Effects of folic acid supplementation on serum homocysteine levels, lipid profiles, and vascular parameters in post-menopausal Korean women with type 2 diabetes mellitus

Folic acid and plasma lipids: Interactions and effect of folate supplementation

Dyslipidaemia and hyperhomocysteinemia are known risk factors for cardiovascular disease. While it is evident that optimization of plasma lipid is associated with low risk of cardiovascular disease in the general population, it is not yet fully clear whether reduction of homocysteinemia is associated with an improvement in risk in all subjects. The aim of our narrative review is to highlight eventual effects of folate supplementation on LDL-C levels, LDL-C oxidation and atherosclerosis-related complications. A comprehensive literature search was done in electronic database, including PubMed, Web of Science, Cochrane, and Scopus from inception up to January 2024. Based on the available evidence, epidemiological data, pathophysiological observations and meta-analyses of randomized clinical trials suggest that folic acid supplementation may modestly but significantly improve plasma lipid levels, lipid atherogenicity, and atherosclerosis-related early vascular damage, and that folic acid supplementation may significantly reduce the risk of cerebrovascular disease. Considering the low-cost and high safety profile of folic acid, its long-term supplementation could be considered for dyslypidaemic patients in secondary prevention for cardiovascular disease.

Folic acid supplementation on inflammation and homocysteine in type 2 diabetes mellitus: systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The beneficial effects of folate have been observed under different conditions, but the available evidence on inflammation and reduction of cardiovascular disease (CVD) in type 2 diabetes mellitus (T2DM) is limited. The study aimed to explore the effects of folate on inflammation and homocysteine amongst individuals with T2DM.

METHODS

PubMed, Scopus, and Cochrane Library were used to search for evidence. A random-effect model meta-analysis through Review Manager (version 5.4) and metaHun was performed. Results were reported as standardized mean differences (SMD) and 95% confidence intervals graphically using forest and funnel plots.

RESULTS

Data from 9 trials with 426 patients living with T2DM were analyzed. Folic acid supplementation significantly revealed a large effect size on homocysteine levels compared to placebo, SMD = -1.53, 95%CI (-2.14,-0.93), p < 0.05. Additionally, we observed a medium marginal effect size on C-reactive protein (SMD = -0.68, 95%CI (-1.34, -0.01), p = 0.05). However, no significant effect on tumor necrosis factor-α (SMD = -0.86, 95%CI (-2.65, 0.93), p = 0.34), and interleukin-6 (SMD = -0.04, 95%CI (-1.08, 1.01), p = 0.95) was observed.

CONCLUSION

Evidence analyzed in this study suggests that folic acid supplementation in T2DM reduces homocysteine and may mitigate CVDs. However, its effect on inflammation is inconclusive.

The efficacy of vitamin B12 supplementation for treating vitamin B12 deficiency and peripheral neuropathy in metformin-treated type 2 diabetes mellitus patients: A systematic review

BACKGROUND AND AIMS

Metformin-treated type 2 diabetes mellitus (T2DM) patients are at higher risk of vitamin B₁₂ deficiency and more severe neuropathy symptoms. There is still no guideline suggesting vitamin B₁₂ supplementation for this population. This study aimed to analyze the efficacy of vitamin B₁₂ supplementation in this population.

METHOD

Studies reporting the efficacy of vitamin B₁₂ supplementation in metformin-treated T2DM patients were systematically searched in PubMed, Cochrane, EBSCOHost, and Scopus following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Additional relevant studies were searched manually through citations. Study quality and risk of bias were assessed using suitable tools.

RESULTS

Seven clinical trials with a total of 506 participants were included. Using the Cochrane's Risk of Bias 2 tools for clinical trials, 4 studies were assessed to have high risk of bias and 3 studies had low risk of bias. There were 5 studies that measured changes in serum vitamin B₁₂ level, all of which reported a statistically significant increase after supplementation. Significant reductions in homocysteine after supplementation were found in 2 studies. Its effect on neuropathy symptoms was still unclear, with 2 studies reporting a significant improvement and 1 study reporting no significant effect.

CONCLUSIONS

The results of this systematic review support the implementation of vitamin B₁₂ supplementation for metformin-treated T2DM to prevent or treat vitamin B₁₂ deficiency and neuropathy. More high-quality clinical studies are required to generate quantitative analysis and to encourage supplementation in available guidelines.

Folic acid effect on homocysteine, sortilin levels and glycemic control in type 2 diabetes mellitus patients

Aim

The present study aimed to determine the folic acid supplement (FAS) effects on serum homocysteine and sortilin levels, glycemic indices, and lipid profile in type II diabetic patients.

Method

A double-blind randomized controlled clinical trial have been performed on 100 patients with T2DM randomly divided into two groups that received either placebo or folic acid 5 mg/d for 12 weeks.

Results

FAS caused a significant decrease in homocysteine and sortilin serum levels (28.2% and 33.7%, P < 0.0001, respectively). After 3 months of intervention, 8.7% decrease in fasting blood glucose (P = 0.0005), 8.2% in HbA1c (P = 0.0002), 13.7% in serum insulin (P < 0.0001) and 21.7% in insulin resistance (P < 0.0001) were found in the folic acid group, however no significant difference was observed in the placebo group. Serum hs-CRP level showed significant positive associations with sortilin (r = 0.237, P = 0.018), homocysteine (r = 0.308, P = 0.002) and fasting blood glucose (r = 0.342, P = 0.000). There were no significant changes in lipid profile in both groups after 12 weeks.

Conclusion

FAS might be beneficial for reducing homocysteine and sortilin levels, enhancing glycemic control, and improved insulin resistance in patients with T2DM.

Plasma Homocysteine Level Is Independently Associated With Conventional Atherogenic Lipid Profile and Remnant Cholesterol in Adults

Background

Homocysteine (Hcy) is an independent risk factor for cardiovascular disease, while mechanisms are unclear. Despite inconsistent and limited, epidemiological and experimental studies indicated that hyperhomocysteinemia (HHcy) affected lipid metabolism. This study aims to investigate the association of plasma Hcy with traditional lipid profiles and remnant cholesterol (RC) in Chinese adults.

Methods

In total, 7,898 subjects aged 20–79 years who underwent a physical examination at Beijing Chao-Yang Hospital in Beijing were included in this study. Fasting plasma total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein A1 (ApoA1), apolipoprotein B (ApoB), lipoprotein (a) [Lp(a)], Hcy, and other metabolic risk factors were measured by routine automated laboratory methods. RC was calculated as TC minus HDL-C and LDL-C. The linear regression model and logistic regression model were used to assess the relationship between Hcy and lipids after adjusting potential confounders.

Results

Of the subjects, the median level of plasma Hcy was 13.0 μmol/L and 32.3% had HHcy. Plasma Hcy was negatively associated with HDL-C, ApoA1, and Lp(a) and positively associated with TG levels after adjusting age, sex, body mass index, blood pressure, alanine transaminase, aspartate transaminase, creatinine, uric acid, and glucose. HHcy significantly increased the risk of low HDL-C [odds ratio (OR) 1.26; 95%CI (1.11–1.44); p &lt; 0.001]. The net mediation effects of ApoA1 on the relationship between Hcy and HDL-C before and after adjusting confounders were 46.9 and 30.6%, respectively. More interestingly, the RC level was significantly elevated in subjects with HHcy after adjusting other influencing factors (p = 0.025). Hcy presented a positive correlation with RC levels after adjusting the above confounding factors (β = 0.073, p = 0.004), and the correlation was still significant even after controlling other lipids, including TG, LDL-C, HDL-C, ApoA1, ApoB, and Lp(a).

Conclusion

Our study showed that plasma Hcy was not only significantly associated with conventional atherogenic lipids but also independently correlated with RC levels beyond other lipids after controlling potential confounders. This finding proposes that identifying Hcy-related dyslipidemia risk, both traditional lipids and RC residual risk, is clinically relevant as we usher in a new era of targeting Hcy-lowering therapies to fight against dyslipidemia or even cardiovascular disease.

Beneficial effects of folic acid supplementation on lipid markers in adults: A GRADE-assessed systematic review and dose-response meta-analysis of data from 21,787 participants in 34 randomized controlled trials

Folic acid supplementation has received considerable attention in the literature, yet there is a large discrepancy in its effects on lipid markers in adults. Therefore, this systematic review and meta-analysis of 38 randomized controlled trials (RCTs) evaluated the effects of folic acid supplementation on triglyceride (TG), total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol concentrations in a cohort of 21,787 participants. A systematic search current as of March 2021 was performed in PubMed/Medline, Scopus, Web of Science, and Embase using relevant keywords to identify eligible studies. A fix or random-effects model was used to estimate the weighted mean difference (WMD) and 95% confidence intervals (CIs). Thirty-four RCTs were included in this meta-analysis. The pooled analysis revealed that serum TG (WMD: -9.78 mg/dL; 95% CI: -15.5 to -4.00; p = 0.001, I²=0.0%, p = 0.965) and TC (WMD: -3.96 mg/dL; 95% CI: -6.71 to -1.21; p = 0.005, I²=46.9%, p = 0.001) concentrations were significantly reduced following folic acid supplementation compared to placebo. However, folic acid supplementation did not affect serum concentrations of LDL (WMD: -0.97 mg/dL; 95% CI: -6.82 to 4.89; p = 0.746, I²=60.6%, p < 0.001) or HDL cholesterol (WMD: 0.44 mg/dL; 95% CI: -0.53 to 1.41; p = 0.378, I²= 0.0%, p = 0.831). A significant dose-response relationship was observed between the dose of folic acid supplementation and serum concentrations of HDL cholesterols (r = 2.22, p = 0.047). Folic acid supplementation reduced serum concentrations of TG and TC without affecting LDL or HDL cholesterols. Future large RCTs on various populations are needed to show further beneficial effects of folic acid supplementation on lipid profile.

Association between food and nutrients intakes and coronary plaque vulnerability in patients with coronary heart disease: An optical coherence tomography study

BACKGROUND AND AIMS

Dietary intakes play important roles in the prevention and treatment of coronary heart disease (CHD). Coronary plaque vulnerability is the key mechanism leading to CHD progression. We aimed to explore the association between dietary intakes and plaque vulnerability via optical coherence tomography (OCT).

METHODS AND RESULTS

A total of 314 CHD patients were included in this study. Dietary intake status was assessed by semi-quantitative food frequency questionnaire and plaque vulnerability was measured by OCT. The results showed that vegetables were negatively associated with macrophage infiltration, thin cap fibroatheroma (TCFA) and thrombus [odds ratio (OR) = 0.48, 0.38, 0.38, 95% confidence interval (95% CI) = 0.24-0.93, 0.17-0.84, 0.15-0.94, all P < 0.05]; fruits were negatively associated with lipid plaque, TCFA, rupture and thrombus (OR = 0.17, 0.11, 0.12, 0.20, 95% CI = 0.07-0.39, 0.04-0.29, 0.05-0.28, 0.08-0.55, all P < 0.05); salt was positively associated with lipid plaque and TCFA (OR = 2.59, 2.83, 95% CI = 1.14-5.90, 1.23-6.51, all P < 0.05). Regarding nutrients intakes, dietary fiber was negatively associated with macrophage infiltration (OR = 0.34, 95% CI = 0.14-0.85, P = 0.021); folate was negatively associated with lipid plaque, TCFA and rupture (OR = 0.22, 0.16, 0.20, 95% CI = 0.09-0.58, 0.06-0.41, 0.08-0.51, all P < 0.05); vitamin C was negatively associated with TCFA, rupture and thrombus (OR = 0.26, 0.22, 0.05, 95% CI = 0.07-0.95, 0.07-0.65, 0.01-0.25, all P < 0.05); sodium was positively associated with lipid plaque, TCFA, rupture and thrombus (OR = 3.43, 3.96, 2.73, 4.84, 95% CI = 1.51-7.80, 1.66-9.45, 1.18-6.27, 1.76-9.28, all P < 0.05).

CONCLUSION

Salt and sodium were dietary risk factors for plaque vulnerability, whereas vegetables, fruits, dietary fiber, folate and vitamin C were dietary protective factors for plaque vulnerability.

Hyperhomocysteinemia and Low Folate and Vitamin B12 Are Associated with Vascular Dysfunction and Impaired Nitric Oxide Sensitivity in Morbidly Obese Patients

There is a high prevalence of hyperhomocysteinemia that has been linked to high cardiovascular risk in obese individuals and could be attributed to poor nutritional status of folate and vitamin B12. We sought to examine the association between blood homocysteine (Hcy) folate, and vitamin B12 levels and vascular dysfunction in morbidly obese adults using novel ex vivo flow-induced dilation (FID) measurements of isolated adipose tissue arterioles. Brachial artery flow-mediated dilation (FMD) was also measured. Subcutaneous and visceral adipose tissue biopsies were obtained from morbidly obese individuals and non-obese controls. Resistance arterioles were isolated in which FID, acetylcholine-induced dilation (AChID), and nitric oxide (NO) production were measured in the absence or presence of the NO synthase inhibitor, L-NAME, Hcy, or the superoxide dismutase mimetic, TEMPOL. Our results demonstrated that plasma Hcy concentrations were significantly higher, while folate, vitamin B12, and NO were significantly lower in obese subjects compared to controls. Hcy concentrations correlated positively with BMI, fat %, and insulin levels but not with folate or vitamin B12. Brachial and arteriolar vasodilation were lower in obese subjects, positively correlated with folate and vitamin B12, and inversely correlated with Hcy. Arteriolar NO measurements and sensitivity to L-NAME were lower in obese subjects compared to controls. Finally, Hcy incubation reduced arteriolar FID and NO sensitivity, an effect that was abolished by TEMPOL. In conclusion, these data suggest that high concentrations of plasma Hcy and low concentrations of folate and vitamin B12 could be independent predictors of vascular dysfunction in morbidly obese individuals.

A pilot study to assess the effect of a three-month vitamin supplementation containing L-methylfolate on systemic homocysteine plasma concentrations and retinal blood flow in patients with diabetes

Purpose

The aim of the present study was to investigate the effect of a three-month dietary supplementation with a methylfolate formulation on homocysteine plasma concentrations and ocular blood flow parameters in patients with diabetes.

Methods

Twenty-four patients with diabetes received a dietary supplement (Oculofolin, Aprofol AG, Switzerland) containing 900 µg L‑methylfolate (levomefolate calcium or [6S]-5-methyltetrahydrofolic acid, calcium salt), methylcobalamin, and other ingredients for three consecutive months. The patients' plasma homocysteine concentration and retinal blood flow were assessed at baseline and after three months of folate intake. Retinal blood flow was measured using a custom-built dual-beam Doppler optical coherence tomography (OCT) system. In addition, flicker-induced retinal vasodilatation was assessed by means of a commercially available dynamic vessel analyzer (IMEDOS, Jena, Germany).

Results

Supplementation was well tolerated by all patients. After three months, plasma homocysteine concentration significantly decreased from 14.2 ± 9.3 to 9.6 ± 6.6 µmol/L (p < 0.001). In addition, a tendency toward an increased total retinal blood flow from 36.8 ± 12.9 to 39.2 ± 10.8 µl/min was observed, but this effect did not reach the level of significance (p = 0.11). Supplementation had no effect on retinal vessel diameter or flicker-induced vasodilatation.

Conclusions

The present data show that a three-month intake of a dietary supplement containing methylfolate can significantly reduce blood homocysteine levels in patients with diabetes. This is of importance because higher homocysteine plasma levels have been found to be associated with an increased risk of vascular associated systemic diseases and eye diseases. Whether systemic methylfolate supplementation affects retinal perfusion must be studied in a larger population.

Prediction model for the efficacy of folic acid therapy on hyperhomocysteinaemia based on genetic risk score methods

No risk assessment tools for the efficacy of folic acid treatment for hyperhomocysteinaemia (HHcy) have been developed. We aimed to use two common genetic risk score (GRS) methods to construct prediction models for the efficacy of folic acid therapy on HHcy, and the best gene-environment prediction model was screened out. A prospective cohort study enrolling 638 HHcy patients was performed. We used a logistic regression model to estimate the associations of two GRS methods with the efficacy. Performances were compared using area under the receiver operating characteristic curve (AUC). The simple count genetic risk score (SC-GRS) and weighted genetic risk score (wGRS) were found to be independently associated with the efficacy of folic acid treatment for HHcy. Using the SC-GRS, per risk allele increased with a 1·46-fold increased failure risk (P < 0·001) after adjustment for traditional risk factors, including age, sex, BMI, smoking, alcohol consumption, history of diabetes, history of hypertension, history of hyperlipidaemia, history of stroke and history of CHD. When used the wGRS, the association was strengthened (OR = 2·08, P < 0·001). Addition of the SC-GRS and wGRS to the traditional risk model significantly improved the predictive ability by AUC (0·859). A precise gene-environment predictive model with good performance was developed for predicting the treatment failure rate of folic acid therapy for HHcy.

Effect of a balanced nutrition meal replacement diet with altered macromolecular composition along with caloric restriction on body weight control

The prevalence of obesity and its related metabolic syndrome (MetS) has shown an upsurge in recent years due to modified lifestyle patterns. The present study was designed to investigate the impact of a nutritionally balanced conventional meal replacement diet with modified macromolecular composition (rich in soy/pea protein and soluble fibers) and caloric restriction on Taiwanese obese subjects. Obese subjects (BMI > 27; n = 50, male 23, female 27) were recruited and requested to replace two meals per day (breakfast and lunch or dinner) with the balanced nutritional meal replacement diet (equal to 240 kcal) for 8 weeks with one regular meal and make sure that the daily target calorie limit (caloric restriction) was less than 1500 kcal day-1 for men and 1200 kcal day-1 for women. After eight weeks of intervention with a calorie-restricted balanced partial meal replacement diet, the levels of body weight, body fat, and waist circumference were significantly reduced by 4.1 kg, 2.38%, and 5.06 cm, respectively. The levels of serum total cholesterol (TC), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-c) were significantly decreased (p < 0.05) with a significant increase (p < 0.05) in high-density lipoprotein cholesterol (HDL-c) levels after 8 weeks of intervention with the meal replacement diet. Moreover, the levels of insulin, homeostatic model assessment-insulin resistance (HOMA-IR), leptin, thiobarbituric acid reactive substances (TBARS) and cardiovascular risk factors were significantly attenuated (p < 0.05). To conclude, the present intervention with meal replacement and caloric restriction on obese subjects could concomitantly decrease the body weight and glycemic and cardiovascular risk factors and thereby lower the risk of various metabolic disorders.

Associations of the MTHFR rs1801133 polymorphism with coronary artery disease and lipid levels: a systematic review and updated meta-analysis

BACKGROUND

The associations of the 5,10-methylenetetrahydrofolate reductase gene (MTHFR) rs1801133 polymorphism with coronary artery disease (CAD) and plasma lipid levels have been widely investigated, but the results were inconsistent and inconclusive. This meta-analysis aimed to clarify the relationships of the rs1801133 polymorphism with CAD and plasma lipid levels.

METHODS

By searching in PubMed, Google Scholar, Web of Science, Cochrane Library, Wanfang, VIP and CNKI databases, 123 studies (87,020 subjects) and 65 studies (85,554 subjects) were identified for the CAD association analysis and the lipid association analysis, respectively. Odds ratio (OR) and standardized mean difference (SMD) were used to determine the effects of the rs1801133 polymorphism on CAD risk and lipid levels, respectively.

RESULTS

The variant T allele of the rs1801133 polymorphism was associated with increased risk of CAD under allelic model [OR = 1.11, 95% confidence interval (CI) = 1.06-1.17, P < 0.01], additive model (OR = 1.25, 95% CI = 1.14-1.37, P < 0.01), dominant model (OR = 1.11, 95% CI = 1.04-1.17, P < 0.01), and recessive model (OR = 1.22, 95% CI = 1.12-1.32, P < 0.01). The T carriers had higher levels of total cholesterol (TC) (SMD = 0.04, 95% CI = 0.01-0.07, P = 0.02) and low-density lipoprotein cholesterol (LDL-C) (SMD = 0.07, 95% CI = 0.01-0.12, P = 0.01) than the non-carriers.

CONCLUSIONS

The meta-analysis suggested that the T allele of the rs1801133 polymorphism is a risk factor for CAD, which is possibly and partly mediated by abnormal lipid levels.

The effects of folate supplementation on lipid profiles among patients with metabolic diseases: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVE

Although several studies have assessed the effect of folate supplementation on lipid profiles among patients with metabolic diseases, findings are inconsistent. This review of randomized controlled trials (RCTs) was conducted to summarize the evidence on the effects of folate supplementation on lipid profiles among patients with metabolic diseases.

METHODS

Randomized-controlled trials (RCTs) published in PubMed, EMBASE, Web of Science and Cochrane Library databases up to until 20 August 2017 were searched. Two review authors independently assessed study eligibility, extracted data, and evaluated risk of bias of included studies. Heterogeneity was measured with a Q-test and with I₂ statistics. Data were pooled by using the fix or random-effect model based on the heterogeneity test results and expressed as standardized mean difference (SMD) with 95% confidence interval (CI).

RESULTS

A total of thirteen randomized controlled trials were included. Folate supplementation did not affect systolic blood pressure (SMD -0.87; 95% CI, -1.83, 0.09) and diastolic blood pressure (SMD -0.59; 95% CI, -1.55, 0.37), and lipid profiles including triglycerides (SMD 0.10; 95% CI, -0.42, 0.63), total- (SMD 0.06; 95% CI, -0.31, 0.43), HDL- (SMD 0.04; 95% CI, -0.36, 0.44), VLDL- (SMD 0.08; 95% CI, -0.24, 0.41), and LDL-cholesterol (SMD -0.14; 95% CI, -0.55, 0.28).

CONCLUSIONS

Folate supplementation did not affect blood pressures and lipid profiles among patients with metabolic diseases. Additional prospective studies regarding the impact of folate supplementation on blood pressures and lipid profiles in patients with metabolic diseases are necessary.

The Effects of Folate Supplementation on Diabetes Biomarkers Among Patients with Metabolic Diseases: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Although several studies have evaluated the effect of folate supplementation on diabetes biomarkers among patients with metabolic diseases, findings are inconsistent. This review of randomized controlled trials (RCTs) was performed to summarize the evidence on the effects of folate supplementation on diabetes biomarkers among patients with metabolic diseases. Randomized-controlled trials (RCTs) published in PubMed, EMBASE, Web of Science and Cochrane Library databases up to 1 September 2017 were searched. Two review authors independently assessed study eligibility, extracted data, and evaluated risk of bias of included studies. Heterogeneity was measured with a Q-test and with I2 statistics. Data were pooled by using the fix or random-effect model based on the heterogeneity test results and expressed as standardized mean difference (SMD) with 95% confidence interval (CI). A total of sixteen randomized controlled trials involving 763 participants were included in the final analysis. The current meta-analysis showed folate supplementation among patients with metabolic diseases significantly decreased insulin (SMD -1.28; 95% CI, -1.99, -0.56) and homeostasis model assessment of insulin resistance (HOMA-IR) (SMD -1.28; 95% CI, -1.99, -0.56). However, folate supplementation did not affect fasting plasma glucose (FPG) (SMD -0.30; 95% CI, -0.63, 0.02) and hemoglobin A1C (HbA1c) (SMD -0.29; 95% CI, -0.61, 0.03). The results of this meta-analysis study demonstrated that folate supplementation may result in significant decreases in insulin levels and HOMA-IR score, but does not affect FPG and HbA1c levels among patients with metabolic diseases.