Effect of short-term folic acid supplementation on insulin sensitivity and inflammatory markers in overweight subjects

Folic Acid as a Potential Vitamin in Glycemic Control: A Systematic Review

PURPOSE

This systematic review aims to examine the relationship between serum folate level and folic acid supplements with glycemic control parameters (fasting blood glucose (FBG), insulin level, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), and Hemoglobin A1C (HbA1c)) in adult individuals with current studies.

METHODS

In this study, which was designed as a systematic review, the searches were performed on Web of Science, Science Direct, Medline, Wiley, and Cochrane Library databases between April 10, 2023, and May 10, 2023, and the searches were updated between October 16, 2023, and November 14, 2023. Of the 1855 studies obtained from the screening, 17 met the criteria and were included in the systematic review. The PROSPERO system registered the study protocol (ID: CRD42023472434).

RECENT FINDINGS

Although no significant correlation was found between serum folate levels and glycemic control parameters in most of the cross-sectional studies included in this systematic review, most of the randomized controlled trials showed that glycemic control parameters (FBG, insulin, HOMA-IR) decreased significantly in the intervention group receiving folic acid supplementation compared to the control group. However, study durations were short, and HbA1c needed to be evaluated in most studies. This makes it difficult to get information about the long-term effects of folic acid supplementation. More comprehensive studies should be conducted to draw more precise conclusions about the relationship between folic acid levels and folic acid supplementation with glycemic control parameters.

Trends and Motivations in Dietary Supplement Use Among People with Diabetes: A Population-Based Analysis Using National Health and Nutrition Examination Survey Data from the 2009-2020 Period

OBJECTIVES

Dietary supplements have gained attention among people with diabetes as an alternative and complementary treatment, yet there is a limited understanding of supplement use and the motivations behind it.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES) from the 2009-2020 period were analyzed, including data on 5784 people with diabetes aged 20 years or older. Dietary supplement use was self-reported. Trends in supplement use were examined across three periods: 2009-2012, 2013-2016, and 2017-2020. Statistical analyses were conducted while considering NHANES's complex survey design to provide nationally representative estimates for the general noninstitutionalized population of the United States.

RESULTS

A total of 61.72% of individuals reported using dietary supplements with a notable increase over time. Supplement users were generally older, more likely to be female, better educated, and had superior blood glucose control with lower smoking rates compared to non-users. Common supplements included multivitamins, multimineral supplements, vitamin D, calcium, zinc, vitamin C, and fish oil. Only 44.58% of individuals used dietary supplements based on medical advice, with the rest opting for self-directed usage. The primary specific health reasons for supplement use were to improve bone health and heart health and enhance the immune system.

CONCLUSIONS

Dietary supplement use is prevalent among people with diabetes, and most diabetic supplement use is self-directed, which reflects a growing trend toward complementary therapies. Healthcare providers are encouraged to inquire about patients' use of supplements and offer appropriate guidance as an integral component of comprehensive diabetes management.

Association between serum folate levels and migraine or severe headaches: A nationwide cross-sectional study

Migraine and severe headaches are common neurological disorders with significant societal impact. Previous research indicates a potential link between serum folate levels and migraine occurrence, yet there is a lack of sufficient relevant studies and more are required. This study aimed to determine the association between a severe headache or migraine and serum folate levels in large populations. Using data from the National Health and Nutrition Examination Survey, we conducted a cross-sectional study. Using multivariable logistic regression models, we investigated the association between serum folate and severe headache or migraine. In a subsequent subgroup analysis, several confounding factors were also explored to investigate the association between migraine and serum folate. A total of 13,351 individuals participated in the study, with 2742 reporting severe headache or migraine in the previous 3 months. Serum folate was negatively associated with severe headache or migraine (odds ratio [OR] = 0.5, 95% confidence interval [CI] = 0.28-0.89, P = .018). The stratified analysis revealed this association persisted among female (OR = 0.38, 95% CI = 0.18-0.82, P < .001), individuals aged 20 to 50 years (OR = 0.53, 95% CI = 0.28-0.99, P < .001), and non-Hispanic White participants (OR = 0.38, 95% CI = 0.17-0.87, P < .001). We found that greater levels of serum folate were significantly related to a decreased likelihood of migraine onset, especially among women, young and middle-aged populations, and non-Hispanic White participants. Further research is required to validate and expand upon our results.

Transcriptome analysis identifies the NR4A subfamily involved in the alleviating effect of folic acid on mastitis induced by high concentration of Staphylococcus aureus lipoteichoic acid

BACKGROUND

Staphylococcus aureus (S. aureus) mastitis results in economic losses during dairy production. Understanding the biological progression of bovine S. aureus mastitis is vital for its prevention. Lipoteichoic acid is a key virulence factor of S. aureus (aLTA), but the main biological pathways involved in its effect on bovine mammary epithetionallial cells (Mac-T) apoptosis and necrosis have not been fully explored. Folic acid (FA) has anti-inflammatory and anti-apoptotic effects. However, the role of FA in mediating the effects of aLTA on apoptosis and necrosis remains unknown.

RESULTS

We found that low concentration of aLTA inhibited apoptosis and necrosis and that high concentration promoted the apoptosis and necrosis of Mac-T. FA pretreatment alleviated high concentration of aLTA induced apoptosis. Through transcriptomic analysis, we found that nuclear receptor subfamily 4 group A (NR4A), which alters the expression of downstream genes involved in apoptosis, proliferation, and inflammation, decreased under stimulation with a low concentration of aLTA and increased under stimulation with a high concentration of aLTA. Under stimulation with a high concentration of aLTA, the expression of the NR4A subfamily could be inhibited by FA. The results showed that aLTA may affect apoptosis and necrosis through the NR4A subfamily by targeting genes involved in bacterial invasion of epithelial cells, the IL-17 signaling pathway, DNA replication, longevity regulation, the cell cycle, and tight junction pathways. We further found that the expression trends of NR4A1 and the target genes of the NR4A subfamily (PTGS2, ESPL1, MCM5, and BUB1B) in the blood of healthy cows (Healthy), subclinical mastitis cows (SCM), and SCM supplemented with FA (SCM_FA) were consistent with those observed at the cellular level in this study.

CONCLUSIONS

Our study revealed that low and high concentrations of aLTA have opposite effects on apoptosis and necrosis of Mac-T and that FA can alleviate the apoptosis induced by high concentration of aLTA. Transcriptome analysis revealed that the NR4A subfamily play a role in the ability of FA to alleviate the apoptosis and necrosis induced by high concentration of aLTA.

Joint B Vitamin Intake and Type 2 Diabetes Risk: The Mediating Role of Inflammation in a Prospective Shanghai Cohort

BACKGROUND AND AIMS

Type 2 diabetes (T2D) is a global and complex public health challenge, and dietary management is acknowledged as critical in its prevention. Recent studies have highlighted the involvement of micronutrients in T2D pathophysiology; our study aims to assess the association between B vitamin intake and T2D risks and the mediating role of inflammation.

METHODS

In a prospective cohort design, data on B vitamins intake, including thiamine (B1), riboflavin (B2), niacin (B3), pyridoxine (B6), folate (B9), and cobalamin (B12), was obtained using a validated food frequency questionnaire (FFQ), and blood inflammatory biomarkers were analyzed according to standard protocol in the local hospitals at baseline from 44,960 adults in the Shanghai Suburban Adult Cohort and Biobank (SSACB). Incident T2D cases were identified according to a physician's diagnosis or medication records from the electronic medical information system. We employed logistic and weighted quantile sum regression models to explore the associations of single and combined levels of B vitamins with T2D and mediation analyses to investigate the effects of inflammation.

RESULTS

Negative correlations between B vitamins and T2D were observed in the single-exposure models, except for B3. The analyses of joint exposure (B1, B2, B6, B9, and B12) also showed an inverse association (OR 0.80, 95% CI 0.71 to 0.88), with vitamin B6 accounting for 45.58% of the effects. Further mediation analysis indicated a mediating inflammatory impact, accounting for 6.72% of the relationship.

CONCLUSIONS

Dietary intake of B vitamins (B1, B2, B6, B9, B12) was associated with a reduced T2D risk partially mediated by inflammation in Shanghai residents.

One-Carbon Metabolism Nutrients, Genetic Variation, and Diabetes Mellitus

Diabetes mellitus (DM) affects about 9.3% of the population globally. Hyperhomocysteinemia (HHcy) has been implicated in the pathogenesis of DM, owing to its promotion of oxidative stress, β-cell dysfunction, and insulin resistance. HHcy can result from low status of one-carbon metabolism (OCM) nutrients (e.g., folate, choline, betaine, vitamin B6, B12), which work together to degrade homocysteine by methylation. The etiology of HHcy may also involve genetic variation encoding key enzymes in OCM. This review aimed to provide an overview of the existing literature assessing the link between OCM nutrients status, related genetic factors, and incident DM. We also discussed possible mechanisms underlying the role of OCM in DM development and provided recommendations for future research and practice. Even though the available evidence remains inconsistent, some studies support the potential beneficial effects of intakes or blood levels of OCM nutrients on DM development. Moreover, certain variants in OCM-related genes may influence metabolic handling of methyl-donors and presumably incidental DM. Future studies are warranted to establish the causal inference between OCM and DM and examine the interaction of OCM nutrients and genetic factors with DM development, which will inform the personalized recommendations for OCM nutrients intakes on DM prevention.

The Effect of Folic Acid Supplementation on Endothelial Function and Arterial Stiffness Markers in Adults: A Systematic Review and Meta-Analysis

Folic acid might improve endothelial function, but the results are inconclusive. This systematic review evaluated the effect of folic acid supplementation on endothelial parameters and arterial stiffness in adults. The study protocol was registered with the PROSPERO database (CRD42021290195). The PubMed, Web of Sciences, Cochrane and Scopus databases were searched to identify English-language randomised controlled trials of the effect of folate supplementation on arterial stiffness and endothelial function markers in adults. There were significant differences between the effect of folic acid and placebo on flow-mediated dilation (random-effects model, standardized mean differences (SMD): 0.888, 95% confidence interval (CI): 0.447, 1.329, p < 0.001) and monocyte chemotactic protein 1 (random-effects model, SMD: -1.364, 95% CI: -2.164, -0.563, p < 0.001), but there was no significant difference in the central pulse wave velocity (fixed-effects model, SMD: -0.069, 95% CI: -0.264, 0.125, p = 0.485) and peripheral pulse wave velocity (fixed-effects model, SMD: -0.093, 95% CI: -0.263, 0.077, p = 0.284). In conclusion, folic acid might have a favourable effect on endothelial function but may not affect arterial stiffness. Further studies are needed to confirm these results.

Behavioral and biochemical investigations to explore the efficacy of quercetin and folacin in experimental diabetes induced vascular endothelium dysfunction and associated dementia in rats

OBJECTIVES

Vascular dementia (VaD), being strongly associated with metabolic conditions is a major health concern around the world. Diabetes is a major risk factor for the development of VaD. This study investigates the efficacy of quercetin and folacin in diabetes induced vascular endothelium dysfunction and related dementia.

METHODS

Single dose streptozotocin (STZ) (50 mg/kg i.p) was administered to albino Wistar rats (male, 200-250 g) by dissolving in citrate buffer. Morris water maze (MWM) and attentional set shifting tests were used to assess the spatial learning, memory, reversal learning, and executive functioning in animals. Body weight, serum glucose, serum nitrite/nitrate, vascular endothelial function, aortic superoxide anion, brains' oxidative markers (thiobarbituric acid reactive species-TBARS, reduced glutathione-GSH, superoxide dismutase-SOD, and catalase-CAT), mitochondrial enzyme complex (I, II, and IV), inflammatory markers (interleukin-IL-6, IL-10, tumor necrosis factor-TNF-α, and myeloperoxidase-MPO), and acetylcholinesterase activity-AChE were also assessed. Quercetin (30 mg kg-1/60 mg kg-1) and folacin (30 mg kg-1/60 mg kg-1) were used as the treatment drugs. Donepezil (0.5 mg kg-1) was used as a positive control.

RESULTS

STZ administered rats showed reduction in learning, memory, reversal learning, executive functioning, impairment in endothelial function, increase in brains' oxidative stress; inflammation; AChE activity, and decrease in mitochondrial complex (I, II, and IV) activity. Administration of quercetin and folacin in two different doses, significantly attenuated the STZ induced diabetes induced impairments in the behavioral, endothelial, and biochemical parameters.

CONCLUSIONS

STZ administration caused diabetes and VaD which was attenuated by the administration of quercetin and folacin. Therefore, these agents may be studied further for the assessment of their full potential in diabetes induced VaD conditions.

A holistic view of muscle metabolic reprogramming through personalized metabolic modeling in newly diagnosed diabetic patients

Type 2 diabetes mellitus (T2DM) is a challenging and progressive metabolic disease caused by insulin resistance. Skeletal muscle is the major insulin-sensitive tissue that plays a pivotal role in blood sugar homeostasis. Dysfunction of muscle metabolism is implicated in the disturbance of glucose homeostasis, the development of insulin resistance, and T2DM. Understanding metabolism reprogramming in newly diagnosed patients provides opportunities for early diagnosis and treatment of T2DM as a challenging disease to manage. Here, we applied a system biology approach to investigate metabolic dysregulations associated with the early stage of T2DM. We first reconstructed a human muscle-specific metabolic model. The model was applied for personalized metabolic modeling and analyses in newly diagnosed patients. We found that several pathways and metabolites, mainly implicating in amino acids and lipids metabolisms, were dysregulated. Our results indicated the significance of perturbation of pathways implicated in building membrane and extracellular matrix (ECM). Dysfunctional metabolism in these pathways possibly interrupts the signaling process and develops insulin resistance. We also applied a machine learning method to predict potential metabolite markers of insulin resistance in skeletal muscle. 13 exchange metabolites were predicted as the potential markers. The efficiency of these markers in discriminating insulin-resistant muscle was successfully validated.

Effects of Folic Acid Supplementation on Liver Enzymes, Lipid Profile, and Insulin Resistance in Patients with Non-Alcoholic Fatty Liver Disease: A Randomized Controlled Trial

BACKGROUND

Previous evidence revealed an association between folate deficiency and non-alcoholic fatty liver disease (NAFLD). This study is the first one investigating the effects of folic acid on hepatic steatosis grade, liver enzymes, insulin resistance, and lipid profile in NAFLD cases.

MATERIALS AND METHODS

Sixty-six participants with NAFLD were allocated randomly to take either a placebo or one oral tablet of folic acid (1 mg) on a daily basis within eight weeks. Serum folate, homocysteine, glucose, aminotransferases, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and lipids were assessed. Ultrasonography was used for assessing the liver steatosis grade.

RESULTS

The serum alanine transaminase, grade of hepatic steatosis, and aspartate transaminase significantly were decreased within both study groups; however, the between-group comparison was not statistically significant. Of note, the decrease in ALT was more pronounced in folic acid compared with the placebo group (-5.45 ± 7.45 vs. -2.19 ± 8.6 IU/L). The serum homocysteine was decreased after receiving folic acid compared to the placebo (-0.58 ± 3.41 vs. +0.4 ± 3.56 μmol/L; adjusted P = 0.054). Other outcomes did not significantly change.

CONCLUSION

Supplementation with folic acid (1 mg/d) for eight weeks among cases with NAFLD did not change significantly the serum levels of liver enzymes, the hepatic steatosis grade, insulin resistance and lipid profile. However, it was able to prevent the increase in homocysteine in comparison with the placebo. Conducting further research is suggested with the longer duration and different doses of folic acid, adjusted to the genotypes of methylenetetrahydrofolate reductase polymorphism, among NAFLD patients.

The effect of folic acid supplementation on body weight and body mass index: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVE

Several trials have evaluated the effects of folate supplementation on obesity indices. However, their results were inconsistent. Therefore, the current meta-analysis was conducted to summarize data from available randomized clinical trials (RCTs) about the impact of folate supplementation on weight and body mass index (BMI).

METHOD

Medline/PubMed, Scopus, Embase, and ISI web of science were searched to identify relevant articles up to December 2020. The effect sizes were expressed as weighted mean difference (WMD) and 95% confidence intervals (CI) using the random-effects model.

RESULTS

Pooled data from nine studies showed that folic acid supplementation did not change body weight (WMD: -0.16 kg, 95%CI: -0.47 to 0.16, P = 0.32) and BMI (WMD: -0.23 kg/m², 95%CI: -0.49 to 0.03, P = 0.31), but there was significant heterogeneity between the included studies for BMI (I² = 90.1%, P < 0.001). Moreover, subgroup analyses in level of homocysteine and health status indicated significant effect of folic acid supplementation on BMI in those with homocysteine level ≥15 μmol/L (WMD: -0.17 kg/cm2, -0.33 to -0.01, p = 0.03) and in women with polycystic ovary syndrome (PCOS) (WMD: - 0.30kg/cm2, -0.54 to -0.06, p = 0.01).

CONCLUSION

Our outcomes demonstrated that folic acid improves BMI in those with homocysteine levels ≥15 μmol/L and women with PCOS.

Beneficial effects of folic acid on inflammatory markers in the patients with metabolic syndrome: Meta-analysis and meta-regression of data from 511 participants in 10 randomized controlled trials

Previous clinical studies on the anti-inflammatory effects of folic acid (FA) in patients with metabolic syndrome (MetS) have shown controversial results. This study aimed to synthesize the evidence on the effect of FA on inflammatory marker levels in MetS patients. We screened PubMed, Embase, Medline, and the Cochrane Library (from inception to March 2022) to identify relevant randomized controlled trials (RCTs). DerSimonian and Laird random effects were used to estimate the pooled weighted mean difference (WMD) with 95% confidence interval (CI). Funnel plot, Egger's test, and the Begg-Mazumdar correlation test was used to assess publication bias. Subgroup analysis, meta-regression and sensitivity analysis were performed to find out possible sources of between-study heterogeneity. Ten RCTs with a total of 511 participants were included. The analysis showed that FA reduced high sensitivity C-reactive protein (hs-CRP) (WMD, -0.94; 95% CI, -1.56 to -0.32; P = 0.00), interleukin-6 (IL-6) (WMD, -0.39; 95% CI, -0.51 to -0.28; P = 0.00), and tumor necrosis factor-alpha (TNF-α) (WMD, -1.28; 95% CI, -1.88 to -0.68; P = 0.00), but did not decrease the C-reactive protein (CRP) (WMD, 0.10; 95% CI, -0.13 to 0.33; P = 0.38). Sensitivity analysis, subgroup analysis, and meta-regression showed that the effect sizes remained stable. Our findings suggest that FA supplementation could reduce inflammatory markers, such as hs-CRP, IL-6, TNF-α in patients with MetS. This study is registered with PROSPERO (CRD42021223843).

The Role of Nutrition on Meta-inflammation: Insights and Potential Targets in Communicable and Chronic Disease Management

PURPOSE OF REVIEW

Chronic low-grade inflammation may contribute to the onset and progression of communicable and chronic diseases. This review examined the effects and eventual mediation roles of different nutritional factors on inflammation.

RECENT FINDINGS

Potential nutritional compounds influencing inflammation processes include macro and micronutrients, bioactive molecules (polyphenols), specific food components, and culinary ingredients as well as standardized dietary patterns, eating habits, and chrononutrition features. Therefore, research in this field is still required, taking into account critical aspects of heterogeneity including type of population, minimum and maximum intakes and adverse effects, cooking methods, physiopathological status, and times of intervention. Moreover, the integrative analysis of traditional variables (age, sex, metabolic profile, clinical history, body phenotype, habitual dietary intake, physical activity levels, and lifestyle) together with individualized issues (genetic background, epigenetic signatures, microbiota composition, gene expression profiles, and metabolomic fingerprints) may contribute to the knowledge and prescription of more personalized treatments aimed to improving the precision medical management of inflammation as well as the design of anti-inflammatory diets in chronic and communicable diseases.

Folate intake and incident chronic kidney disease: a 30-year follow-up study from young adulthood to midlife

BACKGROUND

The relation of long-term dietary folate intake with incident chronic kidney disease (CKD) remains uncertain.

OBJECTIVES

We aimed to investigate the association between dietary folate intake and incident CKD in a 30-y follow-up study from young adulthood to midlife.

METHODS

A total of 4038 American adults aged 18-30 y and without reduced estimated glomerular filtration rate (eGFR) were enrolled in 1985-1986 and monitored until 2015-2016 in the CARDIA (Coronary Artery Risk Development in Young Adults) study. Diet was assessed by a validated dietary history questionnaire at baseline, in 1992-1993, and in 2005-2006. The primary outcome was incident CKD, defined as an eGFR <60 mL · min-1 · 1.73 m-2 or a urinary albumin to creatinine ratio (ACR) ≥30 mg/g. The secondary outcomes included 1) incident decreased eGFR, defined as an eGFR <60 mL · min-1 · 1.73 m-2, and 2) incident albuminuria, defined as an ACR ≥30 mg/g.

RESULTS

During the follow-up, 642 (15.9%) participants developed CKD. Overall, there was a significant L-shaped relation of dietary folate with incident CKD after adjustment for potential confounders. Compared with the lowest quintile of total folate intake, the multivariable-adjusted HRs (95% CIs) in quintiles 2-5 for incident CKD were 0.69 (0.56, 0.85), 0.35 (0.27, 0.45), 0.34 (0.26, 0.45), and 0.39 (0.30, 0.51), respectively. Similar results were found for the secondary outcomes. Moreover, the L-shaped association was confirmed in a subset of the cohort (n = 1462) with serum folate measured at baseline, in 1992, and in 2000.

CONCLUSIONS

Higher folate intake in young adulthood was longitudinally associated with a lower incidence of CKD later in life. Additional studies are warranted to establish the causal inference.

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.

The consumption of micronutrients in relation to calorie intake and risk of insulin resistance

BACKGROUND AND AIMS

Adequate dietary intakes of essential micronutrients are critical to prevent insulin resistance (IR)-related diseases. Even though the excess calorie intake linked with obesity is also associated with such diseases, no previous studies evaluated the importance of meeting the Dietary Reference Intake (DRI) of micronutrients in relation to calorie intake in those at risk for developing IR.

METHODS AND RESULTS

We evaluated the relationship between the ability or failure to meet the DRI of micronutrients in relation to daily calorie intake in 463 childbearing-age women with a higher prevalence of IR. 56-65% women met the DRIs for vitamin B12, vitamin C, thiamine, and riboflavin while only 0%-49% met the DRIs for folate, pyridoxine, niacin, pantothenic acid, total carotene, vitamins A, D and E by consuming an acceptable number of calories. Women who met the DRIs of folate and vitamin C within acceptable daily calorie intakes were 59% and 66% less likely to have higher Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) compared to women who did not.

CONCLUSIONS

Understanding the mechanisms that explain our findings will be of value to address IR-associated with exposure to high calorie/low-micronutrient dense diets consumed by childbearing-age women. Since there is a global recognition that IR has been increasing in adults and children, similar studies of this nature in pregnant women at risk for IR will provide much needed data to assess the burden of such adverse dietary habits in the offspring. Our study approach may form the foundation for such studies.

Folate derivatives, 5-methyltetrahydrofolate and 10-formyltetrahydrofolate, protect BEAS-2B cells from high glucose-induced oxidative stress and inflammation

Folate (vitamin B₉) and its biologically active derivatives are well-known antioxidant molecules protecting cells from oxidative degradation. The presence of high glucose, often found in diabetic patients, causes oxidative stress resulting in cellular stress and inflammatory injury. Cells in organs such as the lung are highly prone to inflammation, and various protective mechanisms exist to prevent the progressive disorders arising from inflammation. In the present study, the synthetic form of folate, i.e. folic acid, and active forms of folate, i.e. 5-methyltetrahydrofolate and 10-formyltetrahydrofolate, were evaluated for their antioxidant and antiinflammatory potential against high glucose (50 mM)–mediated oxidative stress and inflammation in BEAS-2B cells, an immortalised bronchial epithelial cell line. High glucose treatment showed a 67% reduction in the viability of BEAS-2B cells, which was restored to the viability levels seen in control cultures by the addition of active folate derivatives to the culture media. The DCFH-DA fluorometric assay was performed for oxidative stress detection. The high glucose–treated cells showed a significantly higher fluorescence intensity (1.81- and 3.8-fold for microplate assay and microscopic observation, respectively), which was normalised to control levels on supplementation with active folate derivatives. The proinflammatory NF-κB p50 protein expression in the active folate derivative–supplemented high glucose–treated cells was significantly lower compared to the folic acid treatment. In support of these findings, in silico microarray GENVESTIGATOR database analysis showed that in bronchiolar small airway epithelial cells exposed to inflammatory condition, folate utilization pathway genes are largely downregulated. However, the folate-binding protein gene, which encodes to the folate receptor 1 (FOLR1), is significantly upregulated, suggesting a high demand for folate by these cells  in inflammatory situations. Supplementation of the active folate derivatives 5-methyltetrahydrofolate and 10-formyltetrahydrofolate resulted in significantly higher protection over the folic acid from high glucose–induced oxidative stress and inflammation. Therefore, the biologically active folate derivatives could be a suitable alternative over the folic acid for alleviating inflammatory injury-causing oxidative stress.

Effects of folate supplementation on recurrence and metabolic status of cervical intraepithelial neoplasia grade 2/3 in overweight and obese women: a randomized double-blind placebo-controlled trial

BACKGROUND AND OBJECTIVE

Inconsistent evidence showed that folate supplementation may be associated with reduced risk of cancer due to improved metabolic profiles and reduced markers of oxidative stress and inflammation. The aim of this investigation was to quantify the effects of folate supplementation on the recurrence and other metabolic factors of women with cervical intraepithelial neoplasia grade 2/3 (CIN2/3).

METHODS

This randomized, double-blind, placebo-controlled clinical trial was performed among 60 overweight/obese women with CIN2/3. Definitive CIN2/3 confirmation was done via biopsy, pathological diagnosis, as well as colposcopy. Participants were randomly assigned to the intervention group to take 5 mg/day folate supplements or placebo group (n = 30 in each group) for 12 weeks.

RESULTS

The results of the current study showed a non-significant decrease in recurrence of CIN2/3 in the folate group in comparison with the placebo group (3.3% vs. 16.7%, P = 0.08). Compared with the placebo, folate supplementation significantly decreased plasma homocysteine (Hcy) levels (P < 0.001), serum insulin values (in the crude model) (P = 0.01), and homeostasis model assessment of insulin resistance (P = 0.01). Also, folate supplementation resulted in a significant improvement in the quantitative insulin sensitivity check index (P = 0.002) and total antioxidant capacity (P = 0.04) and a significant reduction in high-sensitivity C-reactive protein (P = 0.015) in comparison with the placebo group.

CONCLUSIONS

In conclusion, folate supplementation for 12 weeks among overweight/obese women with CIN2/3 showed a non-significant decrease in its recurrence and had beneficial effects on insulin sensitivity, inflammation, and oxidative stress markers.

Interaction of Serum Alkaline Phosphatase and Folic Acid Treatment on Chronic Kidney Disease Progression in Treated Hypertensive Adults

The relation of alkaline phosphatase (ALP) with chronic kidney disease (CKD) is still uncertain. We aimed to examine the prospective association between serum ALP and CKD progression, and the modifying effect of serum ALP on folic acid in preventing CKD progression in treated hypertensive patients. This is a post-hoc analysis of 12,734 hypertensive adults with relevant measurements and without liver disease at baseline from the renal sub-study of the China Stroke Primary Prevention Trial, where participants were randomly assigned to daily treatments of 10 mg enalapril and 0.8 mg folic acid, or 10 mg enalapril alone. The primary outcome was CKD progression, defined as a decrease in estimated glomerular filtration rate (eGFR) of ≥30% and to a level of <60 ml/min/1.73 m² if baseline eGFR was ≥60 ml/min/1.73 m²; or a decrease in eGFR of ≥50% if baseline eGFR was <60 ml/min/1.73 m²; or end-stage renal disease. Over a median of 4.4 years, in the enalapril only group, participants with baseline serum ALP≥110IU/L (quartile 4) had a significantly higher risk of CKD progression (3.4% vs 2.3%; adjusted OR,1.61; 95%CI:1.11, 2.32), compared with those with ALP<110IU/L. For those with enalapril and folic acid treatment, compared with the enalapril only treatment, the risk of CKD progression was reduced from 3.4 to 2.1% (adjusted OR, 0.53; 95%CI:0.34, 0.83) among participants with baseline ALP≥110IU/L, whereas there was no significant effect among those with ALP<110IU/L. In hypertensive patients, higher serum ALP was associated with increased risk of CKD progression, and this risk was reduced by 47% with folic acid treatment.

The Effects of Folic Acid Supplementation on Pro-inflammatory Mediators: a Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled Trials

PURPOSE

Despite extensive research, findings regarding the effects of folic acid supplementation on inflammatory mediators have been controversial and inconclusive. This study therefore aimed to summarize the findings of all available clinical trials regarding the effects of folic acid supplementation on inflammatory biomarkers in adults.

METHODS

A systematic search was conducted of PubMed/MEDLINE, Scopus, Web of Science, EMBASE, and Google Scholar until April 2020. All randomized controlled trials that examined the influence of folic acid supplementation on C-reactive protein, interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α) were included. Pooled effect sizes were calculated based on the random effects model, and dose-response analysis was modeled by using a fractional polynomial model.

FINDINGS

In total, 18 randomized controlled trials involving 2286 participants were analyzed. Folic acid supplementation significantly reduced serum levels of C-reactive protein (mean difference [MD], -0.21 mg/L; 95% CI, -0.41 to -0.01; n = 16), TNF-α (MD, -14.88 pg/mL; 95% CI, -23.68 to -6.09; n = 10), and IL-6 (MD, -0.93 pg/mL; 95% CI, -1.72 to -0.14; n = 11). Subgroup analyses suggested a significant reduction at doses ≤5 mg/d and studies longer than 12 weeks in duration. A significant nonlinear association was also found between folic acid dosage (P_nonlinearity <0.001) and duration of administration (P_nonlinearity <0.001) with serum TNF-α levels.

IMPLICATIONS

This meta-analysis indicates the beneficial effects of folic acid supplementation on pro-inflammatory cytokines. Further studies with a longer duration of administration, higher doses, and larger sample sizes should be performed exclusively on patients with chronic inflammatory disorders to elucidate the favorable role of folate intake on inflammatory biomarkers. International Prospective Register of Systematic Reviews identifier: CRD42021249947.

Hematological and renoprotective effects of folic acid and lentil extract in diclofenac sodium exposed rats

Excessive intake of non-steroidal anti-inflammatory drugs such as, diclofenac sodium (DS) may lead to toxicity in the rats. In this work, we aimed to examine the protective impact of lentil extract (LE) and folic acid (FA) on the hematological markers, the kidney tissue oxidative stress and the renal function against diclofenac sodium (DS) in male albino rats. The rats (120-150 g) were divided into four equal groups randomly, the first group kept as the untreated control. The second group was administrated with DS (11.6 mg/kg b.wt. orally once/day). The third group was received DS+FA (11.6 mg/kg b.wt.+76.9 microgram/kg b.wt.) orally once/day. The fourth group was treated with DS+LE (11.6 mg/kg b.wt.+500 mg/kg b.wt.) orally once/day. After four weeks, the results revealed that DS produced a significant decrease in the values of red blood cells (RBCs), hemoglobin concentration (Hb), hematocrit (HCT) and white blood cells (WBCs). On the other hand, there was a significant increase in the platelets count. Also, DS induced a renal deterioration; this was evidenced by the significant increase in the serum levels of urea, creatinine, uric acid, Na, Ca, Mg as well as the nitric oxide (NO) level in the kidney tissue. Also, there were a significant reduction in the serum levels of potassium (K) and reduced glutathione (GSH) in the kidney homogenates. Moreover, the findings in the rats treated by DS+LE or DS+FA showed a potential protection on the hematological markers, oxidative stress in the kidney tissue and the renal function disturbed by DS. LE and FA could play a potent role for the prevention the adverse hematological, the kidney tissue oxidative stress and the renal dysfunction caused by DS via their anti-oxidative and bioactive phytochemicals.

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.

Folic acid supplementation and blood pressure: a GRADE-assessed systematic review and dose-response meta-analysis of 41,633 participants

Hypertension is a predisposing factor for cardiovascular disease (CVD). The extant literature regarding the effects of folic acid supplementation on blood pressure (BP) is inconsistent. Therefore, this systematic review and meta-analysis of randomized controlled trials was conducted to summarize the effects of folic acid supplementation on BP. A systematic search was carried out in PubMed, Scopus, ISI Web of Science, and Cochrane library, from database inception to August 2021. Data were pooled using the random-effects method and were expressed as weighted mean difference (WMD) and 95% confidence intervals (CI). The pooled results of 22 studies, including 41,633 participants, showed that folic acid supplementation significantly decreased systolic BP (SBP) (WMD: -1.10 mmHg; 95% CI: -1.93 to -0.28; p = 0.008). Subgroup analysis showed that the results remained significant when baseline SBP was ≥120 mmHg, intervention duration was ≤6 weeks, intervention dose was ≥5 mg/d, in patients with CVD, males and females, and overweight participants, respectively. Furthermore, the changes observed in diastolic BP (DBP) (WMD: -0.24 mmHg; 95% CI: -0.37 to -0.10; p < 0.001) were also statistically significant. However, subgroup analysis showed that the results remained significant in subject with elevated DBP, long term duration of intervention (>6 weeks), low dose of folic acid (<5 mg/day), CVD patients, both sexes and male, and participants with normal BMI. Dose-response analysis showed that folic acid supplementation changed SBP and DBP significantly based on dose and duration. However, meta-regression analysis did not reveal any significant association between dose and duration of intervention with changes in SBP. The present study demonstrates the beneficial effects of folic acid supplementation on BP by decreasing both SBP and DBP.

Effect of folic acid combined with pravastatin on arteriosclerosis in elderly hypertensive patients with lacunar infarction

ABSTRACT

This study aimed to assess the effect of folic acid combined with pravastatin on atherosclerosis-related indexes in elderly patients with hypertension complicated with lacunar cerebral infarction.A total of 134 elderly hypertensive patients with lacunar cerebral infarction were randomly divided into 3 groups using the random number table method. Group A, the folic acid group, had 45 cases and received low-dose folic acid (0.8 mg/d) treatment on the basis of antihypertensive treatment. Group B, the pravastatin group, had 45 cases and received pravastatin (20 mg/d) treatment on the basis of antihypertensive treatment. Group C, the folic acid combined with the pravastatin group, had 44 cases. Members of this group received pravastatin (20 mg/d) and low-dose folic acid (0.8 mg/d) based on antihypertensive treatment. Levels of folic acid, homocysteine (Hcy), tumor necrosis factor alpha (TNF-a), matrix metallopeptidase 9 (MMP-9), cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) were measured by ELISA before treatment in all 3 groups. Carotid intima-media thickness (IMT) was measured using ultrasound, and systolic and diastolic blood pressure were measured with a mercury column. After 8 weeks of treatment, the levels of folic acid, Hcy, TNF-a, MMP-9, TC, LDL-C, and systolic and diastolic blood pressure were compared among the 3 groups. IMT levels were measured at 12 weeks of treatment.After 8 weeks of treatment, compared with group B, patients in groups A and C had folic acid levels significantly higher than baseline levels, with significantly lower Hcy levels (both P < .05). Patients in group C presented significantly decreased TNF-a, MMP-9, TC, and LDL-C levels and systolic and diastolic blood pressure after 8 weeks of treatment, compared with those in groups A and B (both P < .05). These patients also showed significantly decreased IMT levels compared with those in the other groups (P < .05).Low-dose folic acid combined with pravastatin in elderly patients with lacunar cerebral infarction can reduce the level of homocysteine, improve the degree of carotid atherosclerosis, protect vascular endothelium, and reduce blood lipids and blood pressure, presenting better benefits than pravastatin alone.

Folic Acid Supplementation Improves Glycemic Control for Diabetes Prevention and Management: A Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled Trials

Background: There is a growing interest in the considerable benefits of dietary supplementations, such as folic acid, on the glycemic profile. We aimed to investigate the effects of folic acid supplementation on glycemic control markers in adults. Methods: Randomized controlled trials examining the effects of folic acid supplementation on glycemic control markers published up to March 2021 were detected by searching online databases, including Scopus, PubMed, Embase, and ISI web of science, using a combination of related keywords. Mean change and standard deviation (SD) of the outcome measures were used to estimate the mean difference between the intervention and control groups at follow-up. Meta-regression and non-linear dose-response analysis were conducted to evaluate the association between pooled effect size and folic acid dosage (mg/day) and duration of the intervention (week). From 1814 detected studies, twenty-four studies reported fasting blood glucose (FBG), fasting insulin, hemoglobin A1C (HbA1C), and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) as an outcome measure. Results: Results revealed significant reductions in FBG (weighted mean difference (WMD): −2.17 mg/dL, 95% CI: −3.69, −0.65, p = 0.005), fasting insulin (WMD: −1.63 pmol/L, 95% CI: −2.53, −0.73, p < 0.001), and HOMA-IR (WMD: −0.40, 95% CI: −0.70, −0.09, p = 0.011) following folic acid supplementation. No significant effect was detected for HbA1C (WMD: −0.27%, 95% CI: −0.73, 0.18, p = 0.246). The dose-response analysis showed that folic acid supplementation significantly changed HOMA-IR (r = −1.30, p-nonlinearity = 0.045) in non-linear fashion. However, meta-regression analysis did not indicate a linear relationship between dose, duration, and absolute changes in FBG, HOMA-IR, and fasting insulin concentrations. Conclusions: Folic acid supplementation significantly reduces some markers of glycemic control in adults. These reductions were small, which may limit clinical applications for adults with type II diabetes. Further research is necessary to confirm our findings.

Effects of Folic Acid Supplementation on Inflammatory Markers: A Grade-Assessed Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled Trials

It has been theorized that folic acid supplementation improves inflammation. However, its proven effects on inflammatory markers are unclear as clinical studies on this topic have produced inconsistent results. To bridge this knowledge gap, this systematic review and meta-analysis of randomized controlled trials (RCTs) aimed to evaluate the effects of folic acid supplementation on serum concentrations of the inflammatory markers C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). Methods: To identify eligible RCTs, a systematic search up to April 2021 was completed in PubMed/Medline, Scopus, Web of Science, EMBASE, Cochrane databases, and Google Scholar using relevant keywords. A fix or random-effects model was utilized to estimate the weighted mean difference (WMD) and 95% confidence interval (95% CI). Results: Twelve RCTs were included in the present meta-analysis. The pooled analysis revealed that serum concentrations of CRP (WMD: −0.59 mg/L, 95% CI −0.85 to −0.33, p < 0.001) were significantly reduced following folic acid supplementation compared to placebo, but did not affect serum concentrations of IL-6 (WMD: −0.12, 95% CI −0.95 to 0.72 pg/mL, p = 0.780) or TNF-α (WMD: −0.18, 95% CI −0.86 to 0.49 pg/mL, p = 0.594). The dose–response analysis demonstrated a significant relationship between an elevated dosage of folic acid supplementation and lower CRP concentrations (p = 0.002). Conclusions: We found that folic acid supplementation may improve inflammation by attenuating serum concentrations of CRP but without significant effects on IL-6 and TNF-α. Future RCTs including a larger number of participants and more diverse populations are needed to confirm and expand our findings.

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.

Dietary folate intake and metabolic syndrome in participants of PREDIMED-Plus study: a cross-sectional study

PURPOSE

We examined the association between dietary folate intake and a score of MetS (metabolic syndrome) and its components among older adults at higher cardiometabolic risk participating in the PREDIMED-Plus trial.

METHODS

A cross-sectional analysis with 6633 with overweight/obesity participants with MetS was conducted. Folate intake (per 100 mcg/day and in quintiles) was estimated using a validated food frequency questionnaire. We calculated a MetS score using the standardized values as shown in the formula: [(body mass index + waist-to-height ratio)/2] + [(systolic blood pressure + diastolic blood pressure)/2] + plasma fasting glucose-HDL cholesterol + plasma triglycerides. The MetS score as continuous variable and its seven components were the outcome variables. Multiple robust linear regression using MM-type estimator was performed to evaluate the association adjusting for potential confounders.

RESULTS

We observed that an increase in energy-adjusted folate intake was associated with a reduction of MetS score (β for 100 mcg/day = - 0.12; 95% CI: - 0.19 to - 0.05), and plasma fasting glucose (β = - 0.03; 95% CI: - 0.05 to - 0.02) independently of the adherence to Mediterranean diet and other potential confounders. We also found a positive association with HDL-cholesterol (β = 0.07; 95% CI: 0.04-0.10). These associations were also observed when quintiles of energy-adjusted folate intake were used instead.

CONCLUSION

This study suggests that a higher folate intake may be associated with a lower MetS score in older adults, a lower plasma fasting glucose, and a greater HDL cholesterol in high-risk cardio-metabolic subjects.

Folic acid ameliorates palmitate-induced inflammation through decreasing homocysteine and inhibiting NF-κB pathway in HepG2 cells

OBJECTIVE

Prevention of inflammation is one of the possible remedy procedure for steatohepatitis during NAFLD. In this study, we researched the folic acid (FA) potency to attenuate the inflammation of palmitate-treated HepG2 cells and the related signalling pathways.

METHODS

The molecular mechanisms related to FA anti-inflammatory effect in palmitate and Hcy-treated HepG2 cell line were assessed.

RESULTS

The results indicated that while palmitate enhances the expression and secretion of TNF-α, IL-6, and IL-1β, and also intracellular ROS level, FA at concentrations of 25, 50, and 75 µg/mL significantly reversed these effects in HepG2 cells. In addition, FA could ameliorate inflammation and decrease ROS production induced by Hcy. Furthermore, FA pre-treatment suppress palmitate -induced (NF-κB) p65 level in palmitate or Hcy stimulated cells.

CONCLUSIONS

Overall, these results suggest that FA reduces inflammation in HepG2 cells through decreasing ROS and Hcy concentration level resulting in inhibiting the NF-κB pathway.

Synthesis of Some New Folic Acid-Based Heterocycles of Anticipated Biological Activity

To date, no fused heterocycles have been formed on folic acid molecules; for this reason, and others, our target is to synthesize new derivatives of folic acid as isolated or fused systems. Folic acid 1 reacted with ethyl pyruvate, triethyl orthoformate, ethyl chloroformate, thioformic acid hydrazide, and aldehydes to give new derivatives of folic acid 2-6a,b. Moreover, It reacted with benzylidene malononitrile, acetylacetone, ninhydrin, ethyl acetoacetate, ethyl cyanoacetate, and ethyl chloroacetate to give the pteridine fused systems 10-15, respectively. Ethoxycarbonylamino derivate 5 reacted with some nucleophiles containing the NH2 group, such as aminoguanidinium hydrocarbonate, hydrazine hydrate, glycine, thioformic acid hydrazide, and sulfa drugs in different conditions to give the urea derivatives 16-20a,b. Compound 4 reacted with the same nucleophiles to give the methylidene amino derivatives 21-24a,b. The fused compound 10 reacted with thioglycolic acid carbon disulfide, malononitrile, and formamide to give the four cyclic fused systems 25-30, respectively. The biological activity of some synthesized showed moderate effect against bacteria, but no effect shown towards fungi.

Unexplored nutritive potential of tomato to combat global malnutrition

Tomato, a widely consumed vegetable crop, offers a real potential to combat human nutritional deficiencies. Tomatoes are rich in micronutrients and other bioactive compounds (including vitamins, carotenoids, and minerals) that are known to be essential or beneficial for human health. This review highlights the current state of the art in the molecular understanding of the nutritional aspects, conventional and molecular breeding efforts, and biofortification studies undertaken to improve the nutritional content and quality of tomato. Transcriptomics and metabolomics studies, which offer a deeper understanding of the molecular regulation of the tomato's nutrients, are discussed. The potential uses of the wastes from the tomato processing industry (i.e., the peels and seed extracts) that are particularly rich in oils and proteins are also discussed. Recent advancements with CRISPR/Cas mediated gene-editing technology provide enormous opportunities to enhance the nutritional content of agricultural produces, including tomatoes. In this regard, genome editing efforts with respect to biofortification in the tomato plant are also discussed. The recent technological advancements and knowledge gaps described herein aim to help explore the unexplored nutritional potential of the tomato.

Intakes of Folate, Vitamin B6, and Vitamin B12 in Relation to Diabetes Incidence Among American Young Adults: A 30-Year Follow-up Study

OBJECTIVE

To prospectively examine intakes of folate, vitamin B₆, and vitamin B₁₂ in relation to diabetes incidence in a large U.S. cohort.

RESEARCH DESIGN AND METHODS

A total of 4,704 American adults aged 18-30 years and without diabetes were enrolled in 1985-1986 and monitored until 2015-2016 in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Dietary assessment was conducted by a validated dietary history questionnaire at baseline, in 1992-1993, and in 2005-2006. The cumulative average intakes of folate, vitamin B₆, and vitamin B₁₂ were used in the analyses. Incident diabetes was ascertained by plasma glucose levels, oral glucose tolerance tests, hemoglobin A_1c concentrations, and/or antidiabetic medications.

RESULTS

During 30 years (mean 20.5 ± 8.9) of follow-up, 655 incident cases of diabetes occurred. Intake of folate, but not vitamin B₆ or vitamin B₁₂, was inversely associated with diabetes incidence after adjustment for potential confounders. Compared with the lowest quintile of total folate intake, the multivariable-adjusted hazard ratios (95% CI) in quintiles 2-5 were 0.85 (0.67-1.08), 0.78 (0.60-1.02), 0.82 (0.62-1.09), and 0.70 (0.51-0.97; P _trend = 0.02). Higher folate intake was also associated with lower plasma homocysteine (P _trend < 0.01) and insulin (P _trend < 0.01). Among supplement users, folate intake was inversely associated with serum C-reactive protein levels (P _trend < 0.01).

CONCLUSIONS

Intake of folate in young adulthood was inversely associated with diabetes incidence in midlife among Americans. The observed association may be partially explained by mechanisms related to homocysteine level, insulin sensitivity, and systemic inflammation.

Unmetabolized folic acid is associated with TNF-α, IL-1β and IL-12 concentrations in a population exposed to mandatory food fortification with folic acid: a cross-sectional population-based study in Sao Paulo, Brazil

PURPOSE

The study assessed associations between inflammatory markers, as cytokines, adhesion molecules and unmetabolized folic acid (UMFA) among a population exposed to mandatory fortification.

METHODS

Data were collected from a cross-sectional population-based survey (n = 302) conducted in São Paulo City, Brazil. UMFA was assayed by a modified affinity-HPLC method with electrochemical detection to measure the different forms of the folate in plasma. We used a commercial test kit to analyze cytokines and adhesion molecules. Multiple logistic regressions were applied to investigate the association between inflammatory markers and UMFA. Multiple models were adjusted for sex, age, self-reported skin color, BMI and smoking status.

RESULTS

The prevalence of detectable UMFA in this population was high (81.2%), with median concentration of 1.67 nmol/L. The odds ratios (95% CIs) for having higher immunological markers levels among individuals in the highest tertile of UMFA were 0.44 (0.24; 0.81) for TNF-α, 0.92 (0.49; 1.75) for CRP, 1.32 (0.70; 2.48) for ICAM, 0.99 (0.54; 1.81) for VCAM, 0.45 (0.25; 0.83) for IL-1β, 0.74 (0.40; 1.38) for IL-6, 1.34 (0.73; 2.44) for IL-8, 0.65 (0.36; 1.18) for IL-10 and 0.49 (0.27; 0.89) for IL-12.

CONCLUSION

UMFA concentrations were inversely associated with elevated proinflammatory markers (TNF-α, IL-1β and IL-12). These results signalize a link between folate metabolism and the inflammatory status of adults in an apparently folate-replete population.

Relationships of inflamm-aging with circulating nutrient levels, body composition, age, and pituitary pars intermedia dysfunction in a senior horse population

Similarly to aged humans, senior horses (≥20 years) exhibit chronic low-grade inflammation systemically, known as inflamm-aging. Inflamm-aging in the senior horse has been characterized by increased circulating inflammatory cytokines as well as increased inflammatory cytokine production by lymphocytes and monocytes in response to a mitogen. Little is currently known regarding underlying causes of inflamm-aging. However, senior horses are also known to present with muscle wasting and often the endocrinopathy pituitary pars intermedia dysfunction (PPID). Despite the concurrence of these phenomena, the relationships inflamm-aging may have with measures of body composition and pituitary function in the horse remain unknown. Furthermore, nutrition has been a focus of research in an attempt to promote health span as well as life span in senior horses, with some nutrients, such as omega-3 fatty acids, having known anti-inflammatory effects. Thus, an exploratory study of a population of n = 42 similarly-managed senior horses was conducted to determine relationships between inflamm-aging and measures of circulating nutrients, body composition, age, and PPID. Serum was collected to determine vitamin, mineral, and fatty acid content. Peripheral blood mononuclear cells were also isolated to determine inflammatory cytokine production of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) following stimulation with a mitogen, as well as to determine gene expression of interleukin(IL)-1β, IL-6, IL-10, IFN-γ, and TNF-α. Serum IL-6 and C-reactive protein were determined by enzyme-linked immunosorbent assay. Whole blood was collected for hematological and biochemical analysis. Body composition was evaluated via ultrasound and muscle scoring for all 42 horses as well as by deuterium oxide dilution for a subset of n = 10 horses. Pituitary function was evaluated by measuring basal adrenocorticotropin hormone concentrations as well as by thyrotropin releasing hormone stimulation testing (to determine PPID status). Results showed various relationships between inflammatory markers and the other variables measured. Most notably, docosadienoic acid (C22:2n6c), docosapentaenoic acid (C22:5n3c), and folate were positively associated with numerous inflammatory parameters (P ≤ 0.05). Although no relationships were found between inflamm-aging and PPID, being positive for PPID was negatively associated with vitamin B12 (P ≤ 0.01). No relationships between inflammation and body composition were found. Even within this senior horse population, age was associated with multiple parameters, particularly with numerous inflammatory cytokines and fatty acids. In summary, inflamm-aging exhibited relationships with various other parameters examined, particularly with certain fatty acids. This exploratory study provides insights into physiological changes associated with inflamm-aging in the senior horse.

A Randomized Pilot Trial to Evaluate the Bioavailability of Natural versus Synthetic Vitamin B Complexes in Healthy Humans and Their Effects on Homocysteine, Oxidative Stress, and Antioxidant Levels

The vitamin B complex comprises 8 different water-soluble constituents that humans must sequester from the diet. This pilot study compared natural versus synthetic vitamin B complexes for their bioavailability, accumulation, and their impact on antioxidants, homocysteine levels, and oxidative stress. We conducted a double-blind randomized clinical trial with thirty healthy participants. They were randomly assigned to group N (natural) and group S (synthetic). Vitamin B was ingested daily for 6 weeks in the range of about 2.5 times above the recommended daily allowance. Blood samples were taken at baseline, 1.5 h, 4 h, 7 h (diurnal), 6 w (discontinuation of supplements), and 8 w (washout). Blood levels of thiamine (B₁), riboflavin (B₂), pyridoxine (B₆), folic acid (B₉), cobalamin (B₁₂), homocysteine, total antioxidants, peroxidase activity, polyphenols, and total peroxides were determined. Compared to initial values, serum levels of each B vitamin increased at the end of the supplementation period: i.e., B₁ (+23% N; +27% S), B₂ (+14% N; +13% S), B₆ (+101% N; +101% S), B₉ (+86% N; +153% S), and B₁₂ (+16% N) (p < 0.05). Homocysteine (-13% N) decreased, while peroxidase activity (+41% S) and antioxidant capacity increased (+26% N). Short-term effects were already observed after 1.5 h for B₉ (+238% N; +246% S) and after 4 h for vitamin B₂ (+7% N; +8% S), B₆ (+59% N; +51% S), and peroxidase activity (+58% N; +58% S). During the washout period, serum levels of B vitamins decreased except for thiamine and peroxidase activity, which increased further. This clinical pilot study revealed comparable bioavailability for both natural and synthetic B vitamins but did not show statistically noticeable differences between groups despite some favourable tendencies within the natural vitamin group, i.e., sustained effects for cobalamin and endogenous peroxidase activity and a decrease in homocysteine and oxidative stress levels.

Correlations of C-Reactive Protein and Folate with Smoking, Sport, Hematological Inflammation Biomarkers and Anthropometrics in Syrian University Female Students Cross-Sectional Study

In Syria, high-Sensitive C-Reactive (hsCRP), folate, and, other health risk data in young women are limited. This cross-sectional study evaluates hsCRP and folate levels along with anthropometric characteristics, lifestyle factors and some biomarkers linked to cardiovascular disease (CVD) risk factors in healthy female students (n = 207, 18-25 years old). Among participants, hsCRP level was at average or high risk of CVD in 20.7% and 2.5% respectively and it was significantly higher in participants who had high body mass index (BMI) (Nonparametric statistical tests, p value < 0.05). Unexpectedly, it did not vary significantly between smokers and nonsmokers. And, it correlated positively with anthropometric and erythrocyte sedimentation rate (ESR) measurements. While folate level was low in 3.4% of participants, no association between hsCRP and folate levels was found. Finally, low hemoglobin level and habit of waterpipe smoking are spreading; and, sport practicing is shrinking. After reviewing similar works, this study suggests that the possible correlation between hsCRP and folate could be displayed in patients older than 30 years. Also, the marked decrease in hemoglobin level needs more attention. Finally, young females in Syria are advised to consider a lifestyle free of smoking and packed with physical activity.

Glucose and insulin responses to an intravenous glucose tolerance test administered to feed-restricted dairy cows receiving folic acid and vitamin B12 supplements

The present experiment was conducted to determine whether, during periods of negative energy balance, the increase in glucose availability, despite similar DMI and greater milk production, induced by a combined supplement of folic acid and vitamin B₁₂ was related to effects of insulin on metabolism. Sixteen multiparous Holstein cows averaging 45 days in milk (standard deviation: 3) were assigned to 8 blocks of 2 animals each according to their milk production (45 kg/d; standard deviation: 6) during the week preceding the beginning of the experiment. Within each block, they received weekly intramuscular injections of either saline (CON) or folic acid and vitamin B₁₂ (VIT) during 5 consecutive weeks. During the last week, the cows were fed 75% of their ad libitum intake during 4 d. Blood samples were taken the morning before starting the feed restriction and on the third day of feed restriction. On the fourth day of feed restriction, the daily meal was not served and an intravenous glucose tolerance test was performed. During the 4 wk preceding the feed restriction, milk production and DMI were not affected by treatments. During the feed restriction, the vitamin supplement tended to decrease milk fat concentration and increase milk concentration of lactose. Plasma concentrations of homocysteine, Ile, Leu, Val, and branched-chain AA increased in VIT cows during the restriction but not in CON cows. During the glucose tolerance test, insulin peak height was lower and insulin incremental positive area under the curve tended to be lower for VIT than for CON [83 (95% confidence interval, CI: 64-108) vs. 123 (95% CI: 84-180) µg·180 min/L, respectively]. Free fatty acid nadir was reached earlier for VIT than for CON [34 (95% CI: 26-43) vs. 46 (95% CI: 31-57) min, respectively]. Glucose area under the curve, clearance rate and peak height, insulin time to reach the peak and clearance rate, and free fatty acid nadir did not differ between VIT and CON. The reduction in insulin release during a glucose tolerance test without changes in glucose clearance rate or area under the curve suggests that the vitamin supplement improved insulin sensitivity in feed-restricted lactating dairy cows.

Effects of folic acid supplementation on C-reactive protein: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Given the contradictory results of previous randomized controlled trials (RCTs), we performed a systematic review and meta-analysis to quantify and summarize the effects of folic acid supplementation on C-reactive protein (CRP).

METHODS AND RESULTS

We performed a systematic search of all available RCTs conducted up to October 2018 in the following databases: PubMed, Scopus, and Cochrane. RCTs that investigated the effect of folate on CRP were included in the present study. Data were combined with the use of generic inverse-variance random-effects models. Statistical heterogeneity between studies was evaluated using Cochran's Q-test. Ten RCTs (1179 subjects) were included in the present meta-analysis. Pooled analysis results showed that folate supplementation significantly lowered the serum CRP level (weighted mean difference (WMD): -0.685 mg/l, 95% CI: -1.053, -0.318, p < 0.001). However, heterogeneity was significant (I² = 96.7%, p = 0.000). Stratified analyses indicated that sex, intervention period, and type of study population were sources of heterogeneity. Following analysis, results revealed that the greatest impact was observed in women (WMD: -0.967 mg/l, 95% CI: -1.101, -0.833, p = 0.000), patients with type 2 diabetes mellitus (WMD: -1.764 mg/l, 95% CI: -2.002, -1.526, p = 0.000), and intervention period less than 12 weeks (WMD: -0.742 mg/l, 95% CI: -0.834, -0.650, p = 0.000).

CONCLUSION

This meta-analysis suggested that folic acid supplementation could significantly lower the serum CRP level. Folic acid leads to greater CRP lowering effect in women, patients with T2DM, and those with less than 12-week intervention.

Folic Acid and Vitamin B12 Administration in CKD, Why Not?

Patients affected by chronic kidney disease (CKD) or end-stage renal disease (ESRD) experience a huge cardiovascular risk and cardiovascular events represent the leading causes of death. Since traditional risk factors cannot fully explain such increased cardiovascular risk, interest in non-traditional risk factors, such as hyperhomocysteinemia and folic acid and vitamin B12 metabolism impairment, is growing. Although elevated homocysteine blood levels are often seen in patients with CKD and ESRD, whether hyperhomocysteinemia represents a reliable cardiovascular and mortality risk marker or a therapeutic target in this population is still unclear. In addition, folic acid and vitamin B12 could not only be mere cofactors in the homocysteine metabolism; they may have a direct action in determining tissue damage and cardiovascular risk. The purpose of this review was to highlight homocysteine, folic acid and vitamin B12 metabolism impairment in CKD and ESRD and to summarize available evidences on hyperhomocysteinemia, folic acid and vitamin B12 as cardiovascular risk markers, therapeutic target and risk factors for CKD progression.

Effect of folate supplementation on insulin sensitivity and type 2 diabetes: a meta-analysis of randomized controlled trials

Background

Various mechanisms link higher total homocysteine to higher insulin resistance (IR) and risk of type 2 diabetes (T2D). Folate supplementation is recognized as a way to lower homocysteine. However, randomized controlled trials (RCTs) show inconsistent results on IR and T2D outcomes.

Objective

The aim of this study was to examine the effect of folate supplementation on IR and T2D outcomes.

Design

We conducted a systematic literature search in PubMed, Web of Science, and EMBASE and prior systematic reviews and meta-analyses and identified 29 RCTs (22,250 participants) that assessed the effect of placebo-controlled folate supplementation alone or in combination with other B vitamins on fasting glucose, insulin, homeostasis model assessment for insulin resistance (HOMA-IR), glycated hemoglobin (HbA1c), or risk of T2D. The meta-analysis was conducted using both random- and fixed-effects models to calculate weighted mean differences (WMDs) or risk ratios with 95% CIs. Subgroup analyses were conducted based on intervention type (folate alone or in combination with other B vitamins), as well as analysis based on population characteristics, duration, dose, and change in homocysteine.

Results

When compared with placebo, folate supplementation lowered fasting insulin (WMD: -13.47 pmol/L; 95% CI: -21.41, -5.53 pmol/L; P < 0.001) and HOMA-IR (WMD: -0.57 units; 95% CI: -0.76, -0.37 units; P < 0.0001), but no overall effects were observed for fasting glucose or HbA1c. Heterogeneity was low in all meta-analyses, and subgroup analysis showed no signs of effect modification except for change in homocysteine, with the most pronounced effects in trials with a change of >2.5 µmol/L. Changes in homocysteine after folate supplementation correlated with changes in fasting glucose (β = 0.07; 95% CI: 0.01, 0.14; P = 0.025) and HbA1c (β = 0.46; 95% CI: 0.06, 0.85; P = 0.02). Only 2 studies examined folate supplementation on risk of T2D, and they found no change in RR (pooled RR: 0.91; 95% CI: 0.80, 1.04; P = 0.16).

Conclusion

Folate supplementation might be beneficial for glucose homeostasis and lowering IR, but at present there are insufficient data to conclusively determine the effect on development of T2D. This trial was registered on the Prospero database as CRD42016048254.

An oral supplementation based on myo-inositol, folic acid and liposomal magnesium may act synergistically with antibiotic therapy and can improve metabolic profile in patients affected by Hidradenitis suppurativa: our experience

BACKGROUND

Over recent years, the link between obesity, metabolic syndrome and Hidradenitis suppurativa (HS) has been explored. It has been demonstrated that HS patients have a high prevalence of the metabolic syndrome and an increased frequency of insulin resistance. The objective of our study is to estimate the effectiveness of an oral supplementation based on myo-inositol (MI), folic acid and liposomal magnesium (Levigon^®, Sanitpharma; Milan, Italy) on the clinical and metabolic profile of patients affected by HS.

METHODS

Twenty subjects with HS and an impaired glucose metabolism were enrolled. Group A: 10 subjects received for 6 months MI 2000 mg, liposomal magnesium and folic acid associated to topical antibiotic therapy (clindamycin gel 1%), systemic antibiotic therapy (clindamycin 300 mg b.i.d. and rifampicin 600 mg daily for 6 weeks) and a normocaloric diet group B: 10 subjects received topical and systemic antibiotic therapy associated to a normocaloric diet for 6 months.

RESULTS

After 6 months group A patients showed an average reduction of Sartorius Score from 38.3±7.75 to 27.3±13.53 (P value <0.04) while in the control group there was a reduction of the Sartorius from 38.4±7.88 to 31.1±8.02 (P value =0.55). Moreover in group A Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) was significantly reduced from 2.43±0.35 to 2.1±0.31 (P<0.01) whereas in group B HOMA-IR did not significantly decrease (2.51±0.65 at T0 at 2.40±0.67 at T1).

CONCLUSIONS

Our study underlines the importance of the evaluation of metabolic profile in patients with HS. Moreover, it suggests that the supplementation of MI, folic acid and liposomal magnesium in HS can improve the efficacy of concomitant therapies and the metabolic profile.

Folic Acid Supplementation Attenuates Chronic Hepatic Inflammation in High-Fat Diet Fed Mice

Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease worldwide. Hepatic inflammation is an important pathogenic mediator of NAFLD. There is currently no pharmacological agent approved for the treatment of NAFLD. Folic acid is a water-soluble B vitamin that has been shown to have lipid-lowering and antioxidant effects. The objective of this study was to investigate the effect of folic acid supplementation on hepatic inflammation and to identify the underlying mechanisms. Male C57BL/6 J mice were fed a control diet (10% kcal fat), a high-fat diet (HFD) (60% kcal fat), or a HFD supplemented with folic acid (26 mg/kg diet) for 8 weeks. HFD feeding led to increased body mass gain, lipid accumulation, activation of transcription factor nuclear factor-κB (NF-κB), and elevation of inflammatory cytokine gene expression in the liver. Folic acid supplementation attenuated hepatic lipid accumulation and aggregation of inflammatory foci induced by HFD feeding. This was associated with a significant reduction of NF-κB activation and inflammatory cytokine expression. These results suggest that the hepatoprotective effect of folic acid in NAFLD may be attributed, in part, to its anti-inflammatory action.

Folic Acid Improves the Inflammatory Response in LPS-Activated THP-1 Macrophages

DNA methylation has been suggested as a regulatory mechanism behind some inflammatory processes. The physiological actions of methyl donors, such as folic acid, choline, and vitamin B₁₂ on inflammation-related disease have been associated with the synthesis of the universal methyl donor S-adenosyl methionine (SAM). The aim of this study was to evaluate the effects of folic acid, choline, vitamin B₁₂, and a combination of all on preventing the lipopolysaccharide- (LPS-) induced inflammatory response in human THP-1 monocyte/macrophage cells. Folic acid and the mixture of methyl donors reduced interleukin 1 beta (IL1B) and tumour necrosis factor (TNF) expression as well as protein secretion by these cells. Folic acid and choline decreased C-C motif chemokine ligand 2 (CCL2) mRNA levels. In addition to this, the methyl donor mixture reduced Cluster of differentiation 40 (CD40) expression, but increased serpin family E member 1 (SERPINE1) expression. All methyl donors increased methylation levels in CpGs located in IL1B, SERPINE1, and interleukin 18 (IL18) genes. However, TNF methylation was not modified. After treatment with folic acid and the methyl donor mixture, ChIP analysis showed no change in the binding affinity of nuclear factor-κB (NF-κB) to IL1B and TNF promoter regions after the treatment with folic acid and the methyl donor mixture. The findings of this study suggest that folic acid might contribute to the control of chronic inflammation in inflammatory-related disease.

Folic acid supplementation alters the DNA methylation profile and improves insulin resistance in high-fat-diet-fed mice

Folic acid (FA) supplementation may protect from obesity and insulin resistance, the effects and mechanism of FA on chronic high-fat-diet-induced obesity-related metabolic disorders are not well elucidated. We adopted a genome-wide approach to directly examine whether FA supplementation affects the DNA methylation profile of mouse adipose tissue and identify the functional consequences of these changes. Mice were fed a high-fat diet (HFD), normal diet (ND) or an HFD supplemented with folic acid (20 μg/ml in drinking water) for 10 weeks, epididymal fat was harvested, and genome-wide DNA methylation analyses were performed using methylated DNA immunoprecipitation sequencing (MeDIP-seq). Mice exposed to the HFD expanded their adipose mass, which was accompanied by a significant increase in circulating glucose and insulin levels. FA supplementation reduced the fat mass and serum glucose levels and improved insulin resistance in HFD-fed mice. MeDIP-seq revealed distribution of differentially methylated regions (DMRs) throughout the adipocyte genome, with more hypermethylated regions in HFD mice. Methylome profiling identified DMRs associated with 3787 annotated genes from HFD mice in response to FA supplementation. Pathway analyses showed novel DNA methylation changes in adipose genes associated with insulin secretion, pancreatic secretion and type 2 diabetes. The differential DNA methylation corresponded to changes in the adipose tissue gene expression of Adcy3 and Rapgef4 in mice exposed to a diet containing FA. FA supplementation improved insulin resistance, decreased the fat mass, and induced DNA methylation and gene expression changes in genes associated with obesity and insulin secretion in obese mice fed a HFD.

Effect of Combined Treatment With Folic Acid, Vitamin B6, and Vitamin B12 on Plasma Biomarkers of Inflammation and Endothelial Dysfunction in Women

BACKGROUND

The aim of this study was to determine whether reducing plasma homocysteine concentrations with long-term, combined treatment with folic acid, vitamin B6, and vitamin B12 alters plasma biomarkers of inflammation and endothelial dysfunction in women at increased risk of cardiovascular disease.

METHODS AND RESULTS

We conducted a blood substudy of 300 treatment-adherent participants (150 in the active treatment group, 150 in the placebo group) in the WAFACS (Women's Antioxidant and Folic Acid Cardiovascular Study), a randomized, double-blind, placebo-controlled trial testing a daily combination of folic acid (2.5 mg), vitamin B6 (50 mg), vitamin B12 (1 mg), or matching placebo, in cardiovascular disease prevention among women at increased risk of cardiovascular disease. Plasma concentration of 3 biomarkers of inflammation (C-reactive protein, interleukin-6, and fibrinogen) and a biomarker of endothelial dysfunction (intercellular adhesion molecule 1) were measured at baseline and at the end of treatment and follow-up. After 7.3 years of combined treatment with folic acid, vitamin B6, and vitamin B12, homocysteine concentrations were reduced by 18% in the active treatment group as compared with the placebo group (P<0.001). However, there was no difference between treatment groups in change in blood concentration from baseline to follow-up for C-reactive protein (P=0.77), interleukin-6 (P=0.91), intercellular adhesion molecule 1 (P=0.38), or fibrinogen (P=0.68).

CONCLUSIONS

These findings indicate that long-term, combined treatment with folic acid, vitamin B6, and vitamin B12 lowers homocysteine concentrations, but does not alter major biomarkers of vascular inflammation, consistent with the lack of clinical cardiovascular disease benefit in the trial.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000541.

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.

Folic acid supplementation repressed hypoxia-induced inflammatory response via ROS and JAK2/STAT3 pathway in human promyelomonocytic cells

Hypoxia is associated with inflammation and various chronic diseases. Folic acid is known to ameliorate inflammatory reactions, but the metabolism of folic acid protecting against hypoxia-induced injury is still unclear. In our study, we examined the inflammatory signal transduction pathway in human promyelomonocytic cells (THP-1 cells) with or without treatment with folic acid under hypoxic culture conditions. Our results indicated that supplementation with folic acid significantly reduced the levels of interleukin-1β and tumor necrosis factor-α in hypoxic conditions. Treating THP-1 cells with folic acid suppressed oxidative stress and hypoxia-inducible factor-1α in a dose-dependent manner. Folic acid targeted the activation of Janus kinase 2, downregulated the phosphorylation of signal transducer and activator of transcription 3, and decreased the expression of nuclear factor-κB p65 protein in cells. However, the absence of folic acid did not make cells more vulnerable under hypoxic conditions. In conclusion, folic acid efficiently inhibited the inflammatory response of THP-1 cells under hypoxic conditions by inhibiting reactive oxygen species production and the Janus kinase 2/signal transducer and activator of transcription 3 signaling pathway. Our study supports a basis for treatment with folic acid for chronic inflammation, which correlated with hypoxia.

The effects of folate supplementation on glucose metabolism and risk of type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Observationally, homocysteine is associated with higher risk of diabetes. Folate, which reduces homocysteine, is promising for the prevention and treatment of diabetes. Previous meta-analysis of three trials suggested folate might lower hemoglobin A1c (HbA1c).

METHODS

An updated systematic review and meta-analysis of placebo-controlled randomized trials was conducted. We searched PubMed using ("folate" or "folic acid") and trial and ("glucose" or "diabetes" or "insulin" or "hemoglobin A1c" or "HbA1c") in any field until February 3, 2017. We also conducted a bibliographic search of selected studies and relevant reviews. Relative risk of diabetes and mean differences in indicators of glucose metabolism between folate and placebo were summarized in a meta-analysis using inverse variance weighting with random effects. Heterogeneity, publication bias, and risk of bias were also assessed.

RESULTS

Eighteen trials of 21,081 people with/without diabetes were identified. Folate decreased fasting glucose (-0.15 mmol/L, 95% confidence interval [CI] -0.29 to -0.01), homeostatic model assessment-insulin resistance (-0.83, 95% CI -1.31 to -0.34), and insulin (-1.94 μIU/mL, 95% CI -3.28 to -0.61) but had no clear effect on diabetes or HbA1c.

CONCLUSIONS

Our study suggests a potential benefit of folate on insulin resistance and glycemic control; the latter requires examination in more high-quality trials.