Israel Medical Association Journal

Background: Low folate levels are associated with megaloblastic anemia, neural tube defects, and an increased risk of cancer. Data are scarce regarding the sex aspect of this deficiency.

Objectives: To assess sex differences in folate levels in a large cohort of patients and to investigate the effect of low folate levels on homocysteine concentrations.

Methods: Data were collected from medical records of patients examined at a screening center in Israel between 2000 and 2014. Cross sectional analysis was conducted on 9214 males and 4336 females.

Results: The average age was 48.4 ± 9.5 years for males and 47.6 ± 9.4 years for females. Average folate levels were 19.2 ± 8.6 and 22.4 ±10.3 nmol/L in males and females, respectively (P < 0.001). The prevalence of folate levels below 12.2 nmol/L was 19.5% in males compared to 11.6% in females (P < 0.001). In patients with low folate levels and normal B12 levels, homocysteine levels above 15 μmol/L were found in 32.4% of males and 11.4% of females (P < 0.001). Males had a significantly higher odds ratio (OR) of having folate levels below 12.2 nmol/L: OR 1.84 (95% confidence interval [95%CI] 1.66–2.05) in a non-adjusted model, and OR 2.02 (95%CI 1.82–2.27) adjusted for age, smoking status, body mass index, kidney function, albumin, and triglycerides levels.

Conclusions: Folate levels are lower in males compared to females, which may contribute to the higher homocysteine levels found in males and thus to their increased risk of developing atherosclerosis and coronary artery disease.

Abstract

Background: Hyperhomocysteinemia is associated with increased cardiovascular risk, but treatment with folic acid has no effect on outcome in unselected patient populations.

Objectives: To confirm previous observations on the association of homozygosity for the TT MTHFR genotype with B12 deficiency and endothelial dysfunction, and to investigate whether patients with B12 deficiency should be tested for 677MTHFR genotype.

Methods: We enrolled 100 individuals with B12 deficiency, tested them for the MTHFR C677T polymorphism and measured their homocysteine levels. Forearm endothelial function was checked in 23 B12-deficient individuals (13 with TT MTHFR genotype and 10 with CT or CC genotypes). Flow-mediated dilatation (FMD) was tested after short-term treatment with B12 and folic acid in 12 TT MTHFR homozygotes.

Results: Frequency of the TT MTHFR genotype was 28/100 (28%), compared with 47/313 (15%) in a previously published cohort of individuals with normal B12 levels (P = 0.005). Mean homocysteine level was 21.2 ± 16 mM among TT homozygotes as compared to 12.3 ± 5.6 mM in individuals with the CC or CT genotype (P = 0.008). FMD was abnormal (£ 6%) in 9/13 TT individuals with B12 deficiency (69%), and was still abnormal in 7/12 of those tested 6 weeks after B12 and folic treatment (58%).

Conclusions: Among individuals with B12 deficiency, the frequency of the TT MTHFR genotype was particularly high. The TT polymorphism was associated with endothelial dysfunction even after 6 weeks of treatment with B12 and folic acid. Based on our findings we suggest that B12 deficiency should be tested for MTHFR polymorphism to identify potential vascular abnormalities and increased cardiovascular risk. 

Background: High levels of plasma homocysteine constitute a risk for cardiovascular disease. Physical activity, known to reduce CVD[1] risk, has been related to levels of Hcy[2]. Recently, higher Hcy was shown to be associated with lower cardiovascular fitness in women but not in men.

Objectives: To further explore the relationship between cardiorespiratory fitness and plasma total homocysteine levels in a large cohort of adult males and females.

Methods: This cross-sectional study included 2576 fitness and Hcy examinations in adults (62% males) aged 30–59 years, randomly drawn from a population undergoing a periodic health examination in the Sheba Medical Center's Executive Screening Survey. Blood tests were collected for tHcy[3] and a sub-maximal exercise test was performed to estimate cardiorespiratory fitness. Information on CVD/CVD risk factors (coronary heart disease, cerebrovascular accident, diabetes, hypertension or dyslipidemia) was self-reported.

Results: Mean tHcy plasma levels were 14.4 ± 7.7 and 10.2 ± 3.0 µmol/ml, and mean maximal oxygen uptake 36.5 ± 11.7 and 29 2 ± 9.5 ml/kg/min for males and females, respectively. A multiple regression analysis, adjusting for age, body mass index and CVD/CVD risk factors, showed no association between cardiorespiratory fitness and level of tHcy in males (P = 0.09) or in females (P = 0.62).

Conclusions: In this sample no relationship was found between level of cardiorespiratory fitness and plasma tHcy in men or women. The inconsistency of findings and the small number of studies warrant further research of the association between cardiorespiratory fitness and tHcy, an association that may have clinical implications for the modifications of cardiovascular risk factors.

Background: The etiology of chest pain with normal epicardial coronary arteries (cardiac syndrome X) seems to be related to endothelial cell dysfunction. Multiple factors are implicated in the pathophysiology, including evelated levels of homocysteine in the blood. Mutations in the MTHFR gene are associated with evelated levels of homocysteine.

Objectives: To test whether abnormal homocysteine metabolism is associated with syndrome X.

Methods: Forty-two women with chest pain, positive stress test and normal coronary arteries (syndrome X) and 100 asymptomatic women (controls) were studied for the C677T mutation. Vitamin B12, folic acid, and plasma levels of homocysteine were also measured. Endothelial cell function was studied in 10 patients with syndrome X and homozygosity for C677T mutation, and in 10 matched healthy controls. Folic acid (5 mg daily) was prescribed to syndrome X patients after initial measurements of ECF[1]. Following 13 weeks of treatment, ECF and blood tests were repeated and compared to baseline measurements.

Results: Homozygosity for C677T mutation was doubled in syndrome X vs. control (33%, 14/42 vs. 16%, 16/100, P < 0.02), and homocysteine levels were increased (9.16 ± 2.4 vs. 8.06 ± 2.6 μmol/L, P = 0.02). In the 10 homozygous patients, homocysteine levels decreased significantly after treatment with 5 mg/day folic acid (10 ± 3.3 vs. 5.4 ± 1.1 µmol/L, P = 0.004). Abnormal baseline ECF improved after treatment with folic acid: flow-mediated dilatation was greater (11.3 ± 7.9% vs. 0.7 ± 4.5%, P < 0.002), as was nitroglycerin-mediated dilatation (15.2 ± 9.0% vs. 5.6 ± 6.4%, P < 0.003). Frequency of chest pain episodes was significantly reduced after 13 weeks of folic acid treatment.

Conclusion: Our findings establish the association between the C677T mutation, endothelial cell dysfunction and cardiac syndrome X, and provide a novel and simple therapy for a subset of patients with syndrome X and homozygosity for the C677T mutation.

Background: Hyperhomocysteinemia is a well-recognized risk factor for accelerated atherosclerosis in hemodialysis patients.

Objectives: To examine the effects of two doses of vitamins B6 and B12 and folic acid on homocysteine levels in hemodialysis patients and assess the functional impact of the methylenetetrahydrofolate reductase genotype on the response to treatment.

Methods: In a randomized prospective study, we assessed the effects of folic acid and two doses of B-vitamins in 50 hemodialysis patients with hyperhomocysteinemia. Patients were divided into two groups: 26 patients (group A) who received 25 mg of vitamin B₆ daily and one monthly injection of 200 µg vitamin B12, and 24 patients (group B) who received 100 mg of vitamin B6 daily and one monthly injection of 1,000 µg vitamin B12. In addition, both groups received 15 mg folic acid daily. Patients were evaluated for homocysteine levels as well as for coagulation and a thorough lipid profile. Baseline Hcy[1] levels were determined after at least 4 weeks washout from all folic acid and B-vitamins that were given. MFTHR[2] alleles were analyzed, as were activated protein C resistance, von Willebrand factor and lupus anticoagulant.

Results: Basal plasma Hcy levels were significantly elevated in hemodialysis patients compared with normal subjects (33.8 ± 4.3 vs. 4.5 to 14.0 mmol/L). Following treatment, Hcy levels were significantly reduced to 21.2 ± 1.6 in group A and 18.6 ± 1.4 mmol/L in group B (P < 0.01). There was no difference in Hcy reduction following the administration of either high or low dosage of vitamins B6 and B12 utilized in the present study. There was no correlation between Hcy levels or thrombophilia and high incidence of thrombotic episodes in hemodialysis patients. Genotypic evaluation of MTHFR revealed that the presence of homozygous thermolabile MTHFR (n = 5) was associated with higher Hcy levels and better response to treatment (Hcy levels decreased by 58%, from 46.2 ± 14.6 to 19.48 ± 4.1 mmol/L following treatment). In patients with heterozygous thermolabile MTHFR (n = 25), Hcy levels decreased by 34%, from 31.2 ± 3.7 to 18.1 ± 1.1 mmol/L following treatment. The efficacy of high and low doses of B-vitamins on the reduction of homocysteine levels was comparable.

Conclusions: Treatment with B-vitamins in combination with folic acid significantly decreased homocysteine levels in hemodialysis patients, independently of the tested doses. In addition, mutations in MTHFR were associated with elevated plasma levels of Hcy. Neither vascular access nor.

Background: A high total plasma homocysteine level is an independent risk factor for cardiovascular and cerebrovascular disease, but the evidence connecting plasma tHcy level with hypertension is inconsistent.

Objective: To determine the association between plasma tHcy level and some common risk factors for cerebrovascular disease (recurrent  stroke, diabetes mellitus, hypertension, ischemic heart disease and hyperlipidemia) in patients presenting with primary or recurrent acute ischemic strokes.

Methods: This retrospective cross-sectional chart analysis was conducted in a university-affiliated referral hospital. During an 18 month period we identified 113 acute ischemic stroke patients (mean age 71.2), 25 of whom had a recurrent stroke. Plasma tHcy[1] level, obtained 2–10 days after stroke onset, was determined by the high performance liquid chromatography method with fluorescence detection. A multivariate logistic regression model was used to determine the independent relationship between each potential risk factor and tHcy level above or below the 75th percentile.

Results:  Hypertension was more frequent among patients with plasma tHcy level above than below the 75th percentile (51.7% vs. 80.8%, respectively, P = 0.012). After adjusting for demographic and clinical variables, the odds ratio for recurrent stroke and hypertension, with tHcy above or below the 75th percentile, was 3.4 (95% confidence interval 1.01–10.4, P = 0.037) and 4.02 (95% CI[2] 1.2–13.9, P = 0.028), respectively.

Conclusions: A high plasma tHcy level is associated with history of hypertension and recurrent stroke among patients presenting with acute ischemic stroke. These results were independent of other risk factors such as atrial fibrillation, diabetes and hyperlipidemia. Hypertensive stroke patients with hyperhomocysteinemia should be identified as high risk patients as compared to non-hypertensive stroke patients, and may warrant more vigorous measures for secondary prevention.

Background: Obesity is among the well-established risk factors for cardiovascular morbidity and mortality. However, the exact mechanisms are not well understood. Low concentrations of vitamins (fat soluble antioxidants and B vitamins) are linked to accelerated atherosclerosis through increased oxidative stress and homocysteine.

Objective: To compare plasma antioxidant vitamins (carotenoids and vitamin E), B vitamins (folic acid and B12) and homocysteine – all linked to increased cardiovascular morbidity – between patients with severe obesity and lean control subjects.

Methods: We investigated plasma carotenoids, vitamin E, folic acid, B12, and homocysteine in 25 obese patients and their age-matched controls (body mass index 38 ± 3 vs. 21 ± 2 kg/m²), respectively), related to BMI[1] and plasma insulin.

Results: Patients with obesity had normal B vitamins and a non-significant decrease in plasma homocysteine as compared to controls (9.4 ± 2.6 vs. 11.4 ± 4.8 mmol/L, P = 0.07). There was a significant decrease in both plasma carotenoids and vitamin E (0.69 ± 0.32 vs. 1.25 ± 0.72 and 24 ± 10 vs. 33 ± 14 mg/ml, respectively; P < 0.01). Both vitamins were inversely related to BMI and plasma insulin, which was significantly increased in patients with obesity (22 ± 21 vs. 6 ± 2 mU/ml, P < 0.01).

Conclusions: Obese patients with BMI above 35 kg/m² show low plasma antioxidants (carotenoids and vitamin E). This may result in increased oxidative stress and consequently enhanced atherosclerosis in these patients.

Background: Case-control and prospective studies indicate that an elevated plasma homocysteine level is a powerful risk factor for atherosclerotic vascular diseases. Certain medications can induce hyperhomocystinemia, such as methotrexate, trimethoprim and anti-epileptic drugs. There are few reports indicating an interaction between lipid-lowering drugs (cholestyramine and niacin) and homocysteine. Recently, an interaction was shown between fenofibrate and benzafibrates (a fibric acid derivative) and homocysteine plasma levels.

Objectives: To evaluate the effects of different fibrates on plasma homocysteine levels and to measure the reversibility of this effect.

Methods and Results: We investigated the effects of ciprofibrate and bezafibrate on homocysteine levels in patients with type IV hyperlipidemia and/or low high density lipoprotein levels. While a 57% increase in homocysteine was detected in the ciprofibrate-treated group (n=26), a 17% reduction n homocysteine was detected in the group treated with bezafibrate (n=12). The increase in homocysteine in the ciprofibrate-treated group was sustained for the 12 weeks of treatment and was partially reversible after 6 weeks of discontinuing the ciprofibrate therapy.

Conclusions: These results indicate that an increase In plasma homocysteine levels following administration of flbrates is not a class effect, at least in its magnitude. Moreover, it is reversible upon discontinuation of the treatment.