Low concentrations of folate, not hyperhomocysteinemia, are associated with carotid intima-media thickness

Association between dietary folate intake and severe abdominal aorta calcification in adults: A cross-sectional analysis of the national health and nutrition examination survey

BACKGROUND

Prior studies have established a connection between folate intake and cardiovascular disease (CVD). Abdominal aortic calcification (AAC) has been introduced as a good predictor of CVD events, but no previous study has investigated the relationship between dietary folate intake and severe AAC. Therefore, the study aims to explore the association between dietary folate intake and severe AAC in the United States (US) middle-aged and elderly population.

METHODS

This study employed cross-sectional data from the 2013-2014 National Health and Nutrition Examination Survey (NHANES) to examine the relationship between dietary folate intake and severe AAC. Two 24-h dietary recall interviews were conducted to assess dietary folate intake and its sources, while a DXA scan was used to determine the AAC score. To analyze the association between dietary folate intake and severe AAC, a multivariable logistic regression model was applied, and a subgroup analysis was performed.

RESULTS

Our analysis utilized data from 2640 participants aged 40 years and above, including 288 individuals diagnosed with severe AAC. After adjusting for confounding factors, we observed an inverted L-shaped association between folate intake and severe AAC. Upon further adjustment for specific confounding factors and covariates, the multivariable-adjusted odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for the second, third, and fourth quartiles of folate intake, using the first quartile as the reference, were as follows: 1.24 (0.86-1.79), 0.86 (0.58-1.27), and 0.63 (0.41-0.97), respectively. Subgroup analysis results were consistent with the logistic regression models, indicating concordant findings. Moreover, no significant interaction was observed in the subgroup analyses.

CONCLUSIONS

The study findings suggest an inverted L-shaped association between dietary folate intake and severe AAC. However, additional prospective investigations are necessary to explore the impact of dietary folate intake on severe AAC in patients.

Folate Reverses NF-κB p65/Rela/IL-6 Level Induced by Hyperhomocysteinemia in Spontaneously Hypertensive Rats

Hyperhomocysteinemia (HHcy) is derived from the abnormal metabolism of homocysteine (Hcy) and is related to metabolic-related diseases. In addition, HHcy combined with hypertension increases the risk of cardiovascular diseases (CVD). However, the mechanism of HHcy aggravating hypertensive arterial damage and the efficacy of folate (FA) as a beneficial supplement have not been fully elucidated. In this study, we established a rat HHcy model and a hypertension combined with HHcy model. Rat tail artery blood pressure (BP), plasma Hcy, serum superoxide dismutase (SOD), and malondialdehyde (MDA) were measured. Rat thoracic aorta was for pathological analysis after 12 weeks of the experiment. The relative expression levels of oxidative stress and immune/inflammation in rat arterial tissues were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. The results demonstrated that the relative expression levels of oxidative stress and immune/inflammation were the highest in the hypertension combined with HHcy group, followed by the hypertension group. Compared with the hypertension group, the hypertension combined with HHcy group up-regulated the expression levels of interleukin-6 (IL-6) and nuclear factor-κ-gene binding (NF-κB) p65/Rela, but not NADPH oxidase (Nox). Furthermore, folate inhibited the expression of IL-6 and NF-κB p65/Rela, reduced the levels of MDA and HHcy, but significantly increased the SOD level. In conclusion, HHcy synergistically aggravated the arterial damage factor of hypertension through immune/inflammatory response. However, folate demonstrated anti-inflammatory properties and reversed the NF-κB p65/Rela/IL-6 level induced by HHcy in hypertensive rats.

Red blood cell folate and severe abdominal aortic calcification: Results from the NHANES 2013-2014

BACKGROUND AND AIMS

Abdominal aortic calcification (AAC) has been introduced as a good predictor of cardiovascular disease (CVD) events, but no previous study has investigated the relationship between folate levels and AAC. The present study aims to explore the relationship between red blood cell (RBC) folate, a better indicator reflecting long-term folate intake, and severe AAC in the United States (US) middle-aged and elderly population.

METHODS AND RESULTS

Cross-sectional data were derived from the National Health and Nutrition Examination Survey (NHANES) 2013-2014 of 2818 men and women aged 40 years or older. Multivariable logistic regression models were used to determine odds ratios (ORs) and 95% confidence intervals (CIs) for severe AAC of each RBC folate quintile category. The restricted cubic spline model was used for the dose-response analysis. A U-shaped dose-response relation between RBC folate and the odds of severe AAC was found after adjustment for multiple potential confounding factors, p for nonlinear = 0.0032. With the third quintile category of RBC folate as the reference, multivariable-adjusted ORs and 95% CIs of the lowest, second, fourth, and the highest quintile categories were 2.34 (1.37-4.00), 1.24 (0.70-2.19), 1.58 (0.92-2.70), and 2.26 (1.35-3.76), respectively.

CONCLUSIONS

Individuals with either low or high levels of RBC folate were at increased risks of severe AAC in a representative sample of US adults. While folate deficiency is widely recognized as harmful, these results highlight the need to investigate the potential adverse health outcomes of high folate level.

Correlation between plasma homocysteine and first myocardial infarction in young patients: Case-control study in Constanta County, Romania

An elevated level of total plasma homocysteine has been associated with a higher risk of atherosclerosis and coronary heart disease. The aim of our research was to study the relation between homocysteine and myocardial infarction (MI) in young patients. We conducted a case-control study in Constanţa County, Romania including 61 patients, divided in two groups. The first group, the MI group, consisted of 28 patients, male (67.9%) and female (32.1%) aged less than 45 years who were consecutively admitted to the Intensive Coronary Care Unit of the Emergency County Hospital of Constanţa from September 1, 2017 to August 31, 2018 (12 months), with an established diagnosis of first acute MI. The second group, the control group, included 33 patients, male (75.8%) and female (24.2%) aged less than 45 years, with cardiovascular risk factors and/or stable angina pectoris that were consecutively addressed for ambulatory cardiac evaluation at the Outpatient Clinic of Emergency County Hospital of Constanţa during the same period. Fasting plasma homocysteine was determined in both groups, within 24 h after MI onset, respectively after first cardiac exam in the controls. High homocysteine was statistically confirmed to be a risk factor in the study group, especially in association with smoking, chronic kidney disease (CKD), and to a lesser extent with diabetes mellitus (DM) and hypertension. Data analysis was performed using IBM SPSS Statistics 23. The procedures used included descriptive statistics, parametric statistical tests (Independent sample t-test), non-parametric statistical tests [Chi-square test of the association, with the evaluation of odds ratio (OR)]; the significance level used in the analysis (P-value) was 0.05. After adjusting for variables, our study results pointed out a strong association between plasma homocysteine and first acute MI among young patients, emphasising plasma homocysteine as a possible risk factor for myocardial infarction.

Effect of increasing fruit and vegetable intake by dietary intervention on nutritional biomarkers and attitudes to dietary change: a randomised trial

PURPOSE

Low fruit and vegetable consumption is linked with an increased risk of death from vascular disease and cancer. The benefit of eating fruits and vegetables is attributed in part to antioxidants, vitamins and phytochemicals. Whether increasing intake impacts on markers of disease remains to be established. This study investigates whether increasing daily intake of fruits, vegetables and juices from low (approx. 3 portions), to high intakes (approx. 8 portions) impacts on nutritional and clinical biomarkers. Barriers to achieving the recommended fruit and vegetable intakes are also investigated.

METHOD

In a randomised clinical trial, the participants [19 men and 26 women (39-58 years)] with low reported fruit, juice and vegetable intake (<3 portions/day) were randomised to consume either their usual diet or a diet supplemented with an additional 480 g of fruit and vegetables and fruit juice (300 ml) daily for 12 weeks. Nutritional biomarkers (vitamin C, carotenoids, B vitamins), antioxidant capacity and genomic stability were measured pre-intervention, at 4-, 8- and 12 weeks throughout the intervention. Samples were also taken post-intervention after a 6-week washout period. Glucose, homocysteine, lipids, blood pressure, weight and arterial stiffness were also measured. Intake of fruit, fruit juice and vegetables was reassessed 12 months after conducting the study and a questionnaire was developed to identify barriers to healthy eating.

RESULTS

Intake increased significantly in the intervention group compared to controls, achieving 8.4 portions/day after 12 weeks. Plasma vitamin C (35%), folate (15%) and certain carotenoids [α-carotene (50%) and β-carotene (70%) and lutein/zeaxanthin (70%)] were significantly increased (P < 0.05) in the intervention group. There were no significant changes in antioxidant capacity, DNA damage and markers of vascular health. Barriers to achieving recommended intakes of fruits and vegetables measured 12 months after the intervention period were amount, inconvenience and cost.

CONCLUSION

While increasing fruit, juice and vegetable consumption increases circulating level of beneficial nutrients in healthy subjects, a 12-week intervention was not associated with effects on antioxidant status or lymphocyte DNA damage.

TRIAL REGISTRATION

This trial was registered at Controlled-Trials.com; registration ISRCTN71368072.

Green Juice in Human Metabolism: A Randomized Trial

OBJECTIVE

Fruits and vegetables contain many compounds presenting potential antioxidant activity. The objective of this study was to evaluate the effect of a green juice recipe in adult metabolism in order to identify new preventive dietary sources.

METHOD

This was a single-blind randomized controlled clinical trial. Recruitment and data were, respectively, made and collected at the Universidade Federal de Ciências da Saúde de Porto Alegre. Individuals who met all the inclusion criteria during the period of recruitment were included. Green juice (experimental group) or placebo (control group) were consumed from Monday to Friday between 8 and 9 am, in the amount of 300 mL for 60 days (except Saturdays and Sundays). To verify the effect of green juice on metabolism, the following were evaluated: (a) glycemia, plasma lipid profile, renal and liver functions, redox profile, and antioxidant enzymes; (b) anthropometry; and (c) well-being and anxiety.

RESULTS

This study included 14 participants in the test group (juice group) and 13 controls (placebo group), with mean ages of 31.07 and 30.15 years, respectively. We did not observe a significant difference between the treatments. Dietary properties of vegetable and fruit juices are an area of significant interest.

CONCLUSIONS

Together with an analysis of previous works, we suggest that green juice did not cause an improvement in metabolic function and there is a need for further research on this issue, mainly through different interventions and other samples.

Dietary micronutrient intake and atherosclerosis in systemic lupus erythematosus

Objective

The aim of this study was to investigate the role of dietary micronutrient intake in systemic lupus erythematosus (SLE).

Methods

This study included 111 SLE patients and 118 age and gender-matched controls. Data on diet (food frequency questionnaires) were linked with data on Systemic Lupus Activity Measure, Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and carotid atherosclerotic/echolucent plaque (B-mode ultrasound). Dietary micronutrient intake were compared between SLE patients and controls and in relation to lupus activity and atherosclerosis in SLE. Associations between micronutrient intake and plaque were analyzed through logistic regression, adjusted for potential confounders.

Results

Micronutrient intake did not differ between patients and controls, and between lower and higher lupus activity, apart from the fact that phosphorus was associated with SLEDAI > 6. In SLE patients, some micronutrients were associated with atherosclerotic plaque, left side. Lower intake of riboflavin and phosphorus was associated with atherosclerotic plaque, left side (odds ratio (OR) 3.06, 95% confidence interval (CI) 1.12–8.40 and OR 4.36, 95% CI 1.53–12.39, respectively). Higher intake of selenium and thiamin was inversely associated with atherosclerotic plaque, left side (OR 0.28, 95% CI 0.09–0.89 and OR 0.26, 95% CI 0.08–0.80, respectively). In addition, higher intake of thiamin was inversely associated with echolucent plaque, left side (OR 0.22, 95% CI 0.06–0.84). Lower intake of folate was inversely associated with bilateral echolucent plaque (OR 0.36, 95% CI 0.13–0.99).

Conclusions

SLE patients did not have different dietary micronutrient intake compared to controls. Phosphorus was associated with lupus activity. Riboflavin, phosphorus, selenium and thiamin were inversely associated with atherosclerotic plaque, left side in SLE patients, but not in controls. Dietary micronutrients may play a role in atherosclerosis in SLE.

Nutritional B vitamin deficiency alters the expression of key proteins associated with vascular smooth muscle cell proliferation and migration in the aorta of atherosclerotic apolipoprotein E null mice

Low B vitamin status is linked with human vascular disease. We employed a proteomic and biochemical approach to determine whether nutritional folate deficiency and/or hyperhomocysteinemia altered metabolic processes linked with atherosclerosis in ApoE null mice. Animals were fed either a control fat (C; 4 % w/w lard) or a high-fat [HF; 21 % w/w lard and cholesterol (0/15 % w/w)] diet with different B vitamin compositions for 16 weeks. Aorta tissue was prepared and global protein expression, B vitamin, homocysteine and lipoprotein status measured. Changes in the expression of aorta proteins were detected in response to multiple B vitamin deficiency combined with a high-fat diet (P < 0.05) and were strongly linked with lipoprotein concentrations measured directly in the aorta adventitia (P < 0.001). Pathway analysis revealed treatment effects in the aorta-related primarily to cytoskeletal organisation, smooth muscle cell adhesion and invasiveness (e.g., fibrinogen, moesin, transgelin, vimentin). Combined B vitamin deficiency induced striking quantitative changes in the expression of aorta proteins in atherosclerotic ApoE null mice. Deregulated expression of these proteins is associated with human atherosclerosis. Cellular pathways altered by B vitamin status included cytoskeletal organisation, cell differentiation and migration, oxidative stress and chronic inflammation. These findings provide new insight into the molecular mechanisms through which B vitamin deficiency may accelerate atherosclerosis.

B-vitamin levels and genetics of hyperhomocysteinemia are not associated with arterial stiffness

BACKGROUND AND AIMS

Hyperhomocysteinemia is associated with arterial stiffness, but underlying pathophysiological mechanisms explaining this association are to be revealed. This study was aimed to explore two potential pathways concerning the one-carbon metabolism. A potential causal effect of homocysteine was explored using a genetic risk score reflecting an individual's risk of having a long-term elevated plasma homocysteine level and also associations with B-vitamin levels were investigated.

METHODS AND RESULTS

Baseline cross-sectional data of the B-PROOF study were used. In the cardiovascular subgroup (n = 567, 56% male, age 72.6 ± 5.6 yrs) pulse wave velocity (PWV) was determined using applanation tonometry. Plasma concentrations of vitamin B12, folate, methylmalonic acid (MMA) and holo transcobalamin (holoTC) were assessed and the genetic risk score was based on 13 SNPs being associated with elevated plasma homocysteine. Associations were examined using multivariable linear regression analysis. B-vitamin levels were not associated with PWV. The genetic risk score was also not associated with PWV. However, the homocysteine-gene interaction was significant (p < 0.001) in the association of the genetic risk score and PWV. Participants with the lowest genetic risk of having long-term elevated homocysteine levels, but with higher measured homocysteine levels, had the highest PWV levels.

CONCLUSION

Homocysteine is unlikely to be causally related to arterial stiffness, because there was no association with genetic variants causing hyperhomocysteinemia, whereas non-genetically determined hyperhomocysteinemia was associated with arterial stiffness. Moreover, the association between homocysteine and arterial stiffness was not mediated by B-vitamins. Possibly, high plasma homocysteine levels reflect an unidentified factor, that causes increased arterial stiffness.

Serum level of homocysteine is correlated to carotid artery atherosclerosis in Chinese with ischemic stroke

OBJECTIVES

To investigate the relationship between serum level of homocysteine (Hcy) and carotid artery atheroscleosis (CAA).

METHODS

Both sides of the common carotid artery and internal carotid artery in 126 Chinese patients with ischemic stroke were measured by B-mode ultrasound. The patients were divided into groups: normal, A, B, C and D according to the severity of CAAs. With fasting serum, Hcy as well as folate, vitamin B(12) and lipids were detected. The mean +/- SD age was 64 +/- 13 years (range 39-87 years).

RESULTS

In a logistic regression model, the Hcy concentrations were associated with an elevated risk of CAAs independent of all traditional risk factors, and when CAAs became severer, the serum Hcy was higher. The levels of the normal group and A, B, C, D groups were 13.22 +/- 6.15 micromol/L, 16.29 +/- 9.81 micromol/l, 19.49 +/- 11.16 micromol/l, 27.21 +/- 17.47 micromol/l, and 24.14 +/- 8.64 micromol/l, respectively. Rank test showed a significant difference between normal and other groups (p<0.05). The levels of folate and vitamin B(12) were negatively correlated with the Hcy concentrations. Spearman correlation coefficient were -0.23 and -0.42 (p<0.05).

CONCLUSIONS

Hyperhomocysteinaemia is an independent risk factor of CAAs and the degree of CAAs is highly correlated with the level of Hcy in serum. The causes of hyperhomocysteinemia may be the result from the decrease in folate and vitamin B(12). Clinical trials are now required to evaluate the effect of treatment with these vitamins on the primary and secondary prevention of cerebral vascular diseases.

Nutritional B vitamin deficiency disrupts lipid metabolism causing accumulation of proatherogenic lipoproteins in the aorta adventitia of ApoE null mice

SCOPE

Cardiovascular disease is the major cause of death in the world. Low dietary folate, elevated homocysteine, and high circulating cholesterol are risk factors.

METHODS AND RESULTS

We investigated whether folate and/or B vitamin deficiency would change lipoprotein and fatty acid metabolism and lipid accumulation in the aorta adventitia of ApoE null mice. Mice (n = 10 per group) were fed a control (C; 4%) or high saturated fat (HF; 21%), and high cholesterol (0.15%) diet for 16 weeks. Folate (F-) or folate, B6 and B12 deficiency (F-B-) were imposed on these diets. Feeding a HF diet increased plasma and liver total cholesterol and HDL cholesterol (two- to threefold; p < 0.05). Total cholesterol increased (twofold; p < 0.05) in aorta adventitial lipid in response to HF. Feeding a diet depleted of folate and B vitamins (F-B-) significantly increased cholesterol accumulation in both liver and aorta adventitial lipid (approximately 50-70%; p < 0.05). Moreover, the proportions of fatty acids in hepatic and adventitial lipid was significantly changed by B vitamin depletion, measured as an increase in saturated fatty acids (approximately 15%) and a decrease (approximately 11%) in monounsaturated fatty acids (p < 0.05).

CONCLUSION

B vitamin deficiency perturbs lipid metabolism in ApoE null mice, causing accumulation of proatherogenic cholesterol and fatty acids in the aorta adventitia.

Role of surrogate markers of atherosclerosis in clinical and subclinical thyroidism

Background. Data on the relationship between homocysteine, plasminogen activator inhibitor 1, hs-CRP, fibrinogen, and carotid intima media thickness (CA-IMT) is plenty but contradicting and the majority of the studies investigated this issue in only specific thyroidism groups. The aim of this paper was to investigate these relations in patients with subclinical and clinical hypo- and hyperthyroidism. Methods. In this cross-sectional study, 16 patients from each thyroidism group and 20 healthy cases were enrolled. Fibrinogen levels and plasminogen activator inhibitor 1 (PAI-1) activity were assessed. CA-IMT was determined by gray-scale high-resolution color Doppler ultrasound. Results. Serum homocysteine levels were higher in hypothyroidic patients compared to the control (P = 0.003). Fibrinogen levels were higher in patients with subclinical hypothyroidism compared to other groups (P < 0.05). There was no difference between groups regarding PAI-1. Whereas total cholesterol, homocysteine, and LDL were correlated with CAIMT, hs-CRP, PAI-1, and fibrinogen were not. In the clinical hypothyroidism group, the correlation of homocysteine with CA-IMT was derived from the correlation between CA-IMT and homocysteine. Conclusions. Homocysteine and fibrinogen levels are higher in patients with clinical and subclinical hypothyroidism, respectively. Homocysteine level is associated with CA-IMTonly in patients with clinical hypothyroidism.

No effect of folic acid supplementation on global DNA methylation in men and women with moderately elevated homocysteine

A global loss of cytosine methylation in DNA has been implicated in a wide range of diseases. There is growing evidence that modifications in DNA methylation can be brought about by altering the intake of methyl donors such as folate. We examined whether long-term daily supplementation with 0.8 mg of folic acid would increase global DNA methylation compared with placebo in individuals with elevated plasma homocysteine. We also investigated if these effects were modified by MTHFR C677T genotype. Two hundred sixteen participants out of 818 subjects who had participated in a randomized double-blind placebo-controlled trial were selected, pre-stratified on MTHFR C677T genotype and matched on age and smoking status. They were allocated to receive either folic acid (0.8 mg/d; n = 105) or placebo treatment (n = 111) for three years. Peripheral blood leukocyte DNA methylation and serum and erythrocyte folate were assessed. Global DNA methylation was measured using liquid chromatography-tandem mass spectrometry and expressed as a percentage of 5-methylcytosines versus the total number of cytosine. There was no difference in global DNA methylation between those randomized to folic acid and those in the placebo group (difference = 0.008, 95%CI = −0.05,0.07, P = 0.79). There was also no difference between treatment groups when we stratified for MTHFR C677T genotype (CC, n = 76; CT, n = 70; TT, n = 70), baseline erythrocyte folate status or baseline DNA methylation levels. In moderately hyperhomocysteinemic men and women, long-term folic acid supplementation does not increase global DNA methylation in peripheral blood leukocytes.

ClinicalTrials.gov NCT00110604

Study of serum homocysteine, folic Acid and vitamin b(12) in patients with preeclampsia

The present study was carried out to evaluate the occurrence of association between homocysteine, folic acid and vitamin B(12) in patients with preeclampsia. Fifty preeclamptic patients from gynecology ward were studied for estimation of serum homocysteine, folic acid and vitamin B(12) over a period of October 2007 to June 2010. Serum homocysteine and folic acid, and vitamin B(12) were determined by means of Immulite 1000 analyzer. The statistical analysis of study group of preeclampsia compared with normotensive control group, showed significant alterations in serum homocysteine, folic acid and vitamin B(12) concentrations in preeclampsia. Inverse association between serum homocysteine and folic acid, and vitamin B(12) levels were observed in preeclampsia. The present study found hyperhomocysteinemia and deficiency of folic acid and vitamin B(12) along with increased blood pressure as a risk factor for cardiovascular disease (CVD) in preeclampsia.

Serum homocysteine, folate, vitamin B12 levels and arterial stiffness in diabetic patients: which of them is really important in atherogenesis?

AIM

Hyperhomocystinaemia is associated with macro- and microangiopathic diabetic complications. However, the role of homocysteine (Hcy), serum folate, and vitamin B12 level in the development of premature vascular damage in type 2 diabetic patients is not clear. The present study was designed to assess the relationship between total Hcy, folate, and vitamin B12 levels and arterial stiffness, an early marker of generalized atherosclerosis.

METHODS

As many as 86 subjects with type 2 diabetes mellitus were studied. All participants were evaluated for glucose, HbA(1C), lipid profile, hs-CRP, endothelin, Hcy, vitamin B12, and folate. Pulse wave velocity (PWV) and augmentation index (AI) were performed as a non-invasive recording and computer analysis of the two artery sites pressure waveform using SphygmoCor (version 7.1, AtCor Medical, Sydney, Australia).

RESULTS

Hcy was significantly positively associated with age, serum creatinine, and vitamin B12 levels. No association between Hcy and folate was observed. The Hcy concentration was significantly positively associated with PWV (r = 0.540, p < 0.0001) and AI (r = 0.390, p < 0.0001). In a general linear model of PWV, Hcy emerged as an independent predictor of PWV even after controlling for age, creatinine, vitamin B12, and folate levels. In a multiple linear regression analysis, the association between Hcy and arterial stiffness was independent of traditional cardiovascular risk factors. Vitamin B12 levels were significantly inversely associated with tHcy (r = - 0.263, p = 0.015) and marginally associated with PWV(r = - 0.212, p = 0.052). Significant associations between folate levels and PWV were not detected.

CONCLUSIONS

The results lend support to the hypothesis that elevated Hcy may have a key role in the development of atherogenesis in diabetic patients. Additionally, vitamin B12 is significantly associated with tHcy concentrations and is identified as a marginally independent correlate of PWV in diabetic patients in the absence of folate deficiency.

Correlations between plasma homocysteine and folate concentrations and carotid atherosclerosis in high-risk individuals: baseline data from the Homocysteine and Atherosclerosis Reduction Trial (HART)

Abstract

Homocysteine has been proposed as a risk factor for atherosclerosis. The association between plasma total homocysteine (tHcy) concentration and carotid atherosclerosis has not been thoroughly studied in high-risk populations with vascular disease. For this study, carotid atherosclerosis was assessed by measurements of carotid intima-media thickness (IMT) and plaque calcification in 923 patients with vascular disease or diabetes. Associations with tHcy and plasma folate concentrations were examined. The mean and single maximum carotid IMT were 1.27 ± 0.34 mm and 2.41 ± 0.83 mm, respectively. The mean segment plaque calcification score was 27.8%. tHcy correlated with mean ( r = 0.13; p < 0.001) and single maximum ( r = 0.12; p < 0.001) carotid IMT. There was a progressive increase in mean and single maximum carotid IMT across quartiles of tHcy ( p < 0.0001 for trend). These associations were no longer significant after adjusting for other CV risk factors. A trend towards an inverse association between plasma folate and mean max carotid IMT was found in both univariate and multivariable analyses. However, the plaque calcification score increased across quartiles of tHcy ( p < 0.01) and decreased across quartiles of plasma folate concentrations ( p < 0.05) after multiple adjustments. In conclusion, in high-risk individuals, tHcy and low folate concentrations were only weakly associated with carotid IMT. In contrast, we found an independent association with the plaque calcification score, a measure of more advanced atherosclerosis. The effect of tHcy lowering on carotid atherosclerosis and stroke prevention warrants further investigation.

Measuring subclinical atherosclerosis: is homocysteine relevant?

OBJECTIVES

We systematically reviewed published studies looking at the relationship between total serum homocysteine (tHcy) and subclinical markers of atherosclerosis, such as carotid intimal-medial thickness (C-IMT), coronary artery calcium (CAC) and ankle-brachial index (ABI) in asymptomatic individuals. We analyzed these studies to examine this relationship as well as to guide future avenues of investigation by identifying studies that will help in the inclusion of tHcy levels in current guidelines on atherosclerotic disease management.

BACKGROUND

tHcy has been known to be associated with clinically evident atherosclerotic disease. However, tHcy is not incorporated in current guidelines for diagnosis of subclinical disease in high-risk asymptomatic individuals.

METHODS

We searched online databases (e.g., PUBMED, MEDLINE) for published articles assessing the relationship between tHcy and C-IMT, CAC and ABI. We limited the studies to asymptomatic populations, and excluded any study including symptomatic patients or individuals with a history of coronary, peripheral or cerebrovascular disease.

RESULTS

A systemic review of 19 articles revealed a significant association between elevated levels of tHcy and subclinical markers of atherosclerosis in asymptomatic individuals in most studies. Mean tHcy levels were consistently found to be higher in men compared to women. A total of 12 studies showed a significant association between tHcy and other risk markers of atherosclerosis, even after adjusting for age, sex and conventional risk factors. There were seven studies in unique populations that showed no significant relationship. We also observed that studies lowering baseline tHcy levels did not lead to an improvement in C-IMT, CAC or ABI scores. This might indicate that tHcy has a stronger role as a marker of atherosclerotic disease than as a risk factor for the same.

CONCLUSIONS

Based on our review, we conclude that there is a significant association between the subclinical atherosclerotic process and tHcy, and it shows potential as a cheap marker for risk stratification of asymptomatic patients. However, future studies further elucidating this association and elaborating the exact role of tHcy in the atherosclerotic disease process are required. The results of these studies suggest the incorporation of plasma tHcy levels in future risk reduction protocols for identification of individuals at higher risk of atherosclerotic events, and thus to categorize them for more aggressive treatment with established preventive and therapeutic measures.

Blood donation, body iron status and carotid intima-media thickness

Iron could promote free radical formation, which may lead to injury of the arterial wall and atherosclerosis. Blood donation may reduce cardiovascular risk by lowering body iron status. We collected data on blood donation history and intima-media thickness of the common carotid artery (CIMT) in 819 subjects (50-70 years), who were recruited from municipal and blood bank registries in The Netherlands. Serum iron parameters were assessed, including non-transferrin bound iron (NTBI) that has recently been found in conditions of iron overload. Serum ferritin was lower in current donors (n=443; 44 microg/L) than in ex-donors (n=120; 114 microg/L) and never-donors (n=256; 124 microg/L, P for trend <0.001). For NTBI, values were 2.33, 2.54, and 2.51 micromol/L, respectively (P<0.05). CIMT was slightly reduced in frequent donors (i.e., > or =49 times during life or > or =2 times per year), although not statistically significant. CIMT was not significantly related to NTBI. Frequent blood donation, resulting in lowered body iron, might give some protection against accelerated atherosclerosis.

Associations of methylenetetrahydrofolate reductase C677T polymorphism with markers of subclinical atherosclerosis: the Cardiovascular Risk in Young Finns Study

OBJECTIVE

To study whether the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism or serum homocysteine concentration is associated with carotid artery intima media thickness (IMT), carotid artery compliance (CAC) or brachial artery flow mediated dilatation (FMD) in a healthy Finnish adult population.

METHODS

Cross-sectional data obtained in 2001 for the Cardiovascular Risk in Young Finns Study were used. Carotid artery IMT, CAC and brachial FMD were measured by ultrasound and serum homocysteine concentrations using a commercial immunoassay kit. We studied 1,440 subjects (aged 24-39 years). Genotyping was performed using the 5' nuclease TaqMan assay.

RESULTS

Homocysteine values differed between genotypes in women and men (ANOVA, p<0.001 for both sex groups): the genotype raised values in the order of CC, CT, TT. There was a significant difference in CAC values between the MTHFR genotypes in men (ANOVA, p = 0.008), and the CC genotype had the lowest values. In multivariate linear regression analysis adjusted for other major coronary risk factors (e.g. age, smoking, body mass index, systolic blood pressure, C-reactive protein), the association remained significant (R (2) = 25.8 %, beta = 0.091; p = 0.02). Homocysteine level was directly associated with CAC in the whole population (R (2) = 18.0 %, beta = 0.012; p = 0.014) and in women (R (2) = 9.3%, beta = 0.02; p = 0.013), but not in men (R (2) = 15.2 %, beta = 0.004; p = 0.444). We found no association between homocysteine level or the MTHFR polymorphism and carotid IMT or brachial artery FMD.

CONCLUSIONS

The findings suggest that the MTHFR polymorphism does not influence IMT or FMD, but that the T allele may have an effect on CAC in men.

Validation of a food frequency questionnaire to assess folate intake of Dutch elderly people

Folate is required for 1-carbon metabolism and deficiency in folate leads to megaloblastic anemia. Low levels of folate have been associated with increased risk of vascular disease. To investigate whether RDA of folate are met, habitual folate intake needs to be assessed reliably. We developed a FFQ to specifically measure folate intake over the previous 3 months in elderly people in the Netherlands. Major sources of folate intake, i.e. foods contributing to at least 80 % of the average folate intake, were identified through an analysis of the second Dutch Food Consumption Survey for the sub-population of men and women aged 50–70. In 2000 and 2001, folate intake was estimated with this questionnaire in 1286 individuals aged 50–75 years. Concentrations of serum and erythrocyte folate served as biomarkers with which relative validity of the questionnaire was assessed. The same FFQ was repeated after 3 years in 803 subjects in order to assess long-term reproducibility. Mean folate intake was estimated to be 196 (sd 69) μg/d. Spearman correlation coefficients between folate intake and serum and erythrocyte concentrations were 0·14 (P < 0·01) and 0·05 (P = 0·06) respectively. Spearman correlations between folate intakes measured at baseline and after 3 years were 0·58 (P < 0·01). 47 % of the participants were classified in the same quartiles on the two occasions. Our FFQ showed a weak correlation between folate intake and blood folate concentrations and reproducibility was acceptable. This FFQ is able to rank subjects according to their folate intake.

B-vitamins, genotype and disease causality

Despite a great deal of research effort there is still considerable uncertainty surrounding the importance of the B-vitamins in health and disease. This continuing uncertainty is partly a result of the difficulty of measuring intake, confounding in observational studies and the very large numbers required to evaluate primary prevention in randomised controlled trials. Consequently, genetic data are increasingly being used to infer nutritional effects on health and even in the formulation of nutrition policy using the approach of ‘mendelian randomisation’. Genetic information has already contributed greatly to the understanding of B-vitamin metabolism and the heterogeneity of responses to intake. It has the potential to provide further nutritional insights and to assist in the elucidation of causal mechanisms, but it is important that genetic data is not viewed as an alternative to nutritional information, both are necessary when addressing nutritional problems. Similarly, the interpretation of nutrient and biomarker status in some experimental designs may require knowledge of genotype. Formal tests of gene–gene and gene–nutrient interaction are of limited value in nutritional studies and the formulation of policy. Graphical representation of diet–genotype–health data greatly assists in the elucidation of the nature of genetic effects, their interaction with nutrition and the implications for nutrition policy.

Dietary intake and status of folate and vitamin B12 and their association with homocysteine and cardiovascular disease in European populations

BACKGROUND/OBJECTIVES

Folate and vitamin B12 have been suggested to play a role in chronic diseases like cardiovascular diseases. The objectives are to give an overview of the actual intake and status of folate and vitamin B12 in general populations in Europe, and to evaluate these in view of the current vitamin recommendations and the homocysteine concentration.

METHODS

Searches in Medline with 'folic acid', 'folate' and 'vitamin B12', 'B12' or 'cobalamin' as key words were combined with the names of the European countries. Populations between 18 and 65 years were included.

RESULTS

Sixty-three articles reporting on studies from 15 European countries were selected. Low folate intakes were observed in Norway, Sweden, Denmark and the Netherlands. Low intakes of vitamin B12 were not common and only seen in one small Greek study. In the countries with a low intake of folate, the recommended levels were generally not achieved, which was also reflected in the folate status. Vitamin B12 intake was not strongly associated with the vitamin B12 status, which can explain why in the Netherlands and Germany the vitamin B12 status was inadequate, despite sufficient intake levels. In countries with a low folate intake in particular, the Hcy concentration was higher than ideal.

CONCLUSIONS

Populations from the Nordic countries, the Netherlands, Germany and Greece may need to improve their intakes of folic acid, B12 or both to either meet the recommendations or to optimize their statuses. This could be achieved via a food-based approach, food fortification or supplements.

Plasma folate concentration and cognitive performance: Rotterdam Scan Study

BACKGROUND

Evidence is increasing for beneficial and independent effects of folate on cognitive function, but the underlying biologic mechanism is as yet unknown.

OBJECTIVE

We examined the independent association of plasma folate concentration with cognitive performance and explored the nature of this association by evaluating brain-imaging markers for cerebrovascular disease and brain cell loss.

DESIGN

In the population-based Rotterdam Scan Study, 1033 nondemented participants aged 60-90 y underwent extensive cognitive testing and brain imaging. We cross-sectionally examined the association between plasma folate concentration and cognitive test performance by multivariate linear regression. To evaluate the role of vascular or other mechanisms in this association, we subsequently studied whether plasma folate was related to the presence of white matter lesions and hippocampal and amygdalar volumes.

RESULTS

After multivariate adjustment, the mean change in test score per 1-SD increase in plasma folate was 0.05 (95% CI: 0.01, 0.09) for global cognitive function, 0.08 (95% CI: 0.04, 0.13) for psychomotor speed, and 0.02 (95% CI: -0.04, 0.07) for memory function. Adjustment for homocysteine concentration only slightly diminished these associations. The odds ratio relating a 1-SD increase in plasma folate to the presence compared with the absence of severe white matter lesions was 0.79 (95% CI: 0.66, 0.94), whereas no relation was seen between folate status and hippocampal or amygdalar volume.

CONCLUSIONS

Higher plasma folate concentrations are associated with better global cognitive function and better performance on tests of psychomotor speed, regardless of homocysteine concentration. These associations may be mediated by vascular mechanisms.

Augmentation index and carotid intima-media thickness are differently related to age, C-reactive protein and oxidized low-density lipoprotein

OBJECTIVE

Ageing, plasma circulating C-reactive protein (CRP), oxidized low-density lipoprotein (OxLDL) and homocysteine (Hcy) are associated with atherosclerosis. The aim of this study was to evaluate the relationship between age, inflammatory and oxidative stress-related markers with functional and structural changes of the arteries in asymptomatic persons.

METHODS

CRP, OxLDL and Hcy were measured in 175 clinically healthy subjects, aged 40-70 years. Ultrasonography and pulse wave analysis were used to measure carotid intima-media thickness (IMT) and augmentation index (AIx).

RESULTS

OxLDL was correlated with IMT (r = 0.24, P = 0.003), whereas CRP was correlated with AIx (r = 0.21, P = 0.005). No correlation was detected between Hcy and AIx or age-adjusted IMT. There was a significant association between AIx and age <or=50 years (r = 0.33; P = 0.001) and between IMT and age > 50 years (r = 0.40; P = 0.001). In stepwise regression analysis age, weight, white blood cell count, OxLDL, heart rate and timing of the reflected waveform adjusted for height were significantly and independently associated with IMT (R = 0.41; P < 0.001). At the same time, AIx as the dependent variable correlated positively with age, gender, CRP and mean arterial pressure, and negatively with heart rate, weight and height, in stepwise regression analysis (R = 0.63; P < 0.001).

CONCLUSION

The results of the present study showed that CRP, OxLDL, Hcy and age are not similarly related to AIx and IMT in asymptomatic persons. The results suggest that CRP and younger age are related to arterial stiffness, whereas OxLDL and older age become more important determinants of structural changes of the arteries in asymptomatic persons.

Folic acid does not improve endothelial function in obese children and adolescents

OBJECTIVE

Obese children have severe endothelial dysfunction as measured by flow-mediated dilation (FMD). We have shown that folic acid normalizes endothelial function in children with type 1 diabetes who have a similar degree of endothelial dysfunction but lower total plasma homocyst(e)ine (tHcy) and higher folate status. Our aim was to evaluate, for the first time, the effect of folate supplementation on endothelial dysfunction in obese children.

RESEARCH DESIGN AND METHODS

A total of 53 obese subjects (26 male, mean +/- SD age 13.3 +/- 2.2 years, and BMI Z score 2.29 +/- 0.25) participated in a randomized, double-blind, placebo-controlled, parallel trial of oral folic acid (5 mg/day) or placebo for 8 weeks. Before and after the intervention, we assessed endothelial function (FMD), smooth muscle function (glyceryl trinitrate-induced dilatation [GTN]), high-sensitivity C-reactive protein (hsCRP), tHcy, serum folate, red cell folate (RCF), and lipids.

RESULTS

There were no group differences at baseline. FMD did not change with the intervention (folic acid group pre- and postintervention: 6.42 +/- 5.03 and 6.56 +/- 4.79%, respectively, vs. placebo group: 5.17 +/- 3.54 and 5.79 +/- 4.26%, respectively; P = 0.6). Folate supplementation increased serum folate and RCF by 18.4 nmol/l (P < 0.001) and 240.1 nmol/l (P < 0.001), respectively, and decreased tHcy by 0.95 microl (P = 0.008). The intervention did not change GTN, hsCRP, or lipids.

CONCLUSIONS

Folic acid supplementation does not improve endothelial function in obese children without diabetes despite increasing folate status and reducing tHcy. This is in contrast to the response to folate in children with type 1 diabetes.

Circulating homocysteine and large arterial stiffness and thickness in a population-based sample of middle-aged and elderly men

Elevated plasma homocysteine (tHcy) is considered as a risk factor for cardiovascular events, and has been associated with arterial stiffness and subclinical atherosclerosis in subjects with classical cardiovascular risk factors. The aim of this study is to investigate the association of plasma tHcy with functional and structural changes in the large arteries by measuring aortic pulse-wave velocity (PWV) and carotid artery intima-media thickness (CIMT). In a population-based sample of 376 middle-aged and elderly men, tHcy levels were measured by using fluorescence polarization immunoassay. Aortic stiffness was assessed non-invasively by measuring carotid-femoral PWV with the use of applanation tonometry. CIMT was measured by ultrasonography. We used multivariate linear regression analysis with the log-transformed value of tHcy as the determinant, and aortic PWV and CIMT as outcomes. In the univariate model, PWV increased with increasing tHcy concentration; PWV increased by 2.64 m/s (95% confidence interval (CI) 1.74; 3.54) per unit change in log tHcy. After adjustment for confounders, no statistically significant association remained; PWV increased by 0.42 m/s (95% CI -0.27; 1.11) per unit change in log tHcy. Furthermore, in the univariate model, CIMT increased significantly with increasing tHcy concentration; CIMT increased by 0.19 mm (95% CI 0.11; 0.26) per unit increase log tHcy. This association was attenuated and did not remain significant after additional adjustment for age and cardiovascular confounders (beta=0.06 (95% CI -0.01; 0.13)). The results of this study do not support the presence of an independent relationship between circulating tHcy levels and large artery stiffness and thickness.

Carotid intima-media thickness in coronary slow flow: relationship with plasma homocysteine levels

BACKGROUND AND OBJECTIVE

Coronary slow-flow phenomenon is characterized by delayed opacification of coronary vessels in a normal coronary angiogram. Although clinical and pathological features have been previously described, the underlying pathophysiology has not been fully elucidated. Thus, it still remains to be determined whether either microvascular or epicardial diffuse atherosclerotic disease is related to slow flow. In this study, we aimed to determine the carotid artery intima-media thickness, which is a marker of atherosclerosis in patients with coronary slow flow, and its possible relationship with the total homocysteine level.

METHOD

The study population consisted of 88 patients who underwent coronary angiography because of typical and quasi-typical symptoms of angina. Forty-four patients with angiographically proven coronary slow flow and 44 individuals with normal coronary flow pattern with similar risk profiles were enrolled in the study. Coronary flow patterns of the latter were determined by the thrombolysis in myocardial infarction frame count method. Intima-media thickness was measured by recording ultrasonographic images of both the left and the right common carotid artery with a 12-MHz linear array transducer. Plasma homocysteine, folate and B12 levels were measured from blood samples.

RESULTS

Plasma homocysteine levels (mumol/l) and carotid intima-media thickness (mm) of patients with coronary slow flow were found to be significantly higher than that of controls (12.4+/-4.9 vs. 8.5+/-2.8, P=0.0001; 0.75+/-0.08 vs. 0.69+/-0.06, P=0.0001, respectively). The plasma folate level (ng/ml) was lower in coronary slow-flow patients than in controls (13.8+/-4.4 vs. 16.5+/-5.6, P=0.014). The plasma homocysteine level was significantly positively correlated with the mean thrombolysis in myocardial infarction frame count and intima-media thickness of the carotid artery in correlation analysis (r=0.58, P=0.0001; r=0.41, P=0.0001; respectively).

CONCLUSION

Homocysteine levels and carotid intima-media thickness increased but folate levels decreased in patients with coronary slow flow. The present findings allow us to conclude that the possible disturbance in the metabolism of homocysteine in patients with coronary slow flow may have a role in the etiopathogenesis of this phenomenon by causing generalized atherosclerosis.

Folic acid supplementation delays atherosclerotic lesion development in apoE-deficient mice

Folic acid is a vitamin that when used as a dietary supplementation can improve endothelial function. To assess the effect of folic acid on the development of atherosclerosis, male apolipoprotein E-deficient mice fed a standard chow diet received either water (control group) or an aqueous solution of folic acid that provided a dose of 75 microg/kg/day, for ten weeks. At the time of sacrifice, blood was drawn and the heart removed. The study measured plasma homocysteine, lipids, lipoproteins, low-density lipoprotein (LDL) oxidation, isoprostane, paraoxonase, and apolipoproteins, and aortic atherosclerotic areas. In folic acid-treated animals, total cholesterol, mainly carried in very low-density and low-density lipoproteins, increased significantly, and homocysteine, HDL cholesterol, paraoxonase, and triglyceride levels did not change significantly. Plasma isoprostane and apolipoprotein (apo) B levels decreased. The resistance of LDL to oxidization and plasma apoA-I and apoA-IV levels increased with a concomitant decrease in the area of atherosclerotic lesions. The administration of folic acid decreased atherosclerotic lesions independently of plasma homocysteine and cholesterol levels, but was associated with plasma levels of apolipoproteins A-I, A-IV and B, and decreased oxidative stress.

Carotid intima-media thickness as a surrogate marker for cardiovascular disease in intervention studies

BACKGROUND

Cardiovascular trials using clinical endpoints to assess efficacy typically require follow-up of large numbers of participants for 3-5 years. This disadvantage has encouraged the search for well-validated surrogate markers for cardiovascular disease (CVD). These markers may provide earlier indications of efficacy in trials involving fewer participants. One approach gaining interest in recent years is the measurement of atherosclerotic progression, a major underlying cause of CVD.

SCOPE

This review article aims to further substantiate the evidence supporting the use of measurement of carotid intima-media thickness (CIMT) as a surrogate marker for atherosclerosis and cardiovascular risk.

FINDINGS

CIMT has consistently been related to future CVD events in population studies. CIMT is significantly related with other markers for CVD risk, such as elevated levels of risk factors and presence of atherosclerosis in the coronary arteries. Furthermore, almost all lipid-lowering trials and a large number of blood pressure lowering trials have consistently shown a reduction in progression of CIMT. In addition, the ultrasound technique for measuring CIMT is safe and highly reproducible.

CONCLUSION

Thus, CIMT may be used as a surrogate endpoint in clinical trials to enable the benefits of new therapies or regimens to be more rapidly translated into clinical practice.

Homocysteine and carotid intima-media thickness in a german population: lack of clinical relevance

BACKGROUND AND PURPOSE

Common carotid artery intima-media thickness (CCA IMT) is a predictor of stroke. This study aimed to analyze whether homocysteine (Hcys) metabolism influences CCA IMT.

METHODS

We analyzed the association of personal, clinical, and biochemical data (multivariate analysis) and of 9 polymorphisms involved in Hcys metabolism (ANOVA) with CCA IMT in 714 individuals of 187 families.

RESULTS

CCA IMT was significantly predicted by age, sex, creatinine levels, lipoprotein(a) levels, pack-years of smoking, the presence of hypertension, and the presence of diabetes mellitus but not by Hcys levels. Homozygosity for the T allele of the polymorphism methylenetetrahydrofolate reductase c.677C>T was significantly associated with higher Hcys levels but not with a higher CCA IMT.

CONCLUSIONS

These data do not support the thesis that elevated Hcys levels are causally involved in cerebrovascular disease.

Genetic determinants of carotid ultrasound traits

Atherosclerosis is a complex disease with various intermediate phenotypes that are themselves complex and influenced by many factors. Through the use of carotid ultrasound techniques, the intermediate stages of vascular disease can be imaged and studied for association with potential genetic determinants. In this article we review the most recent available data (reports published since 2004) on the genetic determinants of atherosclerosis, as measured by one-, two-, and three-dimensional ultrasonography of the carotid arteries. In general, associations are disparate and modest. For intima-media thickness, promising associations have been found for both TNFRSF1A R92Q and PPARG P12A, but associations also differed in the same individuals depending on the specific ultrasound trait studied (eg, linear intima-media thickness versus total plaque volume in carotid arteries). Some of the challenging issues for future studies include accounting for gene-environment interactions, sex-specific associations, and the distinctiveness of different carotid ultrasound measures.