Vitamin C supplementation lowers serum low-density lipoprotein cholesterol and triglycerides: a meta-analysis of 13 randomized controlled trials

Increased Vitamin C Intake Is Associated With Decreased Pancreatic Cancer Risk

Background

Patients with pancreatic cancer have an unfavorable 5-year survival rate of approximately 3% due to diagnosis occurring at advanced stages. Prior research has proposed vitamin C may have a therapeutic and preventative role in pancreatic cancer.

Methods

A Health Insurance Portability and Accountability Act (HIPAA) compliant national database was utilized to assess pancreatic cancer risk in patients with or without a history of vitamin C intake. The International Classification of Diseases (ICD) codes were used, specifically the International Classification of Diseases, 10th Edition (ICD-10) and International Classification of Diseases, Nineth Edition (ICD-9), between January 2010 and December 2020. Patients were matched, and statistical analyses were implemented. Chi-squared, logistic regression, and odds ratio were used to test for significance and to estimate relative risk.

Results

A total of 83,941 patients were identified as utilizing prescribed vitamin C. Subsequent matching by Charlson Comorbidity Index (CCI) score and age resulted in two groups of 50,384 patients. The incidence of pancreatic cancer was 243 (0.48%) in the group with a history of vitamin C intake compared to 442 (0.88%) in the control group. The difference was statistically significant by P < 3.174 × 10-14 with an odds ratio of 0.548 (95% confidence interval (CI): 0.468 - 0.641). Overall, patients without vitamin C prescription had an increased prevalence of pancreatic cancer throughout all ages and regions of the United States when compared to those with a vitamin C prescription. In addition, healthcare costs were higher in total for the control group when compared to the experimental group.

Conclusions

This retrospective cohort study found a statistically significant correlation between vitamin C and subsequent incidence of pancreatic cancer. Further studies are recommended to explore vitamin C's redox and cofactor activity in the context of preventing and possibly treating pancreatic cancer, as well as consider pancreatic cancer lifestyle risk factors such as smoking.

Association between Dietary Potassium Intake and Nonalcoholic Fatty Liver Disease and Advanced Hepatic Fibrosis in U.S. Adults

Introduction

The correlation between potassium and nonalcoholic fatty liver disease (NAFLD) is currently still poorly understood. We conducted this study to explore the correlation between dietary potassium intake and NAFLD, as well as advanced hepatic fibrosis (AHF). The study also sought to identify any potential interactions.

Methods

The data employed in this study were obtained from the National Health and Nutrition Examination Survey (NHANES) program, encompassing a period from 2007 to 2018. Employing the multiple logistic regression analysis, we evaluated the association of dietary potassium intake with NAFLD and AHF. Subsequently, stratification analysis, based on demographic variables, was constructed so as to assess the stability of the results. In addition, potential interaction effects were assessed by interaction tests.

Results

A total of 9443 participants were included in the analysis. The mean age of the participants was 50.4 years, and their daily mean dietary potassium and vitamin C intake was 2556.49 mg and 82.93 mg, respectively. Following comprehensive statistical analyses, the findings indicated a negative correlation between dietary potassium intake and both NAFLD and AHF. Participants in Q4 group with dietary potassium intake exhibited a 31% and 42% reduction in the odds of developing NAFLD and AHF, respectively, in comparison to Q1 group. An interaction effect of dietary vitamin C intake was observed in the association between dietary potassium intake and NAFLD. The results imply that high dietary vitamin C intake augment the inverse relationship between dietary potassium intake and NAFLD.

Conclusion

Dietary potassium intake was found to have an inverse association with the odds of both NAFLD and AHF. The association between dietary potassium intake and NAFLD was amplified by the presence of vitamin C in the diet.

A scoping review on natural cholesterol lowering supplements sold in South African pharmacies

Background

Dyslipidaemia is defined as elevated total or low-density lipoprotein (LDL) levels or low levels of high-density lipoprotein (HDL). Patients may often make use of natural cholesterol lowering supplements (NCLSs) available at the pharmacy; however, limited information on these supplements is readily available. Pharmacists should be knowledgeable about NCLSs to ensure that the use of these supplements is supported by evidence and to provide appropriate advice to patients for desirable therapeutic outcomes.

Aim

This study aimed to identify the NCLSs being sold in South African pharmacies and review the scientific evidence for each of the ingredients in these NCLSs.

Methods

Seventeen NCLS products were identified, and the Joanna Briggs Institute (JBI) scoping review methodology was used to conduct a literature review of NCLSs.

Results

From the ingredients reviewed it is evident that co-enzyme Q10, probiotics and sterols have sufficient evidence supporting their use. However, there is still limited scientific evidence available to validate the remaining ingredients.

Conclusion

Further research on NCLSs will provide practising pharmacists and practitioners with a guide of the evidence available on the various ingredients in NCLSs.

Contribution

This study provides a review of the available literature on the NCLSs being sold in the pharmacies across South Africa to provide pharmacists with a collated document of the evidence behind these popular supplements to assist them in making evidence based informed decision regarding natural products for cholesterol.

Production performance, haematological parameters, serum biochemistry, and expression of HSP-70 in broiler chickens fed dietary ascorbic acid during heat stress

An experiment was carried out to assess the efficacy of supplemental ascorbic acid (AA) on broiler chicken production performance, blood haematological profile, biochemical profile, and carcass traits under heat stress conditions. A total of 192-day-old broiler chicks were divided into four groups, each with six replicates of eight each (4 × 6 × 8). Four corn-based dietary treatments were formulated: T1 (control diet), T2 (T1 + AA at 200 mg/kg), T3 (T1 + AA at 400 mg/kg), and T4 (T1 + AA at 600 mg/kg) for a period of 42 days. Despite the high temperature and humidity, the 600 mg AA supplemental groups (T4) gained significantly (P ≤ 0.05) more body weight and had a higher feed intake and better feed conversion ratio (FCR) than the control group (T1). After 28 days of feeding the three AA-supplemented diets, antibody titres (humoral immune response) were significantly higher (P ≤ 0.05). The response to intradermally injected phyto-haemagglutinin (PHA-P), an index of the in vivo cell-mediated immune response, was found to be increased (P ≤ 0.05) in the 400 and 600 mg AA-supplemented groups after 35 days. Higher levels of AA (T4) supplementation significantly (P ≤ 0.05) improved haematological values such as haemoglobin (Hb), total erythrocyte count (TEC), total leukocyte count (TLC), and differential leukocyte count (DLC), heterophil:lymphocyte (H:L) in comparison to the control group (T1). The supplemented group improved the serum biochemical profile of the birds, with an increase (P ≤ 0.05) in total serum protein, albumin, and globulin and a decrease in serum cholesterol and corticosterone levels in the T4 group compared to the control group. Heat shock protein-70 (HSP-70) was gradually elevated after increasing the ascorbic acid concentration (P ≤ 0.05) at 14 and 21 days. As a result, it can be concluded that supplementing ascorbic acid at 600 mg/kg is beneficial for improving the performance, immunity, and blood haematological biochemical profile and upregulating the HSP-70 gene of broiler chickens under heat stress conditions.

Therapeutic potential role of vitamin C in prevention and control of heart transplant rejection and cardiac allograft vasculopathy. A need for consideration

The burden of cardiovascular diseases is rising rapidly globally. Heart transplant is one of the most last resort medical option for patients with heart failure. Unfortunately, this surgical intervention is associated with several serious complications including heart transplant rejection (HTR) and Cardiac Allograft Vasculopathy (CAV) which can manifest just within few years' posttransplant. These complications affect significantly the prognosis and quality of life among postheart transplant patients. Several medications including immunosuppressant, antibiotics, antihypertensive, and statins have been used during posttransplant care so as to address such complications. Unfortunately, most of those drugs are expensive and pose a number of serious side effects to the patients enough to compromise patients' quality of life too. Several studies on Vitamin C are therapeutically suggestive that it can be used during postheart transplant care with more cost-effective benefits with less and minimized side effects compared to the current drugs in place. It should be considered pharmacologically that Vitamin C has a great potential role clinically in prevention and control of HTR and CAV development. On the light of such findings as described above, we recommend more studies especially clinical trials and molecular studies to determine whether Vitamin C can be repositioned to replace or to be used along the current drug regimens used in postheart transplant care for prevention and control of HTR and CAV.

Polycystic Ovary Syndrome and Oxidative Stress-From Bench to Bedside

Oxidative stress (OS) is a condition that occurs as a result of an imbalance between the production of reactive oxygen species (ROS) and the body's ability to detoxify and neutralize them. It can play a role in a variety of reproductive system conditions, including polycystic ovary syndrome (PCOS), endometriosis, preeclampsia, and infertility. In this review, we briefly discuss the links between oxidative stress and PCOS. Mitochondrial mutations may lead to impaired oxidative phosphorylation (OXPHOS), decreased adenosine triphosphate (ATP) production, and an increased production of ROS. These functional consequences may contribute to the metabolic and hormonal dysregulation observed in PCOS. Studies have shown that OS negatively affects ovarian follicles and disrupts normal follicular development and maturation. Excessive ROS may damage oocytes and granulosa cells within the follicles, impairing their quality and compromising fertility. Impaired OXPHOS and mitochondrial dysfunction may contribute to insulin resistance (IR) by disrupting insulin signaling pathways and impairing glucose metabolism. Due to dysfunctional OXPHOS, reduced ATP production, may hinder insulin-stimulated glucose uptake, leading to IR. Hyperandrogenism promotes inflammation and IR, both of which can increase the production of ROS and lead to OS. A detrimental feedback loop ensues as IR escalates, causing elevated insulin levels that exacerbate OS. Exploring the relations between OS and PCOS is crucial to fully understand the role of OS in the pathophysiology of PCOS and to develop effective treatment strategies to improve the quality of life of women affected by this condition. The role of antioxidants as potential therapies is also discussed.

Comparison of olanzapine-induced weight gain and metabolism abnormalities between topiramate and vitamin C in patients with schizophrenia: a preliminary study

Background

Topiramate (TPM) may reduce olanzapine (OLZ)-related weight gain and metabolism abnormalities in patients with schizophrenia. However, differences in the efficacy of OLZ-related weight gain and metabolism abnormalities between TPM and vitamin C (VC) are not clear. This study aimed to investigate whether TPM is more effective than VC in reducing OLZ-induced weight gain and metabolic abnormalities in patients with schizophrenia and explore their patterns.

Methods

This was a 12-week longitudinal comparison study in OLZ-treated patients with schizophrenia. Twenty-two patients who received OLZ monotherapy plus VC treatment (OLZ + VC group) was matched to 22 patients who received OLZ monotherapy plus TPM treatment (OLZ + TPM group). Body mass index (BMI) and metabolism indicators were measured at baseline and 12-weeks follow-up.

Results

A significant difference in triglyceride (TG) levels at different time points (pre-treatment: F = 7.89, p = 0.008; 4-weeks treatment: F = 13.19, p = 0.001; 12-weeks treatment: F = 54.48, p < 0.001) was found. Latent profile analysis demonstrated that a 2-class model for OLZ + TPM group (high vs. low BMI in the first 4 weeks) and OLZ + VC group (high vs. low), respectively.

Conclusion

Our findings suggested that TPM could better mitigates OLZ-induced increase in TG levels. The trajectories of change also differed in all metabolic indexes over time between the two groups.

Assessing Effects of Diet Alteration on Carbohydrate-Lipid Metabolism of Antipsychotic-Treated Schizophrenia Patients in Interventional Study

This study aimed at finding whether healthy eating habits could be introduced to and maintained by chronically mentally ill permanent residents of a nursing home. Of interest was also if the effects of the dietary intervention would be observable as improved carbohydrate and lipid metabolism indicators were selected. Assays covered 30 antipsychotics-treated residents diagnosed with schizophrenia. The prospective method applied involved questionnaires, nutrition-related interviews, anthropometric measurements, and determination of selected biochemical parameters of the blood. The dietary intervention as well as the parallel health-promoting nutrition-related education was aimed at balancing the energy and nutrient contents. Schizophrenia patients were shown to be capable of accepting and observing the principles of appropriate nutrition. The intervention was strong enough to result in a significant blood glucose concentration drop to the reference level in all patients, regardless of the antipsychotic they were treated with. The blood lipid levels also improved, but the reduction in triacylglycerols, total cholesterol and LDL-cholesterol levels was significant in the male patients only. Nutritional changes were reflected in overweight and obese women only, in body weight reduction and in waist adipose tissue loss.

Joint effects of paraoxonase 1 rs662 polymorphism and vitamins C/E intake on coronary artery disease severity (Gensini and SYNTAX scores) and lipid profile in patients undergoing coronary angiography

Introduction

Considering the emergence of the concept of personalized nutrition in recent years and its importance in the treatment of diseases, the purpose of this study was to investigate the interaction of paraoxonase (PON)1 rs662 polymorphism and vitamin C/E intake on coronary artery disease (CAD) severity and lipid profile in patients undergoing diagnostic angiography.

Methods

This cross-sectional study was carried out on 428 patients undergoing angiography. The PON-1 genotypes were detected by the polymerase chain reaction-restriction fragment length polymorphism technique. Dietary intake was obtained using a valid questionnaire.

Results

After adjustment for potential confounders, R allele carriers (RR + RQ) have lower HDL-C levels than non-carriers (QQ) (P ≤ 0.05). On the other hand, higher consumption of vitamin C was associated with a reduced risk of high total cholesterol (OR: 0.42, 95% CI 0.23-0.75, P = 0.003) and low-density lipoprotein cholesterol (OR: 0.49, 95% CI 0.25-0.96, P = 0.038) and an increased risk of low high-density lipoprotein cholesterol (OR: 1.88, 95% CI 1.03-3.42, P = 0.037). Furthermore, a significant interaction was observed between vitamin C intake and genotypes of rs66 polymorphism on LDL-C (P = 0.050). In detail, the R-allele carriers with lower vitamin C intake had higher LDL-C levels than QQ genotype carriers. No significant interaction was found between vitamin E intake and rs662 polymorphism genotypes on the Gensini and SYNTAX scores and lipid profile (P > 0.05).

Conclusion

The novel finding of the present study was the existence of a significant interaction between rs662 polymorphism and vitamin C intake on LDL-C. More specifically, R allele carriers with lower vitamin C intake were susceptible to higher LDL-C.

Subclinical Vitamin C Plasma Levels Associated with Increased Risk of CAD Diagnosis via Inflammation: Results from the NHANES 2003-2006 Surveys

Vitamin C remains an important, yet frequently unassessed, component of a healthy immune system though it may prove useful in alleviating the chronic inflammatory processes underlying chronic diseases such as coronary artery disease (CAD). Recent research identified a sizeable proportion of the United States population with insufficient vitamin C plasma levels and significant associations to both acute and chronic inflammation. This cross-sectional study used the 2003-2006 NHANES surveys data to extrapolate associations between plasma vitamin C levels (deficiency, hypovitaminosis, inadequate, adequate, and saturating) and CAD through inflammation (C-reactive protein and red cell distribution width). Increased reports of CAD diagnosis were identified in participants with vitamin C deficiency (OR: 2.31, CI: 1.49-3.58) and inadequate plasma levels (OR: 1.39, CI: 1.03-1.87). No significant correlation was identified between any other plasma vitamin C quintiles and CAD. When inflammation was controlled, previous associations in the deficient level of plasma vitamin C were no longer significant in association with CAD and participants with inadequate plasma vitamin C showed a reduced association to CAD diagnoses (OR: 0.33, CI: 0.13-0.86). Most chronic inflammation and vitamin C plasma statuses do not demonstrate specific signs or symptoms until the deficient level of vitamin C and/or disease. Thus, increased surveillance of both, and healthy nutritional habits remain crucial modifiable risk factors for disease prevention.

Effects of dietary vitamins on obesity-related metabolic parameters

Type 2 diabetes mellitus (T2DM) is one of the leading causes of death worldwide. Genetic factors, some underlying medical conditions, and obesity are risk factors of T2DM. Unlike other risk factors which are non-modifiable, obesity is preventable and usually treatable, and is largely contributed by lifestyle factors. Management of these lifestyle factors may curb the development of T2DM and reduces T2DM prevalence. Dietary vitamins have been recommended as a lifestyle modification intervention to support obesity treatment. Vitamins correlate negatively with body weight, body mass index and body composition. Some of the vitamins may also have anti-adipogenic, anti-inflammatory and antioxidant effects. However, results from pre-clinical and clinical studies of the effects of vitamins on obesity are inconsistent. A clear understanding of the effects of vitamins on obesity will help determine dietary intervention that is truly effective in preventing and treating obesity as well as obesity-related complications including T2DM. This article reviews existing evidences of the effects of vitamin supplementation on obesity and obesity-related metabolic status.

Vitamin C supplementation for diabetes management: A comprehensive narrative review

Growing evidence suggests that vitamin C supplementation may be an effective adjunct therapy in the management of people with diabetes. This paper critically reviews the current evidence on effects of vitamin C supplementation and its potential mechanisms in diabetes management. Evidence from meta-analyses of randomized controlled trials (RCTs) show favourable effects of vitamin C on glycaemic control and blood pressure that may be clinically meaningful, and mixed effects on blood lipids and endothelial function. However, evidence is mostly of low evidence certainty. Emerging evidence is promising for effects of vitamin C supplementation on some diabetes complications, particularly diabetic foot ulcers. However, there is a notable lack of robust and well-designed studies exploring effects of vitamin C as a single compound supplement on diabetes prevention and patient-important outcomes (i.e. prevention and amelioration of diabetes complications). RCTs are also required to investigate potential preventative or ameliorative effects of vitamin C on gestational diabetes outcomes. Oral vitamin C doses of 500-1000 mg per day are potentially effective, safe, and affordable for many individuals with diabetes. However, personalisation of supplementation regimens that consider factors such as vitamin C status, disease status, current glycaemic control, vitamin C intake, redox status, and genotype is important to optimize vitamin C's therapeutic effects safely. Finally, given a high prevalence of vitamin C deficiency in patients with complications, it is recommended that plasma vitamin C concentration be measured and monitored in the clinic setting.

Vitamin C mitigates hematological and biochemical alterations caused by di(2-ethylhexyl) phthalate toxicity in female albino mice, Mus musculus

Di(2-ethylhexyl) phthalate (DEHP) is ubiquitous environmental contaminant and identified as endocrine-disrupting chemical (EDC), present in plastics as plasticizer. Due to its versatile use, human exposure level reaches to danger limit. The main focus of our study is to see the effect of vitamin C on hematological and biochemical alterations caused by Di(2-ethylhexyl) Phthalate toxicity in female albino mice, Mus musculus. It is found to cause defects of the liver, kidney, and lungs. Its anti-androgenic nature brings the main focus on its toxicity associated with reproductive and endocrine system. In this experimental study, 18 young female Swiss albino mice, Mus musculus, were used and divided into 3 groups of 6 animals each as control (corn oil vehicle), DEHP group (100 mg/kg body weight dissolved in corn oil), and DEHP + vitamin-C group (100 mg/kg body weight each, dissolved in corn oil and double distilled water, respectively) for 90 days. In this research, serum metabolites were evaluated to study the effect of DEHP on glucose, total protein, and lipid profile along with some hematological, enzymological, and oxidative stress parameters. Simultaneously, we compared the effectiveness of vitamin-C against DEHP toxicity to mitigate the serum homeostasis disturbance. In present study, we observed, in DEHP-treated animals, glucose, triglycerides, very-low-density lipoprotein (VLDL), total protein, alkaline phosphatase (ALP), acid phosphatase (ACP), and alanine aminotransferase (ALT) levels increased remarkably, whereas total cholesterol, high-density lipoproteins (HDL), aspartate aminotransferase (AST), total RBC count, total WBC count, and hemoglobin (Hb) level significantly decreased as compared to control group. In addition, we noticed there was a decrease in superoxide dismutase (SOD) and increase in levels of lipid peroxidation (MDA) and interleukin-6 (IL-6) in DEHP treatment group as compared to control group. The results indicated vitamin C had a better improving effect against DEHP toxicity on balancing metabolic abnormalities and inflammation-related comorbidities.

Associations of serum multivitamin levels with the risk of non-alcoholic fatty liver disease: A population-based cross-sectional study in U.S. adults

Vitamins were closely associated with non-alcoholic fatty liver disease (NAFLD) development, but no study had explored the association of serum multivitamin levels with NAFLD risk. We assessed the association between serum levels of both single-vitamin and multivitamins (VA, VB6, VB9, VB12, VC, VD, and VE) and the risk of NAFLD, using the database of National Health and Nutrition Examination Survey (NHANES) (cycles 2003–2004 and 2005–2006). We employed multivariable logistic regression and weighted quantile sum (WQS) regression models to explore the association of serum multivitamin levels with NAFLD. Among all 2,294 participants, 969 participants with NAFLD were more likely to be male, older, less educated, or have hypertension/high cholesterol/diabetes. After adjustment of covariates, serum VC/VD/VB6/VB9 levels were negatively correlated with NAFLD risk, while serum VA/VE levels were positively correlated with NAFLD risk. In the WQS model, elevated serum VA/VE levels and lowered serum VC/VD/VB6 levels were linearly associated with increased NAFLD risk. There was a non-linear relationship between serum VB9/VB12 levels and NAFLD risk. There were evident associations between serum multivitamin levels and reduced NAFLD risk, which was mainly driven by VD/VB9/VC. In conclusion, our findings suggested that serum multivitamin levels were significantly associated with the risk of NAFLD.

Iron metabolism mediates the relationship between Vitamin C and hepatic steatosis and fibrosis in NAFLD

Vitamin C (Vit C) and iron metabolism are closely related to metabolic disorders. However, the relation between iron storage protein ferritin and Vit C has not been elucidated. We aimed to investigate the crosstalk between Vit C and ferritin and its implications on non-alcoholic fatty liver disease (NAFLD). Clinical information of 3,614 subjects was obtained from the NHANES Public Data 2017–2018. FibroScan data, which estimates liver steatosis and fibrosis and Vit C, were selected to assess factors influencing NAFLD in this cross-sectional study. Ferritin and Vit C among different categories of liver steatosis and fibrosis were assessed by CAP and E value. Logistic regression and RCS models were used to analyze the correlations. In vitro study in hepG2 were conducted to validate the regulations. Ferritin increased while Vit C decreased with more severe hepatic steatosis and hepatic fibrosis (all P < 0.001). Logistic regression models indicated that increased serum ferritin was a risk factor for NAFLD while increased Vit C was a protective factor for NAFLD and hepatic fibrosis after adjusting the continuous and categorical variables. Vitamin C was negatively associated with ferritin. Further mediation analysis identified that ferritin mediates the impact of Vit C on NAFLD (P < 0.05) and cirrhosis (P < 0.001). The experiments on cellular level suggested Vit C alleviated PA/OA induced steatosis and maintains iron homeostasis through inhibiting PA/OA induced upregulation of iron bound protein ferritin and labile iron pool (LIP) induction in hepG2 cells. In conclusion, Vit C was a protective factor, whereas ferritin was a risk factor for hepatic steatosis and fibrosis. Vitamin C alleviated NAFLD and maintained iron homeostasis via ferritin suppression and LIP induction.

Evaluation of the combination effect of rutin and vitamin C supplementation on the oxidative stress and inflammation in hemodialysis patients

Background: Hemodialysis (HD) patients are at risk of malnutrition, cardiovascular complications, and all-cause mortality due to oxidative stress and inflammation. Some studies have demonstrated that rutin attenuates oxidative stress and inflammation in CKD rats, but its effects in HD patients are unknown to date. Aim: The aim of this study was to evaluate the effect of rutin and vitamin C versus vitamin C alone on oxidative stress and inflammation in HD patients. Methods: A prospective randomized, open-label, controlled trial enrolled on hundred and five HD patients divided into three groups as follows: patients in group 1 were given a rutin/vitamin C combination (Ruta C group as the combination trade name is known as Ruta C 60 tablets), patients in group 2 were given vitamin C (1 g) (vitamin C group), and group 3 was the control group; the study period was 16 weeks. The following were assessed at baseline and at the end of the study: serum malondialdehyde (MDA), glutathione peroxidase (GPx), high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-α (TNF-α), lipid profile levels, and erythrocyte sedimentation rate. Results: It was found that vitamin C significantly increased serum GPx in group 2 (p = 0.001) compared to a non-significant result in both group 1 and 3; in addition, serum MDA and TNF-α values had decreased significantly in the three groups compared to their baselines; however, a non-significant difference was seen among the studied groups at the end of the study. On the other hand, MDA levels were reduced by 50% in interventional groups compared to 28% in the control group, while the Ruta C group showed an 80% reduction in the level of TNF α compared to the 78% reduction observed in the vitamin C group, and finally, the interventional drugs showed a significant improvement in the lipid profile. Conclusion: Vitamin C supplementation alone for 16 weeks had a potential effect on the antioxidant's GPx activity. Moreover, it was reported that both vitamin C alone or the rutin/vitamin C combination (Ruta C) showed a protective role against lipid peroxidation, evidenced by the reduced levels of MDA. Finally, rutin had a favorable synergistic effect with vitamin C in reducing TG and TNF-α levels and increasing HDL-C level.

Plasma Circulating Vitamin C Levels and Risk of Endometrial Cancer: A Bi-Directional Mendelian Randomization Analysis

Background

Observational studies indicated that circulating vitamin C (VitC) levels may be correlated with the risk of endometrial cancer (EC). However, the causal effects and direction between them were still unclear.

Methods

In this study, 11 single nucleotide polymorphisms (SNPs) robustly correlated with plasma VitC levels were extracted from the latest genome-wide association study (GWAS), containing 52,018 individuals. Genetic data of EC were obtained from the Endometrial Cancer Association Consortium (ECAC) (12,906 cases and 108,979 controls). An inverse-variance weighted method was utilized as the primary analysis of Mendelian randomization (MR), supplemented by the weighted median, MR Pleiotropy Residual Sum and Outlier test (MR-PRESSO), and MR-Egger methods. Additional sensitivity analyses excluding 3 SNPs with secondary phenotypes were conducted to rule out the possible pleiotropic effects. Potential impacts of several risk factors of EC, such as obesity, body mass index (BMI), hypertension, and diabetes on VitC levels, were assessed. We additionally evaluated the effects of VitC on LDL cholesterol levels, HDL cholesterol levels, and triglycerides levels to probe into the possible mediators in the VitC-EC pathway.

Results

Genetically predicted higher plasma VitC levels (per 1 SD increase, approximately 20 μmol/L) were causally associated with an increased risk of EC overall [odds ratio (OR) 1.374, 95% CI 1.128–1.674, p = 0.0016], supported by complementary sensitivity analyses. In the subgroup analyses, genetically predicted higher levels of VitC were associated with a tendency of increased risks of both endometrioid (OR_SD 1.324, 95% CI 0.959–1.829, p = 0.0881) and non-endometrioid histology (OR_SD 1.392, 95% CI 0.873–2.220, p = 0.1647) while without statistical significance. The association remained significant after the exclusion of the three pleiotropic SNPs (OR_SD 1.394, 95% CI 1.090–1.784, p = 0.0082). The confounders and mediators were unlikely to affect the VitC-EC relationship. The causal effect of EC on VitC levels was not supported (OR 1.001, 95% CI 0.998–1.004, p = 0.4468).

Conclusions

This bi-directional MR study demonstrated a causal risk role of higher circulating VitC at physiological levels on an increased risk of EC, which was independent of confounders and mediators. Further studies are warranted to elucidate the possible mechanisms.

Prevalence and Predictors of Insufficient Plasma Vitamin C in a Subtropical Region and Its Associations with Risk Factors of Cardiovascular Diseases: A Retrospective Cross-Sectional Study

Background: to evaluate the prevalence and predictors of insufficient plasma vitamin C among adults in a subtropical region and its associations with cardiovascular disease risk factors including dyslipidemia and lipid-independent markers, namely homocysteine, high-sensitivity C-reactive protein (hs-CRP) and lipoprotein(a). Methods: Data of this retrospective cross-sectional study were extracted from electronic medical database of a Medical Center. Based on plasma vitamin C status, subjects were split into two groups—subjects with sufficient and insufficient plasma vitamin C levels (<50 µmol/L, ≤8.8 mg/L). Results: Prevalence of insufficient plasma vitamin C in 3899 adults was 39%. Multivariate logistic regression identified male gender, high body mass index, age 20−39, and winter/spring as independent predictors of insufficient vitamin C among all subjects. Greater proportions of subjects with insufficient plasma vitamin C had lower high-density lipoprotein cholesterol levels and elevated levels of triglyceride, homocysteine and hs-CRP (all p < 0.001). There were no differences in total cholesterol, low-density lipoprotein cholesterol and lipoprotein(a) between groups. Conclusions: There was a high prevalence of insufficient plasma vitamin C in the subtropical region, which indicates that insufficient plasma vitamin C remains a public health issue. Further study is needed to confirm these findings and to determine the underlying mechanisms.

Association of sex hormones with hepatic steatosis in men with chronic hepatitis B

BACKGROUND

No study on the relationship between hepatic steatosis and sex hormone levels in male patients with chronic hepatitis B (CHB) infection has been conducted.

AIMS

We aimed to investigate the association between serum sex hormones and hepatic steatosis among a cohort of males with CHB.

METHODS

In this cross-sectional study, 268 male patients with CHB were enrolled. All participants underwent anthropometric measurement, blood testing, and FibroScan test. Multiple logistic regression analysis was used to investigate the association of serum sex hormones with hepatic steatosis.

RESULTS

We included 137 males with and 131 without hepatic steatosis in this study. Subjects with serum testosterone (T) levels in the highest tertile had an odds ratio (OR) (95% confidence interval [CI]) of 0.35 (0.18-0.70) (P for trend=0.003); those with serum prolactin (PRL) levels in the highest tertile had an OR (95%CI) of 0.21 (0.10-0.45) (P for trend<0.001); and those with serum estradiol/testosterone (E2/T) in the highest tertile had an OR (95%CI) of 4.02 (1.97-8.20) (P for trend<0.001) for hepatic steatosis.

CONCLUSION

Lower serum total T and PRL levels and higher total E2/T are independently associated with presence of hepatic steatosis in male patients with CHB.

Reactive Oxygen Species (ROS) and Antioxidants as Immunomodulators in Exercise: Implications for Heme Oxygenase and Bilirubin

Exercise is commonly prescribed as a lifestyle treatment for chronic metabolic diseases as it functions as an insulin sensitizer, cardio-protectant, and essential lifestyle tool for effective weight maintenance. Exercise boosts the production of reactive oxygen species (ROS) and subsequent transient oxidative damage, which also upregulates counterbalancing endogenous antioxidants to protect from ROS-induced damage and inflammation. Exercise elevates heme oxygenase-1 (HO-1) and biliverdin reductase A (BVRA) expression as built-in protective mechanisms, which produce the most potent antioxidant, bilirubin. Together, these mitigate inflammation and adiposity. Moderately raising plasma bilirubin protects in two ways: (1) via its antioxidant capacity to reduce ROS and inflammation, and (2) its newly defined function as a hormone that activates the nuclear receptor transcription factor PPARα. It is now understood that increasing plasma bilirubin can also drive metabolic adaptions, which improve deleterious outcomes of weight gain and obesity, such as inflammation, type II diabetes, and cardiovascular diseases. The main objective of this review is to describe the function of bilirubin as an antioxidant and metabolic hormone and how the HO-1-BVRA-bilirubin-PPARα axis influences inflammation, metabolic function and interacts with exercise to improve outcomes of weight management.

Targeting dyslipidemia with antioxidative vitamins C, D, and E; a systematic review of meta-analysis studies: Dyslipidemia and antioxidative vitamins

Background

There is controversial evidence for the beneficial effects of antioxidative vitamins (vits) on dyslipidemia. In this regard, we aimed to systematically review all meta-analyses of trials on this topic.

Methods

We comprehensively searched PubMed, Web of Science, Scopus, and Cochrane Library databases until January 2021 to explore the published English meta-analyses of trials conducted to assess the effects of single or combined vits C, D and E consumption on lipid profile. The meta-analyses of observational, in vivo/in vitro, or case-report studies were excluded. Search results were reported based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) flowchart.

Results

Overall, 25 meta-analyses including 32,177 individuals with different underlying disorders met our inclusion criteria. Numerous studies had assessed supplementation with Vit-D or its combination with other agents on lipid profile. Consumption of 400 IU/day (d) to 50,000 IU/week (w) Vit-D for at least eight weeks improved the levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG) in type 2 diabetes mellitus or polycystic ovary syndrome (PCOS) patients. This treatment reduced the levels of TC and TG in patients with chronic kidney disease. A significant increase in high-density lipoprotein cholesterol (HDL-C) levels was only observed in coronary artery disease patients. Sole intake of 500-2000 mg/d Vit-C for at least 3 weeks improved LDL-C and TG values in hypercholesterolemic patients. Nevertheless, sole intake of Vit-E had controversial effects on lipid profile. The combination of 400-1800 IU/d omega-3 free fatty acid (FFA) and 400 IU/d Vit-E significantly reduced the levels of LDL-C and TG in overweight individuals, without any significant effect on other components. A significant improvement of TG values was observed after consumption of 1000-2000 mg/d omega-3 FFA plus 400 IU/d Vit-E along with 50,000 IU/each 2w Vit-D for at least 6 weeks in diabetic patients.

Conclusion

The beneficial effects of antioxidative vitamins (C, D, E) or their combination with other agents on lipid profile varied based on their dosage, intake duration, and the health status of the individuals.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-021-00919-8.

Dietary Vitamin C and Age-Induced Lipid and Hormonal Metabolic Changes in a Humanized Mouse Model Not Synthesizing Vitamin C and Producing Lipoprotein(a) [Gulo (-/-); Lp(a)+]

The lack of ability to produce vitamin C innately and the ability to synthesize human lipoprotein(a) (Lp(a)) are two unique metabolic features present in humans, compared with most other animal species. The Gulo (-/-) and Lp(a)+ mouse model displays these two features and is therefore suitable for the study of metabolic aspects relevant to human metabolism. It is a well-known fact that vitamin C is essential in collagen synthesis, and in maintaining extracellular matrix integrity, as well as being a powerful antioxidant and cofactor in many metabolic pathways, which makes it a critically important micronutrient for health and healthy aging. In this study, we investigated the effects of a long-term intake of high and low doses of vitamin C on age-related metabolic lipid and hormonal changes in young (eight to nine months), mid-aged (one year), and old (two years) Gulo (-/-) and Lp(a)+ mice. We observed that chronic vitamin C deficiency resulted in a less healthy metabolic lipid profile, impaired serum insulin-like growth factor (IGF-1), and sex-hormones secretion, all of which can accelerate the development of various pathological conditions in the aging process. The most susceptible to the negative impact of vitamin C deficiency were the young (eight to nine months) and old (two years) mice. Our study conducted in this humanized mouse model indicates that sustained adequate vitamin C intake is essential in maintaining a healthier metabolic profile, important in preventing age-related pathologies throughout the aging process.

Vitamin C Deficiency Inhibits Nonalcoholic Fatty Liver Disease Progression through Impaired de Novo Lipogenesis

Despite the increasing clinical importance of nonalcoholic fatty liver disease (NAFLD), little is known about its underlying pathogenesis or specific treatment. The senescence marker protein 30 (SMP30), which regulates the biosynthesis of vitamin C (VC) in many mammals, except primates and humans, was recently recognized as a gluconolactonase. However, the precise relation between VC and lipid metabolism in NAFLD is not completely understood. Therefore, this study aimed to clearly reveal the role of VC in NAFLD progression. SMP30 knockout (KO) mice were used as a VC-deficient mouse model. To investigate the precise role of VC on lipid metabolism, 13- to 15-week-old SMP30 KO mice and wild-type mice fed a 60% high-fat diet were exposed to tap water or VC-containing water (1.5 g/L) ad libitum for 11 weeks. Primary mouse hepatocytes isolated from the SMP30 KO and wild-type mice were used to demonstrate the relation between VC and lipid metabolism in hepatocytes. Long-term VC deficiency significantly suppressed the progression of simple steatosis. The high-fat diet-fed VC-deficient SMP30 KO mice exhibited impaired sterol regulatory element-binding protein-1c activation because of excessive cholesterol accumulation in hepatocytes. Long-term VC deficiency inhibits de novo lipogenesis through impaired sterol regulatory element-binding protein-1c activation.

Natural and synthetic antioxidants targeting cardiac oxidative stress and redox signaling in cardiometabolic diseases

Cardiometabolic diseases (CMDs) are metabolic diseases (e.g., obesity, diabetes, atherosclerosis, rare genetic metabolic diseases, etc.) associated with cardiac pathologies. Pathophysiology of most CMDs involves increased production of reactive oxygen species and impaired antioxidant defense systems, resulting in cardiac oxidative stress (OxS). To alleviate OxS, various antioxidants have been investigated in several diseases with conflicting results. Here we review the effect of CMDs on cardiac redox homeostasis, the role of OxS in cardiac pathologies, as well as experimental and clinical data on the therapeutic potential of natural antioxidants (including resveratrol, quercetin, curcumin, vitamins A, C, and E, coenzyme Q10, etc.), synthetic antioxidants (including N-acetylcysteine, SOD mimetics, mitoTEMPO, SkQ1, etc.), and promoters of antioxidant enzymes in CMDs. As no antioxidant indicated for the prevention and/or treatment of CMDs has reached the market despite the large number of preclinical and clinical studies, a sizeable translational gap is evident in this field. Thus, we also highlight potential underlying factors that may contribute to the failure of translation of antioxidant therapies in CMDs.

The effect of vitamin C supplementation on lipid profile of type 2 diabetic patients: a systematic review and meta-analysis of clinical trials

BACKGROUND AND AIMS

We conducted a systematic review and meta-analysis of clinical trials evaluating the role of vitamin C supplementation on lipid profiles among diabetic patients to summarize the available findings.

METHODS

A comprehensive search of PubMed, ScienceDirect, Google Scholar, and Cochrane Library databases was performed. Clinical trials conducted on adult type 2 diabetic patients evaluating the effect of vitamin C supplementation and reported lipid profiles (cholesterol (TC), triglycerides (TG), low density lipoprotein (LDL), high density lipoprotein (HDL)) were included. Weighted mean difference (WMD) was calculated.

RESULTS

Vitamin C supplementation had no significant effect on TC (WMD = - 4.36 mg/dl (95% CI - 10.24, 1.52) p-value = 0.146), LDL level (WMD = 2.73 mg/dl (95% CI - 1.72, 7.17) p-value = 0.229), and HDL level (WMD = 0.91 mg/dl (CI - 0.45, 2.27) p-value = 0.191). However, it reduced TG and secondary outcomes (FBS and HgA1C): TG (WMD = - 11.15 mg/dl (95% CI - 21.58, - 0.71) p-value = 0.036), FBS (WMD = - 16.94 mg/dl CI - 21.84, - 12.04, p-value = 0.000), and HgA1C (WMD = - 1.01% CI - 1.18, - 0.83, p-value = 0.001. Subgroup analysis also depicted younger patients, longer duration of treatment and higher dose were important factors. In addition, meta-regression analysis indicated the significant role of patient age, duration of treatment, supplementation dose, BMI and other baseline variables.

CONCLUSION

There is no adequate evidence to support vitamin C supplementation for dyslipidemias in diabetic patients. Specific group of patients might have benefited including younger diabetic patients. Future researches should give emphasis on the duration of treatment, the dose of vitamin C and baseline values.

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.

Repositioning Vitamin C as a Promising Option to Alleviate Complications associated with COVID-19

Vitamin C, also known as L-ascorbic acid, is an essential vitamin with pleiotropic functions, ranging from antioxidant to anti-microbial functions. Evidence suggests that vitamin C acts against inflammation, oxidative stress, autophagy chaos, and immune dysfunction. The ability to activate and enhance the immune system makes this versatile vitamin a prospective therapeutic agent amid the current situation of coronavirus disease 2019 (COVID-19). Being highly effective against the influenza virus, causing the common cold, vitamin C may also function against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and its associated complications. Severe infections need higher doses of the vitamin to compensate for the augmented inflammatory response and metabolic demand that commonly occur during COVID-19. Compelling evidence also suggests that a high dose of vitamin C (1.5 g/kg body weight) in inflammatory conditions can result in effective clinical outcomes and thus can be employed to combat COVID-19. However, further studies are crucial to delineate the mechanism underlying the action of vitamin C against COVID-19. The current review aims to reposition vitamin C as an alternative approach for alleviating COVID-19-associated complications.

Ascorbic acid enhances low-density lipoprotein receptor expression by suppressing proprotein convertase subtilisin/kexin 9 expression

Ascorbic acid, a water-soluble antioxidant, regulates various biological processes and is thought to influence cholesterol. However, little is known about the mechanisms underpinning ascorbic acid-mediated cholesterol metabolism. Here, we determined if ascorbic acid can regulate expression of proprotein convertase subtilisin/kexin 9 (PCSK9), which binds low-density lipoprotein receptor (LDLR) leading to its intracellular degradation, to influence low-density lipoprotein (LDL) metabolism. At cellular levels, ascorbic acid inhibited PCSK9 expression in HepG2 and Huh7 cell lines. Consequently, LDLR expression and cellular LDL uptake were enhanced. Similar effects of ascorbic acid on PCSK9 and LDLR expression were observed in mouse primary hepatocytes. Mechanistically, ascorbic acid suppressed PCSK9 expression in a forkhead box O3-dependent manner. In addition, ascorbic acid increased LDLR transcription by regulating sterol regulatory element-binding protein 2. In vivo, administration of ascorbic acid reduced serum PCSK9 levels and enhanced liver LDLR expression in C57BL/6J mice. Reciprocally, lack of ascorbic acid supplementation in L-gulono-γ-lactone oxidase deficient (Gulo ^-/-) mice increased circulating PCSK9 and LDL levels, and decreased liver LDLR expression, whereas ascorbic acid supplementation decreased PCSK9 and increased LDLR expression, ameliorating LDL levels in Gulo ^-/- mice fed a high fat diet. Moreover, ascorbic acid levels were negatively correlated to PCSK9, total and LDL levels in human serum samples. Taken together, these findings suggest that ascorbic acid reduces PCSK9 expression, leading to increased LDLR expression and cellular LDL uptake. Thus, supplementation of ascorbic acid may ameliorate lipid profiles in ascorbic acid-deficient species.

The effect of dietary nitrate and vitamin C on endothelial function, oxidative stress and blood lipids in untreated hypercholesterolemic subjects: A randomized double-blind crossover study

BACKGROUND

Vitamin C may enhance nitric oxide (NO) production through stepwise reduction of dietary nitrate (NO₃) to nitrite (NO₂) to NO. The combined effect of vitamin C and NO₃ supplementation is relatively unexplored in untreated hypercholesterolemia.

AIMS

We aimed to examine whether co-administration of vitamin C and nitrate for 4-weeks would improve endothelial function (primary outcome), plasma NO metabolites, oxidative stress, and blood lipids (secondary outcomes).

METHODS

Subjects 50-70 years of age with low density lipoprotein (LDL) > 130 mg/dL and RHI ≤2 were enrolled in this randomized double-blind crossover study. Subjects were assigned to two 4-week supplementation treatments starting with 70 ml of concentrated beetroot juice (CBJ) with 1000 mg of vitamin C (NC) or CBJ with matched placebo (N), then switched to alternate treatment following 2-week washout. The change in reactive hyperemia index (RHI), sum of plasma NO metabolites (NO₂ + NO₃ (NOx)), oxidized LDL (oxLDL), and serum lipids were assessed at baseline and at 4-weeks of each treatment period.

RESULTS

Eighteen subjects (11M:7F) completed all study visits. No significant treatment differences were observed in RHI change (N: 0.21 ± 0.12; NC: 0.20 ± 0.17; p = 0.99). Secondary analysis revealed that a subgroup of NC subjects who started with a baseline RHI of <1.67 (threshold value for ED) had greater improvements in RHI compared to subjects with RHI >1.67 (1.23 ± 0.15 to 1.96 ± 0.19; n = 8 vs. 1.75 ± 0.11 to 1.43 ± 0.10; n = 8; p = 0.02). Compared to N, NC experienced a significant increase in plasma NOx (N: 94.2 ± 15.5 μmol/L; NC: 128.7 ± 29.1 μmol/L; p = 0.01). Although there was no significant difference in oxLDL change between treatments (N: -1.08 ± 9.8 U/L; NC: -6.07 ± 9.14 U/L; p = 0.19), NC elicited significant reductions in LDL (N: 2.2 ± 2; NC: -10.7 ± 23; p = 0.049), triglycerides (N: 14.6 ± 43; NC: -43.7 ± 45; p = 0.03), and no change in serum high density lipoprotein. Within treatment group comparisons showed that only NC reduced oxLDL significantly from baseline to 4 weeks (p = 0.01).

CONCLUSIONS

No between intervention differences were observed in RHI. RHI only improved in NC subjects with ED at intervention baseline. Four weeks of NC enriched the NO pool and promoted reduction of blood lipids and oxidative stress in subjects with hypercholesterolemia. These preliminary findings highlight a supplementation strategy that may reduce the progression of atherosclerotic disease and deserves further attention in studies using flow mediated dilation methods.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov (NCT04283630).

Prophylactic and therapeutic effects of different doses of vitamin C on high-fat-diet-induced non-alcoholic fatty liver disease in mice

Epidemiological studies support the association between inadequate vitamin C (Vc) intake and non-alcoholic fatty liver disease (NAFLD). However, the intervention dose of Vc, and the prophylactic and therapeutic effects on NAFLD are unclear. This study aimed to investigate the prophylactic and therapeutic effects of low (LVc), medium (MVc) and high (HVc) doses of Vc on NAFLD. C57BL/6 mice were randomly assigned to prophylactic groups (mice received a high-fat diet (HFD) concomitant with different doses of Vc) and therapeutic groups (HFD-induced NAFLD mice treated with different doses of Vc). Results showed that prophylactic LVc and MVc administration reduced the risk of NAFLD development in HFD-fed mice, as evidenced by significantly lowered body weight, perirenal adipose tissue mass, and steatosis, whereas prophylactic HVc administration did not prevent HFD-induced NAFLD development. Furthermore, therapeutic MVc administration significantly ameliorated HFD-induced increase in body weight, perirenal adipose tissue mass and steatosis, whereas therapeutic LVc and HVc administration did not ameliorate NAFLD symptoms. In fact, therapeutic HVc administration significantly increased body weight, perirenal adipose tissue mass, and lobular inflammation. Moreover, prophylactic LVc administration was more effective than therapeutic LVc administration as evidenced by significantly lower body weight, perirenal adipose tissue mass, steatosis, ballooned hepatocytes, and lobular inflammation in prophylactic LVc administration. The same trends were observed between prophylactic HVc administration and therapeutic HVc administration. In addition, all Vc-administered mice exhibited low blood glucose, triglycerides and homeostasis model assessment of insulin resistance values and high adiponectin levels compared to HFD-fed mice. Our study suggested that MVc was beneficial for HFD-induced NAFLD prophylaxis and therapy. LVc prevented HFD-induced NAFLD development, while HVc for NAFLD management was risky. This study offers valuable insight into the effect of various Vc doses on NAFLD management.

Effects of intermittent fasting and energy-restricted diets on lipid profile: A systematic review and meta-analysis

OBJECTIVES

To the best of our knowledge, no systematic review and meta-analysis has evaluated the cholesterol-lowering effects of intermittent fasting (IF) and energy-restricted diets (ERD) compared with control groups. The aim of this review and meta-analysis was to summarize the effects of controlled clinical trials examining the influence of IF and ERD on lipid profiles.

METHODS

A systematic review of four independent databases (PubMed/Medline, Scopus, Web of Science and Google Scholar) was performed to identify clinical trials reporting the effects of IF or ERD, relative to non-diet controls, on lipid profiles in humans. A random-effects model, employing the method of DerSimonian and Laird, was used to evaluate effect sizes, and results were expressed as weighted mean difference (WMD) and 95% confidence intervals (CIs). Heterogeneity between studies was calculated using Higgins I², with values ≥50% considered to represent high heterogeneity. Subgroup analyses were performed to examine the influence of intervention type, baseline lipid concentrations, degree of energy deficit, sex, health status, and intervention duration.

RESULTS

For the outcomes of low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and triacylglycerols (TG), there were 34, 33, 35, and 33 studies meeting all inclusion criteria, respectively. Overall, results from the random-effects model indicated that IF and ERD interventions resulted significant changes in TC (WMD, -6.93 mg/dL; 95% CI, -10.18 to -3.67; P < 0.001; I² = 78.2%), LDL-C (WMD, -6.16 mg/dL; 95% CI, -8.42 to -3.90; P ˂ 0.001; I² = 52%), and TG concentrations (WMD, -6.46 mg/dL; 95% CI, -10.64 to -2.27; P = 0.002; I² = 61%). HDL-C concentrations did not change significantly after IF or ERD (WMD, 0.50 mg/dL; 95% CI, -0.69 to 1.70; P = 0.411; I² = 80%). Subgroup analyses indicated potentially differential effects between subgroups for one or more lipid parameters in the majority of analyses.

CONCLUSIONS

Relative to a non-diet control, IF and ERD are effective for the improvement of circulating TC, LDL-C, and TG concentrations, but have no meaningful effects on HDL-C concentration. These effects are influenced by several factors that may inform clinical practice and future research. The present results suggest that these dietary practices are a means of enhancing the lipid profile in humans.

Ameliorative activity of Adansonia digitata fruit on high sugar/high fat diet-simulated Metabolic Syndrome model in male Wistar rats

Metabolic syndrome is a complex of metabolic disorders characterized by oxidative stress which compromises cell functions and entails multiple organs pathologies. We investigated the therapeutic and protective potential of Adansonia digitata fruit -a potent antioxidant- in high sugar/high fat diet-simulated metabolic syndrome in Wistar rats. 42 male rats (140-200 g) were randomly divided into 7 groups. G1 was kept on standard laboratory diet (SLD) for all 9 weeks (negative control). 5 groups were fed high Sugar/high fat diet for 6 weeks then switched to SLD for another 3 weeks + oral treatment as follows: G2+ no treatment (positive control), G3-G5 + 200, 400 and 800 mg/kg/day aqueous A. digitata fruit respectively, G6 + 10 mg/kg/day Simvastatin. G7 + HS/HFD + 400 mg/kg/day A. digitata fruit simultaneously and was terminated at W6. Our results showed that G2-G6 develops dyslipidemia, hyperglycaemia, weight gain, elevated hepatic biomarkers, elevated creatinine and urea plus pathological derangements in the heart, liver and kidney tissues compared to negative control at W6. 200 mg/kg/day A. digitata fruit significantly ameliorated the induced dyslipidemia (P ≤ 0.001), hyperglycaemia (P ≤ 0.001) with a significant reduction in the Atherogenic Index of Plasma (P ≤ 0.000) after 3 weeks treatment. The fruit normalized the elevated hepatic biomarkers as well as creatinine and urea. A dose dependent partial reduction in lesion intensity was observed in the hepatic tissue while the heart and kidney showed mostly reversed to normal histology. The inflammatory infiltration was eliminated. Relevant results were observed for the two higher doses. The simultaneous treatment showed significant lower levels in all biomarkers investigated compared to positive control which could be interpreted as protective activity. A reduction of 4-11% in whole body weight was achieved. CONCLUSION: MetS was successfully simulated with a HS/HFD formula in male Wistar rats. Treatment with aqueous A. digitata fruit showed anti-Metabolic Syndrome potential reflected by weight loss, anti-inflammatory, hypolipidemic, hypoglycaemic, renal, hepatic and cardio-protective activities.

Vitamin C: A Review on its Role in the Management of Metabolic Syndrome

Oxidative stress and inflammation are two interlinked events that exist simultaneously in metabolic syndrome (MetS) and its related complications. These pathophysiological processes can be easily triggered by each other. This review summarizes the current evidence from animal and human studies on the effects of vitamin C in managing MetS. In vivo studies showed promising effects of vitamin C, but most of the interventions used were in combination with other compounds. The direct effects of vitamin C remain to be elucidated. In humans, the current state of evidence revealed that lower vitamin C intake and circulating concentration were found in MetS subjects. A negative relationship was observed between vitamin C intake / concentration and the risk of MetS. Oral supplementation of vitamin C also improved MetS conditions. It has been postulated that the positive outcomes of vitamin C may be in part mediated through its anti-oxidative and anti-inflammatory properties. These observations suggest the importance of MetS patients to have an adequate intake of vitamin C through food, beverages or supplements in order to maintain its concentration in the systemic circulation and potentially reverse MetS.

Dietary Approaches to Stop Hypertension (DASH): potential mechanisms of action against risk factors of the metabolic syndrome

The metabolic syndrome is a cluster of disorders dominated by abdominal obesity, hypertriacylglycerolaemia, low HDL-cholesterol, high blood pressure and high fasting glucose. Diet modification is a safe and effective way to treat the metabolic syndrome. Dietary Approaches to Stop Hypertension (DASH) is a dietary pattern rich in fruits, vegetables and low-fat dairy products, and low in meats and sweets. DASH provides good amounts of fibre, K, Ca and Mg, and limited quantities of total fat, saturated fat, cholesterol and Na. Although DASH was initially designed for the prevention or control of hypertension, using a DASH diet has other metabolic benefits. In the present review, the effect of each dietary component of DASH on the risk factors of the metabolic syndrome is discussed. Due to limited fat and high fibre and Ca content, individuals on the DASH diet are less prone to overweight and obesity and possess lower concentrations of total and LDL-cholesterol although changes in TAG and HDL-cholesterol have been less significant and available evidence in this regard is still inconclusive. Moreover, high amounts of fruit and vegetables in DASH provide great quantities of K, Mg and fibre, all of which have been shown to reduce blood pressure. K, Mg, fibre and antioxidants have also been effective in correcting glucose and insulin abnormalities. Evidence is provided from cross-sectional investigations, cohort studies and randomised controlled trials, and, where available, from published meta-analyses. Mechanisms are described according to human studies and, in the case of a lack of evidence, from animal and cell culture investigations.

Nutritional Health Considerations for Persons with Spinal Cord Injury

Chronic spinal cord injury (SCI) often results in morbidity and mortality due to all-cause cardiovascular disease (CVD) and comorbid endocrine disorders. Several component risk factors for CVD, described as the cardiometabolic syndrome (CMS), are prevalent in SCI, with the individual risks of obesity and insulin resistance known to advance the disease prognosis to a greater extent than other established risks. Notably, adiposity and insulin resistance are attributed in large part to a commonly observed maladaptive dietary/nutritional profile. Although there are no evidence-based nutritional guidelines to address the CMS risk in SCI, contemporary treatment strategies advocate more comprehensive lifestyle management that includes sustained nutritional guidance as a necessary component for overall health management. This monograph describes factors in SCI that contribute to CMS risks, the current nutritional profile and its contribution to CMS risks, and effective treatment strategies including the adaptability of the Diabetes Prevention Program (DPP) to SCI. Establishing appropriate nutritional guidelines and recommendations will play an important role in addressing the CMS risks in SCI and preserving optimal long-term health.

Association between the consumption of antioxidant nutrients with lipid alterations and cardiometabolic risk in adolescents

ABSTRACT Objective This study aimed at validating the associations between the consumption of antioxidant nutrients as well as lipid alterations and cardiometabolic risks in adolescents. Methods This cross-sectional study included 327 adolescents aged 14-19 years. Sociodemographic and dietary information, anthropometric and blood pressure measurements, and biochemical data were obtained. Cardiometabolic risk was calculated by aggregating the risk factors, which were expressed as the sum of Z-scores. Poisson regression was performed to estimate the prevalence ratios. Results In boys, low intake of zinc was associated with elevated total cholesterol and triglyceride levels, whereas it was associated with low high-density lipoprotein cholesterol levels and high low-density lipoprotein cholesterol and total cholesterol levels in girls, thus indicating a cardiometabolic risk. Furthermore, low intake of copper was associated with high triglyceride levels and cardiometabolic risk in girls. The high prevalence ratios of high low-density lipoprotein cholesterol and total cholesterol levels and cardiometabolic risk were higher in those with low intake of vitamin A. Among girls, associations were also observed between lower intake of vitamin A and high triglyceride levels. Low intake of vitamin C among boys was associated with elevated high low-density lipoprotein cholesterol and triglyceride levels. Among girls, the intake of this vitamin was associated with lower low high-density lipoprotein cholesterol levels. In girls, low intake of vitamin E was associated with low low high-density lipoprotein cholesterol levels and high total cholesterol levels. Conclusion The associations between antioxidant micronutrients as well as lipid alterations and cardiometabolic risk emphasize the importance of encouraging the consumption of foods that are rich in these nutrients to modulate lipid alterations and cardiometabolic risk.

Emerging Evidence on Neutrophil Motility Supporting Its Usefulness to Define Vitamin C Intake Requirements

Establishing intake recommendations for vitamin C remains a challenge, as no suitable functional parameter has yet been agreed upon. In this report, we review the emerging evidence on neutrophil motility as a possible marker of vitamin C requirements and put the results in perspective with other approaches. A recent in vitro study showed that adequate levels of vitamin C were needed for this function to work optimally when measured as chemotaxis and chemokinesis. In a human study, neutrophil motility was optimal at intakes ≥250 mg/day. Interestingly, a Cochrane review showed a significant reduction in the duration of episodes of common cold with regular vitamin C intakes in a similar range. Additionally, it was shown that at a plasma level of 75 µmol/L, which is reached with vitamin C intakes ≥200 mg/day, incidences of cardiovascular disease were lowest. This evidence would suggest that daily intakes of 200 mg vitamin C might be advisable for the general adult population, which can be achieved by means of a diverse diet. However, additional studies are warranted to investigate the usefulness of neutrophil motility as a marker of vitamin C requirements.

Vitamin C supplementation for the primary prevention of cardiovascular disease

BACKGROUND

Vitamin C is an essential micronutrient and powerful antioxidant. Observational studies have shown an inverse relationship between vitamin C intake and major cardiovascular events and cardiovascular disease (CVD) risk factors. Results from clinical trials are less consistent.

OBJECTIVES

To determine the effectiveness of vitamin C supplementation as a single supplement for the primary prevention of CVD.

SEARCH METHODS

We searched the following electronic databases on 11 May 2016: the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library; MEDLINE (Ovid); Embase Classic and Embase (Ovid); Web of Science Core Collection (Thomson Reuters); Database of Abstracts of Reviews of Effects (DARE); Health Technology Assessment Database and Health Economics Evaluations Database in the Cochrane Library. We searched trial registers on 13 April 2016 and reference lists of reviews for further studies. We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials of vitamin C supplementation as a single nutrient supplement lasting at least three months and involving healthy adults or adults at moderate and high risk of CVD were included. The comparison group was no intervention or placebo. The outcomes of interest were CVD clinical events and CVD risk factors.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, abstracted the data and assessed the risk of bias.

MAIN RESULTS

We included eight trials with 15,445 participants randomised. The largest trial with 14,641 participants provided data on our primary outcomes. Seven trials reported on CVD risk factors. Three of the eight trials were regarded at high risk of bias for either reporting or attrition bias, most of the 'Risk of bias' domains for the remaining trials were judged as unclear, with the exception of the largest trial where most domains were judged to be at low risk of bias.The composite endpoint, major CVD events was not different between the vitamin C and placebo group (hazard ratio (HR) 0.99, 95% confidence interval (CI) 0.89 to 1.10; 1 study; 14,641 participants; low-quality evidence) in the Physicians Health Study II over eight years of follow-up. Similar results were obtained for all-cause mortality HR 1.07, 95% CI 0.97 to 1.18; 1 study; 14,641 participants; very low-quality evidence, total myocardial infarction (MI) (fatal and non-fatal) HR 1.04 (95% CI 0.87 to 1.24); 1 study; 14,641 participants; low-quality evidence, total stroke (fatal and non-fatal) HR 0.89 (95% CI 0.74 to 1.07); 1 study; 14,641 participants; low-quality evidence, CVD mortality HR 1.02 (95% 0.85 to 1.22); 1 study; 14,641 participants; very low-quality evidence, self-reported coronary artery bypass grafting (CABG)/percutaneous transluminal coronary angioplasty (PTCA) HR 0.96 (95% CI 0.86 to 1.07); 1 study; 14,641 participants; low-quality evidence, self-reported angina HR 0.93 (95% CI 0.84 to 1.03); 1 study; 14,641 participants; low-quality evidence.The evidence for the majority of primary outcomes was downgraded (low quality) because of indirectness and imprecision. For all-cause mortality and CVD mortality, the evidence was very low because more factors affected the directness of the evidence and because of inconsistency.Four studies did not state sources of funding, two studies declared non-commercial funding and two studies declared both commercial and non-commercial funding.

AUTHORS' CONCLUSIONS

Currently, there is no evidence to suggest that vitamin C supplementation reduces the risk of CVD in healthy participants and those at increased risk of CVD, but current evidence is limited to one trial of middle-aged and older male physicians from the USA. There is limited low- and very low-quality evidence currently on the effect of vitamin C supplementation and risk of CVD risk factors.

Systematic review and meta-analysis of randomised controlled trials testing the effects of vitamin C supplementation on blood lipids

BACKGROUND & AIMS

Randomised controlled trials (RCTs) in humans revealed contradictory results regarding the effect of vitamin C supplementation on blood lipids. We aimed to conduct a systematic review and meta-analysis of RCTs investigating the effect of vitamin C supplementation on total cholesterol, low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C) and triglycerides and to determine whether the effects are modified by the participants' or intervention characteristics.

METHODS

Four databases (PubMed, Embase, Scopus and Cochrane Library) were searched from inception until August 2014 for RCTs supplementing adult participants with vitamin C for ≥ 2 weeks and reporting changes in blood lipids.

RESULTS

Overall, vitamin C supplementation did not change blood lipids concentration significantly. However, supplementation reduced total cholesterol in younger participants (≤52 years age) (-0.26 mmol/L, 95% CI: -0.45, -0.07) and LDL-C in healthy participants (-0.32 mmol/L, 95% CI: -0.57, -0.07). In diabetics, vitamin C supplementation reduced triglycerides significantly (-0.15 mmol/L, 95% CI: -0.30, -0.002) and increased HDL-C significantly (0.06 mmol/L, 95% CI: 0.02, 0.11). Meta-regression analyses showed the changes in total cholesterol (β: -0.24, CI: -0.36, -0.11) and in triglycerides (β: -0.17, CI: -0.30, -0.05) following vitamin C supplementation were greater in those with higher concentrations of these lipids at baseline. Greater increase in HDL-C was observed in participants with lower baseline plasma concentrations of vitamin C (β: -0.002, CI: -0.003, -0.0001).

CONCLUSIONS

Overall, vitamin C supplementation had no significant effect on lipid profile. However, subgroup and sensitivity analyses showed significant reductions in blood lipids following supplementation in sub-populations with dyslipidaemia or low vitamin C status at baseline. PROSPERO Database registration: CRD42014013487, http://www.crd.york.ac.uk/prospero/.

Variation in the SLC23A1 gene does not influence cardiometabolic outcomes to the extent expected given its association with L-ascorbic acid

BACKGROUND

Observational studies showed that circulating L-ascorbic acid (vitamin C) is inversely associated with cardiometabolic traits. However, these studies were susceptible to confounding and reverse causation.

OBJECTIVES

We assessed the relation between L-ascorbic acid and 10 cardiometabolic traits by using a single nucleotide polymorphism in the solute carrier family 23 member 1 (SLC23A1) gene (rs33972313) associated with circulating L-ascorbic acid concentrations. The observed association between rs33972313 and cardiometabolic outcomes was compared with that expected given the rs33972313-L-ascorbic acid and L-ascorbic acid-outcome associations.

DESIGN

A meta-analysis was performed in the following 5 independent studies: the British Women's Heart and Health Study (n = 1833), the MIDSPAN study (n = 1138), the Ten Towns study (n = 1324), the British Regional Heart Study (n = 2521), and the European Prospective Investigation into Cancer (n = 3737).

RESULTS

With the use of a meta-analysis of observational estimates, inverse associations were shown between L-ascorbic acid and systolic blood pressure, triglycerides, and the waist-hip ratio [the strongest of which was the waist-hip ratio (-0.13-SD change; 95% CI: -0.20-, -0.07-SD change; P = 0.0001) per SD increase in L-ascorbic acid], and a positive association was shown with high-density lipoprotein (HDL) cholesterol. The variation at rs33972313 was associated with a 0.18-SD (95% CI: 0.10-, 0.25-SD; P = 3.34 × 10⁻⁶) increase in L-ascorbic acid per effect allele. There was no evidence of a relation between the variation at rs33972313 and any cardiometabolic outcome. Although observed estimates were not statistically different from expected associations between rs33972313 and cardiometabolic outcomes, estimates for low-density lipoprotein cholesterol, HDL cholesterol, triglycerides, glucose, and body mass index were in the opposite direction to those expected.

CONCLUSIONS

The nature of the genetic association exploited in this study led to limited statistical application, but despite this, when all cardiometabolic traits were assessed, there was no evidence of any trend supporting a protective role of L-ascorbic acid. In the context of existing work, these results add to the suggestion that observational relations between L-ascorbic acid and cardiometabolic health may be attributable to confounding and reverse causation.

Effect of ascorbic acid and alpha-tocopherol supplementations on serum leptin, tumor necrosis factor alpha, and serum amyloid A levels in individuals with type 2 diabetes mellitus

OBJECTIVE

Diabetes mellitus Type 2 is one of the most widespread chronic metabolic diseases. In most cases, this type of diabetes is associated with alterations in levels of some inflammatory cytokines and hormones. Considering anti-inflammatory properties of plant extracts rich in ascorbic acid (vitamin C) and alpha-tocopherol (vitamin E), anti-diabetic properties of these two well-known antioxidant vitamins were investigated through measurement of serum levels of high-sensitivity C-reactive protein (hs-CRP), insulin, leptin, tumor necrosis factor alpha (TNF-α), and serum amyloid A (SAA) in patients with diabetes mellitus type 2.

MATERIALS AND METHODS

Male patients (n=80) were randomly divided into two groups each consisted of 40 subjects. Test groups were supplemented with ascorbic acid (1000 mg/day) or alpha-tocopherol (300 mg/day) orally during four weeks. Before and after treatment, serum biochemical factors of subjects were measured and compared.

RESULTS

Our results showed that both ascorbic acid and alpha-tocopherol could induce significant anti-inflammatory effects by decreasing the level of inflammatory factors such as TNF-α, SAA, and hs-CRP in diabetes mellitus type 2 patients. Effects of alpha-tocopherol and ascorbic acid in decreasing serum leptin level were similar. Ascorbic acid in contrast to alpha-tocopherol diminished fasting insulin and HOMA index but had no effect on LDL serum level.

CONCLUSION

Concerning the obtained results, it is concluded that consumption of supplementary vitamins C and E could decrease induced inflammatory response in patients with diabetes mellitus type 2. It is also possible that vitamin C and vitamin E supplementation can attenuate incidence of some proposed pathological effects of diabetes mellitus.

Does vitamin C deficiency promote fatty liver disease development?

Obesity and the subsequent reprogramming of the white adipose tissue are linked to human disease-complexes including metabolic syndrome and concurrent non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). The dietary imposed dyslipidemia promotes redox imbalance by the generation of excess levels of reactive oxygen species and induces adipocyte dysfunction and reprogramming, leading to a low grade systemic inflammation and ectopic lipid deposition, e.g., in the liver, hereby promoting a vicious circle in which dietary factors initiate a metabolic change that further exacerbates the negative consequences of an adverse life-style. Large epidemiological studies and findings from controlled in vivo animal studies have provided evidence supporting an association between poor vitamin C (VitC) status and propagation of life-style associated diseases. In addition, overweight per se has been shown to result in reduced plasma VitC, and the distribution of body fat in obesity has been shown to have an inverse relationship with VitC plasma levels. Recently, a number of epidemiological studies have indicated a VitC intake below the recommended daily allowance (RDA) in NAFLD-patients, suggesting an association between dietary habits, disease and VitC deficiency. In the general population, VitC deficiency (defined as a plasma concentration below 23 μM) affects around 10% of adults, however, this prevalence is increased by an adverse life-style, deficiency potentially playing a broader role in disease progression in specific subgroups. This review discusses the currently available data from human surveys and experimental models in search of a putative role of VitC deficiency in the development of NAFLD and NASH.

Vitamin C may have similar beneficial effects to Gemfibrozil on serum high-density lipoprotein-cholesterol in type 2 diabetic patients

Objective:

Type 2 diabetes mellitus (DM-T2) is commonly associated with increased triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and low high-density lipoprotein cholesterol (HDL-C) levels. Fibrates like gemfibrozil are frequently used in diabetic patients to decrease TG and increase HDL-C levels. We compared the efficacy of Vitamin C, an antioxidant vitamin, with gemfibrozil on serum HDL-C in diabetic patients.

Methods:

Type 2 diabetic patients, referred to our out-patient clinic were randomly divided into three groups. After 1 month of lifestyle and diet modifications, groups A, B, and C were prescribed 1000 mg Vitamin C, 600 mg gemfibrozil and combination of both, respectively. Before the study initiation and after 6^th week of drug prescription, the blood samples were taken and analyzed for total cholesterol (Total-C), HDL-C, TG, fasting blood sugar (FBS), and hemoglobin A1c (HbA1c) levels.

Findings:

Sixty-seven patients entered, and 50 patients (18 male, 32 female) finished the study. Overall, serum HDL-C increased significantly from 39.8 to 45.2 mg/dL in the participants (P = 0.001). HDL-C increased 6.3, 4.4 and 5.0 mg/dL in groups A, B and C, respectively (related significances were 0.017, 0.022 and 0.033, respectively). Significant decrease of serum TG and Total-C occurred in gemfibrozil and combination groups, but not in Vitamin C group. Changes in serum HDL-C between three groups were not significant (P = 0.963). We found a significant decrease in TG and Total-C in the groups B and C (P < 0.05), but no significant changes of TG, Total-C, LDL-C, FBS and HbA1c in group A (P > 0.05).

Conclusion:

The results demonstrated that Vitamin C may have beneficial effects on HDL-C in diabetic patients without significant effects on plasma glucose or other lipid parameters; however, its role for the treatment of low HDL-C patients should be evaluated in larger studies.