A reduction in homocysteine concentration due to the use of supplemental folic acid is well recognized, although evidence of the same effect for natural folate sources, such as fruits and vegetables (FV), is lacking. The traditional statistical analysis approaches do not provide further information. As an alternative, quantile regression allows for the exploration of the effects of covariates through percentiles of the conditional distribution of the dependent variable.
To investigate how the associations of FV intake with plasma total homocysteine (tHcy) differ through percentiles in the distribution using quantile regression.
Materials and Methods
A cross-sectional population-based survey was conducted among 499 residents of Sao Paulo City, Brazil. The participants provided food intake and fasting blood samples. Fruit and vegetable intake was predicted by adjusting for day-to-day variation using a proper measurement error model. We performed a quantile regression to verify the association between tHcy and the predicted FV intake. The predicted values of tHcy for each percentile model were calculated considering an increase of 200 g in the FV intake for each percentile.
The results showed that tHcy was inversely associated with FV intake when assessed by linear regression whereas, the association was different when using quantile regression. The relationship with FV consumption was inverse and significant for almost all percentiles of tHcy. The coefficients increased as the percentile of tHcy increased. A simulated increase of 200 g in the FV intake could decrease the tHcy levels in the overall percentiles, but the higher percentiles of tHcy benefited more.
This study confirms that the effect of FV intake on lowering the tHcy levels is dependent on the level of tHcy using an innovative statistical approach. From a public health point of view, encouraging people to increase FV intake would benefit people with high levels of tHcy.
Background: Epidemiological research has shown that increased total homocysteine (tHcy) levels are associated with an increased risk of thromboembolic disease; however, controversy still exists over which subtype of stroke is allied to hyperhomocysteinemia. This study aimed to investigate whether elevated tHcy is an independent risk factor for ischemic stroke and to compare tHcy levels in patients with ischemic stroke subtypes.
Methods: We performed a case-control study, in which 171 ischemic stroke patients aged over 16 years and 86 age and sex-matched controls were eligible to participate and were enrolled from January 2009 to January 2010. The patients’ demographic data, traditional stroke risk factors, and the results of fasting tHcy, vitamin B12, and folate of serum were collected in the first 5 days after ischemic stroke. Stroke subtypes were classified according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. SPSS software (version 13) was used for the statistical analysis of the data, and a P value smaller than 0.05 was considered statistically significant.
Results: The mean fasting Hcy levels was significantly higher in the cases (16.2 μmol/L, 95% CI: 14.8 to 17.5) than in the controls (13.5 μmol/L, 95% CI: 12.4 to 14.6) (P=0.013). The mean Hcy levels was elevated significantly in those with cardioembolic strokes compared with the controls (17.7 μmol/L, 95% CI: 14.8 to 20.5; P=0.010). The plasma Hcy level was associated with an adjusted odds ratio of 2.17 (95% CI: 1.24 to 3.79; P=0.004) for Hcy above 15 μmol/L concentration for all types of stroke.
Conclusion: Our data showed that elevated serum Hcy is an independent risk factor for ischemic stroke and it has a strong association with cardioembolic subtype.
Homocysteine; Risk factors; Vascular disease
OBJECTIVE: To establish guidelines for the screening and treatment of hyperhomocysteinemia in the investigation and management of coronary artery disease (CAD). OPTIONS: Measurement of plasma total homocysteine (tHcy) levels in the fasting state or 4-6 hours after oral methionine load; vitamin supplementation with folic acid and vitamins B6 and B12; adherence to the recommended daily allowance of dietary sources of folate and vitamins B6 and B12. OUTCOMES: This article reviews the available evidence on the association between plasma tHcy levels and CAD and the effect of lowering tHcy levels through vitamin supplementation or dietary intake. EVIDENCE: MEDLINE was searched for relevant English-language articles published from January 1966 to June 1999; also reviewed were additional articles identified from the bibliographies. BENEFITS, HARMS AND COSTS: Cardiovascular disease is the leading cause of death in Canada. Homocysteine, generated in the metabolism of methionine, may have a role in the development of cardiovascular disease. The prevalence of hyperhomocysteinemia in the general population is between 5% and 10% and may be as high as 30%-40% in the elderly population. If population-based studies are correct, tHcy may be responsible for up to 10% of CAD events and thus may represent an important and potentially modifiable risk factor for cardiovascular disease. Laboratory testing for tHcy is currently restricted to research centres, and costs range from $30 to $50 per person. Newer, less costly techniques have been developed and should become readily available with time. VALUES: The strength of evidence was evaluated using the methods of the Canadian Task Force on Preventive Health Care. RECOMMENDATIONS: Although there is insufficient evidence to recommend the screening or management of hyperhomocysteinemia at present (grade C recommendation), adherence to recommended daily allowance of dietary sources of folate and vitamins B12 and B6 should be encouraged. If elevated tHcy levels are discovered, vitamin deficiency should be ruled out to allow specific treatment and prevention of complications, such as neurological sequelae due to vitamin B12 deficiency. Experts in the field advocate treatment of elevated tHcy levels in high-risk people, such as those with a personal or family history of premature atherosclerosis or a predisposition to develop hyperhomocysteinemia. Definitive guidelines for the management of hyperhomocysteinemia await the completion of randomized trials to establish the effect of vitamin supplementation on CAD events. VALIDATION: The findings of this analysis were reviewed through an iterative process by the members of the Canadian Task Force on Preventive Health Care. SPONSORS: The Canadian Task Force on Preventive Health Care is funded through a partnership between the Provincial and Territorial Ministries of Health and Health Canada.
Dietary patterns are associated with plasma total homocysteine (tHcy) concentrations in healthy populations, but the associations between dietary protein and tHcy, total cysteine (tCys) in high risk populations are unclear. We therefore examined the association between dietary protein and tHcy and tCys concentrations in coronary angiographic subjects.
We conducted a cross-sectional study of 1015 Chinese patients who underwent coronary angiography (40–85 y old). With the use of food-frequency questionnaires, we divided the total protein intakes into high animal-protein and high plant-protein diets. Circulating concentrations of tHcy and tCys were simultaneously measured by high-performance liquid chromatography with fluorescence detection.
We found that high animal-protein diet was positively associated with hyperhomocysteinemia after adjustment for potential confounders, with the subjects in the highest quartile of intake having the greatest increase in risk (OR: 4.14, 95% CI: 2.67-6.43), whereas high plant-protein diet was inversely related to hyperhomocysteinemia, with a higher intake being protective. Compared with the first quartile of intake, the adjusted OR was 0.59 (95% CI: 0.38-0.91) for the fourth quartile. The total protein intake was positively associated with the risk of hypercysteinemia and the participants in highest quartile had significant OR of 1.69 (95% CI: 1.02-2.87) compared with those in lowest quartile. In multivariate linear regression analyses, high animal-protein and total-protein intakes were positively associated with plasma tHcy and tCys concentrations. The plant-protein intake was a negative determinant of plasma tHcy concentrations.
High animal-protein diet was positively associated with high tHcy concentrations, whereas high plant-protein diet was inversely associated with tHcy concentrations. Furthermore the total protein intake was strongly related to tCys concentrations.
Diet; Dietary protein; Total homocysteine; Total cysteine; Coronary artery disease
High total plasma homocysteine (tHcy) is associated with increased risk of cardiovascular events and depression. Consumption of B-vitamins (B6, B9 and B12) reduces tHcy by about 15%, but has equivocal effects on these health outcomes, suggesting that this relationship is either not causal or is confounded by other factors. The results of recent randomized trials suggest that antiplatelet therapy may confound these associations. This cross-sectional study assessed 3687 men aged 69–87 years for history of clinically significant depression (Geriatric Depression Scale 15 items ⩾7) or a recorded diagnosis of depression in the Western Australian Data Linkage System, and collected information on the use of aspirin, B-vitamins and antidepressant medication, along with age, education, living arrangements, smoking history and medical comorbidity as assessed by the Charlson index. Participants donated a blood sample for the measurement of tHcy, and concentrations⩾15 μmol l−1 were considered high. Five hundred and thirteen (13.9%) men showed evidence of depression, and of those 31.4% had high tHcy, 41.5% were using aspirin, 6.8% were consuming B-vitamins. Multivariate logistic regression showed that high tHcy was associated with increased odds of depression (odds ratio (OR)=1.60, 95% confidence interval (CI)=1.20–2.14), as was the use of B-vitamins (OR=1.95, 95% CI=1.21–3.13). There was a significant interaction between high tHcy and aspirin use (OR=0.57, 95% CI=0.36–0.91), but not between high tHcy and B-vitamin use (OR=0.80, 95% CI=0.26–2.46). The analyses were adjusted for smoking status, Charlson index and use of antidepressants. The results of this study indicate that older men with high tHcy who use aspirin have lower risk of depression, and suggest that antiplatelet therapy may be an effective preventive or management strategy for these cases. Randomized trials are required to confirm the antidepressant effect of aspirin in people with high tHcy.
ageing; aspirin; B-vitamins; cardiovascular disease; depression; homocysteine
Low folate and high homocysteine (Hcy) concentrations are associated with pregnancy-related pathologies such as spina bifida. Polymorphisms in folate/Hcy metabolic enzymes may contribute to this potentially pathogenic biochemical phenotype.
The study comprised 26 Caucasian and 23 African-American premenopausal women. Subjects gave fasting blood samples for biochemical phenotyping and genotyping. Total Hcy (tHcy) and both plasma and red blood cell (RBC) folate derivatives [i.e. tetrahydrofolate (THF), 5-methylTHF (5-MTHF), and 5,10-methenylTHF (5,10-MTHF)] were measured using stable isotope dilution liquid chromatography, multiple reaction monitoring, mass spectrometry. Eleven polymorphisms from nine folate/Hcy pathway genes were genotyped. Tests of association between genetic, lifestyle, and biochemical variables were applied.
In African American women, tHcy concentrations were associated (p<0.05) with total RBC folate, RBC 5-MTHF, B12, and polymorphisms in methionine synthase (MTR) and thymidylate synthase (TYMS). In Caucasian women, tHcy concentrations were not associated with total folate levels, but were associated (p<0.05) with RBC THF, ratios of RBC 5-MTHF: THF, and polymorphisms in 5,10-methylenetetrahydrofolate reductase (MTHFR) and MTR . In African Americans, folate derivative levels were associated with smoking, B12, and polymorphisms in MTR, TYMS, methionine synthase reductase (MTRR), and reduced folate carrier1 (RFC1). In Caucasians, folate derivative levels were associated with vitamin use, B12, and polymorphisms in MTHFR, TYMS, and RFC1.
Polymorphisms in the folate/Hcy pathway are associated with tHcy and folate derivative levels. In African American and Caucasian women, different factors are associated with folate/Hcy phenotypes and may contribute to race-specific differences in the risks of a range of pregnancy-related pathologies.
Genetics; folate; homocysteine; women; reproductive age; spina bifida risk
The amino acid intermediate homocysteine (Hcy) is formed during the metabolism of methionine to cysteine. Hyperhomocysteinemia (HHcy) is recognized as an independent risk factor for coronary atherosclerosis. The circulating levels of total Hcy (tHcy) can increase due to intake of foods rich in methionine or deficiencies of vitamins such as folate, pyridoxine and cyanocobalamin, which are required for the metabolism of Hcy. In addition, mutations in the genes coding for Hcy metabolizing enzymes can contribute to an increase in tHcy levels. Clinical and epidemiological studies have shown that an elevated level of tHcy measured in serum or plasma is a strong predictor of cardiovascular disease risk, which appears to be greatest in patients who have HHcy following a methionine load. Intimal hyperplasia (IH) (intima/media [I/M] ratio) is the universal response of a vessel to injury and may result in vasoconstriction when left unattended. The effect of dietary HHcy on balloon catheter-injured carotid artery and its modulation (if any) by the peroxisome proliferator-activated receptor agonist gamma rosiglitazone was evaluated in 12-week-old female Sprague-Dawley rats fed either a control diet or a diet containing 1% L-methionine. Once the rats were established on the diet, the group that was fed 1% L-methionine was further subdivided and either given an aqueous preparation of 3 mg/kg/day rosiglitazone or the vehicle via oral gavage for one week. This was followed by surgically injuring the left carotid artery using a Maverick Over-The-Wire catheter (2.0 mm × 20 mm, 3.2F; Boston Scientific, USA). The rats were continued on their respective diets and drug regimen for 21 days postsurgery. On day 22 of the procedure, the rats were sacrificed for collection of blood, the carotid arteries and liver for biochemical and histological evaluation. Compared with controls there was a significant increase in both tHcy levels and I/M ratio in the rats fed 1% L-methionine (5.4±0.28 μM versus 32.8±3.01 μM, P<0.002; and 0.175±0.05 versus 1.05±0.23, P<0.005, respectively). The effect of rosiglitazone in rats fed the control diet was not prominent. On the other hand, administration of rosiglitazone to the rats on the 1% L-methionine diet significantly reduced the levels of serum tHcy (16.6±2.1 μM versus 32.8±3.01 μM, P<0.001); however, the tHcy levels remained significantly elevated compared with animals on the control diet (P<0.002). The group receiving the L-methionine diet plus rosiglitazone had an inhibition in the development of IH compared with those receiving the L-methionine diet alone (I/M of 0.278±0.041 versus 1.05±0.23, P<0.01). Moreover, the development of IH in the group receiving the L-methionine diet plus rosiglitazone treatment was not significantly different from that observed in the group on the control diet without rosiglitazone (0.278±0.041 versus 0.175±0.05, respectively). These findings may have important implications in deciphering the molecular mechanisms involved in the augmentation of IH in HHcy and modulation of this process by rosiglitazone.
Carotid; Hyperhomocysteinemia; Metabolism; Methionine; Vasoconstriction
Methionine (Met) loading increases total plasma homocysteine (tHcy) and assesses homocysteine metabolism. We tested the hypothesis that pre- or post-Met tHcy will predict recurrent stroke or coronary artery disease (CAD) in a subgroup analysis of the Vitamin Intervention for Stroke Prevention (VISP) trial. VISP subjects with non-disabling stroke underwent measurement of tHcy at baseline (fasting pre- and post-Met load) and were randomized to high/low-dose B-vitamin therapy for prevention of recurrent stroke or CAD. In the sample cohort of 2,124 subjects, mean ± SD tHcy levels in µmol/L were: pre-Met 13.2 ± 4.3, post-Met 30.4 ± 9.76, and pre/post-Met Δ 17.1 ± 8.3. The hazard ratio (HR) for recurrent stroke was 1.16 (p=0.026) for 1 SD higher pre-Met tHcy and 1.15 (p=0.054) for 1 SD higher post-Met tHcy. For CAD, the HR for 1 SD higher pre-Met tHcy was 1.27 (p=0.001) and was 1.00 (p=0.99) for post-Met tHcy. In survival analyses using pre- or post-Met as covariates, the coefficient of pre/post-Met Δ was not significant for stroke and was only marginally significant for CAD (p<0.08), but was negative. We conclude that fasting, pre-Met tHcy is as effective as post-Met tHcy or pre/post-Met Δ in predicting the risk for stroke and CAD.
Homocyst(e)ine; Methionine; Vitamins; Stroke; Myocardial Infarction
Background: Hyperhomocysteinemia is a risk factor for vascular diseases. This study aimed to investigate the serum total homocysteine (tHcy) level and nutritional status in elderly inpatients and determine the relationship between tHcy level and nutritional status. Methods: This cross sectional study was carried out in the Tongji hospital, and 142 subjects were consecutively recruited. Fasting blood was collected, and the liver and kidney function, blood glucose, glycosylated hemoglobin (HbA1c), plasma protein, lipid profile, folic acid, vitamin B12 and serum total tHcy were measured. Anthropometric measurements, grip strength and the shortened MNA form (MNA-SF) were used to assess the nutritional status. Results: Undernutrition was common in this population. Based on MNA-SF scores, 34.2% of subjects were at risk of malnutrition, and malnourished subjects accounted for 4.9%. The mean tHcy was 14.10±5.46 μmol/l, and the prevalence of hyperhomocysteinemia was 32.4% (46/142). Hyperhomocysteinemia was a risk factor of cerebral infarction (RR=1.636, 95% CI: 1.169-2.288); Serum tHcy was negatively correlated with serum folic acid, vitamin B12 and MNA-SF score (r=-0.348,P=0.000; r=-0.236, P=0.005; r=-0.208, P=0.014), and positively with BMI within normal range (18.5-23.9; r=0.232, P=0.044). Serum tHcy was negatively correlated with HbA1c, (r=-0.196, P=0.021) and positively with serum creatinine (r=0.327, P=0.000), but unrelated to fasting blood glucose (r=-0.098, P=0.250). Multivariate stepwise regression analysis showed serum folic acid, serum creatinine, MNA-SF score and HbA1c were independent determinants of serum tHcy. Conclusion: Elderly subjects have higher serum tHcy level. Compromised renal function, poor nutritional status and lower blood glucose are likely to influence the serum tHcy level.
Homocysteine; nutritional status; MNA-SF; HbA1c
To evaluate the relation between plasma homocysteine (tHcy) and brain MRI in a community-based sample.
Elevated tHcy levels have been associated with an increased risk of dementia and stroke, but it is uncertain if the mediating mechanisms are predominantly cellular, vascular or both.
Our sample comprised 1965 Framingham Offspring participants (1050 women; age 62±9 yrs) who were free of clinical stroke, dementia, or other neurological disease affecting brain MRI and who had at least one measurement of plasma tHcy (1991-2001) and a brain MRI (1999-2002). We used multivariable regressions to relate initial (1991-95) and concurrent (1998-2001) plasma tHcy concentrations to total cerebral brain volume (TCBV) and lobar volumes as measures of neuronal loss and atrophy; and to the presence or absence of silent brain infarcts (SBI) and extensive white matter hyperintensity (log-WMH ≥1 SD above the age-adjusted mean) as separate measures of vascular injury.
Mean TCBV was 78%. 218 participants had SBI; 250 had extensive WMH. Participants with a plasma tHcy level in the highest age-, sex-specific quartile had a smaller TCBV (-0.37% and -0.48%; p=0.01 and <0.001 respectively), compared to participants with lower levels. Initial tHcy levels were associated with an increased prevalence of SBI (RR: 1.5; 95% CI: 1.1-2.1; p=0.02) and concurrent tHcy levels with smaller frontal and temporal lobar volumes (-0.14% and -0.10%; p=0.001 and 0.04 respectively). Prevalence of extensive WMH did not differ according to initial or concurrent plasma tHcy levels (RR: both 1.0, 95% CIs: 0.7-1.4 and 0.8-1.4, respectively).
Higher plasma tHcy levels are associated with smaller brain volumes and presence of silent infarcts on MRI, even in healthy, middle-aged adults. Thus, both cellular and vascular mechanisms may underlie the association of plasma tHcy with brain aging, as reflected by the effects on subclinical as well as overt disease.
magnetic resonance imaging; homocysteine; brain volume; silent brain infarcts; white matter hyperintensity; epidemiology
Circulating homocysteine levels (tHcy), a product of the folate one carbon metabolism pathway (FOCM) through the demethylation of methionine, are heritable and are associated with an increased risk of common diseases such as stroke, cardiovascular disease (CVD), cancer and dementia. The FOCM is the sole source of de novo methyl group synthesis, impacting many biological and epigenetic pathways. However, the genetic determinants of elevated tHcy (hyperhomocysteinemia), dysregulation of methionine metabolism and the underlying biological processes remain unclear. We conducted independent genome-wide association studies and a meta-analysis of methionine metabolism, characterized by post-methionine load test tHcy, in 2,710 participants from the Framingham Heart Study (FHS) and 2,100 participants from the Vitamin Intervention for Stroke Prevention (VISP) clinical trial, and then examined the association of the identified loci with incident stroke in FHS. Five genes in the FOCM pathway (GNMT [p = 1.60×10−63], CBS [p = 3.15×10−26], CPS1 [p = 9.10×10−13], ALDH1L1 [p = 7.3×10−13] and PSPH [p = 1.17×10−16]) were strongly associated with the difference between pre- and post-methionine load test tHcy levels (ΔPOST). Of these, one variant in the ALDH1L1 locus, rs2364368, was associated with incident ischemic stroke. Promoter analyses reveal genetic and epigenetic differences that may explain a direct effect on GNMT transcription and a downstream affect on methionine metabolism. Additionally, a genetic-score consisting of the five significant loci explains 13% of the variance of ΔPOST in FHS and 6% of the variance in VISP. Association between variants in FOCM genes with ΔPOST suggest novel mechanisms that lead to differences in methionine metabolism, and possibly the epigenome, impacting disease risk. These data emphasize the importance of a concerted effort to understand regulators of one carbon metabolism as potential therapeutic targets.
Elevated homocysteine (tHcy) is strongly associated with risk for common disorders such as stroke, cardiovascular disease and Alzheimer disease. Lowering tHcy levels has proven to have variable success in reducing clinical risk, so the question remains, “Are we correctly targeting these disorders by lowering tHcy?” Understanding folate one-carbon metabolism pathway (FOCM) genetic variation will aid us in developing new targets for therapy. The FOCM is essential in regulation of the epigenome, which controls genes in ways beyond nucleotide sequence. We present data generated from stroke-only and general populations where we identify strong association of genetic risk factors for variation in one-carbon metabolism function, characterized by the post-methionine load test. We show that GNMT harbors genetic and epigenetic differences that influence gene function, which may have downstream effects on the epigenome of the cell, affecting disease risk. We developed a genetic risk score that predicts post-methionine load homocysteine levels that may be useful in clinic. Finally, we identified a novel association between ischemic stroke and ALDH1L1, which emphasizes the clinical importance of this work. Our results highlight the importance of a concerted effort to target the FOCM (beyond tHcy) and parallel pathways in future pharmacogenetic work using the genetic variation we describe here.
Nitrous oxide inactivates vitamin B12, inhibits methionine synthase and consequently increases plasma total homocysteine (tHcy). Prolonged exposure to nitrous oxide can lead to neuropathy, spinal cord degeneration and even death in children. We tested the hypothesis that nitrous oxide anesthesia causes a significant increase in plasma tHcy in children.
Twenty-seven children (age 10-18 years) undergoing elective major spine surgery were enrolled and serial plasma samples from 0 – 96 hours after induction were obtained. The anesthetic regimen, including the use of nitrous oxide, was at the discretion of the anesthesiologist. Plasma tHcy was measured using standard enzymatic assays.
The median baseline plasma tHcy concentration was 5.1 μmol/L (3.9 – 8.0 μmol/L, interquartile range) and increased in all patients exposed to nitrous oxide (n=26) by an average of +9.4 μmol/L (geometric mean; 95% CI 7.1 – 12.5 μmol/L) or +228% (mean; 95% CI 178% - 279%). Plasma tHcy peaked between 6-8 hours after induction of anesthesia. One patient who did not receive nitrous oxide had no increase in plasma tHcy. Several patients experienced a several-fold increase in plasma tHcy (max. +567%). The increase in plasma tHcy was strongly correlated with the duration and average concentration of nitrous oxide anesthesia (r= 0.80; p<0.001).
Pediatric patients undergoing nitrous oxide anesthesia develop significantly increased plasma tHcy concentrations. The magnitude of this effect appears to be greater compared to adults; however, the clinical relevance is unknown.
Increased plasma total homocysteine (tHcy) and high sensitivity C-reactive protein (hsCRP) levels are independent risk factors for cardiovascular disease. However, the predictive value of tHcy in combination with hsCRP in patients with stroke is not known. To determine the relationship between tHcy and hsCRP, we enrolled 291 patients with first-onset stroke (196 ischemic and 95 hemorrhagic). Plasma tHcy and hsCRP levels were measured and subsequent vascular events and deaths were determined over a 5-year period. Using the arbitrary cutoff for tHcy (<18 μmol/L and ≥18 μmol/L) and hsCRP (<1 mg/L, 1–3 mg/L and >3 mg/L), the patients were divided into 6 groups. Survival analysis showed that the probability of death or new vascular events during a 5-year follow-up increased according to tHcy and hsCRP levels (P<0.01). The relative risk (RR) of death or new vascular events was 4.67 (95% CI, 1.96 to 11.14, P=0.001) in patients with high tHcy (≥18 μmol/L) and hsCRP (>3 mg/L) compared with those with low tHcy (<18 μmol/L) and hsCRP (<1 mg/L). The increased tHcy level (≥18 μmol/L) combined with increased hsCRP level (>3 mg/L) was still significantly associated with the risk of death or new vascular events (RR, 4.10, 95% CI, 1.61 to 10.45, P=0.003) even when adjusted for other risk factors at inclusion. The combination of increased tHcy and hsCRP levels had a stronger predictive value than increased hsCRP alone or increased tHcy level alone. Further studies are required to evaluate the potential decrease in risks associated with lowering both Hcy and hsCRP levels in patients that present with both increased tHcy and hsCRP.
homocysteine; C-reactive protein; inflammation; stroke
The aim of this study was to investigate the determinants of serum total homocysteine level (tHcy) in patients with type 2 diabetes mellitus (DM) according to sex.
A total of 1,276 Japanese, diabetics (n = 280) with a control group of non-diabetics (n = 996), were enrolled into the study from 2003 to 2005. This cross-sectional study was conducted for all the subjects, using personal data regarding clinical characteristics and lifestyle. Multiple regression analysis was performed to analyze the association of tHcy with selected factors.
In diabetic subjects, estimated glomerular filtration rate (eGFR) and serum creatinine levels (Cre), even those within the normal range, were strongly associated with tHcy after adjustment in both sexes; the standardized partial regression coefficient of eGFR for tHcy was −0.251, (p = 0.001) in diabetic men and −0.523, (p < 0.001) in diabetic women. Furthermore, the eGFR of the diabetics, except patients with nephropathy, also had significant association with tHcy in both sexes. Fasting plasma glucose levels and serum triglyceride levels were strongly associated with tHcy in diabetic men only. HbA1c was also associated with tHcy in diabetic men only, though not as significantly. Age and presence of hypertension were significantly associated with tHcy in women.
This study suggests that there are some differences in the factors associated with tHcy between diabetics and non-diabetics, and between the sexes. There is, therefore, circumstantial evidence that elevated tHcy should be evaluated clinically. Because tHcy was strongly associated with eGFR and Cre, even within the normal ranges, tHcy may have important implications regarding the microangiopathy of the kidney and atherosclerosis.
Homocysteine; Type 2 diabetes mellitus; Lifestyle; Estimated glomerular filtration rate; Serum creatinine
Many available data have suggested that hyperhomocysteinaemia, an established independent risk factor for thrombosis (arterial and venous), may be associated with an increased risk of retinal vein occlusion (RVO).
Aim of the study
To evaluate homocysteine metabolism in consecutive caucasian patients affected by RVO from Northern Italy.
Patients and Methods
69 consecutive patients from Northern Italy (mean age 64.1 ± 14.6 yy) with recent RVO, were tested for plasma levels of homocysteine (tHcy: fasting and after loading with methionine), cyanocobalamine and folic acid levels (CMIA-Abbot) and looking for MTHFR C677T mutation (Light Cycler-Roche) and compared to 50 volunteers, enrolled as a control group.
Fasting levels of tHcy were significantly higher in patients than in controls: mean value 14.7 ± 7.7 vs 10.2 ± 8 nmol/ml. Post load levels were also significantly higher: mean value 42.7 ± 23.7 vs 30.4 ± 13.3 nmol/ml; Total homocysteine increase was also evaluated (i.e. Δ-tHcy) after methionine load and was also significantly higher in patients compared to control subjects: mean Δ-tHcy 27.8 ± 21.5 vs 21.0 ± 16 nmol/ml (normal value < 25 nmol/ml). Furthermore, patients affected by RVO show low folic acid and/or vitamin B12 levels, although differences with control group did not reach statistical significance. Heterozygous and homozygous MTHFR mutation were respectively in study group 46% and 29% vs control group 56% and 4%.
our data confirm that hyperhomocysteinaemia is a risk factor for RVO, and also that TT genotype of MTHFR C677T is more frequently associated with RVO: if the mutation per se is a risk factor for RVO remains an open question to be confirmed because another study from US did not reveal this aspect.
Hyperomocysteinemia is modifiable risk factor for thrombotic diseases. Therefore, a screening for tHcy plasma levels in patients with recent retinal vein occlusion could allow to identify patients who might benefit from supplementation with vitamins and normalization of homocysteine levels, in fasting and after methionine load.
retinal vein occlusion; thrombophilia; homocysteine; MTHFR C677T; folic acid
Few data have been published on the association of variables of the insulin resistance syndrome and serum total homocysteine (tHcy), a putative risk factor for cardiovascular morbidity, in representative samples of total populations or in Hispanic Americans.
To describe the distributions of serum tHcy concentration and variables associated with insulin resistance in Mexican American men and to assess their association, data from a cross-sectional survey of a large national sample, the Third National Health and Nutrition Examination Survey were analyzed. Analyses were restricted to Mexican American men aged 40–74 years with data on glycated hemoglobin (%), body mass index (BMI), body fat distribution, HDL cholesterol, fasting serum insulin, serum triglycerides and serum tHcy concentrations.
Cumulative distributions of serum tHcy shifted to the right with increasing age. Log serum tHcy was not associated with prevalence of diagnosed diabetes mellitus or glycated hemoglobin percent or other risk factors other than age. Log serum tHcy concentration showed borderline significant (p = 0.049) positive association with fasting serum insulin concentration independent of age and BMI, only in men aged 60–74.
No consistent association of tHcy with diabetes prevalence or variables of the insulin resistance syndrome were found in Mexican American men aged 40–74 years. Further research is needed on the associations of serum tHcy concentration with insulin resistance and other components of the insulin resistance syndrome in persons of varying ethnicity.
Total homocysteine; serum; Hispanics; glucose tolerance; insulin; serum; diabetes mellitus; Obesity.
Hypothyroidism is associated with an increased risk for cardiovascular disease, which can not be fully explained by the atherogenic lipid profile, particularly total cholesterol and LDL-C, and other pathogenic factors may be involved. Plasma total homocysteine (tHcy) is an independent risk factor for cardiovascular disease and accelerated atherosclerosis. The aim of this study was to investigate the serum total homocysteine (tHcy) levels and its relation to total cholesterol, creatinine and thyroid hormones fT3, fT4 and TSH levels in overt hypothyroid patients compared to control subjects. In this study thirty recently diagnosed, non-treated overt hypothyroid patients (f=27, m=3) and twenty normal volunteers control (f=18, m=2) were included and subjected to determination of serum tHcy by enzyme immunoassay (EIA) technique, fT3, fT4 and TSH by Elecsys cobas e 601 analyzer, total cholesterol by enzymatic method and creatinine by kinetic method. The data was statistically analysed by SPSS-10 and p values less than 0.05 were considered significant.Our results showed that there were a significant increase of tHcy, TSH, T.cholesterol and creatinine levels by 113%, 12-folds, 58% and 54%, respectively, and a significant decrease of fT4 and fT3 levels by 49.6% and 56.4% , respectively, in hypothyroid patients than in control group. For tHcy (Mean±SD, 24.45±5.50 μmol/l vs 11.48±3.03 μmol/l, respectively; P < 0.001). tHcy was significantly positively correlated with TSH, creatinine and age and negatively correlated with free thyroxine (fT4) and no significant correlations with fT3 and T.cholesterol. In conclusion, our study confirmed the observation of elevated serum tHcy, T.cholesterol and creatinine in overt hypothyroidism and the presence of an inverse relation between tHcy with fT4 and a positive relation with TSH.
Hypothyroidism; Homocysteine; Cardiovascular disease; Atherosclerosis; Cholesterol; Creatinine; Thyroxine; Triiodothyronine; Thyroid stimulating hormone
Plasma total homocysteine (tHcy) is commonly elevated in persons with diabetes. This may be due to effects of insulin and/or glucose and/or metabolic control on the metabolism or plasma levels of tHcy. This study examined the effects of fasting plasma glucose status on fasting tHcy levels among adults without diabetes, and diabetes per se among adults with a self-report history of diabetes.
Analysis of data on adults (≥ 20y) who had fasted at least 8 hours, from the National Health and Nutrition Examination Survey (1999–2000 and 2001–2002). Subjects with no self-report history of diabetes were grouped according to fasting plasma glucose status as normal (< 100 mg/dL = NFG, n = 2,244), impaired (≥ 100 < 126 mg/dL = IFG, n = 1,108), or a provisional diagnosis of diabetes (≥ 126 mg/dL = DFG, n = 133). Subjects with a self-report history of diabetes (n = 275) were examined separately.
Fasting tHcy was higher (Ps < 0.01) among non-diabetic subjects with DFG and IFG, compared to NFG (median [95% confidence interval] = 8.6 [8.0–9.2], 8.3 [8.1–8.5], and 7.4 [7.3–7.5] μmol/L, respectively). Diabetic subjects had levels similar to non-diabetic subjects with DFG and IFG (8.3 [7.9–8.6] μmol/L). Age and estimated creatinine clearance were strong correlates of fasting tHcy among non-diabetic subjects (r = 0.38 to 0.44 and r = -0.35 to -0.46, respectively) and diabetic subjects (r = 0.41 and r = -0.46, respectively) (Ps < 0.001), while fasting glucose and glycohemoglobin (HbA1c) were weaker (but still significant) correlates of tHcy in non-diabetic and diabetic subjects. Fasting glucose status was not a significant independent predictor of fasting tHcy levels in non-diabetic subjects, and HbA1c was not a significant independent predictor of tHcy in diabetic subjects (Ps > 0.05).
Fasting tHcy levels are elevated among non-diabetic adults with elevated fasting glucose levels, compared to persons with normal fasting glucose levels, and among diabetic adults. However, elevations in fasting tHcy appear to be mediated primarily by age and kidney function, and not by measures of glucose metabolism.
Although elevated levels of C-reactive protein (CRP), interleukin (IL)-6, serum amyloid A protein (SAA) and total homocysteine (tHcy) have been associated with the increased likelihood of cardiovascular events, the relative or combined utility of these biomarkers in predicting atherosclerosis and death in an angiography cohort is unknown.
A cohort of 1117 consecutive patients (797 men and 320 women), referred to 2 Vancouver teaching hospitals for selective coronary angiography, was recruited between 1993 and 1995. Angiography results were obtained for 1019 patients. In 2004 we determined that of 1050 patients who could be traced, 231 had died, 95 of CAD-related causes. We compared the relative utility of baseline measurements of CRP, IL-6, SAA and tHcy as well as of lipids for predicting angiographic CAD and all-cause and CAD-related death.
The risk of death increased across quartiles for CRP, IL-6, SAA and tHcy. When comparing the highest and lowest quartiles, the greatest hazard ratios were associated with IL-6 (2.57, 95% confidence interval [CI] 1.62–4.09) and tHcy (2.36, 95% CI 1.53–3.65). A Cox regression model containing all plasma biomarkers and traditional risk factors indicated that age, angiographic CAD and baseline plasma levels of IL-6 and tHcy remained independent predictors of CAD-related death, whereas age, sex, smoking, diabetes and apolipoprotein B levels were independent predictors of angiographic CAD. Kaplan–Meier survival curves indicated a utility in combining measures of CRP, SAA, IL-6 and tHcy for predicting risk of all-cause and CAD-related death.
A comparison of elevated levels of CRP, IL-6, SAA and tHcy with traditional CAD risk factors indicated that IL-6 and tHcy were the strongest independent biomarkers for CAD-related death. Elevated levels of multiple biomarkers were associated with an increasing rate of all-cause and CAD-related death.
BACKGROUND—Raised levels of total plasma homocysteine (tHcy) are associated with an increased risk of retinal vascular occlusive disease. A thermolabile form of a pivotal enzyme in homocysteine metabolism, methylenetetrahydrofolate reductase (MTHFR), has been associated with vascular occlusive disease and raised tHcy levels. The relation between thermolabile MTHFR genotype, tHcy, and retinal vascular occlusive disease has not been determined.
METHODS—A retrospective case-control study involving hospital based controls and cases with retinal vascular occlusions in whom tHcy levels had been determined was undertaken. Genotyping for the MTHFR 677 C-T mutation that specifies the thermolabile form of the enzyme was performed by established methods in all subjects. The relation between homozygosity for thermolabile MTHFR genotype (TT), raised tHcy levels, and risk of retinal vascular occlusive disease was examined.
RESULTS—87 cases of retinal vascular occlusive disease (mean age 68.7 years) comprising 26 cases of retinal artery occlusion and 61 of retinal vein occlusion were compared with 87 controls (mean age 70.2 years). The TT genotype did not confer a significantly increased risk of retinal vascular occlusive disease. The mean tHcy level was significantly higher in the cases than in the controls (p<0.0001). Overall, and in both the cases and controls, the frequency of the TT genotype was higher in those with normal tHcy levels than in those with increased levels of tHcy. However, the TT genotype did not significantly alter the risk of increased tHcy levels in these patients.
CONCLUSIONS—The TT genotype is not associated with an increased risk of retinal vascular occlusive disease or increased tHcy levels in this group of elderly patients. In older patients, nutritional rather than genetic factors may be more important in increasing tHcy levels, a known risk factor for retinal vascular occlusive disease.
Elevated plasma homocysteine (tHcy) and the MTHFR c.677C > T variant have been postulated to increase the risk of venous thromboembolism (VTE), although mechanisms and implications to pediatrics remain incompletely understood. The objectives of this study were to determine the prevalences of elevated tHcy and MTHFR variant in a pediatric population with VTE or arterial ischemic stroke (AIS), and to determine associations with thrombus outcomes.
Subjects were enrolled in an institution-based prospective cohort of children with VTE or AIS. Inclusion criteria consisted of objectively confirmed thrombus, ≤21 years at diagnosis, tHcy measured and MTHFR c.677C > T mutation analysis. Clinical and laboratory data were collected. Frequencies for elevated tHcy and MTHFR variant were compared with NHANES values for healthy US children and also between study groups (VTE vs AIS, provoked vs idiopathic) and by age.
The prevalences of hyperhomocysteinemia or MTHFR variant were not increased in comparison to NHANES. tHcy did not differ between those with wild-type MTHFR versus either c.677C > T heterozygotes or homozygotes. There was no association between tHcy or MTHFR variant and thrombus outcomes.
In this cohort of US children with VTE or AIS, neither the prevalence of hyperhomocysteinemia nor that of MTHFR variant was increased relative to reference values, and adverse thrombus outcomes were not definitively associated with either. While it is important to consider that milder forms of pyridoxine-responsive classical homocystinuria will be detected only by tHcy, we suggest that routine testing of MTHFR c.677C > T genotype as part of a thrombophilia evaluation in children with incident thromboembolismis not warranted until larger studies have been performed in order to establish or refute a link between MTHFR and adverse outcomes.
MTHFR c.677C >T; Hyperhomocysteinemia; Venous thromboembolism; Arterial ischemic stroke; Children; Thrombophilia
Objective: Cigarette smoking is associated with reduced pulmonary function and increased risk factors for cardiovascular disease. This randomized placebo-controlled double-blind study evaluated the effects of two different combinations of mixed fruit and vegetable juice powder concentrate (Juice Plus+, NSA, Collierville, TN) on heavy smokers.
Methods: At baseline (T0) and after 3 months’ supplementation (T1), pulmonary function parameters and cardiovascular risk factors—that is, plasma total homocysteine (tHcy) with related B vitamins and cysteine (tCys) concentrations—were assessed in 75 apparently healthy smokers (aged 49.2 ± 10.6 years, 20 cigarettes/d, duration > 10 years) randomized into 3 groups: placebo (P), fruit/vegetable (FV) and fruit/vegetable/berry (FVB).
Results: T0: most smokers showed abnormalities in tHcy and tCys concentrations. T1: respiratory function was unchanged in P and slightly, but not significantly, improved in FV, whereas FVB showed a significant improvement in forced expiratory flow at 25% (FEF25; p < 0.0001 vs P and FV) and significant improvement in CO diffusion lung/alveolar volume (DLCO/VA). FV and FVB (50%) showed significant reduction in tHcy and tCys compared to T0 (p < 0.0001) and P (p < 0.0001).
Conclusions: At T1, both supplemented groups, but to a greater extent the FVB group, showed improvements in some pulmonary parameters, cardiovascular risk factors, and folate status. The beneficial effects of Juice Plus+ supplementation could potentially help smokers, even if smoking cessation is advisable.
tobacco; homocysteine; cysteine; folate; nutraceutical
The role of circulating levels of total homocysteine tHcy in the development of coronary heart disease (CHD) is still under debate. One reason for conflicting results between previous studies on homocysteine and heart diseases could be consequence of different interactions between homocysteine and genes in different study populations. Many genetic factors play a role in folate-homocysteine metabolism, like functional polymorphism (Val108Met) in the Catechol-O-methyltransferase (COMT) gene.
Methodology and Findings
Our aim was to examine the role of COMT Val158Met polymorphism and interaction of this polymorphism with serum tHcy and folate concentration on the risk of acute coronary and events in middle-aged men from eastern Finland. A population-based prospective cohort of 792 men aged 46–64 years was examined as part of the Kuopio Ischaemic Heart Disease Risk Factor Study. During an average follow-up of 9.3 years, there were 69 acute coronary events in men with no previous history of CHD. When comparing the COMT low activity genotype with the others, we found an age and examination year adjusted hazard rate ratio (HRR) of 1.73 (95% confidence interval (CI), 1.07–2.79), and an age, examination year, serum LDL and HDL cholesterol, and triglyceride concentration, systolic blood pressure and smoking adjusted HRR of 1.77 (95% CI, 1.05–2.77). Although serum tHcy concentration was not statistically significantly associated with acute coronary events (HRR for the highest third versus others 1.52, 95% CI, 0.93–2.49), subjects with both high serum tHcy and the COMT low activity genotype had an additionally increased adjusted risk of HRR 2.94 (95% CI 1.50–5.76) as compared with other men.
This prospective cohort study suggests that the functional COMT Val158Met polymorphism is associated with increased risk of acute coronary events and it may interact with high serum tHcy levels.
Elevated plasma total homocysteine (tHcy) concentration has been associated with an increased risk for cardiovascular events in type 2 diabetic individuals independent of conventional risk factors. Available study in Nigerian-Africans is scare.
Seventy (30 males) and (40 females) type 2 diabetes mellitus, with age mean of 54 ± 11.52 years were selected for this study and thirty apparently healthy volunteers were included as controls. The biochemical parameters and anthropometric indices were determined using standard procedures.
Significant increases were obtained in body weight, body mass index (p<0.001) and waist circumference (p<0.012) when compared with the corresponding control values respectively. The fasting plasma glucose (p<0.01), tHcy (p<0.02), and triglyceride (p<0.03) were significantly higher in the diabetes group when compared with the corresponding control values. The plasma folic acid and vitamin B12 (p<0.05) were significantly reduced compared to the control values. The tHcy (p<0.01) was significantly higher in the males when compared with the corresponding female value. Significant decrease was obtained in the plasma triglyceride (p<0.003) in the male patients when compared with the female patients.
Our result showed increased plasma tHcy, triglyceride and waist circumference as well as decreased folic acid and vitamin B12 in type 2 diabetes mellitus. These alterations are risk factors for premature CVD events.
Type 2 diabetes; glucose; folic acid; homocysteine; high density lipoprotein; cardiovascular disease; triglyceride; vitamin B12
To investigate the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C genotypes and plasma concentrations of total homocysteine (tHcy) in Pakistani patients with primary open angle glaucoma (POAG) and primary closed angle glaucoma (PCAG).
This was a prospective case-control study. A total of 295 patients (173 POAG, 122 PCAG) and 143 age- and sex-matched controls were subdivided into two ethnic groups, Punjabis (Punjab province, central Pakistan) and Pathans (North-West Frontier Province, northern Pakistan). Genotypes of the MTHFR C677T and A1298C polymorphisms were detected by polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP). An enzyme-linked immunosorbent assay was used to determine the total serum homocysteine (tHcy) levels. Associations were determined by logistic regression analysis.
Frequency distributions of genotypes and combined genotypes as well as homocysteine levels were obtained. The overall distribution of the C677T genotype was found to be significantly associated with PCAG (CC 69%, CT 21%, TT 10%; p=0.001, χ2=12.6), but not with POAG (CC 71%, CT 28%, TT 1%; p=0.98, χ2=0.02) as compared to the controls (CC 71%, CT 29%, TT 1%). The Pathan cohorts revealed no association with the disease; however, the Punjabis demonstrated a significant association with PCAG (CC 75%, CT 11%, TT 13%; p<0.001, χ2=17.2). PCAG in the Punjabi subjects was also significantly associated with the A1298C polymorphism (AA 43%, AC 54%, CC 3%; p<0.001, χ2=33.9) as compared to the controls. Combined genotype data showed no association with POAG; however, a significant association with all combined genotypes was observed in the overall PCAG subjects (p<0.05, χ2=20.1). This difference was particularly apparent in the TTAA and TTAC combinations that were completely absent in the control groups (p<0.05. χ2=49.6). Mean serum tHcy levels were found to be significantly increased in the POAG (15.2±1.28 µmol/l, p<0.001) and PCAG (20.8±4.8 µmol/l) groups as compared to the controls (10.0±0.97 µmol/l). The tHcy levels in the TT and AC genotype were significantly elevated in the PCAG group (67±12.39 µmol/l, p<0.001; 23±5.94 µmol/l, p=0.027) as compared to the controls.
The TT and AC genotypes of MTHFR C677T and A1298C polymorphisms and the combined genotype TTAC were associated with PCAG in Punjabi subjects of Pakistani origin and correlated with the high serum tHcy levels seen in these patients.