Determinants of Vitamin D Status in Healthy Young Adults from Mexico City

BACKGROUND AND AIMS

Vitamin D deficiency is a global health problem. The determinants of this deficiency have not been evaluated in developing countries such as Mexico. Thus, this study aimed to determine vitamin D intake and sun exposure and its relationship with plasma concentrations of 25-hydroxyvitamin D -25(OH)D- in young adults from Mexico City.

METHODS

One hundred fifty five urban adult subjects were enrolled during 2017 and 2018. Sociodemographic, anthropometric, and clinical data, vitamin D intake, and sun exposure habits were collected. Plasma concentrations of 25(OH)D were also determined.

RESULTS

The proportion of vitamin D deficiency was significantly higher in women than in men (65.7 vs. 43.4%, p = 0.012). The overall median dietary vitamin D intake was 112 IU/d (less than 20% of the recommended daily intake; RDI). 25-hydroxyvitamin D correlated directly with vitamin D intake, sun exposure score, waist-to-hip ratio, and age; an inverse significant association was found with body fat percentage. A multiple regression analysis was performed; simultaneous and significant (p <0.01) effects of sun exposure score, dietary vitamin D, the season of the year (spring-summer vs. fall-winter), and age were observed on 25(OH)D levels.

CONCLUSION

High rates of vitamin D deficiency and insufficiency were observed in young adults from Mexico City. According to the RDI of this vitamin, its consumption, assessed by a 24 h multi-step nutritional questionnaire, was significantly low. A linear multiple regression model identified several predictors of plasma 25(OH)D concentrations. This multiple regression model was statistically validated.

Pilot study on the effect of supplementation with long-chain ω-3 polyunsaturated fatty acids on body composition in children with acute lymphoblastic leukemia: randomized clinical trial

BACKGROUND

N-3 polyunsaturated fatty acids (LCPUFA-ω3), particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) might have beneficial effects on lean mass and fat mass synthesis.

OBJECTIVE

To investigate the effect of LCPUFA-ω3 supplementation on body composition changes in children with acute lymphoblastic leukemia (ALL) at remission and three months (3 mo) after supplementation.

METHODS

This randomized controlled trial enrolled 72 children (3-13 y) with newly diagnosed ALL (placebo group [500 mg sunflower oil]: 36 patients; LCPUFA-ω3 group [225 mg DHA, 45 mg EPA]: 36 patients). LCPUFA-ω3 was administered at 0.100 g/kg of body weight/day for 3 mo. Both groups were provided with an oral milkshake supplement.

MAIN OUTCOMES AND MEASURES

Body composition was measured at diagnosis, remission, and 3 months after supplementation by dual-energy X-ray absorptiometry (DXA). Red blood cell fatty acid analyses were performed with gas chromatography. Student's t test compared the percentage changes in body weight, total body fat percentage (TBFP), and lean body mass (LBM) between the groups. The Mann-Whitney U test was used to compare the groups, and the Friedman range test and Wilcoxon signed rank test were used for intratreatment comparisons. Spearman correlation coefficients were calculated for LBM and erythrocyte LCPUFA-ω3 content.

RESULTS

LBM decreased significantly in both groups. This loss was greater in the placebo group than in the LCPUFA-ω3 group at remission (p = 0.044) and at 3 months of supplementation (p = 0.039). There were significant and progressive increases in DHA and EPA concentrations in the LCPUFA-ω3 group (p < 0.001). LBM at remission was directly correlated with increased DHA (r = 0.487, p = 0.034) and EPA (r = 0.499, p = 0.030) erythrocytes in the LCPUFA-ω3 group.

CONCLUSION

At ALL diagnosis and during the first three months of treatment, 100 mg/kg of body weight/d DHA and EPA decreased LBM loss and allowed the incorporation of fatty acids into cell membranes (clinicaltriasl.gov #: NCT01051154).

Obesity and Hyperandrogenemia in Polycystic Ovary Syndrome: Clinical Implications

Polycystic ovary syndrome (PCOS) is often accompanied with metabolic disturbances attributed to androgen excess and obesity, but the contribution of each has not been defined, and the occurrence of metabolic disturbances is usually not investigated. Ninety-nine women with PCOS and forty-one without PCOS were evaluated. The clinical biomarkers of alterations related to glucose (glucose, insulin, and clamp-derived glucose disposal - M), liver (aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase), and endothelium (arginine, asymmetric dymethylarginine, carotid intima-media thickness, and flow-mediated dilation) metabolism were measured; participants were categorized into four groups according to their obesity (OB) and hyperandrogenemia (HA) status as follows: Healthy (no-HA, lean), HA (HA, lean), OB (no-HA, OB), and HAOB (HA, OB). Metabolic disturbances were very frequent in women with PCOS (≈70%). BMI correlated with all biomarkers, whereas free testosterone (FT) correlated with only glucose- and liver-related indicators. Although insulin sensitivity and liver enzymes were associated with FT, women with obesity showed lower M (coef = 8.56 - 0.080(FT) - 3.71(Ob); p < 0.001) and higher aspartate aminotransferase (coef = 26.27 + 0.532 (FT) + 8.08 (Ob); p = 0.015) than lean women with the same level of FT. Women with obesity showed a higher risk of metabolic disorders than lean women, independent of hyperandrogenemia. Clinicians are compelled to look for metabolic alterations in women with PCOS. Obesity should be treated in all cases, but hyperandrogenemia should also be monitored in those with glucose-or liver-related disturbances.

Effect of long-chain omega-3 polyunsaturated fatty acids on cardiometabolic factors in children with acute lymphoblastic leukemia undergoing treatment: a secondary analysis of a randomized controlled trial

Introduction

Increased triglycerides (TGs) are a major risk factor for cardiovascular disease. Furthermore, hypertriglyceridemia is commonly associated with a reduction of high-density lipoprotein cholesterol (HDL-C) and an increase in atherogenic small-dense low-density lipoprotein (LDL-C) levels. Studies provide support that polyunsaturated omega-3 fatty acids (ω3-LCPUFAs) are cardioprotective and have antithrombotic and anti-inflammatory effects. The potential effects of ω3-LCPUFAs on cardiometabolic factors and anti-inflammatory actions in children with acute lymphoblastic leukemia (ALL) are limited. This is a secondary analysis of a previous clinical trial registered at clinical trials.gov (# NCT01051154) that was conducted to analyze the effect of ω3-LCPUFAs in pediatric patients with ALL who were receiving treatment.Objective: To examine the effect of supplementation with ω3-LCPUFAs on cardiometabolic factors in children with ALL undergoing treatment.

Methods

Thirty-four children (placebo group: 20 patients; ω3-LCPUFAs group: 14 patients) aged 6.7 ± 2.7 years who were newly diagnosed with ALL were evaluated. Children were randomized to receive either ω3-LCPUFAs or placebo capsules (sunflower oil). ω3-LCPUFAs were administered in the form of 500-mg soft capsules. The ω3-LCPUFA capsules contained 225 mg of DHA, 45 mg of EPA, and 20 mg of another ω3-LCPUFAs. The omega-3 dose was administered at a rate of 0.100 g/kg of body weight/day for three months. Main outcomes: Fasting cholesterol, HDL-C, very-low-density lipoprotein (VLDL-C), TGs, atherogenic index of plasma (AIP), android/gynoid ratio (A/GR), IL-6, TNF-α, and percentage of fat mass (DXA) were measured in all patients. Fatty acid analyses in red blood cells were performed with gas chromatography.

Results

We found significantly lower levels of TGs (p=0.043), VLDL-C (p=0.039), IL-6 (p=0.025), and AIP (p=0.042) in the ω3-LCPUFAs group than in the placebo group at three months. In contrast, the total cholesterol concentration was higher at 3 months in the ω3-LCPUFAs group than in the placebo group (155 mg/dl vs. 129 mg/dl, p=0.009). The number of children with hypertriglyceridemia (85% vs. 50%; p=0.054) tended to be lower between the time of diagnosis and after 3 months of supplementation with ω3-LCPUFAs.

Conclusion

These findings support the use of ω3-LCPUFAs to reduce some adverse cardiometabolic and inflammatory risk factors in children with ALL.

Clinical trial registration

ClinicalTrials.gov, identifier NCT01051154.

Efficacy and Safety of Vitamin D Supplementation to Prevent COVID-19 in Frontline Healthcare Workers. A Randomized Clinical Trial

Background

Associations between vitamin D (VD) deficiency and the risk of SARS-CoV-2 infection have been documented in cross-sectional population studies. Intervention studies in patients with moderate to severe COVID-19 have failed to consistently document a beneficial effect.

Objective

To determine the efficacy and safety of VD-supplementation in the prevention of SARS-CoV-2 infection in highly exposed individuals.

Methods

A double-blind, parallel, randomized trial was conducted. Frontline healthcare workers from four hospitals in Mexico City, who tested negative for SARS-CoV-2 infection, were enrolled between July 15 and December 30, 2020. Participants were randomly assigned to receive 4,000 IU VD (VDG) or placebo (PG) daily for 30 d. RT-PCR tests were taken at baseline and repeated if COVID-19 manifestations appeared during follow-up. Serum 25-hydroxyvitamin D3 and antibody tests were measured at baseline and at day 45. Per-protocol and intention-to-treat analysis were conducted.

Results

Of 321 recruited subjects, 94 VDG and 98 PG completed follow-up. SARS-CoV-2 infection rate was lower in VDG than in PG (6.4 vs. 24.5%, p <0.001). The risk of acquiring SARS-CoV-2 infection was lower in the VDG than in the PG (RR: 0.23; 95% CI: 0.09–0.55) and was associated with an increment in serum levels of 25-hydroxyvitamin D3 (RR: 0.87; 95% CI: 0.82–0.93), independently of VD deficiency. No significant adverse events were identified.

Conclusions

Our results suggest that VD-supplementation in highly exposed individuals prevents SARS-CoV-2 infection without serious AEs and regardless of VD status.

Uso de la prueba de aliento con 13C-glucosa para evaluar la adherencia al tratamiento en ensayos de intervención nutricional

Objetivo: Validar el uso de la prueba de aliento con 13C-glucosa para evaluar la adherencia a un tratamiento nutricional. Métodos: Se realizó una prueba piloto, con once adultos, que ingirieron una botana compuesta de soya/almidón de maíz y enriquecida con U-13C-glucosa. Los participantes se dividieron en tres grupos de estudio y consumieron la botana en diferentes períodos de tiempo durante dos semanas (A=14 días, B=10 días, C=6 días). Diariamente se colectaron muestras de aliento para analizar los valores de δ13C, mediante espectrometría de masas de relaciones isotópicas. Resultados: la mediana del AUC (área bajo la curva) de los valores de δ13C del grupo A fue mayor comparada con la del grupo C (p = 0.029); por otro lado, se encontraron diferencias significativas al combinar los grupos (medianas A y B) y ser comparados con el grupo C (p = 0.038). Finalmente, se encontró una asociación negativa entre los valores de AUC δ13C y la intensidad del tratamiento (rho de Spearman = -0,708; p = 0,015). Se pudo establecer un punto de corte ≤ 3,78, para identificar a los sujetos que cumplieron con menos del 70% del tratamiento, con un 100% de especificidad y un 86% de sensibilidad. Conclusiones: La prueba de aliento con 13C-glucosa, sugiere un buen rendimiento diagnóstico para evaluar la adherencia al tratamiento.

Effect of Milk-Based Infant Formula Fortified with PUFAs on Lipid Profile, Growth and Micronutrient Status of Young Children: A Randomized Double-Blind Clinical Trial

BACKGROUND

Polyunsaturated fatty acids (PUFAs) are essential to child growth and development.

OBJECTIVE

To assess the effect of PUFAs-fortified infant formula on lipid profile, growth and micronutrient status in children 12 to 30 months old.

METHODS

This study is a double-blind randomized controlled clinical trial. Two study groups were assessed: (a) milk-based infant formula with micronutrients and PUFAs (PUFAs) and (b) milk-based infant formula with micronutrients, no PUFAs added (Non-PUFAs). Children received prepared formula (240 mL) twice a day, according to the color-code assigned to each infant. Anthropometric measurements and venous blood samples were taken at each day-care center at baseline, and again after four months. Total serum lipid extraction was 0.5 mL. Samples were treated and modified by the Folch method and analyzed with gas chromatography.

RESULTS

Changes in serum lipid profile (expressed as % FA) between baseline and four months showed a statistically significant increase in docosahexaenoic acid (DHA) (0.22 vs. -0.07, p < 0.05) and Alpha-Linoleic acid (0.08 vs. 0.02, p < 0.05) in infants who consumed PUFAs-fortified formula compared to Non-PUFAs-fortified formula. Infants increased their length/height-for-age Z-score: median change for the PUFAs group was 0.16 (95% CI = 0.08, 0.28) and 0.23 (95% CI = 0.14, 0.33) for Non-PUFAs, with no differences between groups. Median folate level was significantly higher among the PUFAs group compared to Non-PUFAs: -0.87 (95% CI = -1.38, -0.44) and -3.83 (95% CI = -4.65, -3.03) respectively. Consumption of both supplements was adequate and stable during the intervention.

CONCLUSION

A significant improvement was observed in the lipid profile of children who received the PUFAs-fortified milk-based formula.

The role of LCPUFA-ω3 on the obesity-associated hyperandrogenemia of pubertal girls: secondary analysis of a randomized clinical trial

Introduction Hyperandrogenism (HA), either clinical or biochemical, is associated with obesity in adolescent girls. Long chain polyunsaturated fatty acids ω3 (LCPUFA-ω3) play protective roles in some obesity-associated morbidities, but their contribution to preventing HA is unclear. Our aim was to examine the potential positive relationships between erythrocyte LCPUFA-ω3, with or without supplementation, and hyperandrogenemia. Methods Secondary analysis of a clinical trial that was conducted previously to analyze the effect of LCPUFA-ω3 on insulin resistance and body weight. Here, we present a cross-sectional analysis of 180 girls with obesity, and a longitudinal analysis of 117 girls who completed a 3-month supplementation period (57 LCPUFA-ω3 [DO3] and 60 placebo [DP)]). Dehydroepiandrosterone sulfate (DHEAS), total testosterone (TT) and steroid hormone binding globulin (SHBG) were measured with chemiluminescence; free testosterone (FT) was calculated. Erythrocyte fatty acids were determined by gas chromatography. Non-parametric statistics was used for analysis. Results In cross-sectional analysis, age (odds ratio [OR] = 1.35; 95% confidence interval [CI] = 1.03, 1.78; p = 0.027), insulin (OR = 1.05; 95% CI: 1.00, 1.10; p = 0.018), and erythrocytes eicosapentaenoic acid (EPA) (OR = 0.04; 95% CI: 0.01, 0.65; p = 0.012) were predictors of hyperandrogenemia (FT >0.63 ng/mL). In longitudinal analysis, EPA, adiponectin and SHBG increased, while FT decreased, in the DO3 group (p < 0.05). The risk of hyperandrogenemia at the end of follow-up was predicted by basal hyperandrogenemia (OR = 18.16, 95% CI: 5.37, 61.4; p < 0.001) and by increases in EPA (OR = 0.40; 95% CI: 0.01, 0.65; p = 0.06 marginal significance). Conclusions Our results suggest a preventive role of EPA on the risk for hyperandrogenemia in girls with obesity, but further studies are needed to demonstrate a benefit.

Accuracy of the 13C-glucose breath test to identify insulin resistance in non-diabetic adults

AIMS

To assess the validity of the ¹³C-glucose breath test (¹³C-GBT) to identify insulin resistance (IR) in non-diabetic individuals, using hyperinsulinemic-euglycemic clamps as gold standard. This validity was compared with that of other IR surrogates.

METHODOLOGY

Non-diabetic adults were studied in a cross-sectional design. In a first appointment, oral glucose tolerance tests were conducted simultaneously with ¹³C-GBTs. Oral 75 g glucose dissolved in 150 ml water, followed by 1.5 mg/Kg body weight U-¹³C-glucose dissolved in 50 ml water, was administered. Breath and blood samples were collected at baseline and at 30-min intervals. The percentages of glucose-oxidized dose at given periods were calculated. Clamps were conducted a week later. A clamp-derived M value ≤ 6.0 mg/kg*min was used as cut-off. ROC curves were constructed for ¹³C-GBT, fasting insulin, HOMA, and ISI-composite.

RESULTS

Thirty-eight subjects completed the study protocol. The correlation coefficient between the ¹³C-GBT derived glucose-oxidized dose at 180 min and M values was 0.524 (p = 0.001). The optimal value to identify IR with the ¹³C-GBT was 4.23% (AUC 0.81; ₉₅CI 0.66, 0.96; accuracy 0.82, ₉₅CI 0.66, 0.92). The ¹³C-GBT sensitivity (0.88) was higher than HOMA and fasting insulin sensitivities (0.83 and 0.75 respectively), while their specificities were comparable (0.71, 0.71, and 0.79, respectively). The sensitivity of ISI-C was higher (0.92) than that of the ¹³C-GBT, but its specificity was poor (0.36). The accuracy of the ¹³C-GBT was superior to that of the other studied surrogates.

CONCLUSIONS

The ¹³C-GBT is a valid and accurate method to detect IR in non-diabetic adults. Therefore, it is potentially useful in clinical and community settings.

A randomized control trial of the impact of LCPUFA-ω3 supplementation on body weight and insulin resistance in pubertal children with obesity

BACKGROUND

Paediatric obesity and insulin resistance (IR) are potentially reversible inflammatory conditions. Long chain polyunsaturated fatty acids omega-3 (LCPUFA-ω3) show anti-inflammatory and metabolic properties, but their clinical efficacy is unclear.

OBJECTIVE

The objective of this study is to evaluate whether supplementation with LCPUFA-ω3 for 3 months reduces insulin resistance and weight to adolescents with obesity.

METHODS

Double-blind trial of 366 adolescents with obesity randomly assigned to 1.2-g LCPUFA-ω3 (DO3) or 1-g sunflower oil (DP) daily for 3 months; both groups received an energy-restricted diet. Children attended monthly for anthropometric, dietary, and clinical measurements. Basal and final blood samples were obtained to measure metabolic markers and erythrocytes fatty acids. Regression models were used for analysis.

RESULTS

A total of 119 DO3 and 126 DP children completed follow-up. At baseline, 92% of children presented IR, 66% hypertriglyceridemia, 37% low-grade inflammation, and 32% metabolic syndrome. Despite erythrocytes LCPUFA-ω3 increased more in DO3 (Median differences = 0.984 w/w%; 95 IC = 0.47, 1.53, P < 0.001), body weight, insulin, and HOMA changed similarly in both groups at the end of intervention. Adjusting for basal values, changes in weight, insulin, and HOMA was not related with supplementation.

CONCLUSIONS

Supplementation with LCPUFA-ω3 does not affect body weight or insulin in adolescents with obesity.

Enteral Docosahexaenoic Acid and Retinopathy of Prematurity: A Randomized Clinical Trial

BACKGROUND

Retinopathy of prematurity (ROP) is a disorder of the retina of low-birth-weight preterm infants that potentially leads to blindness. Docosahexaenoic acid (DHA), is protective in experimental models, but its administration as part of parenteral nutrition has shown inconsistent results. We test the effect of enteral DHA to prevent ROP and/or severity and to reduce hospital stay.

METHODS

This was a double-blind parallel clinical trial. Preterm infants (n = 110; 55 per group) with birth weight <1500 g but ≥1000 g were recruited in a neonatal intensive care unit. Infants were randomized to receive 75 mg of DHA/kg/d (DHA group) or high oleic sunflower oil (control group) for 14 days by enteral feeding. The effect of DHA was evaluated on any stage of ROP, severe ROP (stage ≥3) incidence, and hospital stay. Groups were compared with relative risk (RR) and 95% confidence interval (CI), Fisher's exact test, Student's t-test, or Mann-Whitney U-test, as appropriate. Logistic regression was applied to adjust for confounders.

RESULTS

There was no difference between the DHA and control groups in ROP risk (RR for DHA = 0.79; 95% CI, 0.49-1.27; P = 0.33). However, patients who received DHA showed lower risk for stage 3 ROP (RR for DHA = 0.66; 95% CI, 0.44-0.99; P = 0.03). After adjusting for confounders, this decreased risk remained significant (adjusted odds ratio = 0.10; 95% CI, 0.011-0.886; P = 0.04). Hospital stay was similar between groups.

CONCLUSION

Enteral DHA may reduce the incidence of stage 3 ROP.

Two parenteral amino acid solutions and plasma levels of amino acids in the neonate: A randomized trial

OBJECTIVE

In neonates on total parenteral nutrition (TPN), amino acids may be a risk factor for developing total parenteral nutrition-associated cholestasis (TPNAC). We aimed, first, to compare methionine, cysteine, and taurine plasma levels between neonates on TPN who were receiving an intravenous amino acid solution based on a breast milk aminogram and those on an intravenous solution of pediatric amino acids based on an umbilical cord aminogram, and second, to determine the frequency of TPNAC.

METHODS

A double-blind randomized controlled trial was conducted. Ninety-four neonates with a birthweight of 1000g or more and a gestational age of 30 wk or older were admitted and enrolled. Blood samples were obtained at 0, 7, and 14 d of TPN, and plasma amino acid concentrations were determined by ultra-high-resolution liquid chromatography. Continuous variables were compared using the Wilcoxon rank-sum test or Student's t test; categorical variables were compared using the Fisher exact test.

RESULTS

Thirty-five neonates completed the study (Primene, n = 14; TrophAmine, n = 21). On day 14, methionine plasma concentrations were significantly lower in the Primene group than in the TrophAmine group (27 µmol/L versus 32.9 µmol/L, P = 0.044); the taurine concentration was significantly higher in the same group (72.4 µmol/L versus 45.3 µmol/L, P < 0.0001). There were no differences in TPNAC incidence.

CONCLUSIONS

Administering an intravenous solution of pediatric amino acids based on the umbilical cord aminogram yielded a higher taurine and lower methionine plasma concentration than did administering a similar solution based on the breast milk aminogram.

Optimal Cut-off Points of Fasting and Post-Glucose Stimulus Surrogates of Insulin Resistance as Predictors of Metabolic Syndrome in Adolescents According to Several Definitions

OBJECTIVE

The aim of this study was to determine optimal cut-off points for fasting and post-glucose stimulus surrogates of insulin resistance to predict metabolic syndrome in adolescents according to several definitions.

METHODS

One hundred fifty-five adolescents living in Mexico City were enrolled during 2011 and 2012. Waist circumference and blood pressure were recorded. Subjects received an oral glucose load of 1.75 g per kg up to a maximum dose of 75 g. Blood samples were drawn at baseline and 120 minutes. Concentrations of plasma glucose, triglycerides, high-density lipoprotein cholesterol and insulin were determined.

RESULTS

The frequency of metabolic syndrome showed a large variability when using a variety of published definitions; in contrast, the optimal cut-off points for fasting insulin, homeostatic model assessment of insulin resistance and two-hour oral glucose tolerance test insulin were very similar in almost all the definitions considered and had adequate diagnostic performance: area under the curve >0.869, sensitivity >0.835 and specificity >0.755. Insulin resistance surrogates had substantial agreements with Ford, Cook and Salas definitions (Kappa~0.62; agreement~82%); moderate agreement was observed for International Diabetes Federation, Cruz and Ferranti definitions (Kappa~0.41–0.59; agreement~77%).

CONCLUSION

Insulin resistance surrogates may be a better approach for metabolic syndrome assessment in an adolescent population because of reduced variability and a higher predictive value.

The 13C-Glucose Breath Test for Insulin Resistance Assessment in Adolescents: Comparison with Fasting and Post-Glucose Stimulus Surrogate Markers of Insulin Resistance

OBJECTIVE

To evaluate the use of the 13C-glucose breath test (13C-GBT) for insulin resistance (IR) detection in adolescents through comparison with fasting and post-glucose stimulus surrogates.

METHODS

One hundred thirty-three adolescents aged between 10 and 16 years received an oral glucose load of 1.75 g per kg of body weight dissolved in 150 mL of water followed by an oral dose of 1.5 mg/kg of U-13C-Glucose, without a specific maximum dose. Blood samples were drawn at baseline and 120 minutes, while breath samples were obtained at baseline and at 30, 60, 90, 120, 150, and 180 minutes. The 13C-GBT was compared to homeostasis model assessment (HOMA) IR (≥p95 adjusted by gender and age), fasting plasma insulin (≥p90 adjusted by gender and Tanner stage), results of 2-h oral glucose tolerance test (OGTT), insulin levels (≥65 μU/mL) in order to determine the optimal cut-off point for IR diagnosis.

RESULTS

13C-GBT data, expressed as adjusted cumulative percentage of oxidized dose (A% OD), correlated inversely with fasting and post-load IR surrogates. Sexual development alters A% OD results, therefore individuals were stratified into pubescent and post-pubescent. The optimal cut-off point for the 13C-GBT in pubescent individuals was 16.3% (sensitivity=82.8% & specificity=60.6%) and 13.0% in post-pubescents (sensitivity=87.5% & specificity=63.6%), when compared to fasting plasma insulin. Similar results were observed against HOMA and 2-h OGTT insulin.

CONCLUSION

The 13C-GBT is a practical and non-invasive method to screen for IR in adolescents with reasonable sensitivity and specificity.

The 13C-glucose breath test is a valid non-invasive screening tool to identify metabolic syndrome in adolescents

BACKGROUND

Metabolic syndrome (MS) is an important risk factor in pediatric population for the early onset of type 2 diabetes mellitus and cardiovascular disease. New non-invasive tools are required to identify MS in at risk populations; the aim of this study was to determine an optimal cut-off point for the 13C-glucose breath test (13C-GBT) for the diagnosis of MS in adolescents.

METHODS

A total of 136 adolescents between 10 and 16 years old were recruited. MS was defined as: waist circumference >90th percentile and at least two of the following; high density lipoprotein-cholesterol (HDL-C) <50 mg/dL, triglycerides >110 mg/dL, diastolic and/or systolic blood pressure >90th percentile adjusted by age, gender and height, and/or fasting glucose >100 mg/dL. After the ingestion of a glucose load of 1.75 g/kg of body weight (up to 75 g) and an oral dose of 1.5 mg of universally labeled 13C-glucose/kg dissolved in water, breath samples were taken at baseline, 30, 60, 90, 120, 150 and 180 min. Exhaled 13CO2 in breath samples was measured by isotope ratio mass spectrometry.

RESULTS

13C-GBT data, expressed as adjusted cumulative percentage of oxidized dose (A% OD) at 180 min, was significantly higher in the healthy subjects group (17.72%±4.9%) in comparison with subjects with ≥3, 2 or 1 components of the MS (9.95%±4.73%, 14.3%±4.47% and 14.62%±4.62%, respectively). The optimal cut-off point for the A% OD was 16.09, with a sensitivity of 81.5% and a specificity of 66.7%.

CONCLUSIONS

Our results demonstrate that the 13C-glucose breath test could be a valid screening method to identify MS in adolescents.

The [(13)c]glucose breath test is a reliable method to identify insulin resistance in Mexican adults without diabetes: comparison with other insulin resistance surrogates

BACKGROUND

Insulin resistance (IR) precedes type 2 diabetes, but tests used to detect it in clinical settings reported poor reproducibility. We assessed the reliability of the [(13)C]glucose breath test ((13)C-GBT) in a sample of subjects without diabetes. Repeatability of the test was compared with that of other IR surrogates derived from the fasting or oral glucose tolerance test (OGTT).

SUBJECTS AND METHODS

Eighty-six healthy volunteers received an oral load of 75 g of glucose in 150 mL of water followed by 1.5 mg/kg of [U-(13)C]glucose in 50 mL of water. Breath and blood samples were collected at baseline and at 10, 20, 30, 60, 90, 120, 150, and 180 min following the glucose load; the same procedure was repeated within 1 week. The enrichment of breath (13)CO2 was measured by ratio mass spectrometry and expressed as percentage oxidized dose at a given time period. Intrasubject variability was assessed with Bland-Altman plots and coefficients of variation (CVs).

RESULTS

The overall CV of the (13)C-GBT was 12.99±11.61%, compared with 18.42% of fasting insulin, 19.44% for homeostasis model assessment, 17.06% of the composite insulin sensitivity index, and 29.99% for insulin in the 2-h oral glucose tolerance test. The variability of the (13)C-GBT tended to be higher in lean (17.40%) than in overweight (10.17%) and obese (12.61%) individuals.

CONCLUSIONS

The variability of the (13)C-GBT is lower than that of other IR surrogates, making it a reproducible method to estimate insulin sensitivity in overweight and obese adults without diabetes. Because the individuals did not have diabetes but were within a high range of insulin sensitivity, the test should have application in clinical and population-based studies, given the evidence for the utility and limitations of this surrogate.

Validity and reliability of the 13C-methionine breath test for the detection of moderate hyperhomocysteinemia in Mexican adults

BACKGROUND

Hyperhomocysteinemia (Hhcy) is considered an independent risk factor for vascular diseases and, more recently, for dementia. The methionine loading test (MLT) is useful for diagnosing additional subjects with moderate Hhcy. However, it is a complex and time-consuming procedure. A noninvasive test for the diagnosis of moderate Hhcy is desirable.

METHODS

The study protocol consisted of three consecutive visits. During the first visit, we performed an MLT to characterize the Hhcy status of 75 healthy adult subjects. For the breath test protocol, we selected a subsample and assigned to the control group 17 subjects with fasting and post-loading homocysteine (Hcy) ≤12 and <42.3 μmol/L, respectively, and to the Hhcy group 16 subjects with fasting Hcy ≤12 and >42.3 μmol/L after loading. Selected subjects were requested to have a second visit to perform a breath test within 1-4 weeks following the MLT test and received an oral dose of 2.5 mg/kg of 1-13C-methionine dissolved in water. Breath samples were collected at basal, 20, 40, 60, 80, 100 and 120 min (test 1). The same procedure was repeated within 1 week (test 2).

RESULTS

MLT was useful for diagnosing almost twice the number of individuals with Hhcy (24%) in comparison with the fasting determination alone (13.3%). The 13C-methionine breath test reported a sensitivity of 81.3% and a specificity of 64.7% against the MLT. The coefficient of variation between breath test 1 and breath test 2 was 9.0±5.4%.

CONCLUSIONS

The 13C-methionine breath test is a valid and reliable method for identifying subjects with moderate Hhcy.

[Homocysteine after a methionine load in healthy subjects with adequate B-vitamin status]

BACKGROUND

Plasma homocysteine (Hcy) determination at 6-8 h after an oral methionine load (OML) allows for identification of some, but not all, individuals at risk to develop cardiovascular disease. It is probable that in some cases the Hcy increases occur later, or it elevates between normal ranges but in a sustained manner. However, the entire Hcy response curve has not been described. We undertook this study to determine Hcy concentrations from baseline to 24- and 48-h after an OML in non-B-vitamin deficient adult subjects with other risk factors for high levels of Hcy such as smoking and overweight.

METHODS

In a cross-over, clinical design, Hcy concentrations were determined at 2-h intervals throughout 12 h and at 24 h and 48 h after an OML (0.1 g/kg). Hcy and vitamin B6 (VB6) concentrations were measured by high-performance liquid chromatography (HPLC). Folic acid (FA) and vitamin B12 (VB12) were measured by radioimmunoassay (RIA). Statistical analysis included delta values and areas under the curve. Student t-test and repeated measurement analyses were conducted to control for confounders.

RESULTS

Twenty-nine subjects with adequate Hcy, FA, VB6 and VB12 status were included. The maximum Hcy concentration occurred 8 h after the load and returned to baseline concentrations after 24 h. All subjects presented Hcy after the load within normal ranges, but smoking and overweight synergistically influenced the response to the challenge, producing a sustained elevation after the dose.

CONCLUSIONS

Hcy concentrations after an OML remained above baseline for at least 24 h. Smoking and overweight affected the response to the methionine challenge.