Helicobacter pylori eradication lowers serum homocysteine level in patients without gastric atrophy

The Correlation between Helicobacter pylori Immunoglobulin G Seropositivity and Plasma Homocysteine Levels in Adults

Objectives

Helicobacter pylori (H. pylori) immunoglobulin G (IgG) seropositivity is prevalent, but its correlation with homocysteine (Hcy), a biomarker of vascular risk events, is unclear. This study is aimed at exploring the correlation of H. pylori IgG seropositivity and plasma Hcy levels in adults.

Methods

Data was obtained from the National Health and Nutrition Examination Survey (NHANES) cycle 1999-2000. Hcy was measured by the Abbott homocysteine assay, and H. pylori IgG was measured by enzyme-linked immunosorbent assays. The weighted multiple logistic regression analyses with adjustments for potential confounders were conducted. Subgroup analyses stratified by gender, age, and race were performed.

Results

A total of 4029 subjects aged 20-85 years were included. Population prevalence of H. pylori IgG seropositivity was 44.7% in the overall population with higher prevalence found in those with older age, Mexican Americans, lower education, and lower household income. Levels of plasma Hcy were not elevated in those with H. pylori IgG seropositivity versus seronegativity (β -0.120 (-0.438, 0.199) P = 0.462). This difference was not significant after stratifying by gender and age. However, in the subgroup analyses stratified by race, a negative correlation between H. pylori seropositivity and plasma Hcy levels was observed in Mexican Americans (β -0.802 (-1.253, -0.352) P < 0.001).

Conclusions

H. pylori IgG seropositivity was not associated with plasma Hcy levels in the general population, but there may be a negative correlation in Mexican Americans. These findings provide new insights to advance the research of the link between plasma Hcy levels and stomach health.

Extracellular vesicles from helicobacter pylori-infected cells and helicobacter pylori outer membrane vesicles in atherosclerosis

BACKGROUND

The role of H. pylori infection has been reported in various extragastric diseases, particularly, the correlation between H. pylori and atherosclerosis (AS) have received lots of attention. Some scholars demonstrated that the presence of H. pylori-specific DNA in the sclerotic plaques of atheromatous patients provides biological evidences, with indicating that H. pylori infection is a potential factor of AS. However, the underlying mechanism of H. pylori or their products cross the epithelial barriers to enter the blood circulation remains unclear. Recent studies have shown that the extracellular vesicles (EVs) derived from H. pylori-infected gastric epithelial cells encapsulated H. pylori virulence factor cytotoxin-associated gene A (CagA) and existed in the blood samples of patients or mice, which indicating that they can carry CagA into the blood circulation. Based on these findings, some researchers proposed a hypothesis that H. pylori is involved in the pathogenesis of AS via EVs-based mechanisms. In addition, outer membrane vesicles (OMVs) serve as transport vehicles to deliver H. pylori virulence factors to epithelial cells. It is necessary to discuss the role of H. pylori OMVs in the development of AS.

OBJECTIVES

This review will focus on the correlation between H. pylori infection and AS and tried to unveil the possible role of EVs from H. pylori-infected cells and H. pylori OMVs in the pathogenesis of AS, with a view to providing help in refining our knowledge in this aspect.

METHODS

All of information included in this review was retrieved from published studies on H. pylori infection in AS.

RESULTS

H. pylori infection may be an atherosclerotic risk factor and drives researchers to reevaluate the role of H. pylori in the pathogenesis of AS. Some findings proposed a new hypothesis that H. pylori may be involved in the pathogenesis of AS through EVs-based mechanisms. Besides EVs from H. pylori-infected cells, whether H. pylori OMVs may play some role in the pathogenesis of AS is still remain unclear.

CONCLUSION

Existing epidemiological and clinical evidence had shown that there is a possible association between H. pylori and AS. However, except for the larger randomized controlled trials, more basic research about EVs from H. pylori-infected cells and H. pylori OMVs is the need of the hour to unveil the possible role of H. pylori infection in the pathogenesis of AS.

Vitamins and Helicobacter pylori: An Updated Comprehensive Meta-Analysis and Systematic Review

Background

Over recent decades, epidemiological studies have shown relationships between vitamins and Helicobacter pylori (H. pylori) infection and eradication, but the results are controversial.

Methods

A comprehensive meta-analysis and systematic review were conducted to clarify the relationships between common types of vitamins and H. pylori. We applied meta-regression, subgroup analysis and sensitivity analysis to obtain available evidence. Articles published from January 1991 to June 2021 in PubMed, EMBASE, and the Cochrane Library were searched.

Results

In total, we identified 48 studies. The results indicate that H. pylori -positive patients had lower serum vitamin B₁₂ [standardized mean difference (SMD) = −0.30; 95% confidence interval (CI): −0.53 – −0.08], folate (SMD = −0.69; 95% CI: −1.34 – −0.04), vitamin C (SMD = −0.37; 95%CI: −0.57 – −0.18) and vitamin D (SMD = −0.34; 95% CI: −0.49 – −0.18) levels than H. pylori-negative patients. Patients in which H. pylori had been successfully eradicated had higher serum vitamin D levels (SMD = 1.37; 95% CI: 0.37–2.38) than in patients in which eradication had been unsuccessful. The serum vitamin B₁₂ levels of H. pylori-positive patients improved after successful H. pylori eradication therapy (SMD = 1.85; 95% CI: 0.81–2.90), and antioxidant vitamin supplementation to an H. pylori eradication regimen improved the eradication rate (risk ratio = 1.22; 95% CI: 1.02–1.44 for per-protocol analysis; risk ratio = 1.25; 95% CI: 1.06–1.47 for intention-to-treat analysis).

Conclusions

H. pylori infections decrease the serum levels of several types of vitamins, eradication of H. pylori could rescue its adverse effects, and antioxidant vitamin supplementation may improve the H. pylori eradication rate.

Systematic Review Registration

identifier: CRD42021268127.

The relationship between Helicobacter pylori and chronic kidney disease: update 2020

A number of studies has confirmed that the epidemiology of Helicobacter pylori is changing worldwide, with a decrease especially in developed countries. Nevertheless, since this gram-negative bacterium infects almost 50% of the world's population, it remains a global problem. Beyond its role in the pathogenesis of the main gastroduodenal diseases, including gastritis, peptic ulcer and gastric cancer, Helicobacter pylori has been suspected to be involved in several extra-gastroduodenal disorders. Patients with chronic kidney disease (CKD) present gastric mucosal injuries and dyspepsia more often than the general population. However, the reported relationship between CKD and Helicobacter pylori infection is conflicting. In fact, in this population these conditions have a multifactorial pathogenesis and Helicobacter pylori infection could play a limited role in their development. Nevertheless, while it seems that the prevalence of the bacterium is lower in patients with CKD than in controls, Helicobacter pylori has been shown to be associated to an increased occurrence of proteinuria in patients with type 2 diabetes mellitus. This narrative review analyzes the results of recent literature in this field with particular focus on data reported by meta-analyses.

Standard triple therapy in Helicobacter pylori eradication in Turkey: Systematic evaluation and meta-analysis of 10-year studies

BACKGROUND/AIMS

This study aims at evaluating the mean eradication rate by a systematic compilation of the studies which involved the standard triple therapy (STT) in first-line Helicobacter pylori (Hp) eradication in Turkey over a period of 10 years between 2004 and 2013 using the meta-analysis method.

MATERIALS AND METHODS

The systematic compilation and meta-analysis were carried out according to the PRISMA standards defined in the Cochrane handbook. The results of full-text studies published in national and international journals in English and Turkish languages on Turkish population in a period of 10 years, from 2004 to 2013, are included in this study. The studies include open-label trials, controlled trials, treatment arms, and case series that included a triple therapy regimen consisting of standard doses of a proton pump inhibitor (PPI; omeprazole 20 mg BID, lansoprazole 30 mg BID, pantoprazole 40 mg BID, esomeprazole 40 mg BID, or rabeprazole 20 mg BID) along with clarithromycin 500 mg BID and amoxicillin 1 g BID for 7-14 days. They were scanned electronically via the search engines Google Scholar, PubMed, and the Turkish Medicine Index using specific keywords. The related keywords used were Turkey, Helicobacter pylori, infection, standard triple treatment, first-line therapy, eradication, omeprazole, lansoprazole, pantoprazole, rabeprazole, esomeprazole, clarithromycin, and amoxicillin. Studies carried out with adults were included in the evaluation. The publication year of the studies and the included number of patients, their age, gender, treatment duration (7, 10, and 14 days), and PPIs used were evaluated by two separate gastroenterologists and biostatisticians. Studies that used at least one reliable method (histology, urea breath test (UBT), or Helicobacter pylori stool antigen (HpSA) test) four weeks after completing the treatment for the control of Hp eradication were included. Only naive patients were accepted, and patients who had previously received eradication treatment were excluded. The effectiveness of the Hp eradication was analyzed using an intention-to-treat (ITT) or per-protocol (PP) analysis.

RESULTS

The STT regime of 45 studies complying with the inclusion criteria was evaluated. A total of 3715 patients were included in the study. Of the 3010 patients whose gender information was available, 55% were women and 45% were men; the weighted age average given explicitly in the studies was 42.14±0.67. The treatment lasted for 14 days in 42 studies, for 7 days in six studies, and for 10 days in 1 study. The eradication rates evaluated according to the ITT and PP analyses were 60% (95% CI: 56%-63%) and 57% (95% CI: 51%-62%), respectively. The rates for 7 days of treatment were 57% (95% CI: 46%-68%) and 60% (95% CI: 51%-67%) and for 14 days of treatment were 60% (95% CI: 56%-63%) and 56% (95% CI: 50%-62%), respectively. The ITT eradication rate of the only 10-day study was 78% (95% CI: 66%-86%). In the meta-regression analysis, the treatment duration, PPI, age, and gender ratio (women/men) used for the ITT analysis had no effect. The gender ratio and age were not considered in this analysis because they were not clearly stated in studies using the PP analysis. The duration of treatment and the PPI used had no effect.

CONCLUSION

A systematic meta-analysis of studies conducted during the period 2004-2013 in Turkey revealed that the rate of first-line Hp eradication using STT was unacceptably low, and the duration of treatment and PPI used made no difference.

Helicobacter pylori Infection is Associated with Occurrence of Proteinuria in Type 2 Diabetes Patients: A Systemic Review and Meta-Analysis

BACKGROUND

Type 2 diabetes (T2DM) patients are susceptible to Helicobacter pylori (HP), and it has been reported that the occurrence of proteinuria is associated with HP infection in T2DM patients; however, this view remains controversial. This meta-analysis aimed to explore the association between HP infection and the occurrence of proteinuria in T2DM patients. In addition, we hope to provide some recommendations to readers in clinical or related fields.

METHODS

Our meta-analysis was conducted with the methodology of the Cochrane Collaboration. Search strategies were formulated by relevant professionals. Case-control studies that compared the occurrence of proteinuria in T2DM patients with and without HP infection were involved in our meta-analysis. Relevant English or Chinese studies were searched on online databases before 2018, including PubMed, the Cochrane library, Medline, Google Scholar, the China National Infrastructure, and Wanfang database. The search strategies were "diabetic proteinuria, diabetic microalbuminuria, diabetic albuminuria, diabetic kidney disease, diabetic renal dysfunction, diabetic renal disease, diabetic nephropathy, diabetic complications, and diabetic mellitus, combined with HP." The quality of these involved articles was separately assessed by two investigators using the Newcastle-Ottawa Scale (NOS). Odds ratios (ORs) and associated 95% confidence intervals (CIs) were extracted and pooled using fixed-effects models.

RESULTS

Seven studies involving 1029 participants were included. The quality of these seven articles was all above five stars as assessed by NOS, and there was no significant publication bias in our meta-analysis. We found that T2DM patients with HP infection had a 2.00 times higher risk of the occurrence of proteinuria than patients without HP infection (OR: 2.00, 95% CI: 1.48-2.69).

CONCLUSIONS

Our analysis showed that HP infection was associated with the occurrence of proteinuria in T2DM patients. HP radical surgery might be a therapeutic option for protecting kidney function in patients with T2DM.

Clinical Manifestations of Isolated Elevated Homocysteine-Induced Peripheral Neuropathy in Adults

OBJECTIVE

To characterize the clinical features of isolated elevated plasma homocysteine (eHcy)-induced peripheral neuropathy (IHIN) in adults.

METHODS

Charts of subjects with the diagnosis of IHIN who visited neuromuscular clinic from January 01, 2012 to September 30, 2014 were reviewed. Subjects with identifiable etiologies for neuropathy, such as B12/folate deficiency; metabolic, toxic, endocrinologic, infectious/inflammatory renal or liver diseases; or traumatic nerve injury, were excluded. Their clinical presentations were recorded and analyzed.

RESULTS

Thirty subjects (age: 63.2 ± 14.8 years, 13 males) were included. They all had an isolated increased homocysteine level (15.4 ± 5.3 μmol/L) but normal levels of B12, folate, and methylmalonic acid. Of 30, 14 (46.7%) had numb feet, 11 (36.7%) had numb hands, 7 (23.3%) had pain in lower extremities, and 10 (33.3%) had tingling in feet. Distal sensory deficits were present in 18/30 (60%) patients. Distal limb weakness was seen in 4 and decreased tendon reflexes in 12 patients.

CONCLUSIONS

Sensory deficits are predominant components of IHIN. Characterizing clinical features of IHIN would help better understand eHcy-related neuropathy and improve its management.

Helicobacter pylori seropositivity's association with markers of iron, 1-carbon metabolism, and antioxidant status among US adults: a structural equations modeling approach

Objectives

We tested a model in which Helicobacter pylori seropositivity (Hp_s) predicted iron status, which in turn acted as a predictor for markers of 1-C metabolism that were then allowed to predict antioxidant status.

Methods

National Health and Nutrition Examination Surveys (NHANES 1999–2000) cross-sectional data among adults aged 20–85 y were analyzed (n = 3,055). Markers of Hp_s, iron status (serum ferritin and transferrin saturation (TS)); 1-C metabolism (serum folate (FOL_serum), B-12, total homocysteine (tHcy), methylmalonic acid (MMA)) and antioxidant status (vitamins A and E) were entered into a structural equations model (SEM).

Results

Predictors of Hp_s included older age, lower education and income, racial/ethnic groups (lowest among Non-Hispanic Whites), and lifetime cigarette smoking. SEM modeling indicated that Hp_s had a direct inverse relationship with iron status (combining serum ferritin and TS) which in turn was positively related to 1-C metabolites (higher serum folate, B-12 or lower tHcy/MMA) that were positively associated with antioxidant status (combining serum vitamins A and E). Another pathway that was found bypassed 1-C metabolites (Hps → Iron_st → Antiox). The sum of all indirect effects from Hp_s combining both pathways and the other indirect pathways in the model (Hps → Iron_st → OneCarbon; Hps →OneCarbon →Antiox) was estimated at β = -0.006±0.003, p<0.05.

Conclusions

In sum, of the total effect of H. pylori seropositivity on antioxidant status, two significant indirect pathways through Iron status and 1-Carbon metabolites were found. Randomized controlled trials should be conducted to uncover the concomitant causal effect of H. pylori eradication on improving iron status, folate, B-12 and antioxidant status among H. pylori seropositive individuals.

Micronutrients (Other than iron) and Helicobacter pylori infection: a systematic review

BACKGROUND

Many micronutrients depend on a healthy stomach for absorption. Helicobacter pylori chronic gastritis may alter gastric physiology affecting homeostasis of vitamins and minerals.

OBJECTIVES

Systematic review to assess whether H. pylori infection is associated with reduced micronutrient levels (other than iron) in the plasma or gastric juice and whether low micronutrient levels are modified by eradication treatment.

METHOD

Medline was searched for relevant publications from inception to June 2010. Studies describing micronutrient levels in H. pylori-infected and not-infected adults and/or the effect of eradication treatment on micronutrient levels were included.

FINDINGS

Fifty-two publications were selected: 46 investigated the association between H. pylori infection and reduced micronutrient levels and 14 the effect of eradication treatment on micronutrient levels. Sixty-four studies investigated vitamins (23 ascorbic acid, four ß-carotene, 21 cobalamin, 11 folate, and five α-tocopherol) and 10 addressed minerals (one calcium, one copper, one magnesium, one phosphorus, three selenium, and three zinc). Pooled standardized mean differences in micronutrient levels showed positive associations with H. pylori infection for ascorbic acid (gastric juice, -1.087) and cobalamin (-0.744), and a positive effect of eradication treatment, which increased ascorbic acid in the gastric juice (-1.408) and serum cobalamin (-1.910). No significant association between infection and low folate levels was observed. Meta-analyses for other micronutrients were not performed owing to insufficient data.

CONCLUSIONS

Meta-analyses indicate that H. pylori infection is associated with reduced levels of ascorbic acid and cobalamin, supported by the positive effect of eradication treatment. For other micronutrients, further studies are needed.

Homocysteine levels in chronic gastritis and other conditions: relations to incident cardiovascular disease and dementia

BACKGROUND

Homocysteine levels in circulation are determined by several factors and hyperhomocysteinemia is reportedly associated with cardiovascular diseases and dementia. The aim of this study is to determine the relation of chronic gastritis and other conditions to homocysteine levels and their relation to incident cardiovascular diseases and dementia.

METHODS

An adult population-based cohort (N = 488) was screened for H. pylori infection, gastro-duodenitis (endoscopic biopsies), disease history, and lifestyle factors. Blood samples were analyzed for pepsinogen I and II (gastric function), vitamin B12, folate, homocysteine, and cystatin C (renal function). The methylenetetrahydrofolate reductase C677T polymorphism reportedly associated with hyperhomocysteinemia was analyzed by pyrosequencing. Incident cardiovascular diseases and dementia were monitored during a median follow-up interval of 10 years.

RESULTS

At baseline, there was a positive relation of S-homocysteine to male gender, age, S-cystatin C, methylenetetrahydrofolate reductase 677TT genotype and atrophic gastritis. During follow-up, cardiovascular diseases occurred in 101/438 and dementia in 25/488 participants, respectively. Logistic regression analysis (adjusting for gender, age at baseline, follow-up interval, BMI, smoking, alcohol consumption, NSAID use, P-cholesterol, and P-triglycerides) showed an association of S-homocysteine higher than 14.5 mumol/l to cardiovascular diseases (OR 2.05 [95% c.i. 1.14-3.70]), but not to dementia overall.

CONCLUSIONS

Gender, age, vitamin B12, folate, renal function, atrophic gastritis and the methylenetetrahydrofolate 677TT genotype were significant determinants of homocysteine levels, which were positively related to incident cardiovascular diseases.

Vascular risks and complications in diabetes mellitus: the role of helicobacter pylori infection

Patients with diabetes mellitus (DM) are at risk for Helicobacter pylori infection. This infection has been linked to atherosclerosis and its vascular complications. The aim of this study was to evaluate the: (1) prevalence of H pylori infection in patients with DM; (2) association between diabetic vascular complications and H pylori infection; and (3) influence of H pylori infection on atherosclerosis and inflammatory biomarkers. In this study, we evaluated 80 patients with DM for atherosclerosis; cardiac, cerebral, and peripheral vascular diseases; retinopathy; neuropathy; and nephropathy. We estimated the blood levels of glucose, glycosylated hemoglobin, complete blood cell count, erythrocytic sedimentation rate, lipid profile, tumor necrosis factor-alpha, interleukin (IL)-6, and anti-H pylori IgG antibodies. H pylori infection was detected in 85% of patients versus 76.7% for control subjects. Carotid artery intima-media thickness was significant in H pylori-infected patients. IL-6 and tumor necrosis factor-alpha were significantly associated with H pylori infection. In multivariate analysis, blood glucose, triglycerides, erythrocytic sedimentation rate, IL-6, and tumor necrosis factor-alpha increased the odds for atherothrombotic cause of cerebral ischemia in H pylori infection. We concluded that H pylori infection is common in DM and seems to be linked to the presence of atherosclerosis and ischemic cerebrovascular stroke. This effect could be mediated by increasing cytokine levels.

Neural tube defects, micronutrient deficiencies, and Helicobacter pylori: a new hypothesis

BACKGROUND

Previous findings for the Texas Neural Tube Defects Project suggested that while maternal access to nutrients is adequate, bioavailability of nutrients to the fetus is compromised in NTD-affected pregnancies. Helicobacter pylori could cause nutrient loss to the fetus. Folate, B12, and ferritin are depleted in H. pylori infection; these same deficiencies are related to NTD risk.

METHODS

Using H. pylori IgG ELISA Test System, we tested for H. pylori serum antibodies in participants in the population-based case-control study component of the Texas Neural Tube Defect Project conducted along the Texas-Mexico border. Case-women had pregnancies affected by NTD (anencephalus, spina bifida, encephalocele) and resided and delivered in one of the 14 Texas-Mexico border counties from 1995 through 2000. Control-women were study area residents delivering normal live births during the same period.

RESULTS

Of 225 case- and 378 control-women, 103 cases and 156 controls provided questionnaire and H. pylori antibody data. H. pylori seropositivity was modestly associated with NTD-affected pregnancies (OR 1.4; 95% CI: 0.8-2.4). ORs of 2.0 or greater were seen in women younger than age 25 and with less than 7 years education.

CONCLUSIONS

Our findings intimate that H. pylori could play a role in NTD causation in certain populations. While results did not provide compelling support for this proposal, subgroup findings prompt us to advocate an evaluation of this hypothesis in developing nations among populations with higher prevalence of H. pylori, marginal nutrient intake, and young childbearing age.

Elevated homocysteine levels in patients with slow coronary flow: relationship with Helicobacter pylori infection

BACKGROUND AND OBJECTIVE

Elevation of plasma homocysteine (Hcy) level has been implicated in the pathogenesis of slow coronary flow (SCF) as it can severely disturb vascular endothelial function. Helicobacter pylori chronically infect the human stomach and causes malabsorption of vitamin B(12) and folate in food, leading ultimately to an increase in circulating Hcy levels.

METHODS

Forty-three patients with angiographically proven SCF (group I) were enrolled in this study; 43 cases with normal coronary flow pattern (group II) served as controls. Fasting plasma levels of Hcy, vitamin B(12), and folate were measured in all subjects. Presence of H. pylori infection was defined as positive 14 C urea breath test. Coronary flow patterns for each major epicardial coronary artery were determined with the Thrombolysis in Myocardial Infarction (TIMI) frame count method.

RESULTS

Mean TIMI frame count was 46.3 +/- 8.7 in group I and 24.3 +/- 2.9 in Group II (p = .0001). Vitamin B(12) levels were similar, whereas folate levels were dramatically reduced in group I compared to group II (13.2 +/- 4.3 vs. 17.1 +/- 5.2, p = .0001). Plasma Hcy levels were significantly higher in group I compared to group II (13.4 +/- 5.6 vs. 7.9 +/- 2.5, p = .0001) as was the prevalence of H. pylori infection (90.7% in group I vs. 58.1% in group II, p = .001). Hcy levels were elevated (11.7 +/- 5.3 vs. 7.5 +/- 2.7, p = .0001) and folate levels were reduced (13.9 +/- 4.7 vs. 18.6 +/- 4.9, p = .0001) in patients with H. pylori infection, while vitamin B(12) levels were similar in patients with and without H. pylori infection. Correlation analysis revealed a significant negative correlation between plasma folate and Hcy levels and also between folate levels and mean TIMI frame counts (r = -.33, p = .002 vs. r = -.33, p = .003). Moreover, there was a significant positive correlation between plasma Hcy levels and mean TIMI frame counts (r = .66, p = .0001). In addition, the folate level was the only significant determinant of the variance of Hcy in multiple regression analysis (r = -.21, p = .03).

CONCLUSION

Our data showed that plasma folate levels were decreased and plasma Hcy levels were increased in patients with SCF compared to controls. Also, the prevalence of H. pylori infection was increased in patients with SCF. These findings suggest that elevated levels of plasma Hcy, possibly caused by H. pylori infection, and/or a possible disturbance in its metabolism may play a role in the pathogenesis of SCF.

No associations of Helicobacter pylori infection and gastric atrophy with plasma total homocysteine in Japanese

Recent studies have suggested that Helicobacter pylori (H. pylori) infection might be a risk factor for atherosclerosis. Since the bacterium has not been isolated from atherosclerotic lesions, a direct role in atherogenesis is not plausible. We examined associations of plasma total homocysteine (tHcy) and serum folate, independent risk factors for atherosclerosis, with H. pylori infection and subsequent gastric atrophy among 174 patients (78 males and 96 females) aged 20 to 73 years, who visited an H. pylori eradication clinic of Nagoya University from July 2004 to October 2005. Polymorphism genotyping was conducted for methylenetetrahydrofolate reductase (MTHFR) C677T and thymidylate synthase (TS) 28-bp tandem repeats by PCR with confronting two-pair primers and PCR, respectively. H. pylori infection and gastric atrophy were not significantly associated with hyperhomocysteinemia (tHcy > or = 12 nmol/ml), when adjusted by sex, age, smoking, alcohol, and genotypes of MTHFR and TS. The adjusted odds ratio of gastric atrophy for low folate level (< or = 4 mg/ml) was 0.21 (95% confidence interval = 0.05-0.78). The associations of tHcy with serum folate and MTHFR genotype were clearly observed in this dataset. The present study demonstrated that folate and MTHFR genotype were the deterministic factors of plasma tHcy, but not H. pylori infection and subsequent gastric atrophy, indicating that even if H. pylori infection influences the risk of atherosclerosis, the influence may not be through the elevation of homocysteine.