteins were associated with BAZ, HAZ, MUAC, and AMA, respectively (q < 0.05). Insulin-like growth factor (IGF)-I, 2 IGF-binding proteins, and carnosinase-1 were associated with both HAZ and AMA. Proteins involved in nutrient transport, activation of innate immunity, and bone mineralization were associated with HAZ. Several extracellular matrix proteins were positively associated with AMA alone. The proteomes of MUAC and AMA substantially overlapped, whereas no proteins were associated with AFA or triceps and subscapular skinfolds. Myosin light-chain kinase, possibly reflecting leakage from muscle, was inversely associated with BAZ. The proteome of WAZ was the largest (n = 33) and most comprehensive, including proteins involved in neural development and oxidative stress response, among others.

Conclusions: Plasma proteomics confirmed known biomarkers of childhood growth and revealed novel proteins associated with lean mass in chronically undernourished children. Identified proteins may serve as candidates for assessing growth and nutritional status of children in similar undernourished settings. The antenatal micronutrient supplementation trial yielding the study cohort of children was registered at clinicaltrials.gov as NCT00115271.

General intelligence is associated with subclinical inflammation in Nepalese children: A population-based plasma proteomics study

Improving child cognition in impoverished countries is a public health priority. Yet, biological pathways and associated biomarkers of impaired cognition remain poorly understood and largely unknown, respectively. This study aimed to explore and quantify associations between functional plasma protein biomarkers and childhood intellectual test performance. We applied proteomics to quantify proteins in plasma samples of 249 rural Nepalese children, 6-8years of age who, 1year later at 7-9years of age, were administered the Universal Nonverbal Intelligence Test (UNIT). Among 751 plasma proteins quantified, 22 were associated with UNIT scores, passing a false discovery rate threshold of 5.0% (q<0.05). UNIT scores were higher by 2.3-9.2 points for every 50% increase in relative abundance of two insulin-like growth factor binding proteins (IGFBPs), six subclasses of apolipoprotein (Apo) and transthyretin, and lower by 4.0-15.3 points for each 50% increase in relative abundance of 13 proteins predominantly involved in inflammation. Among them, IGFBP-acid labile subunit, orosomucoid 1 (ORM1), Apo C-I, and pyruvate kinase isoenzymes M1/M2 jointly explained 37% of the variance in UNIT scores. After additional adjustment for height-for-age Z-score and household socio-economic status as indicators of long-term nutritional and social stress, associations with 6 proteins involved in inflammation, including ORM1, α-1-antichymotrypsin, reticulocalbin 1, and 3 components of the complement cascade, remained significant (q<0.05). Using untargeted proteomics, stable, constitutive facets of subclinical inflammation were associated with lower developmental test performance in this rural South Asian child population. Plasma proteomics may offer opportunities to identify functional, antecedent biomarkers of child cognitive development.

Biological Systems of Vitamin K: A Plasma Nutriproteomics Study of Subclinical Vitamin K Deficiency in 500 Nepalese Children

Vitamin K (VK) is a fat-soluble vitamin whose deficiency disrupts coagulation and may disturb bone and cardiovascular health. However, the scale and systems affected by VK deficiency in pediatric populations remains unclear. We conducted a study of the plasma proteome of 500 Nepalese children 6–8 years of age (male/female ratio = 0.99) to identify proteins associated with VK status. We measured the concentrations of plasma lipids and protein induced by VK absence-II (PIVKA-II) and correlated relative abundance of proteins quantified by mass spectrometry with PIVKA-II. VK deficiency (PIVKA-II >2 μg/L) was associated with a higher abundance of low-density lipoproteins, total cholesterol, and triglyceride concentrations (p < 0.01). Among 978 proteins observed in >10% of the children, five proteins were associated with PIVKA-II and seven proteins were differentially abundant between VK deficient versus sufficient children, including coagulation factor-II, hemoglobin, and vascular endothelial cadherin, passing a false discovery rate (FDR) threshold of 10% (q < 0.10). Among 27 proteins associated with PIVKA-II or VK deficiency at a less stringent FDR (q < 0.20), a network comprised of hemoglobin subunits and erythrocyte anti-oxidative enzymes were highly and positively correlated each other (all r > 0.7). Untargeted proteomics offers a novel systems approach to elucidating biological processes of coagulation, vascularization, and erythrocyte oxidative stress related to VK status. The results may help elucidate subclinical metabolic disturbances related to VK deficiency in populations.