Serum total homocysteine concentrations in children and adolescents: results from the third National Health and Nutrition Examination Survey (NHANES III)

Associations of methylmalonic acid and depressive symptoms with mortality: a population-based study

Methylmalonic acid (MMA), a biomarker of mitochondrial dysfunction, has been reported to be associated with depression in specific populations (i.e., older adults and postpartum women). Our study aimed to investigate to what extent MMA was associated with depressive symptoms and mortality in the general population, and assess whether depressive symptoms mediate the relationship between MMA and mortality. We analyzed cross-sectional data from 8343 participants from the US National Health and Nutrition Examination Survey. MMA was measured by liquid chromatography-tandem mass spectrometry, while depressive symptoms were measured by the Patient Health Questionnaire-9. Mortality data were obtained through linkage with National Death Index records. Linear regression models were performed to assess the association between MMA and depressive symptoms. The Cox proportional hazard regression model was utilized to assess the association of MMA and depressive symptoms with mortality. Mediation analysis was conducted within the counterfactual framework. In this general population, each SD (around 0.49 μmol/L) increase in MMA was associated with a 0.03 SD (approximately 0.15 score) increase in depressive symptoms (β = 0.033, 95% CI: 0.010, 0.055, p = 0.005). Notably, this association was more pronounced in men and participants over 60 years old. Higher levels of MMA and having more depressive symptoms were associated with a higher risk of mortality. However, depressive symptoms do not mediate the relationship between MMA and mortality. Elevated MMA levels were associated with depressive symptoms and an increased risk of mortality. These findings suggest that mitochondrial dysfunction may contribute to the multifactorial etiology of depression.

Association between elevated homocysteine levels and obstructive sleep apnea hypopnea syndrome: a systematic review and updated meta-analysis

Objective

This study aimed to distinguish between healthy controls and patients with OSAHS regarding homocysteine (HCY) levels and investigate how individuals with OSAHS respond to continuous positive airway pressure ventilation (CPAP) in terms of serum and plasma HCY levels.

Methods

To ascertain published articles about OSAHS, an exhaustive search was performed across medical databases, encompassing PubMed, Web of Science, EMBASE, CNKI, and Cochrane Library, until January 2, 2024. This study reviewed the literature regarding HCY levels in individuals with OSAHS and control groups, HCY levels under pre- and post-CPAP treatment, the Pearson/Spearman correlation coefficients between HCY levels and apnea-hypopnea index (AHI), and the hazard ratio (HR) of HCY levels concerning the occurrence of major adverse cerebrocardiovascular events (MACCEs) in patients with OSAHS. Meta-analyses were performed using weighted mean difference (WMD), correlation coefficients, and HR as effect variables. The statistical analysis was conducted using the R 4.1.2 and STATA 11.0 software packages.

Results

In total, 33 articles were selected for the final analysis. The OSAHS group exhibited significantly higher serum/plasma HCY levels than the control group (WMD = 4.25 μmol/L, 95% CI: 2.60-5.91, P< 0.001), particularly among individuals with moderate and severe OSAHS. Additionally, subgroup analysis using mean age, ethnicity, mean body mass index, and study design type unveiled significantly elevated levels of HCY in the serum/plasma of the OSAHS group compared to the control group. CPAP treatment can significantly decrease serum/plasma HCY levels in patients with OSAHS. Moreover, elevated HCY levels in individuals with OSAHS could be one of the risk factors for MACCEs (adjusted HR = 1.68, 95% CI = 1.10-2.58, P = 0.017). AHI scores show a positive correlation with serum/plasma HCY levels.

Conclusion

Patients with OSAHS had elevated serum/plasma HCY levels compared to healthy controls; however, CPAP therapy dramatically decreased HCY levels in patients with OSAHS. In patients with OSAHS, elevated HCY levels were linked with an increased risk of MACCEs, and HCY was positively connected with AHI values. HCY levels may serve as a useful clinical indicator for determining the severity and efficacy of OSAHS treatments.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42024498806.

Influence of folic acid and vitamin B12 supplementation on arsenic methylation: A double-blinded, placebo-controlled trial in Bangladeshi children

BACKGROUND

Inorganic arsenic is metabolized to monomethyl- (MMAs) and dimethyl- (DMAs) species via one-carbon metabolism (OCM); this facilitates urinary arsenic elimination. OCM is influenced by folate and vitamin B12 and previous randomized control trials (RCTs) showed that folic acid (FA) supplementation increases arsenic methylation in adults. This RCT investigated the effects of FA + B12 supplementation on arsenic methylation in children, a key developmental stage where OCM supports growth.

METHODS

A total of 240 participants (8-11 years, 53 % female) drinking from wells with arsenic concentrations > 50 μg/L, were encouraged to switch to low arsenic wells and were randomized to receive 400 μg FA + 5 μg B12 or placebo daily for 12-weeks. Urine and blood samples were collected at baseline, week 1 (only urine) and week 12. Generalized estimated equation (GEE) models were used to assess treatment effects on arsenic species in blood and urine.

RESULTS

At baseline, the mean ± SD total blood and urinary arsenic were 5.3 ± 2.9 μg/L and 91.2 ± 89.5 μg/L. Overall, total blood and urine arsenic decreased by 11.7% and 17.6%, respectively, at the end of follow up. Compared to placebo, the supplementation group experienced a significant increase in the concentration of blood DMAs by 14.0% (95% CI 5.0, 25.0) and blood secondary methylation index (DMAs/MMAs) by 0.19 (95% CI: 0.09, 0.35) at 12 weeks. Similarly, there was a 1.62% (95% CI: 0.43, 20.83) significantly higher urinary %DMAs and -1.10% (95% CI: -1.73, -0.48) significantly lower urinary %MMAs in the supplementatio group compared to the placebo group after 1 week. The direction of the changes in the urinary %iAs, %MMAs, and %DMAs at week 12 were consistent with those at week 1, though estimates were not significant. Treatment effects were stronger among participants with higher baseline blood arsenic concentrations. Results were consistent across males and females, and participants with higher and lower folate and B12 status at baseline.

CONCLUSION

This RCT confirms that FA + B12 supplementation increases arsenic methylation in children as reflected by decreased MMAs and increased DMAs in blood and urine. Nutritional interventions may improve arsenic methylation and elimination in children, potentially reducing arsenic toxicity while also improving nutritional status.

Potential inflammatory targets in the integrative health care of patients with sickle cell disease

Inflammation plays an integral role in the complications of sickle cell disease (SCD), which can lead to vaso-occlusive crisis and extreme pain. SCD is accompanied by numerous complications, including cardiovascular disease, cognitive decline and endothelial dysfunction, contributing to mortality. As disease severity increases with age, the present study aimed to assess if age is also correlated with a definite pattern of progression of the two inflammatory markers, high-sensitivity C-reactive protein (hsCRP) and total homocysteine (tHCY). The findings of the present study could lead to an improved understanding of the threshold levels of these inflammatory markers and timely interventions to delay complications. In an observational study, levels of hsCRP and tHCY were analyzed in 70 patients (35 male and 35 female patients) with SCD aged between 5 and 16 years. hsCRP levels were in the high-risk range in 64.29% (n=45) of all male and female patients. A sex-wise distribution showed that, of the 35 male patients, 74.28% (n=26) were in the high-risk range, and of the 35 female patients, 54.28% (n=19) were in the high-risk range. An age-wise distribution showed that of the 41 patients in the 5-10-years age group, 70.73% (n=29), were in the high-risk range. In comparison, of the 29 patients in the 11-16-years age group, 55.17% (n=16) were in the high-risk range. tHCY levels were observed to be in the normal range in 98.57% (n=69) of all children, as compared with 1.43% (n=1) in the high-risk range. Furthermore, a sex-wise distribution showed that female patients in the high-risk group of hsCRP had higher concentrations of tHCY as compared with the male patients in that risk group. An age-wise distribution of hsCRP concentration also showed that the risk of CVD in patients in the 11-16-years age group was higher with increased concentrations of tHCY. A weak negative correlation was observed between age and hsCRP concentrations (r-value=-0.280; P=0.026) and a weak positive correlation was detected between tHCY and age (r-value=0.259; P=0.036). In conclusion, the results of the present study indicated that higher levels of hsCRP could be a useful marker in children with SCD, and levels of tHCY may be an adjunct marker as the disease progresses with age.

Plasma homocysteine levels and associated factors in community-dwelling adolescents: the EVA-TYROL study

Background

Homocysteine (Hcy) has been associated with an adverse cardiovascular risk profile in adolescents. Assessment of the association between plasma Hcy levels and clinical/laboratory factors might improve our understanding of the pathogenesis of cardiovascular disease.

Methods

Hcy was measured in 1,900 14- to 19-year-old participants of prospective population-based EVA-TYROL Study (44.3% males, mean age 16.4 years) between 2015 and 2018. Factors associated with Hcy were assessed by physical examination, standardized interviews, and fasting blood analysis.

Results

Mean plasma Hcy was 11.3 ± 4.5 µmol/L. Distribution of Hcy was characterized by extreme right skew. Males exhibited higher Hcy and sex differences increased with increasing age. Univariate associations with Hcy emerged for age, sex, body mass index, high-density lipoprotein cholesterol, and for factors pertaining to blood pressure, glucose metabolism, renal function, and diet quality, whereas the most important multivariate predictors of Hcy were sex and creatinine.

Discussion

Clinical and laboratory factors associated with Hcy in adolescents were manifold, with sex and high creatinine identified as strongest independent determinants. These results may aid when interpreting future studies investigating the vascular risk of homocysteine.

Homocysteine concentrations in overweight children and adolescents

OBJECTIVE

The aim of this study was to describe homocysteine concentrations in overweight and obese children and adolescents and relate them to blood pressure levels, renal function, and insulin resistance.

METHODS

This is a cross-sectional and observational study with 64 overweight children and adolescents (mean age: 11.6±3.5 years) in outpatient follow-up. The following parameters were evaluated: body mass index z-score, waist-to-height circumference ratio, pubertal stage, blood pressure, serum homocysteine, glycemia, insulin, lipid profile, renal function, high-sensitivity C-reactive protein, microalbuminuria, and creatinuria. Statistical analysis: analysis of variance and logistic regression (dependent variable: homocysteine) (p<0.05).

RESULTS

The mean body mass index z-score was 2.9±1.1. The mean homocysteine concentrations were 8.6±2.2 μmol/L (10th and 90th percentiles: 6.6 and 11.2 μmol/L, respectively), with no difference when compared with children with severe obesity and obesity/overweight (p=0.431). High values of waist-to-height ratio (93.8%), systolic blood pressure (18.8%), diastolic blood pressure (12.5%), glycemia (4.7%), low-density lipoprotein cholesterol (31.1%), triglycerides (35.9%), non-high-density lipoprotein cholesterol (34.4%), and microalbuminuria (21.9%) were obtained. The mean glomerular filtration rate was 122.9±24.6 mL/min/1.73 m². Homocysteine concentrations were not associated with any of the studied variables (R²=0.095).

CONCLUSION

Homocysteine concentrations in overweight children and adolescents (mean 8.6±2.2 μmol/L) were not associated with body mass index z-score, blood pressure, renal function, and insulin resistance.

Comparison of Hepatic Metabolite Profiles between Infant and Adult Male Mice Using 1H-NMR-Based Untargeted Metabolomics

Although age-related characteristics of hepatic metabolism are reported, those in infants are not fully understood. In the present study, we performed untargeted metabolomic profiling of the livers of infant (3-week-old) and adult (9-week-old) male ICR mice using ¹H-NMR spectroscopy and compared 35 abundant hepatic metabolite concentrations between the two groups. The liver/body weight ratio did not differ between the two groups; however, serum glucose, blood urea nitrogen, total cholesterol, and triglyceride concentrations were lower in infants than in adults. Hepatic carbohydrate metabolites (glucose, maltose, and mannose) were higher, whereas amino acids (glutamine, leucine, methionine, phenylalanine, tyrosine, and valine) were lower in infant mice than in adult mice. The concentrations of ascorbate, betaine, sarcosine, and ethanolamine were higher, whereas those of taurine, inosine, and O-phosphocholine were lower in infant mice than in adult mice. The differences in liver metabolites between the two groups could be due to differences in their developmental stages and dietary sources (breast milk for infants and laboratory chow for adults). The above results provide insights into the hepatic metabolism in infants; however, the exact implications of the findings require further investigation.

When should a psychiatrist remember to test homocysteine levels? - a literature review

Introduction: Homocysteine is an endogenous sulfur amino acid, formed as a result of biochemical changes in methionine. The normal concentration of homocysteine in healthy people is within the range of 5 - 15 µmol / l, and values above 15 µmol / l are referred to as hyperhomocysteinemia. Moreover, it has been shown that the level of homocysteine may be associated with the occurrence of mental disorders. The aim of this article was to search for a relationship between the level of this amino acid and the incidence and prognosis of bipolar disorder, depression, anxiety disorders, schizophrenia or Alzheimer’s disease.

Material and method: For the review of the literature, available articles from the PubMed database and Google Scholar were used under the following keywords: homocysteine, depression, bipolar disorder, schizophrenia, Alzheimer’s disease in the period from 1992 to 2021.

Results: The research conducted so far shows that there is a significant correlation between elevated levels of homocysteine and the above-mentioned mental disorders.

Conclusion: In order to prevent the consequences of the increased level of homocysteine, its concentration in blood serum should be monitored periodically and appropriate treatment should be implemented in case of abnormal results. It is important to educate patients about the consequences of hyperhomocysteinemia i.a. atherosclerosis, stroke, ischemic heart disease, osteoporosis, neural tube defects, mental disorders and neurodegenerative diseases. It should be also established a strategy to lower the level of this amino acid through lifestyle changes, as well as the supply of folic acid, vitamins B12, B6, B2, N-acetylcysteine and betaine.

Effect of zinc supplementation on hemogram parameters and circulating concentrations of homocysteine, vitamin B12, and folate in zinc-deficient children and adolescents

BACKGROUND

Zinc deficiency may exacerbate some pathologies and may also explain alterations in circulating concentrations of various molecules. Zinc has previously been reported to affect plasma concentrations of vitamin B₁₂, homocysteine, and folate; however, the current evidence is inconclusive. We aimed to evaluate plasma zinc, hemoglobin, red blood cell count, mean corpuscular volume, ferritin, vitamin B₁₂, folate, and homocysteine concentrations during and after zinc supplementation for treatment of zinc deficiency.

METHODS

This prospective, open-label, single-arm study included children who presented to outpatient clinics with symptoms of growth retardation, anorexia or frequent infections, and who were considered deficient based on plasma zinc concentrations (<70 mcg/dl). Zinc supplementation of 15 mg per day was administered to all participants, and fasting blood samples collected 3 months later were analyzed for plasma zinc, vitamin B₁₂, homocysteine, and folate concentrations.

RESULTS

Eighty-three children (27 males and 26 females) admitted to the outpatient clinics with anorexia, growth retardation, and complaints of frequent infections. The mean age of the children was 9.64 ± 5.05 (min-max, 1-15) years, and the mean plasma zinc concentration before zinc supplementation was 61.7 ± 6.3 mcg/dl. Zinc concentrations were significantly elevated after zinc sulfate supplementation for 3 months, at 107.1 ± 18.8 mcg/dl (p < 0.01). Hemoglobin (p < 0.01), mean corpuscular volume (p < 0.01), and ferritin (p = 0.049) levels were significantly increased after zinc supplementation, but no significant difference was found in red blood cell count (p = 0.83). Vitamin B₁₂ and homocysteine concentrations were significantly decreased after zinc treatment (743.5 ± 498.8 vs 373.3 ± 128 mcg/dl p < 0.01; and 11.2 ± 5.3 vs 6.7 ± 3.4 mcg/dl p < 0.01, respectively). However, the change in folate concentrations was not significant (p = 0.05).

CONCLUSIONS

Anemia was not detected in patients with zinc deficiency, but ferritin level significantly increased after zinc treatment. Therefore, it can be said that zinc therapy has a positive effect on iron absorption. Elevations in vitamin B₁₂ and homocysteine may be associated with zinc deficiency, and these elevations may in turn influence the prognoses of liver, kidney, cardiorespiratory, and neoplastic conditions. This can be corrected through appropriate zinc supplementation.

Polycystic Ovary Syndrome: A Brain Disorder Characterized by Eating Problems Originating during Puberty and Adolescence

Polycystic ovary syndrome (PCOS) is an endocrine condition associated with reproductive and psychiatric disorders, and with obesity. Eating disorders, such as bulimia and recurrent dieting, are also linked to PCOS. They can lead to the epigenetic dysregulation of the hypothalamic-pituitary-gonadal (HPG) axis, thereby impacting on ovarian folliculogenesis. We postulate that PCOS is induced by psychological distress and episodes of overeating and/or dieting during puberty and adolescence, when body dissatisfaction and emotional distress are often present. We propose that upregulated activation of the central HPG axis during this period can be epigenetically altered by psychological stressors and by bulimia/recurrent dieting, which are common during adolescence and which can lead to PCOS. This hypothesis is based on events that occur during a largely neglected stage of female reproductive development. To date, most research into the origins of PCOS has focused on the prenatal induction of this disorder, particularly in utero androgenization and the role of anti-Müllerian hormone. Establishing causality in our peripubertal model requires prospective cohort studies from infancy. Mechanistic studies should consider the role of the gut microbiota in addition to the epigenetic regulation of (neuro) hormones. Finally, clinicians should consider the importance of underlying chronic psychological distress and eating disorders in PCOS.

The relationship of severity of depression with homocysteine, folate, vitamin B12, and vitamin D levels in children and adolescents

BACKGROUND

Depression is a heterogeneous disorder and is thought to develop as a result of complex interactions between genetic and environmental factors. One-carbon metabolism that includes vitamin B12, folic acid, and homocysteine has been investigated in psychiatric disorders like depression. In recent years, vitamin D has also been considered to contribute to psychiatric disorders. In this study, serum levels of folate, vitamin B12, and homocysteine related to one-carbon metabolism and vitamin D were investigated in children and adolescents with depression and to assess possible roles in depression pathogenesis.

METHODS

The study included 89 children and adolescents with depression (69 female, 20 male; mean age ± SD = 15.08 ± 1.46) and 43 control subjects (31 female, 12 male; mean age ± SD = 14.41 ± 2.32) without any DSM-5 diagnosis. Each subject completed a sociodemographic form, Childhood Depression Inventory, State-Trait Anxiety Inventory 1-2 and measured serum folate, vitamin B12, homocysteine, and 25-OH vitamin D levels.

RESULTS

There was no significant difference between the groups in terms of folate levels (p = .052). In the patient group, the vitamin B12 and vitamin D levels were clearly low (p values for both levels were <.001), while homocysteine levels were found to be remarkably high (p < .001). In addition, there was a negative correlation between depression severity and vitamin B12 and vitamin D, while a positive correlation was found with homocysteine.

CONCLUSIONS

The results of the study show that vitamin B12 deficiency or insufficiency and elevated homocysteine may contribute to the etiopathogenesis of depression. Additionally, it was shown that lower vitamin D levels may be associated with depression.

KEY PRACTITIONER MESSAGE

Depression of children and adolescents is associated with the interaction of environmental and genetic factors. Homocysteine, vitamin B12, and folate related to one-carbon metabolism are associated with psychiatric disorders such as depression in adulthood. Vitamin D also contributes to psychiatric disorders pathogenesis. There are not enough studies in the literature about these parameters in children with depression. Low vitamin B12 and vitamin D levels and increased homocysteine levels may play a role in the pathogenesis of depression in children and adolescents. Investigation of vitamin B12, folate, homocysteine, and vitamin D levels are recommended in children and adolescents with depression.

Homocysteine: Its Possible Emerging Role in At-Risk Population Groups

Increased plasma homocysteine is a risk factor for several pathological disorders. The present review focused on the role of homocysteine (Hcy) in different population groups, especially in risk conditions (pregnancy, infancy, old age), and on its relevance as a marker or etiological factor of the diseases in these age groups, focusing on the nutritional treatment of elevated Hcy levels. In pregnancy, Hcy levels were investigated in relation to the increased risk of adverse pregnancy outcomes such as small size for gestational age at birth, preeclampsia, recurrent abortions, low birth weight, or intrauterine growth restriction. In pediatric populations, Hcy levels are important not only for cardiovascular disease, obesity, and renal disease, but the most interesting evidence concerns study of elevated levels of Hcy in autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). Finally, a focus on the principal pathologies of the elderly (cardiovascular and neurodegenerative disease, osteoporosis and physical function) is presented. The metabolism of Hcy is influenced by B vitamins, and Hcy-lowering vitamin treatments have been proposed. However, clinical trials have not reached a consensus about the effectiveness of vitamin supplementation on the reduction of Hcy levels and improvement of pathological condition, especially in elderly patients with overt pathologies, suggesting that other dietary and non-dietary factors are involved in high Hcy levels. The importance of novel experimental designs focusing on intra-individual variability as a complement to the typical case-control experimental designs and the study of interactions between different factors it should be emphasized.

Homocysteine Metabolism in Children and Adolescents: Influence of Age on Plasma Biomarkers and Correspondent Genotype Interactions

Background: Imbalance of homocysteine (Hcy) metabolism links with several pathologies; nevertheless, it is poorly characterized in pediatric populations. This study investigated the impact of age on plasma concentrations of Hcy and relevant biomarkers along with correspondent genotype interactions. Methods: A healthy pediatric cohort aged 9 (n = 195) and 17 (n = 128) years old (yo) was studied. Immunoassays and GC-MS-SIM-mode quantified plasma levels of Hcy and biomarkers. PCR-RFLP or quantitative-PCR assays assessed common variations in related genes. Results: Age impacted on levels of Hcy and metabolic markers: older children presented with the lowest folates and total-cobalamin (tCbl), while with the highest Hcy concentrations, whereas methylmalonic acid (MMA) and holotranscobalamin (Holo-TC) levels remained similar in 9-yo and 17-yo children. The relationships between B-vitamins and metabolic markers were also dependent on age. Only in the older children, MMA correlated with tCbl and Holo-TC, and MMA levels were markedly higher in the 17-yo subjects presenting with the lowest quartiles of Holo-TC concentrations. Lastly, age also impacted on the correlations between genotype and biomarkers. In the 17-yo group, however not in the 9-yo children, tHcy differed between MTHFR 677 genotypes, with subjects who had the MTHFR 677TT genotype displaying the highest tHcy concentrations. Conclusions: Age impacts on the Hcy metabolism dynamics in a pediatric population.

Associations between serum homocysteine levels and anxiety and depression among children and adolescents in Taiwan

Although evidence suggests that homocysteine levels are elevated in severe mental illness in children, findings regarding homocysteine levels in youth with anxiety and depression are scarce. Therefore, this study examined the association of homocysteine levels with anxiety and depression in a community sample of students aged 6–13 years. In total, 649 students were selected from the first, fourth, and seventh grades of schools in Taipei, Taiwan, in 2010. These students completed a hospital-based health examination, which included physical examination, blood sample collection, and questionnaire administration. The data were analysed through multiple linear regression. Among the seventh-grade boys, both depression (adjusted β = 0.044, 95% confidence interval (CI) = 0.004–0.084) and anxiety (adjusted β = 0.052, 95% CI = 0.013–0.091) were independently associated with increased homocysteine levels. In further dichotomisation, compared with students with low anxiety levels, those with moderate to high anxiety levels were significantly positively associated with elevated serum homocysteine levels (adjusted β = 0.091, 95% CI = 0.003–0.180). Our results suggest that increased depression and anxiety may be positively associated with higher serum homocysteine levels in older boys. Our results provide essential data on the biological aspects underlying anxiety and depression in the studied population.

Association of CTH variant with sinusoidal obstruction syndrome in children receiving intravenous busulfan and cyclophosphamide before hematopoietic stem cell transplantation

Sinusoidal obstruction syndrome (SOS) is a severe complication of hematopoietic stem cell transplantation (HSCT) that can be fatal, often attributed to the conditioning regimen prior to HSCT. We evaluated the association of SOS risk with gene variants in cystathionase (CTH), an enzyme involved in glutathione synthesis, in 76 children receiving intravenous busulfan (Bu) before HSCT. Our results indicated an association with CTHc.1364 G>T (OR_TT=10.6, 95% confidence interval (CI)=2.16, 51.54) and SOS risk, which was sex dependent (female patients, OR_TT=21.82, 95% CI=3.590–132.649). The interaction between CTHc.1364 G>T and another risk variant (GSTA1*B) was explored. A recessive model with the use of GSTA1*B*B and CTH c.1364 TT genotypes proved to be useful at predicting SOS occurrence, indicating the possibility of using these gene variants as markers of SOS occurrence and to further individualize preemptive treatment aimed at reducing SOS incidence.

Interactions between lifestyle and MTHFR polymorphisms on homocysteine concentrations in young adults belonging to the 1982 Pelotas Birth Cohort

BACKGROUND/OBJECTIVES

Homocysteine (Hcy) is a key intermediate in methionine metabolism. A high plasma concentration of Hcy is an independent risk factor for cardiovascular diseases among other determinants. In this study, we aimed to investigate the interactions between methylenetetrahydrofolate reductase enzyme gene (MTHFR) polymorphisms and lifestyle variables (smoking, alcohol intake and physical activity) on Hcy concentrations in a young Brazilian population.

SUBJECTS/METHODS

The study population comprised 3803 individuals from the Pelotas Birth Cohort, aged 22-23 years. Allelic discrimination assays and chemiluminescence immunoassays were performed for genotyping and serum Hcy measurements, respectively. Linear regression models were used to explore the effect of gene-lifestyle interactions on Hcy concentrations.

RESULTS

Men carrying the MTHFR 677TT genotype, who were also smokers and drinkers (⩾15 g of alcohol per day), had the highest concentration of Hcy (P-value for the interaction <0.001 for smoking and 0.002 for alcohol intake). In contrast, high folate concentrations attenuated the effects of the MTHFR C677T genotype on serum Hcy concentrations (P-value for interaction <0.001). Also, among males, blood folate concentration was the only lifestyle variable able to modify the influence of MTHFR A1298C genotypes on Hcy concentrations (P-value for the interaction <0.001). There was no strong evidence of an interaction between the MTHFR genotypes and the lifestyle variables in women.

CONCLUSIONS

In summary, our study demonstrates a sex difference in Hcy concentrations among Brazilian young adults regarding MTHFR C677T-lifestyle interactions that are worsened under conditions of low blood folate. Identification of potentially modifiable factors related to an increase in homocysteine in young adults, especially in those who are genetically susceptible, is important to prevent negative health consequences in the future.

Influence of Biochemical and Anthropometric Factors on the Presence of Insulin Resistance in Adolescents

BACKGROUND

Insulin resistance plays a determinant role in the development of metabolic syndrome in adolescents. The objective of the present study was to determine the influence of factors commonly associated with insulin resistance in a sample of adolescents.

METHODS

This cross-sectional study included 976 adolescents from southeast Spain. Anthropometric and biochemical measurements were performed, and insulin resistance was assessed using the homeostasis model assessment-insulin resistance (HOMA-IR).

RESULTS

Subjects with abnormal HOMA-IR values had significantly higher body mass index (BMI), body fat content, waist circumference, and systolic blood pressure (BP) than those with normal values. Furthermore, levels of glucose, insulin, glycosylated hemoglobin, total cholesterol, triglycerides, low-density lipoprotein-cholesterol, homocysteine, nonesterified fatty acids, and ceruloplasmin were higher in subjects with abnormal HOMA-IR values. Multivariate logistic regression analysis showed the highest odds ratio (OR) for BMI and that combinations of BMI with body fat content or systolic BP can increase the risk of insulin resistance 7-fold.

DISCUSSION

Anthropometric indicators have different levels of influence on the risk of insulin resistance in adolescents, and a combination of two of these indicators is enough to increase the risk 7-fold. Since the highest OR was observed for BMI, the greatest effort should be directed to reducing this parameter in adolescents. An adequate understanding by nursing personnel of factors associated with insulin resistance is a key factor in the prevention of this pathophysiological condition and its complications in adolescents.

Serum Homocysteine Levels in Czech Children and Adolescents

Aim: The principal aim was to establish reference paediatric data for the serum homocysteine levels in Czech children and adolescents. Methods and Results: 144 children either healthy or not sufferig from acute or chronic inflammation, autoimmune disorders including rheumatic diseases, inflammatory musculoskeletal disorders, inflammatory bowel disease, diabetes mellitus, hypercholesterolemia, epilepsy, chronic renal failure, aged 0–19.9 years (0–6.9 years, n = 40; 7–10.9 y, n = 28; 11–15.9 y, n = 45; 16–19.9 y, n = 31) had their blood samples collected and the serum homocysteine level (S-homocysteine) was evaluated by chemiluminescence. A significant age dependence of the S-homocysteine levels was observed (R = 0.35, p < 0.01); with highest values of upper reference range in the 11–15.9 and 16–19.9 years’ group, respectively. Conclusion: The establishment of S-homocysteine reference Czech pediatric values is a potentially useful tool for proper evaluation of elevated homocysteine levels and corresponding risks in childhood.

Plasma Homocysteine is a Predictive Factor for Arterial Stiffness: A Community-Based 4.8-Year Prospective Study

The authors investigated whether plasma total homocysteine (tHcy) is a predictive factor for arterial stiffness (carotid-femoral pulse wave velocity [cf-PWV] and carotid-radial PWV) in 1447 patients from a 4.8-year prospective study in Beijing, People's Republic of China. Baseline tHcy showed a significant relationship with follow-up cf-PWV (β=0.817, P=.015) in a multivariable linear regression analysis. A stepwise logistic regression model showed that baseline levels of tHcy were significantly associated with follow-up cf-PWV in the adjusted models. Furthermore, the baseline tHcy levels showed a significant association with increases in cf-PWV. There was no association between the change in tHcy and increase in PWV. The present study clearly demonstrated an association between tHcy levels and arterial stiffness, indicating that tHcy is an independent predictive factor for arterial stiffness in a community-based population.

Elevated homocysteine level and folate deficiency associated with increased overall risk of carcinogenesis: meta-analysis of 83 case-control studies involving 35,758 individuals

BACKGROUND

Results of the association of folate metabolism and carcinogenesis are conflicting. We performed a meta-analysis to examine the effect of the interaction of serum concentration of homocysteine (Hcy), folate, and vitamin B12 and 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphism on risk of cancer overall.

METHOD

Two reviewers independently searched for all published studies of Hcy and cancer in PubMed, EMBASE-MEDLINE and Chinese databases. Pooled results were reported as odds ratios (ORs) and mean differences and presented with 95% confidence intervals (95% CIs) and 2-sided probability values.

RESULTS

We identified 83 eligible studies of 15,046 cases and 20,712 controls. High level of Hcy but low level of folate was associated with risk of cancer overall, with little effect by type of cancer or ethnicity. Vitamin B12 level was inversely associated with only urinary-system and gastrointestinal carcinomas and for Asian and Middle Eastern patients. As well, MTHFR C677T, A1298C and G1793A polymorphisms were related to elevated serum level of Hcy, and folate and vitamin B12 deficiency. However, only MTHFR C677T homogeneity/wild-type (TT/CC) polymorphism was positively associated with overall risk of cancer.

CONCLUSION

Elevated serum Hcy level and folate deficiency are associated with increased overall risk of cancer.

The association of homocysteine with metabolic syndrome in a community-dwelling population: homocysteine might be concomitant with metabolic syndrome

OBJECTIVE

Elevated plasma total homocysteine (tHcy) and metabolic syndrome (MetS) are both associated with cardiovascular disease, but the association between tHcy and MetS is not well characterized. The aim of this study was to determine the relationship between tHcy and MetS.

METHODS

To further estimate the time-dependent association of tHcy and MetS, we analyzed the tHcy level and MetS in 1499 subjects from a 4.8-year longitudinal study in Beijing, People's Republic of China.

RESULTS

In multiple linear regression analysis, baseline tHcy levels associated with age, BMI, SBP, DBP, LDL-C and Cr independently over 4.8-years follow-up; age, BMI, SBP, DBP and Cr were found to be associated with tHcy levels independently at the end of follow-up. Logistic regression analysis showed that there was no association between the baseline tHcy level and MetS over the 4.8-year follow-up (odds ratio (OR), 1.32; 95% confidence interval (CI), 0.79-2.19; P = 0.282); rather, there was an association only with hypertension as a MetS component (OR, 1.53; 95% CI, 1.06-2.21; P = 0.024). tHcy levels were associated with MetS at both cross-sectional baseline (OR, 1.38; 95% CI, 1.02-1.88; P = 0.038) and cross-sectional follow-up (OR, 1.60; 95% CI, 1.02-2.50; P = 0.041). The tHcy levels of MetS subjects were higher than those of non-MetS subjects at both cross-sectional baseline (19.35 ± 7.92 µmol/L vs. 17.45 ± 6.70 µmol/L, respectively; P = 0.001) and cross-sectional follow-up (18.95 ± 7.15 µmol/L vs. 17.11 ± 5.98 µmol/L, respectively; P = 0.02).

CONCLUSION

The tHcy level was not predictive of the incidence of MetS; however, it may be a risk factor for hypertension as a MetS component. Furthermore, tHcy levels were associated with MetS at cross-sectional baseline and follow-up, which suggests that a higher level of tHcy might be concomitant with MetS.

Correlation between cystathionine β-synthase T883C genetic polymorphism and primary hypertension

The present study aimed to investigate the correlation between cystathionine β-synthase (CBS) T833C polymorphisms and primary hypertension. A case-control study was conducted by genotyping the representative variation in 545 hypertensive individuals (aged 49.23±7.56 years) and 500 normotensive individuals (aged 49.90±10.01 years). The T833C genetic polymorphisms of the CBS enzyme were detected in all subjects by amplification refractory mutation system polymerase chain reaction (PCR) analysis. The CBS T833C polymorphism was successfully genotyped in the general population with a sample size of 1,045 (545+500) individuals. The genotypic and allelic frequency distributions of the CBS T833C polymorphism were not significantly different between the hypertensive and normotensive groups (P>0.05). The CC genotype was significantly different (P<0.05) from the CT and TT genotypes in terms of body mass index (BMI), and the levels of triglycerides (TG) and homocysteine (Hcy). Multiple logistic regression analysis revealed that BMI, total cholesterol (TC) level, smoking, plasma Hcy level and a family history of hypertension were the independent risk factors for hypertension in the population studied. The results indicate that the level of plasma Hcy was a risk factor for hypertension in the population studied. However, the mutation of the CBS T833C gene was not concluded to be an important hereditary factor for influencing the level of plasma Hcy.

Serum homocysteine and folate concentrations among a US cohort of adolescents before and after folic acid fortification

OBJECTIVE

We assessed serum homocysteine (tHcy) and folate concentrations among US adolescents before and after fortification of cereal-grain products with folic acid, and associations with demographic, behavioural and physiological factors.

DESIGN

Observational study conducted among participants of a randomized trial.

SETTING

The Child and Adolescent Trial for Cardiovascular Health (CATCH) study.

SUBJECTS

Adolescents (n 2445) in grades 8 (pre-fortification, mean age 14 years) and 12 (post-fortification, mean age 18 years).

RESULTS

Average serum concentrations of tHcy, folate and vitamin B6 increased by 17 %, 16 % and 14 %, respectively, while serum concentrations of vitamin B12 decreased by 11 % post-fortification. Folic acid fortification provided, on average, an additional intake of 118 μg folate/d. Male sex (P < 0.0001) and white race (P = 0.0008) were associated with significantly greater increases in tHcy concentration, while increases in BMI (P = 0.006) and serum folate concentration (P < 0.0001) were associated with significant decreases in tHcy concentration. Female sex (P < 0.0001), non-smoking (P < 0.0001), use of multivitamins (P < 0.0001) and higher dietary intake of folate (P = 0.001) were associated with significantly greater increases in serum folate concentrations. From grade 8 to grade 12, the upward age trend in serum tHcy concentration was uninterrupted in its course (P > 0.50); whereas serum folic acid concentration showed a downward trend that incurred a discrete jump upward (17 % higher; P < 0.0001) with fortification. These trends differed significantly for males v. females (P < 0.001 for interaction).

CONCLUSIONS

Fortification had a significant impact on improving folate status but not serum tHcy concentrations among US adolescents.

Homocysteine and cysteine levels in prepubertal children: association with waist circumference and lipid profile

OBJECTIVE

To evaluate homocysteine and total cysteine levels in prepubertal children and to determine the association between these levels and obesity, increased waist circumference, glucose levels, and lipid profile alterations.

METHODS

Using a cross-sectional study, 677 prepubertal students 6 to 11 y old were assessed. The weight, height, and waist circumference of the students were measured. Laboratory analyses included triacylglycerols, total cholesterol and its fractions, glucose, vitamin B12, folate, homocysteine, and cysteine. Chi-square tests and logistic regression (forward-stepwise) were used for statistical analysis; the significance level was set at 5%.

RESULTS

The median age of the students was 8.9 y (6.5-11.5), and the prevalences of overweight and obesity were 90 in 677 (13.3%) and 81 in 677 (12.0%), respectively. An increase in waist circumference was observed in 180 of 677 children (26.6%). Inadequate levels of low-density lipoprotein cholesterol, triacylglycerols, and high-density lipoprotein cholesterol were found in 95 (14.0%), 129 (19.1%), and 179 (26.4%) of the 677 students, respectively. The median homocysteine and total cysteine plasma levels were 5.6 μmol/L (0.1-11.7) and 365.7 μmol/L (191.5-589.2), respectively. A multivariate analysis showed that children with a waist circumference above the 90th percentile (7.3 μmol/L) were 2.4 times (95% confidence interval 1.4-4.0) more likely to have increased homocysteine levels and that children with increased waist circumferences and those with high low-density lipoprotein cholesterol levels were 2.7 (95% confidence interval 1.6-4.6) and 2.1 (95% confidence interval 1.1-4.0) times more likely, respectively, to have total cysteine levels above the 90th percentile (445.0 μmol/L).

CONCLUSION

The association of abdominal obesity in prepuberty with levels of homocysteine and cysteine found in this study of a prepubertal population could be an early and independent predictor of cardiovascular risk.

Reference interval and determinants of the serum homocysteine level in a Korean population

In this study, we estimated the reference intervals of the serum homocysteine (Hcy) level using two automated immunoassays, and we demonstrated the effects of various factors on the Hcy level in a Korean population. We calculated the gender- and assay-specific reference intervals using the data from 809 healthy Koreans, and we assessed the effects of physiologic and lifestyle factors on the Hcy level. The upper limit was higher in males (19.21 and 19.76 μmol/l) than that in females (14.99 μmol/l and 15.16 μmol/l, AxSym and ADVIA centaur, respectively); the upper limits were comparable between the two assays. Smokers, vitamin nonusers, and persons without regular exercise showed a lower folate level and a higher Hcy level. The risk of hyperhomocysteinemia was significantly associated with the male gender (adjusted OR: 5.705, P-value: 0.008) and with the low folate level group (adjusted OR: 10.412, P-value: 0.002) on the multivariate analysis. The Hcy level was significantly different according to various factors, especially in the gender and folate level. The reference interval should be determined for each ethnic population and for each assay. The appropriate cutoff for assessing the risk for cardiovascular disease or stroke should also be validated in each population.

Optimal cutoff points for body mass index, waist circumference and HOMA-IR to identify a cluster of cardiometabolic abnormalities in normal glucose-tolerant Brazilian children and adolescents

OBJECTIVE: The aim of this study was to establish the best cutoff values for waist circumference (WC), body mass index (BMI) and HOMA-IR (HR) to identify a cluster (> 3) of cardiovascular risk factors (CVRF) in normal glucose-tolerant (NGT) Brazilian children and adolescents. SUBJECTS AND METHODS: Cross-sectional study of 319 individuals (aged 10 to 19y) from a southern Brazilian city. Gender-specific receiver-operating characteristics (ROC) curves were constructed to assess cutoffs values of BMI (kg/m², WC (cm), and HR. RESULTS: The areas under the ROC curves to detect a cluster of CVRF were 0.92, 0.93 and 0.68 (females), and 0.93, 0.93 and 0.89 (males), for WC, BMI and HR, respectively. The cutoff values were 83.0 and 80.5 cm (WC), 22.7 and 20.4 kg/m2 (BMI), and 1.65 and 1.95 (HR), for females and males, respectively, to detect the cluster of CVRF. CONCLUSION: These values of BMI, WC-) and (HR) detected a high proportion of NGTt Brazilian children and adolescents with a cluster of CVRF.

Homocysteine: biomarker or cause of adverse pregnancy outcome?

Total fasting plasma homocysteine (tHcy) is significantly reduced during early-mid normal pregnancy. Elevated tHcy during or outside of pregnancy has been associated with adverse pregnancy outcomes, affecting either the fetus or the evolution of the pregnancy. Examples of direct adverse effects on the fetus are neural tube defects, Down's syndrome, congenital heart defects and intrauterine growth retardation. Both fetal and maternal wellbeing can be affected by other adverse outcomes reported to be associated with elevated tHcy, such as recurrent spontaneous abortion, pre-eclampsia or placental vasculopathy. To date, endothelial activation of the placental vascularization system, apoptosis, toxicity and stimulation of uterine contractions have been proposed as possible modes of adverse action of homocysteine. The strength of the clinical evidence for a pathological role of elevated homocysteine in the evolution of pregnancy is examined in this review.

Study of molecular targets influencing homocysteine and cholesterol metabolism in growing rats by manipulation of dietary selenium and methionine concentrations

Inconsistent results exist from human and animal studies for Se and methionine (Met) regarding their influence on homocysteine (HCys) and cholesterol (Chol) metabolism. To elucidate these contradictions, sixty-four weanling albino rats were divided into eight groups of 8, and were fed diets containing four different Se levels (15, 50, 150 and 450 microg/kg) either in combination with the recommended Met level of 3 g/kg (C15, C50, C150 and C450) or with an increased Met concentration of 15 g/kg (M15, M50, M150 and M450) for 8 weeks. Plasma HCys was twofold higher in the Se-supplemented C groups than in group C15. Met addition also doubled plasma HCys compared with the respective C groups. In contrast, the expression of the key enzymes of glutathione biosynthesis in the liver was significantly lowered by Se and in particular by Met. Liver Chol concentration was significantly higher in all the Se-supplemented C and M groups than in groups C15 and M15. Plasma Chol was, however, lowered. The uninfluenced expression of sterol-regulatory element-binding protein 2 and of hydroxymethyl-glutaryl-CoA reductase, the increased LDL receptor expression and the reduced expression of the hepatobiliary Chol exporter ATP-binding-cassette-transporter 8 (ABCG8) by Se and/or Met explain these findings. We conclude that the elevation of plasma HCys in rats by Se and Met results from a higher export into plasma. The fact that Se in particular combined with Met increases liver Chol but reduces plasma Chol should be addressed in future investigations focussing on the regulation of ABCG8, which is also selectively involved in the reverse transport of phytosterols in the small intestine.

Association between cholesterols, homocysteine and silent brain infarcts

BACKGROUND

The aim of this study was to assess the relationship between total plasma homocysteine, cholesterol levels, vitamin B(12), folate, thyroid hormones, urea, ferritin, uric acid, C-reactive protein, cardiovascular risk factors and silent brain infarct (SBI) in patients without any neurological disorder. Whether the factors of interest were associated with SBI is investigated.

METHODS

One hundred and forty-two subjects with a mean age of 52.1 +/- 13.1 years (21-87 years) without any history of stroke, transient ischaemic attack and neurological abnormality were enrolled in this cross-sectional study. The subjects underwent brain magnetic resonance imaging and blood chemistry determinations. Student's t-test was used to compare differences in means of laboratory results between the groups with and without SBI. The chi(2)-test was used for categorized variables. Multiple logistic regression analysis was used to determine the independent predictors of SBI.

RESULTS

The group comprised 56 men and 86 women. SBI were found in 40 patients (28%). The low-density lipoprotein levels were significantly higher in the infarct group (P = 0.019), homocysteine concentrations were significantly higher in the men-infarct group (P = 0,029) and total cholesterol levels were significantly higher in the women-infarct group than the women non-infarct group (P = 0.006).

CONCLUSION

Serum low-density lipoprotein, total cholesterol and homocysteine levels were associated with SBI.

Folate, Cobalamin, Cysteine, Homocysteine, and Arsenic Metabolism among Children in Bangladesh

BACKGROUND

Approximately 35 million people in Bangladesh are chronically exposed to inorganic arsenic (InAs) in drinking water. Methylation of InAs to monomethylarsonic (MMA) and dimethylarsinic acids (DMA) relies on folate-dependent one-carbon metabolism and facilitates urinary arsenic (uAs) elimination.

OBJECTIVES

We examined the relationships between folate, cobalamin, cysteine, total homocysteine (tHcys), and uAs metabolites in a sample of 6-year-old Bangladeshi children (n = 165).

METHODS

Children provided blood samples for measurement of tHcys, folate, cobalamin, and cysteine, and urine specimens for the measurement of total uAs and As metabolites.

RESULTS

Consistent with our studies in adults, mean tHcys concentrations (7.9 micromol/L) were higher than those reported among children of similar ages in other populations. Nineteen percent of the children had plasma folate concentrations < 9.0 nmol/L. The proportion of total uAs excreted as InAs (%InAs) was inversely correlated with folate (r = -0.20, p = 0.01) and cysteine (r = -0.23, p = 0.003), whereas the correlations between %DMA and both folate (r = 0.12, p = 0.14) and cysteine (r = 0.11, p = 0.15) were positive. Homocysteine was inversely correlated (r = -0.27, p = 0.009) with %MMA in males, and the correlation with %DMA was positive (r = 0.13, p = 0.10).

CONCLUSIONS

These findings suggest that, similar to adults, folate and cysteine facilitate As methylation in children. However, the inverse correlation between tHcys and %MMA, and positive correlation with %DMA, are both opposite to our previous findings in adults. We propose that upregulation of one-carbon metabolism, presumably necessary to meet the considerable demands for DNA and protein biosynthesis during periods of rapid growth, results in both increased tHcys biosynthesis and increased As methylation.

Folate, related B vitamins, and homocysteine in childhood and adolescence: potential implications for disease risk in later life

OBJECTIVES

Folate and the metabolically related B vitamins are an important priority throughout life, but few studies have examined their status through childhood and adolescence. The aims of the current study were to investigate age, gender, and lifestyle factors as determinants of folate, related B-vitamin status, and homocysteine concentrations among British children and adolescents and to propose age-specific reference ranges for these biomarkers, which, at present, are unavailable.

PARTICIPANTS AND METHODS

Data from the National Dietary and Nutritional Survey of 2127 young people aged 4 to 18 years were accessed to provide a representative sample of British children. All of the subjects who provided a blood sample for homocysteine concentrations were included in the current study (n = 840). Of these, laboratory biomarkers of folate (serum and red cell folate: n = 832 and 774, respectively), vitamin B(12) (n = 828), vitamin B(6) (n = 770), and riboflavin (n = 839) were also examined.

RESULTS

The biomarker status of all 4 of the relevant B vitamins decreased significantly with age. Correspondingly, homocysteine concentrations progressively increased, with median values of 5.6, 6.3, and 7.9 mumol/L for children aged 4 to 10 years, 11 to 14 years, and 15 to 18 years, respectively, and were higher in boys compared with girls (15-18 years only). Independent of age and gender, fortified breakfast cereal intake (consumed by 89% of the sample) was associated with significantly higher B-vitamin status and lower homocysteine concentrations.

CONCLUSIONS

It is not generally appreciated that the well-established progressive increase in homocysteine from 4 to 18 years reflects decreases in the biomarker status of all 4 metabolically related B vitamins. We suggest age-specific laboratory reference ranges for homocysteine and related B-vitamin concentrations for potential use within a pediatric setting.

Serum total homocysteine concentrations in children and adolescents in Jos, Nigeria

BACKGROUND

Although the elevation of circulating total serum homocysteine (tHcy) concentration in a fasting state is associated with an increased risk of occlusive vascular disease in adults, the levels in children in Nigeria are not known.

AIM

The goals of this study were to describe the distribution of tHcy among a representative sample of children and adolescents in Jos, Nigeria, and to test for differences in tHcy among sex and age categories.

METHODS

The sampling scheme, which included persons aged 10 to 19 years, was a stratified, multistage probability design. This cross sectional study involved 182 school children drawn from secondary schools in Jos, Nigeria between January and July 2003. Fasting venous samples were collected and assayed for tHcy, Total protein and Albumin. Anthropometric measurements were taken.

RESULT

The mean tHcy concentrations were 2.7 +/- 2.4 (95% CI 2.4-2.9), 3.5 +/- 3.2 (3.3-3.8) and 3.6 +/- 3.2 (3.3-4.1), 4.1 +/- 3.6 (4.0-4.4) micromol/l for the girls and boys aged 10-14 and 15-19 years, respectively. Albumin levels correlate positively with plasma total homocysteine, tHcy (r = 0.45, P = 0.03).

CONCLUSION

This study provided age-specific data regarding tHcy concentrations between 10-19 years population in Jos, Nigeria. The tHcy concentration increased as a function of age in both sexes.

Trends in circulating concentrations of total homocysteine among US adolescents and adults: findings from the 1991-1994 and 1999-2004 National Health and Nutrition Examination Surveys

BACKGROUND

The National Health and Nutrition Examination Survey (NHANES) has monitored total homocysteine (tHcy) concentrations in a nationally-representative sample of the US population since 1991. Until recently, however, data could not be compared across survey periods because of changes in analytical methods and specimen matrices. Such an analysis of these data could supplement current knowledge regarding whether the US folic acid fortification program has modified national plasma tHcy concentrations.

METHODS

We examined tHcy data in the prefortification NHANES III survey (phase II, 1991-1994) and in 3 postfortification survey periods (1999-2000, 2001-2002, and 2003-2004). We applied method adjustment equations to the survey data based on method comparison studies of separate samples. Persons with chronic kidney disease were excluded from the analyses.

RESULTS

Mean plasma tHcy concentrations decreased by 8%, 9%, and 10% for adolescent, adult, and older men and by 6%, 3%, and 13% for women, respectively, from before to after fortification. Concentrations remained unchanged between the first and third postfortification survey periods. Prevalence estimates of increased plasma tHcy concentrations (>13 micromol/L) for older men and women decreased from prefortification (32% and 20%, respectively) to postfortification (14% and 5%, respectively) but remained unchanged thereafter (16% and 14%, respectively [males] and 5% and 9%, respectively [females]).

CONCLUSIONS

After adjusting for method changes, we quantified a prefortification to postfortification decrease in circulating tHcy concentrations of about 10% in a national sample of the US population. This change is similar to effects seen in intervention trials with folic acid and in smaller observational studies.

Risk factors for perinatal arterial stroke: a study of 60 mother-child pairs

The objective of the present study was to examine demographic, historical, and prothrombotic risk factors in infants with perinatal arterial stroke and their mothers. Risk factors were evaluated in 60 mother-child pairs with perinatal arterial stroke. Prothrombotic factors analyzed included the DNA mutations factor V Leiden, prothrombin 20210, MTHFR C677T and A1298C; serum activity levels for protein C, protein S, and antithrombin III; serum levels of lipoprotein(a); and, in the mothers, antiphospholipid antibodies. Boys predominated, 36:24. There were four twin sets. Sixty percent were term and 22% were post-date. Ten were large for gestational age. Five mothers had abdominal trauma. Nine mothers (15%) had preeclampsia. Emergency caesarean section was performed in 17 cases (28%). Eight placental exams revealed seven with abnormalities. Seizures were the presenting sign in 70%, and 30% presented with early handedness or cerebral palsy. Prothrombotic risk factors were found in 28 of 51 mothers (55%) and 30 of 60 children (50%). Forty-one pairs (68%) had at least one abnormality in mother, child, or both. Long-term sequelae included cerebral palsy (40 of 51; 78%), cognitive impairment (35 of 51; 68%), seizures (23 of 51; 45%), and microcephaly (26 of 51; 51%). Perinatal arterial stroke is the result of multifactorial, synergistic fetal and maternal factors among which the prothrombotic factors, both fetal and maternal, appear significant.

Homocysteine, folate and cobalamin levels in hypothyroid women before and after treatment

Hypothyroidism may result in accelerated atherosclerosis. Hyperhomocysteinaemia is an independent risk factor for premature atherosclerotic vascular disease. The aim of the present study was to assess plasma total homocysteine (tHcy), folate and cobalamin concentrations in hypothyroid patients before and after treatment. Thirty-one hypothyroid and thirty health young women were studied. The hypothyroid patients were investigated in the untreated state and again after restoration of euthyroidism. The levels of homocysteine, folate, cobalamin and thyroid stimulating hormone (TSH), free thyroxine (fT(4)), free triiodothyronine (fT(3)) and renal function were measured before and after treatment. In hypothyroidism tHcy was higher but not statistically significant than in control group. Serum level of folate was higher and serum cobalamin was lower in the hypothyroid state. Following L-thyroxine therapy tHcy significantly decreased as well as the concentration of cobalamin. Level of folate remained unchanged. Univariate analysis in hypothyroid group indicated that tHcy negative correlated with creatinine clearance, fT(3), fT(4), cobalamin and positive with TSH. In multivariate analysis tHcy correlated with creatinine clearance, cobalamin and fT(4). Thyroid status influences the plasma tHcy. Free triiodothyronine and next free thyroxine have the greatest negative influence. This would account for hyperhomocysteinemia in the hypothyroid state and premature atherogenesis.

High prevalence of hyperhomocysteinemia in Chinese adults is associated with low folate, vitamin B-12, and vitamin B-6 status

Elevated plasma total homocysteine (tHcy) concentrations are associated with lower folate, vitamin B-12, and vitamin B-6 status and are considered an independent risk factor for cardiovascular disease in developed countries, but data in developing countries are limited. We conducted a cross-sectional study to explore tHcy status and its association with plasma B vitamin status in 2471 Chinese men and women aged 35 to 64 y, living in the urban and rural areas of the northern and the southern regions of China. Blood samples were also collected in 2 seasons (spring and fall). The geometric mean plasma tHcy concentration was significantly higher in the north (adjusted geometric mean, 95% CI; 13.0 micromol/L, 12.6-13.3) than in the south (9.1, 8.9-9.4) after controlling for gender, area (urban and rural), age, and season (spring and fall). Twenty-eight percent of northerners and 7% of southerners had plasma tHcy concentrations>or=16.0 micromol/L, a level used to define hyperhomocysteinemia. Within each region, men had higher plasma tHcy concentrations than women (16.1 vs. 10.6 micromol/L in the north, and 10.7 vs. 7.9 micromol/L in the south) and 40% of the northern men had hyperhomocysteinemia. Generally, individuals living in the urban areas had 30% (95% CI, 1.0-1.6) greater odds of having high tHcy levels (>or=16 micromol/L) than those living in the rural areas. Low plasma concentrations of folate, vitamins B-12 and B-6, older age, being male, and living in urban areas were all independently associated with elevated tHcy, with low folate as the strongest determinant.

Pediatric precursors of adult cardiovascular disease: noninvasive assessment of early vascular changes in children and adolescents

BACKGROUND

Until recently, our understanding of the childhood antecedents of adult cardiovascular disease was limited mainly to autopsy studies and pathologic findings in teens and young adults who died from accidental causes. Recent advances in the understanding of atherosclerosis and new technologies allowing detection of early events have made it possible to observe anatomic and physiologic evidence of cardiovascular disease in young adults and children.

OBJECTIVES

The goal of this article was to introduce pediatricians to new methods for noninvasive measurement of cardiovascular disease and its precursors, to describe the potential application of these techniques in detecting childhood precursors of adult cardiovascular disease, and to summarize knowledge gained from this approach.

METHODS

We conducted a computerized search of peer-reviewed articles listed in PubMed and Medline from 1980 to April 2006. We reviewed 63 and 84 articles from the adult and pediatric literature, respectively.

RESULTS

Reviewing the research on childhood antecedents of adult cardiovascular disease is sobering. Vascular alterations in anatomy, physiology, mechanical properties, and proinflammatory and prothrombotic changes are present from a very early age of childhood and are associated with the risk factors common in adult cardiovascular disease. At the same time, this body of research supports the concept that the vascular impairment from childhood may improve over time with appropriate intervention.

CONCLUSIONS

The measurement tools and concepts described in this article offer diagnostic and therapeutic opportunities for collaboration between clinical pediatricians and pediatric researchers. These partnerships will enable pediatricians to contribute in an effort to reduce the burdens of cardiovascular disease to individuals, families, and society.

Homocysteine

Elevated homocysteine levels are associated with a variety of vascular diseases. Specifically, hyperhomocysteinemia is a risk factor for coronary artery disease, cerebrovascular disease, and peripheral arterial disease. Laboratory-based strategies for its detection and quantification have evolved to meet the increasing need for accuracy in risk prediction. Although new technologies have been developed over the past 2 decades that have enhanced the precision of measurement, universal guidelines for circulating homocysteine determination remain lacking.

Stroke following Glenn anastomosis in a child with inherited thrombophilia

The optimal anticoagulation following Fontan operation and its modifications remain controversial and it is even less well defined as regards patients with inherited thrombophilia. We present a case of a child with bidirectional Glenn anastomosis for double inlet left ventricle that suffered a stroke despite aspirin prophylaxis; the patient was combined homozygous for prothrombin G20210A mutation and for methylenetetrahydrofolate reductase C677T mutation as well. The family history was positive for fetal loss and premature cardiovascular disease. Large-scale studies are needed to evaluate whether carriers of thrombophilia mutations need more intense thromboprophylaxis.

The Hordaland Homocysteine Study: a community-based study of homocysteine, its determinants, and associations with disease

The Hordaland Homocysteine Study (HHS) is a population-based study of more than 18,000 men and women in the county of Hordaland in Western Norway. The first investigation (HHS-I) took place in 1992-93, when the subjects were aged 40-67 y. In 1997-99, a follow-up study (HHS-II) of 7,053 subjects was carried out. In this large population, plasma levels of total homocysteine (tHcy) are associated with several physiologic and lifestyle factors and common diseases. Increasing age, male sex, smoking, coffee consumption, high blood pressure, unfavorable lipid profile, high creatinine, and the MTHFR 677C > T polymorphism are among the factors associated with increased tHcy levels; physical activity, moderate alcohol consumption, and a good folate or vitamin B-12 status are associated with lower tHcy levels. Subjects with raised tHcy levels have increased risk of cardiovascular morbidity, cardiovascular and noncardiovascular mortality, and are more likely to suffer from depression and from cognitive deficit (elderly). Among women, raised tHcy levels are associated with decreased bone mineral density and increased risk of osteoporosis. Women with raised tHcy levels also have an increased risk of having suffered from pregnancy complications and an adverse pregnancy outcome. Significant associations between tHcy and clinical outcomes are usually observed for tHcy levels > 15 micromol/L, but for most conditions, there is a continuous concentration-response relation with no apparent threshold concentration. Overall, the findings from HHS indicate that a raised tHcy level is associated with multiple clinical conditions, whereas a low tHcy level is associated with better physical and mental health.

Population references for plasma total homocysteine concentrations for U.S. children and adolescents in the post-folic acid fortification era

Folate intake is inversely related to circulating total homocysteine (tHcy) concentrations. Elevated tHcy is a risk factor for vascular diseases. The objectives of this study were to present plasma tHcy distributions and investigate the association between tHcy and sex, age, and race-ethnicity in U.S. children and adolescents (3264 boys and 3197 girls) using data from the National Health and Nutrition Examination Surveys, 1999-2000 and 2001-2002 conducted in the post-folic acid fortification era. Plasma tHcy was higher in boys than in girls (P < 0.0001), and higher in older children (16-18 y old) than in younger children (3-15 y old) (P < 0.0001). The difference in plasma tHcy between boys and girls was greater in the 16- to 18-y-old group than in any other age group studied (P < 0.05). Age-adjusted plasma tHcy concentrations were approximately 6.8, approximately 10.5, and approximately 8.8% higher in boys than in girls in non-Hispanic White (NHW), non-Hispanic Black (NHB), and Mexican American/Hispanic (MA/H) children, respectively. Sex- and age-adjusted plasma tHcy concentrations (geometric means +/- SE) were 5.04 +/- 0.05, 5.01 +/- 0.06, and 4.99 +/- 0.06 micromol/L in the NHW, NHB, and MA/H groups, respectively. Race-ethnicity was not related to plasma tHcy in age-adjusted analysis for boys (P < 0.77) and girls (P < 0.26), and in sex- and age-adjusted analysis (P < 0.38) for all children. The plasma tHcy concentrations begin to rise between ages 8 and 11 y, and the age-related increase is greater in boys than in girls.

Biochemical indicators of B vitamin status in the US population after folic acid fortification: results from the National Health and Nutrition Examination Survey 1999-2000

BACKGROUND

Mandatory folic acid fortification of cereal-grain products was introduced in the United States in 1998 to decrease the risk that women will have children with neural tube defects.

OBJECTIVE

The objective was to determine the effect of folic acid fortification on concentrations of serum and red blood cell (RBC) folate, serum vitamin B-12, and plasma total homocysteine (tHcy) and methylmalonic acid (MMA) in the US population.

DESIGN

Blood was collected from a nationally representative sample of approximately 7300 participants aged > or = 3 y in the National Health and Nutrition Examination Survey (NHANES) during 1999-2000 and was analyzed for these B vitamin-status indicators. The results were compared with findings from the prefortification survey NHANES III (1988-1994).

RESULTS

The reference ranges (5th-95th percentiles) were 13.1-74.3 nmol/L for serum folate, 347-1167 nmol/L for RBC folate, and 179-738 pmol/L for serum vitamin B-12. For plasma tHcy and MMA, the reference ranges for serum vitamin B-12-replete participants with normal serum creatinine concentrations were 3.2-10.7 mumol/L and 60-210 nmol/L, respectively. The prevalence of low serum folate concentrations (<6.8 nmol/L) decreased from 16% before to 0.5% after fortification. In elderly persons, the prevalence of high serum folate concentrations (>45.3 nmol/L) increased from 7% before to 38% after fortification; 3% had marginally low serum vitamin B-12 concentrations (<148 pmol/L) and 7% had elevated plasma MMA concentrations (>370 nmol/L). Seventy-eight percent of the US population had plasma tHcy concentrations <9 micromol/L.

CONCLUSIONS

Every segment of the US population appears to benefit from folic acid fortification. Continued monitoring of B vitamin concentrations in the US population is warranted.

Total homocysteine and its predictors in Dutch children

BACKGROUND

Vitamin status, methylenentetrahydrofolate reductase (MTHFR) genotype, age, sex, and lifestyle factors are all predictors of total homocysteine (tHcy) concentrations in adults. Limited data are available about the influence of these factors on tHcy in children.

OBJECTIVE

The objective was to describe tHcy and its predictors in Dutch children.

DESIGN

A sample of 234 white children aged 0-19 y was analyzed cross-sectionally.

RESULTS

The geometric mean tHcy concentrations were 5.1 (95% CI: 4.6, 5.6), 4.6 (4.2, 5.1), 6.2 (5.6, 6.9), 7.3 (6.7, 8.0), and 8.7 (7.9, 9.6) micromol/L in the 0-1, 2-5, 6-10, 11-14, and 15-19 y groups, respectively. Plasma folate and vitamin B-12 concentrations decreased markedly with age. The inverse association between tHcy and plasma folate seen at all ages was stronger than that between tHcy and plasma vitamin B-12. A negative association of plasma folate with tHcy was confined to folate concentrations <20 nmol/L. Homozygosity for the MTHFR 677C-->T polymorphism was identified in 8.2% of the children. The homocysteine concentration did not differ significantly between the MTHFR genotypes.

CONCLUSIONS

This study provided age-specific data regarding tHcy concentrations and their predictors in the whole range of childhood. The tHcy concentration increased as a function of age in both sexes. Plasma folate was a concentration-dependent predictor of tHcy. The MTHFR 677C-->T polymorphism played a minor role in determining tHcy concentrations in children.

Correlation between dietary polyunsaturated fatty acids and plasma homocysteine concentration in vitamin B6-deficient rats

BACKGROUND AND AIM

Vitamin B6 as cofactor of Delta6 desaturase is involved in polyunsaturated fatty acid metabolism; moreover, it is a cofactor of the trans-sulfuration pathway of homocysteine. Some studies report that low concentrations of pyridoxine, by increasing homocysteine levels, are associated with coronary artery disease, and carotid and arterial lesions. The aim of this study was to verify whether different dietary amounts of polyunsaturated fatty acids associated with low content of vitamin B6 could modulate homocysteinemia.

METHODS AND RESULTS

Thirty-two rats were divided into two groups, one fed a diet with adequate vitamin B6 content the other a diet containing low amount of the same vitamin. Within each group, rats were divided into two subgroups differing in the polyunsaturated fatty acid content of the diet (63 and 33%, respectively). The vitamin B6-deficient diet induced an increase in homocysteine concentration compared to the vitamin B6-normal diet. This increase was tenfold in the subgroup fed high polyunsaturated fatty acid levels and twofold in the other subgroup. The fatty acid composition of liver phospholipids showed a lower arachidonic acid relative molar content and a lower 20:4/18:2 ratio in vitamin B6-deficient groups compared with B6-normal groups.

CONCLUSIONS

On the basis of the different biological functions of pyridoxine and considering that some factors closely related to atherosclerosis are vitamin B(6) dependent, adequate pyridoxine availability could be necessary to assure a normal long chain fatty acid metabolism and to reduce the risk linked to hyperhomocysteinemia.