The effect of folic acid supplementation on carotid intima-media thickness in patients with cardiovascular risk: A randomized, placebo-controlled trial

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.

The effect of B-vitamins on the prevention and treatment of cardiovascular diseases: a systematic review and meta-analysis

CONTEXT

Previous research evaluating the effects in B-vitamins on the prevention and treatment of cardiovascular disease (CVD) has substantial limitations and lacks recently published large prospective studies; hence, conducting an updated meta-analysis is needed.

OBJECTIVE

We investigated the association between vitamin B status and human CVD development in order to provide more specific advice about vitamin B intake for those at risk of CVD.

DATA SOURCES

Relevant articles were identified by JSTOR, PubMed, and ProQuest databases.

DATA EXTRACTION

Key words used to identify the studies included the different combinations of B-vitamins, folate, folic acid, vitamin B6, vitamin B12, homocysteine, cardiovascular disease, stroke, coronary disease, myocardial infarction, and cerebrovascular and transient ischemic attack. The database search was supplemented by hand-searching of reference lists of selected articles.

DATA ANALYSIS

Pooled estimates were calculated from the mean differences using a random-effects model.

RESULTS

Supplementation with folic acid was reported to have a clinical benefit of significantly reducing carotid intima-media thickness. Higher intakes of folic acid, vitamin B6, and vitamin B12 were generally associated with a lower risk of CVD in the general population, except in those without normal renal function and those with unstable angina or past non-ST-elevation myocardial infarction.

CONCLUSION

Vitamin B supplementation resulted in the greatest cardiovascular benefit in those with normal renal function and without unstable angina or non-ST-elevation myocardial infarction recently. Factors such as age, gender, and genetic polymorphisms contribute to varying effects.

The protective mechanism of folic acid on hyperhomocysteinemia-related arterial injury in spontaneously hypertensive rats: Folic acid against arterial inflammation

BACKGROUND

Hypertension associated with hyperhomocysteinemia (HHcy) is correlated with a high risk of vascular diseases. Studies found that folic acid (FA) supplementation can reduce the risk of cardiovascular and cerebrovascular events. The aim of the present study was to explore the potential mechanisms of FA attenuating HHcy-related arterial injury in spontaneously hypertensive rats (SHRs).

METHODS

24 SHRs were randomized into the control group, the HHcy group, and the HHcy + FA group (8 per group). The SHRs in the HHcy group and the HHcy + FA group were given DL-Hcy intraperitoneally to mimic hypertension associated with HHcy. The SHRs in the HHcy + FA group were given FA by gavage to mimic an FA-fortified diet. The histopathology and immunohistochemistry of rat aorta and carotid artery were analyzed, and the relative expression levels of immune/inflammation and oxidative stress molecules in arterial tissue were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot.

RESULTS

FA significantly reduced the expression levels of nuclear factor-κ-gene binding (NF-κB) p65/Rela and interleukin-6 (IL-6) in rat arterial tissues, as well as the levels of plasma HHcy and serum malondialdehyde (MDA) in hypertension associated with HHcy rats (p < 0.05). At the same time, FA significantly increased the serum superoxide dismutase (SOD) level in hypertension associated with HHcy rats, and even the SOD level of the HHcy + FA group was higher than that of the control group (p < 0.05). However, HHcy induced the opposite results of the above indicators in SHRs compared with the control group (p < 0.05).

CONCLUSIONS

The arterial protection mechanisms of FA are related to reducing the concentration of HHcy to eliminate the tissue toxicity of HHcy, inhibiting NF-κBp65/Rela/IL-6 pathway molecules to regulate inflammatory response, and promoting the potential anti-oxidative stress pathway molecules to reduce oxidative stress level.

Associations between dietary intake of B vitamins and cardiovascular risk factors in elderly men: A cross-sectional study

OBJECTIVE

Low intake of B vitamins can lead to hyperhomocysteinaemia, which is reported as a risk factor for cardiovascular disease (CVD). However, little is known about this relationship. Therefore, we decided to examine the association between dietary intake of B vitamins and cardiovascular risk factors in elderly men.

METHODS

The present cross-sectional study consisted of 357 elderly men. Dietary intake was assessed using a validated and reliable food frequency questionnaire. All biochemical factors [fasting blood sugar (FBS), triglyceride (TG), high-sensitivity C-reactive protein (hs-CRP), interleukin 6 (IL-6) and tumour necrosis factor-α (TNF-α)], waist circumference (WC) and blood pressure (BP) were assessed using standard methods.

RESULTS

A significant inverse association was observed between high dietary intake of total B vitamins (OR_{Total B vitamins} : 0.30; 95% CI: 0.10, 0.86; P = .01) and vitamin B9 (OR_{vitamin B9} : 0.20; 95% CI: 0.02, 0.52; P = .002) with high WC. Furthermore, an inverse association was observed between high dietary intake of vitamin B6 (OR_{vitamin B6} : 0.28; 95% CI: 0.08, 1.00; P = .05) and vitamin B9 (OR_{vitamin B9} : 0.20; 95% CI: 0.06, 0.70; P = .01) with hs-CRP level.

CONCLUSIONS

In elderly men, a high dietary intake of total B vitamins and vitamin B9 was associated with lower odds of having a high WC. Similarly, high dietary intake of vitamin B6 and B9 was associated with lower odds of having a high hs-CRP level.

What Can We Change in Diet and Behaviour in Order to Decrease Carotid Intima-Media Thickness in Patients with Obesity?

Atherosclerosis-considered the major cause of cardiovascular diseases (CVDs)-is strongly associated with obesity, to which it strongly contributes. Moreover, atherosclerosis is characterised by a long asymptomatic phase, and its progression can lead to serious cardiovascular (CV) events. The carotid intima-media thickness (cIMT) has been determined as a predictor of CV events, as well as a marker of subclinical atherosclerosis, and has been used in clinical trials as an alternative assessment method or a surrogate endpoint. It should be noted that several behavioural approaches can directly influence the cIMT values, and decrease or increase the CV risk. In our paper, we aimed to summarize the current knowledge regarding IMT measurement among patients with obesity as a risk group-also in terms of the obesity paradox where the diagnosis of subclinical atherosclerosis is especially essential and implements the early therapeutic approach. We also summarized behavioural, modifiable factors, such as the Mediterranean diet, the Dietary Approach to Stop Hypertension Diets, body weight reduction or the intake of micro- and macronutrients, with a particular focus on the studies where the cIMT values were one of the outcomes. In order to collect the literature data related to the presented topic, the PubMed database was explored.

The role of B vitamins in stroke prevention

Elevated plasma levels of homocysteine (Hcy) are a recognized risk factor for stroke. This relationship represents one aspect of the debated `Hcy hypothesis'. Elevated Hcy may be an independent and treatable cause of atherosclerosis and thrombotic vascular diseases. Further observations indicate that proper dietary supplementation with B-vitamins decreases total plasma Hcy concentrations and may be an effective intervention for stroke prevention. Metabolic vitamin B₁₂ deficiency is a nutritional determinant of total Hcy and stroke risk. Genetic factors may link B vitamins with stroke severity due to the impact on Hcy metabolism of polymorphism in the genes coding for methylenetetrahydrofolate reductase, methionine-synthase, methionine synthase reductase, and cystathionine β-synthase. Several meta-analyses of large randomized controlled trials exist. However, they are not completely in agreement about B vitamins' role, particularly folic acid levels, vitamin B₁₂, and B₆, in lowering the homocysteine concentrations in people at high stroke risk. A very complex relationship exists between Hcy and B vitamins, and several factors appear to modify the preventive effects of B vitamins in stroke. This review highlights the regulating factors of the active role of B vitamins active in stroke prevention. Also, inputs for further large, well-designed studies, for specific, particularly sensitive subgroups are given.

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.

Serum folate modified the association between low-density lipoprotein cholesterol and carotid intima-media thickness in Chinese hypertensive adults

BACKGROUND AND AIMS

While folate is known for its importance in cardiovascular health, it is unknown whether folate status can modify the association between low-density lipoprotein cholesterol (LDL-C) and carotid intima-media thickness (CIMT). We aimed to investigate this question in a Chinese hypertensive population, who are at high-risk of low folate and atherosclerosis.

METHODS AND RESULTS

This report included 14,970 hypertensive adults (mean age 64.5 years; 40.3% male) from the China Stroke Primary Prevention Trial (CSPPT) and analyzed the fasting serum LDL-C and folate, and CIMT data obtained at the last follow-up visit. LDL-C was calculated using the Friedewald equation. Serum folate levels were measured by chemiluminescent immunoassay. CIMT was measured by ultrasound. Non-parametric smoothing plots, multivariate linear regression analysis, subgroup analyses and interaction testing were performed to examine the LDL-C-CIMI relationship and effect modification by folate. Consistent with graphic plots, multivariate linear regression showed that LDL-C levels were independently and positively associated with CIMT (β = 7.69, 95%CI: 5.76-9.62). More importantly, the relationship between LDL-C and CIMT was significantly attenuated with increasing serum folate levels (1st tertile: β = 10.06, 95%CI: 6.67-13.46; 2nd tertile: β = 6.81, 95%CI: 3.55-10.07; 3rd tertile: β = 5.96, 95%CI: 2.55-9.36; P-interaction = 0.045). Subgroup analyses showed the association between LDL-C and CIMT across serum folate tertiles was robust among various strata (all P-interaction >0.05).

CONCLUSIONS

Among Chinese hypertensive adults, the serum folate levels could modify the association between LDL-C and CIMT. Our findings, if further confirmed, have important clinical implications.

Carotid Intima-Media Thickness Progression as Surrogate Marker for Cardiovascular Risk: Meta-Analysis of 119 Clinical Trials Involving 100 667 Patients

BACKGROUND

To quantify the association between effects of interventions on carotid intima-media thickness (cIMT) progression and their effects on cardiovascular disease (CVD) risk.

METHODS

We systematically collated data from randomized, controlled trials. cIMT was assessed as the mean value at the common-carotid-artery; if unavailable, the maximum value at the common-carotid-artery or other cIMT measures were used. The primary outcome was a combined CVD end point defined as myocardial infarction, stroke, revascularization procedures, or fatal CVD. We estimated intervention effects on cIMT progression and incident CVD for each trial, before relating the 2 using a Bayesian meta-regression approach.

RESULTS

We analyzed data of 119 randomized, controlled trials involving 100 667 patients (mean age 62 years, 42% female). Over an average follow-up of 3.7 years, 12 038 patients developed the combined CVD end point. Across all interventions, each 10 μm/y reduction of cIMT progression resulted in a relative risk for CVD of 0.91 (95% Credible Interval, 0.87-0.94), with an additional relative risk for CVD of 0.92 (0.87-0.97) being achieved independent of cIMT progression. Taken together, we estimated that interventions reducing cIMT progression by 10, 20, 30, or 40 μm/y would yield relative risks of 0.84 (0.75-0.93), 0.76 (0.67-0.85), 0.69 (0.59-0.79), or 0.63 (0.52-0.74), respectively. Results were similar when grouping trials by type of intervention, time of conduct, time to ultrasound follow-up, availability of individual-participant data, primary versus secondary prevention trials, type of cIMT measurement, and proportion of female patients.

CONCLUSIONS

The extent of intervention effects on cIMT progression predicted the degree of CVD risk reduction. This provides a missing link supporting the usefulness of cIMT progression as a surrogate marker for CVD risk in clinical trials.

Effects of Folate Supplementation on Carotid Intima-Media Thickness, Biomarkers of Inflammation, and Oxidative Stress in Carbamazepine-Treated Epileptic Children

Background:

This study was conducted to assess the effects of folate supplementation on carotid intima-media thickness (CIMT), biomarkers of inflammation, and oxidative stress in carbamazepine-treated epileptic children.

Methods:

This randomized, double-blind, placebo-controlled trial was carried out in 54 epileptic children aged 2–12 years old receiving carbamazepine monotherapy. Participants were randomly allocated into two groups to receive either 5 mg folate supplements or placebo (n = 27 in each group) for 12 weeks.

Results:

After the 12-week intervention, compared with the placebo, folate supplementation resulted in a significant reduction in plasma homocysteine (Hcy) (changes from baseline − 2.1 ± 2.5 vs. +0.1 ± 0.4 μmol/L, P < 0.001), serum high-sensitivity C-reactive protein (hs-CRP) (changes from baseline − 1.5 ± 3.5 vs. +0.4 ± 1.4 mg/L, P = 0.01), a significant increase in plasma nitric oxide (NO) (changes from baseline + 1.9 ± 5.8 vs. −2.0 ± 6.4 μmol/L, P = 0.02), and total antioxidant capacity (TAC) concentrations (changes from baseline + 88.6 ± 116.0 vs. +1.8 ± 77.4 mmol/L, P = 0.002). We did not observe any significant effects in mean levels of left and right CIMT, maximum levels of left and right CIMT, and total glutathione (GSH) and malondialdehyde (MDA) levels following the supplementation of folate compared with the placebo.

Conclusions:

Overall, folate supplementation at a dosage of 5 mg/day for 12 weeks among epileptic children receiving carbamazepine had beneficial effects on Hcy, hs-CRP, NO, and TAC levels, but did not affect CIMT, and GSH and MDA levels.

Polyamine Metabolism and Gene Methylation in Conjunction with One-Carbon Metabolism

Recent investigations have revealed that changes in DNA methylation status play an important role in aging-associated pathologies and lifespan. The methylation of DNA is regulated by DNA methyltransferases (DNMT1, DNMT3a, and DNMT3b) in the presence of S-adenosylmethionine (SAM), which serves as a methyl group donor. Increased availability of SAM enhances DNMT activity, while its metabolites, S-adenosyl-l-homocysteine (SAH) and decarboxylated S-adenosylmethionine (dcSAM), act to inhibit DNMT activity. SAH, which is converted from SAM by adding a methyl group to cytosine residues in DNA, is an intermediate precursor of homocysteine. dcSAM, converted from SAM by the enzymatic activity of adenosylmethionine decarboxylase, provides an aminopropyl group to synthesize the polyamines spermine and spermidine. Increased homocysteine levels are a significant risk factor for the development of a wide range of conditions, including cardiovascular diseases. However, successful homocysteine-lowering treatment by vitamins (B6, B12, and folate) failed to improve these conditions. Long-term increased polyamine intake elevated blood spermine levels and inhibited aging-associated pathologies in mice and humans. Spermine reversed changes (increased dcSAM, decreased DNMT activity, aberrant DNA methylation, and proinflammatory status) induced by the inhibition of ornithine decarboxylase. The relation between polyamine metabolism, one-carbon metabolism, DNA methylation, and the biological mechanism of spermine-induced lifespan extension is discussed.

The effect of vitamin B12 and folic acid supplementation on routine haematological parameters in older people: an individual participant data meta-analysis

BACKGROUND/OBJECTIVES

Low vitamin B12 and folate levels in community-dwelling older people are usually corrected with supplements. However, the effect of this supplementation on haematological parameters in older persons is not known. Therefore, we executed a systematic review and individual participant data meta-analysis of randomised placebo-controlled trials (RCTs).

SUBJECTS/METHODS

We performed a systematic search in PubMed, EMBASE, Web of Science, Cochrane and CENTRAL for RCTs published between January 1950 and April 2016, where community-dwelling elderly (60+ years) who were treated with vitamin B12 or folic acid or placebo. The presence of anaemia was not required. We analysed the data on haematological parameters with a two-stage IPD meta-analysis.

RESULTS

We found 494 full papers covering 14 studies. Data were shared by the authors of four RCTs comparing vitamin B12 with placebo (n = 343) and of three RCTs comparing folic acid with placebo (n = 929). We found no effect of vitamin B12 supplementation on haemoglobin (change 0.00 g/dL, 95% CI: -0.19;0.18), and no effect of folic acid supplementation (change -0.09 g/dL, 95% CI: -0.19;0.01). The effects of supplementation on other haematological parameters were similar. The effects did not differ by sex or by age group. Also, no effect was found in a subgroup of patients with anaemia and a subgroup of patients who were treated >4 weeks.

CONCLUSIONS

Evidence on the effects of supplementation of low concentrations of vitamin B12 and folate on haematological parameters in community-dwelling older people is inconclusive. Further research is needed before firm recommendations can be made concerning the supplementation of vitamin B12 and folate.

The preventive effects of edible folic acid on cardiomyocyte apoptosis and survival in early onset triple-transgenic Alzheimer's disease model mice

In recent years, neuropathological and epidemiological studies have indicated an association between Alzheimer's disease (AD) and several cardiovascular risk factors. In this study, the cardio-protective effects of folic acid (FA) in early stage AD was elucidated using a triple-transgenic (3xTg) Alzheimer's mouse model. Eleven-month-old C57BL/6 mice and 3xTg mice were assigned to five groups. During the four-month treatment period, the low-FA treatment group received FA through their diet, and the high-FA treatment groups received 3 mg/dl folate in drinking water and were also gastric-fed 1.2 mg/kg folate every day. In the C57B1/6J mice, treatment with high doses of FA (HFA) did not show any considerable effect compared to the control group or the low-dose dietary FA treatment group. However, Alzheimer's mice treated with HFA showed enhanced cardio-protection. Western blot analysis revealed that FA treatment restored SIRT1 expression, which was suppressed in 3xTg mice, through enhanced AMPK expression. FA significantly enhanced the IGF1 receptor survival mechanism in the hearts of the 3xTg mice and suppressed the expression-intrinsic and extrinsic apoptosis-associated proteins. The results suggest that FA intake may significantly alleviate cellular pathological events in the heart associated with AD.

Homocysteine-lowering interventions for preventing cardiovascular events

BACKGROUND

Cardiovascular disease, which includes coronary artery disease, stroke and peripheral vascular disease, is a leading cause of death worldwide. Homocysteine is an amino acid with biological functions in methionine metabolism. A postulated risk factor for cardiovascular disease is an elevated circulating total homocysteine level. The impact of homocysteine-lowering interventions, given to patients in the form of vitamins B6, B9 or B12 supplements, on cardiovascular events has been investigated. This is an update of a review previously published in 2009, 2013, and 2015.

OBJECTIVES

To determine whether homocysteine-lowering interventions, provided to patients with and without pre-existing cardiovascular disease are effective in preventing cardiovascular events, as well as reducing all-cause mortality, and to evaluate their safety.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2017, Issue 5), MEDLINE (1946 to 1 June 2017), Embase (1980 to 2017 week 22) and LILACS (1986 to 1 June 2017). We also searched Web of Science (1970 to 1 June 2017). We handsearched the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search.

SELECTION CRITERIA

We included randomised controlled trials assessing the effects of homocysteine-lowering interventions for preventing cardiovascular events with a follow-up period of one year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease.

DATA COLLECTION AND ANALYSIS

We performed study selection, 'Risk of bias' assessment and data extraction in duplicate. We estimated risk ratios (RR) for dichotomous outcomes. We calculated the number needed to treat for an additional beneficial outcome (NNTB). We measured statistical heterogeneity using the I2 statistic. We used a random-effects model. We conducted trial sequential analyses, Bayes factor, and fragility indices where appropriate.

MAIN RESULTS

In this third update, we identified three new randomised controlled trials, for a total of 15 randomised controlled trials involving 71,422 participants. Nine trials (60%) had low risk of bias, length of follow-up ranged from one to 7.3 years. Compared with placebo, there were no differences in effects of homocysteine-lowering interventions on myocardial infarction (homocysteine-lowering = 7.1% versus placebo = 6.0%; RR 1.02, 95% confidence interval (CI) 0.95 to 1.10, I2 = 0%, 12 trials; N = 46,699; Bayes factor 1.04, high-quality evidence), death from any cause (homocysteine-lowering = 11.7% versus placebo = 12.3%, RR 1.01, 95% CI 0.96 to 1.06, I2 = 0%, 11 trials, N = 44,817; Bayes factor = 1.05, high-quality evidence), or serious adverse events (homocysteine-lowering = 8.3% versus comparator = 8.5%, RR 1.07, 95% CI 1.00 to 1.14, I2 = 0%, eight trials, N = 35,788; high-quality evidence). Compared with placebo, homocysteine-lowering interventions were associated with reduced stroke outcome (homocysteine-lowering = 4.3% versus comparator = 5.1%, RR 0.90, 95% CI 0.82 to 0.99, I2 = 8%, 10 trials, N = 44,224; high-quality evidence). Compared with low doses, there were uncertain effects of high doses of homocysteine-lowering interventions on stroke (high = 10.8% versus low = 11.2%, RR 0.90, 95% CI 0.66 to 1.22, I2 = 72%, two trials, N = 3929; very low-quality evidence).We found no evidence of publication bias.

AUTHORS' CONCLUSIONS

In this third update of the Cochrane review, there were no differences in effects of homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination comparing with placebo on myocardial infarction, death from any cause or adverse events. In terms of stroke, this review found a small difference in effect favouring to homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination comparing with placebo.There were uncertain effects of enalapril plus folic acid compared with enalapril on stroke; approximately 143 (95% CI 85 to 428) people would need to be treated for 5.4 years to prevent 1 stroke, this evidence emerged from one mega-trial.Trial sequential analyses showed that additional trials are unlikely to increase the certainty about the findings of this issue regarding homocysteine-lowering interventions versus placebo. There is a need for additional trials comparing homocysteine-lowering interventions combined with antihypertensive medication versus antihypertensive medication, and homocysteine-lowering interventions at high doses versus homocysteine-lowering interventions at low doses. Potential trials should be large and co-operative.

Association between Micronutrients Intake/Status and Carotid Intima Media Thickness: A Systematic Review

BACKGROUND

Carotid intima media thickness (IMT) is a noninvasive marker of the extent and severity of subclinical atherosclerosis. Micronutrient intake may affect atherosclerosis and play a major role in the development of cardiovascular diseases (CVDs).

OBJECTIVE

The primary aim of this review was to synthesize the evidence regarding the association between carotid IMT and selected micronutrients.

METHOD

The authors searched PubMed, Cochrane, and EMBASE databases from inception to June 2016 for selected micronutrients, CVD, carotid IMT, and antioxidants. Thirty-five original studies met the inclusion criteria and were reviewed following preferred reporting items for systematic review and meta-analysis guidelines.

RESULTS

Although not all studies found consistent results, the weight of the evidence suggests that high intakes and/or circulatory levels of magnesium, as well as vitamin D and the vitamin B group, may be associated with lower carotid IMT or reduced progression of carotid IMT. The majority of studies did not find any significant association between vitamin E and C and carotid IMT. Less evidence was available for associations of retinol, zinc, and iron with carotid IMT.

CONCLUSIONS

In general, the current evidence concerning micronutrient intake and carotid IMT is largely inconclusive. Pragmatic clinical trials are required to determine whether dietary or supplemental intake of specific micronutrients alters carotid IMT, which is a surrogate measure of cardiovascular risk.

The Effects of Folate Supplementation on Carotid Intima-Media Thickness and Metabolic Status in Patients with Metabolic Syndrome

BACKGROUND

This study was carried out to evaluate the effects of folate supplementation on carotid intima-media thickness (CIMT) and metabolic status among patients with metabolic syndrome (MetS).

METHODS

This randomized, double-blind, placebo-controlled trial was conducted among 60 patients with type 2 diabetes mellitus and coronary heart disease. They were all overweight in the age range 40-85 years. Participants were randomly divided into 2 groups: group A (n = 30) received 5 mg folate supplements and group B (n = 30) received placebo for 12 weeks.

RESULTS

Folate supplementation resulted in a significant reduction in maximum levels of left CIMT (-0.05 ± 0.13 vs. +0.02 ± 0.11 mm, p = 0.01) compared with the placebo. Changes in fasting plasma glucose (-2.2 ± 37.5 vs. +30.2 ± 65.8 mg/dl, p = 0.02), serum insulin concentration (-2.0 ± 10.7 vs. +3.0 ± 7.6 µIU/ml, p = 0.04) and homeostasis of assessment-estimated insulin resistance (-0.6 ± 2.3 vs. +0.9 ± 2.3, p = 0.01) in supplemented patients were significantly different from those of patients in the placebo group. Changes in serum triglycerides (p = 0.04), high-density lipoprotein-cholesterol (p = 0.001), high sensitivity C-reactive protein (p = 0.01) and plasma nitric oxide concentrations (p < 0.001) were significantly different between the supplemented patients and placebo group.

CONCLUSIONS

Overall, 5 mg/day folate supplementation for 12 weeks among patients with MetS had beneficial effects on CIMT and the metabolic status.

Homocysteine-lowering interventions for preventing cardiovascular events

BACKGROUND

Cardiovascular disease, which includes coronary artery disease, stroke and congestive heart failure, is a leading cause of death worldwide. Homocysteine is an amino acid with biological functions in methionine metabolism. A postulated risk factor is an elevated circulating total homocysteine level, which is associated with cardiovascular events. The impact of homocysteine-lowering interventions, given to patients in the form of vitamins B6, B9 or B12 supplements, on cardiovascular events. This is an update of a review previously published in 2009 and 2013.

OBJECTIVES

To determine whether homocysteine-lowering interventions, provided in patients with and without pre-existing cardiovascular disease are effective in preventing cardiovascular events, as well as all-cause mortality and evaluate their safety.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2014, Issue 1), MEDLINE (1950 to January week 5 2014), EMBASE (1980 to 2014 week 6) and LILACS (1986 to February 2014). We also searched Web of Science (1970 to 7 February 2014). We handsearched the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search.

SELECTION CRITERIA

We included randomised controlled trials assessing the effects of homocysteine-lowering interventions for preventing cardiovascular events with a follow-up period of one year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease.

DATA COLLECTION AND ANALYSIS

We performed study selection, 'Risk of bias' assessment and data extraction in duplicate. We estimated risk ratios (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic. We used a random-effects model.

MAIN RESULTS

In this second updated Cochrane Review, we identified no new randomised controlled trials. Therefore, this new version includes 12 randomised controlled trials involving 47,429 participants. In general terms, 75% (9/12) trials had a low risk of bias. Homocysteine-lowering interventions compared with placebo did not significantly affect non-fatal or fatal myocardial infarction (1743/23,590 (7.38%) versus 1247/20,190 (6.17%); RR 1.02, 95% confidence interval (CI) 0.95 to 1.10, I(2) = 0%, high quality evidence), stroke (968/22,348 (4.33%) versus 974/18,957 (5.13%); RR 0.91, 95% CI 0.82 to 1.0, I(2) = 11%, high quality evidence) or death from any cause (2784/22,648 (12.29%) versus 2502/19,250 (10.64%); RR 1.01, 95% CI 0.96 to 1.07, I(2) = 6%, high quality evidence). Homocysteine-lowering interventions compared with placebo did not significantly affect serious adverse events (cancer) (1558/18,130 (8.59%) versus 1334/14,739 (9.05%); RR 1.06, 95% CI 0.98 to 1.13; I(2) = 0%, high quality evidence).

AUTHORS' CONCLUSIONS

This second update of this Cochrane Review found no evidence to suggest that homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination should be used for preventing cardiovascular events. Furthermore, there is no evidence to suggest that homocysteine-lowering interventions are associated with an increased risk of cancer.

The role of homocysteine-lowering B-vitamins in the primary prevention of cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of mortality in the Western world. The effort of research should aim at the primary prevention of CVD. Alongside statin therapy, which is maintained to be an effective method of CVD prevention, there are alternative methods such as vitamin B substitution therapy with folic acid (FA), and vitamins B12 and B6 . B-vitamins may inhibit atherogenesis by decreasing the plasma level of homocysteine (Hcy)-a suspected etiological factor for atherosclerosis-and by other mechanisms, primarily through their antioxidant properties. Although Hcy-lowering vitamin trials have failed to demonstrate beneficial effects of B-vitamins in the prevention of CVD, a meta-analysis and stratification of a number of large vitamin trials have suggested their effectiveness in cardiovascular prevention (CVP) in some aspects. Furthermore, interpretation of the results from these large vitamin trials has been troubled by statin/aspirin therapy, which was applied along with the vitamin substitution, and FA fortification, both of which obscured the separate effects of vitamins in CVP. Recent research results have accentuated a new approach to vitamin therapy for CVP. Studies undertaken with the aim of primary prevention have shown that vitamin B substitution may be effective in the primary prevention of CVD and may also be an option in the secondary prevention of disease if statin therapy is accompanied by serious adverse effects. Further investigations are needed to determine the validity of vitamin substitution therapy before its introduction in the protocol of CVD prevention.

Plasma total homocysteine and carotid intima-media thickness in type 1 diabetes: a prospective study

OBJECTIVE

Plasma total homocysteine (tHcy) has been positively associated with carotid intima-media thickness (IMT) in non-diabetic populations and in a few cross-sectional studies of diabetic patients. We investigated cross-sectional and prospective associations of a single measure of tHcy with common and internal carotid IMT over a 6-year period in type 1 diabetes.

RESEARCH DESIGN AND METHODS

tHcy levels were measured once, in plasma obtained in 1997-1999 from patients (n = 599) in the Epidemiology of Diabetes Interventions and Complications (EDIC) study, the observational follow-up of the Diabetes Control and Complications Trial (DCCT). Common and internal carotid IMT were determined twice, in EDIC "Year 6" (1998-2000) and "Year 12" (2004-2006), using B-mode ultra-sonography.

RESULTS

After adjustment, plasma tHcy [median (interquartile range): 6.2 (5.1, 7.5) μmol/L] was significantly correlated with age, diastolic blood pressure, renal dysfunction, and smoking (all p < 0.05). In an unadjusted model only, increasing quartiles of tHcy correlated with common and internal carotid IMT, again at both EDIC time-points (p < 0.01). However, multivariate logistic regression revealed no significant associations between increasing quartiles of tHcy and the 6-year change in common and internal carotid IMT (highest vs. lowest quintile) when adjusted for conventional risk factors.

CONCLUSIONS

In a type 1 diabetes cohort from the EDIC study, plasma tHcy measured in samples drawn in 1997-1999 was associated with measures of common and internal carotid IMT measured both one and seven years later, but not with IMT progression between the two time-points. The data do not support routine measurement of tHcy in people with Type 1 diabetes.

Homocysteine-lowering interventions for preventing cardiovascular events

BACKGROUND

Cardiovascular disease (including coronary artery disease, stroke and congestive heart failure), is a leading cause of death worldwide. Homocysteine is an amino acid with biological functions in methionine metabolism. A postulated risk factor is elevated circulating total homocysteine levels, which are associated with cardiovascular events. This is an update of a review previously published in 2009.

OBJECTIVES

To assess the clinical effectiveness of homocysteine-lowering interventions in people with or without pre-existing cardiovascular disease.

SEARCH METHODS

We searched The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (2012, Issue 2), MEDLINE (1950 to Feb week 2 2012), EMBASE (1980 to 2012 week 07), and LILACS (1986 to February 2012). We also searched ISI Web of Science (1970 to February 2012). We handsearched the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search.

SELECTION CRITERIA

We included randomised controlled trials assessing the effects of homocysteine-lowering interventions for preventing cardiovascular events with a follow-up period of one year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease.

DATA COLLECTION AND ANALYSIS

We performed study selection, 'Risk of bias' assessment and data extraction in duplicate. We estimated risk ratios (RR) for dichotomous outcomes. We measured statistical heterogeneity using I(2). We used a random-effects model.

MAIN RESULTS

In this updated systematic review, we identified four new randomised trials, resulting in a total of 12 randomised controlled trials involving 47,429 participants. In general terms, the trials had a low risk of bias. Homocysteine-lowering interventions compared with placebo did not significantly affect non-fatal or fatal myocardial infarction (pooled RR 1.02, 95% CI 0.95 to 1.10, I(2) = 0%), stroke (pooled RR 0.91, 95% CI 0.82 to 1.0, I(2) = 11%) or death by any cause (pooled RR 1.01 (95% CI 0.96 to 1.07, I(2): 6%)). Homocysteine-lowering interventions compared with placebo did not significantly affect serious adverse events (cancer) (1 RR 1.06, 95% CI 0.98 to 1.13; I(2) = 0%).

AUTHORS' CONCLUSIONS

This updated Cochrane review found no evidence to suggest that homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination should be used for preventing cardiovascular events. Furthermore, there is no evidence suggesting that homocysteine-lowering interventions are associated with an increased risk of cancer.

Vitamin status in elderly people in relation to the use of nutritional supplements

OBJECTIVE

This study aimed to evaluate the status of several vitamins and to investigate the effect of regular individual supplementation on their status in this population.

DESIGN

An observational study.

SETTING

State of Burgenland, Austria.

PARTICIPANTS

A total of 102 non-institutionalized subjects (49% supplementing regularly, 51% without supplementation) aged between 70-90 years were recruited.

MEASUREMENTS

Plasma levels of vitamins A, D, E, K and C were determined by HPLC. The functional parameters of vitamins B1, B2 and B6, i.e. the activities of the erythrocyte enzymes transketolase, glutathione reductase and glutamic oxaloacetic transaminase, were analyzed photometrically; plasma folate and vitamin B12 were determined by RIA.

RESULTS

The status of vitamins A, E and C was generally satisfactory. Eighty-eight percent and 42% of participants were deficient in vitamins D and K, respectively, as were 29% for B6; up to 10% of participants were deficient in vitamins B1, B2, B12 and folate. A considerable percentage of participants was, however, at risk for vitamin deficiencies (vitamins B1, B6, B12, folate: 20-30%, vitamin B2: 60%). Except for vitamins A and K, regular intake of supplements had a significant positive influence on vitamin levels.

CONCLUSION

These results indicate that use of supplements significantly improved the status of several vitamins in elderly people. Due to age-related problems concerning the intake and digestion of nutrients, a moderate, regular supplementation might be a useful option for older people who are otherwise unable to satisfy their micronutrient requirements.

Mitochondrial mitophagic mechanisms of myocardial matrix metabolism and remodelling

High levels of homocysteine (Hcy), known as hyperhomocysteinmia (HHcy), are correlated with an increase in extracellular matrix remodelling (ECM) via the matrix metalloproteinases (MMPs) and plasminogen/plasmin system. This results in an increase deposition of collagen that leads to endothelial-myocyte (EM) and myocyte-myocyte (MM) uncoupling; the physiological consequences are a plethora of cardiovascular pathologies. Homocysteine-induced increase in intracellular and mitochondrial Ca(2+) plays an important role in increasing reactive oxygen species (ROS) within mitochondria and instigating mitophagy within the cell. This occurs via several Hcy-mitigated processes: agonizing N-methyl-d-aspartate receptor-1 (NMDA-R1), decreasing expression of peroxisome proliferator activator receptor (PPAR) [thereby increasing oxidation], impairing Ca(2+) handling via Na(+)/Ca(2+) exchanger (NCX1) and Sarco endoplasmic reticulum Ca(2+) ATPase (SERCA-2a). The end result is an increase in ROS that directly or indirectly lead to MMP activation within mitochondria or the cytoplasm. Hcy induces a mitochondrial permeability transition that allows MMPs to be released from mitochondria thereby metabolizing matrix and impairing cardiac function. Further work remains to be elucidated concerning the specific mitochondrial mitophagic mechanisms under which matrix metabolism and remodelling occurs. Moreover, the therapeutic implications of NMDA and PPAR ligands are some promise to patient.

Effect of folic acid supplementation on the progression of carotid intima-media thickness: a meta-analysis of randomized controlled trials

OBJECTIVES

We conducted a meta-analysis of relevant randomized trials to assess whether folic acid supplementation reduces the progression of atherosclerosis as measured by carotid intima-media thickness (CIMT).

METHODS

This analysis included 2052 subjects from ten folic acid randomized trials with the change in CIMT reported as one of the end points. Summary estimates of weighted mean differences (WMDs) and 95% CIs were obtained by using random-effect models. Meta-regression and subgroup analyses were performed to identify the source of heterogeneity.

RESULTS

Our analysis showed that folic acid supplementation significantly reduces the progression of CIMT (WMD: -0.04 mm; 95%CI: -0.07, -0.02; P<0.001), particularly in subjects with chronic kidney disease (CKD) (WMD: -0.16 mm; 95%CI: -0.26, -0.07; P=0.0006) or high cardiovascular disease (CVD) risk (WMD: -0.05 mm; 95%CI: -0.11, 0.00; P=0.06) but not in subjects who were generally healthy with only elevated homocysteine concentrations (WMD:0.00 mm; 95%CI: -0.01, 0.01; P=0.35). Furthermore, meta-regression analysis of the data showed that the baseline CIMT levels (P=0.011) and the percent reduction of homocysteine (P<0.001) were positively related to the effect size. Consistently, a greater beneficial effect was seen in those trials with baseline CIMT levels ≥0.8 mm (WMD: -0.14 mm; 95%CI: -0.19, -0.08; P<0.0001), and a reduction in the homocysteine concentration ≥30% (WMD: -0.22 mm; 95%CI: -0.38, -0.06; P=0.009). In the corresponding comparison groups, the effect sizes were attenuated and insignificant.

CONCLUSIONS

Our findings indicate that folic acid supplementation is effective in reducing the progression of CIMT, particularly in subjects with CKD or high CVD risk and among trials with higher baseline CIMT levels or a larger homocysteine reduction.

Effect of 3 y of folic acid supplementation on the progression of carotid intima-media thickness and carotid arterial stiffness in older adults

BACKGROUND

Observational studies have shown that low folate and elevated homocysteine concentrations are risk factors for vascular disease in the general population. Randomized controlled trials in vascular patients have failed to show that folic acid reduces the risk of recurrent vascular disease, whereas such trials are lacking in the general population.

OBJECTIVE

The objective was to determine whether folic acid supplementation reduces the progression of atherosclerosis as measured by common carotid intima-media thickness (CIMT)-a validated marker of atherosclerosis and predictor of vascular disease risk.

DESIGN

A randomized, double-blind, placebo-controlled study in 819 men and postmenopausal women aged 50-70 y, free-living in the Netherlands, and with a total homocysteine concentration ≥13 μmol/L at screening was conducted. Participants received either 800 μg folic acid or placebo daily for 3 y. Rate of change in CIMT and arterial distensibility were the primary and secondary outcomes, respectively.

RESULTS

Compared with placebo, serum folate increased by 577% and plasma total homocysteine concentrations decreased by 26% after 3 y of folic acid supplementation. The mean (±SE) rate of change in CIMT was 1.9 ± 0.9 μm/y in the folic acid arm and 1.3 ± 0.8 μm/y in the placebo arm (mean difference: 0.7 μm/y; 95% CI: -1.8, 3.1 μm/y; P = 0.59). No difference was observed (P = 0.23) between the rates of change in distensibility in the folic acid arm (-0.53 ± 0.06 × 10(-3) kPa(-1)) and in the placebo arm (-0.62 ± 0.06 × 10(-3) kPa(-1)).

CONCLUSION

Despite a considerable increase in folate concentrations and a reduction in total homocysteine concentrations, 3-y folic acid supplementation did not slow down atherosclerotic progression or arterial stiffening. This trial was registered at clinicaltrials.gov as NCT00110604.

Why do homocysteine-lowering B vitamin and antioxidant E vitamin supplementations appear to be ineffective in the prevention of cardiovascular diseases?

Homocysteine has been established as a serious, independent risk factor for atherosclerosis. An elevated plasma homocysteine concentration is accompanied by increased cardiovascular risk; therefore, it can be assumed that lowering the plasma homocysteine level results in a decreased risk. Vitamin B complex (folic acid, and vitamins B6 and B12) substitution therapy decreases the plasma homocysteine level, inhibits oxidative stress, and ameliorates some biochemical and clinical parameters that indicate the progression of atherosclerosis. Vitamin E administration may also reduce atherogenesis through its antioxidant effect. The effectiveness of B and E vitamin substitution in decreasing cardiovascular risk has been suggested by cohort as well as prospective and retrospective studies undertaken during the last two decades. On the other hand, recent large, randomized clinical trials did not substantiate a beneficial effect of homocysteine-lowering B vitamin supplementation or vitamin E antioxidant therapies in reducing cardiovascular risk in humans. We analyzed eight B vitamin and four E vitamin trials from a critical point of view, and in this article we reviewed and commented on their results and focused on the contradictions found in them. We showed that the possible factors implicated in the failure of vitamin therapies included inappropriate designs. The protocols neglected an essential fact: that the impact of some confounding factors, such as concomitant use of statins, acetylsalicylic acid, folic acid, and other drugs, might have led to bias and an inappropriate interpretation of the data. The cardiovascular protective and preventive effects of statins and aspirin might have reduced or abolished the possibility of observing a difference in the number of events between the vitamin and placebo groups for the clinical endpoints. We concluded that the vitamin preventive effect on cardiovascular disease may not be rejected in reference to the negative trial evidence.