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Effects of vitamin C supplementation on essential hypertension: A systematic review and meta-analysis.
Guan, Y, Dai, P, Wang, H
Medicine. 2020;(8):e19274
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Abstract
BACKGROUND Vitamin C as a supplement to treat hypertension has been proposed. However, it remains controversial whether vitamin C can improve blood pressure in patients with primary hypertension. OBJECTIVES To analyze the effect of vitamin C (VitC) supplementation on systolic (SBP) and diastolic (DBP) blood pressure in patients with essential hypertension. METHODS We searched the Chinese Knowledge Infrastructure, VIP Database for Chinese Technical Periodicals, WANFANG Data, Cochrane Library, National Library of Medicine's PubMed, EMBASE, and other databases until June 2019. Eight RCTs involving 614 participants were analyzed. SBP and DBP before and after VitC supplementation were compared between the intervention and control groups. The risk of bias of individual studies was assessed using the Cochrane Collaboration risk of bias tool. Two reviewers selected studies independently of each other. The Cochrane Collaboration Review Manager 5.3 was used to perform the meta-analysis. RESULTS There was a significant difference in the change of SBP (weighted mean difference [WMD] = -4.09; 95% confidence interval [CI] -5.56, -2.62; P < .001) and DBP (WMD = -2.30; 95% CI -4.27, -.331; P = .02) between the groups. Further, there was a significant difference in the SBP (WMD = -3.75, 95% CI -6.24, -1.26, P = .003) and DBP (WMD = -3.29, 95% CI -5.98, -.60, P = .02) for the subgroup with an age ≥60 years and that with ≥35 participants. In the subgroup analysis, result for SBP with a study duration ≥6 weeks was statistically significant different (WMD = -4.77; 95% CI -6.46, -3.08; P < .001). For an intervention dose of VitC ≥500 mg daily, SBP was statistically significant (WMD = -5.01; 95% CI -8.55, -1.48; P = .005). CONCLUSION VitC supplementation resulted in a significant reduction of blood pressure in patients with essential hypertension.
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The effect of vitamin C supplementation in the last month of pregnancy on neonatal bilirubin levels; A double-blind randomized clinical trial.
Khadem Al-Hosseini, M, Rahideh, ST, Saadati, A, Rahmati, N, Azadeh, F, Janani, L, Shidfar, F
Complementary therapies in medicine. 2020;:102359
Abstract
OBJECTIVES Jaundice is a typical condition in the neonatal period, particularly in the Asian continent. Drowsiness and disruption of breastfeeding, behavioral and neurological disorders, hearing loss and mental retardation are the results of impairment in controlling it. The increase in oxidant substances can stimulate the heme oxygenase enzyme and increase the conversion of heme to bilirubin. In some studies, vitamin C levels in the blood of infants with hyperbilirubinemia were lower than in healthy infants. DESIGN In this double-blind clinical trial study, 144 healthy pregnant women aged 20-40 years who were in 34th weeks of gestation were randomly divided into intervention, and control groups and until the end of pregnancy, they took a 500 mg tablet of vitamin C or placebo (Preparation of starch) daily. Demographic information, dietary intake, and physical activity level of the participants were also evaluated. The total blood bilirubin level was measured on the fifth day after birth using a sample of the neonatal heel. Statistical analysis was performed using SPSS software version 22. In this study P-value < 0. 05 was considered significant. RESULTS Of the 144 participants, 128 of them completed the intervention. There was no significant difference between the two groups at the level of vitamin C intake through diet, and anthropometric indices, but the total bilirubin level in the neonates of the two groups was statistically different (P = 0.02). CONCLUSION Vitamin C supplementation in the last month of pregnancy had a significant effect on neonatal bilirubin level and decreased it significantly.
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Ascorbic acid inhibits vascular remodeling induced by mental stress in overweight/obese men.
Batista, GMS, Rocha, HNM, Storch, AS, Garcia, VP, Teixeira, GF, Mentzinger, J, Gomes, EAC, Velasco, LL, Nóbrega, ACL, Rocha, NG
Life sciences. 2020;:117554
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Abstract
BACKGROUND Mental stress (MS) is related to endothelial dysfunction in overweight/obese men. It is believed that the pro-oxidant profile, associated with an imbalance in the vascular remodeling process, may contribute to deleterious effects of MS on endothelial function. However, it is unknown whether administration of ascorbic acid (AA), a potent antioxidant, can prevent oxidative and remodeling dysfunction during MS in these subjects. METHODS Fourteen overweight/obese grade I men (27 ± 7 years; 29.7 ± 2.6 kg·m-2) underwent the Stroop Color Word Test for 5 min to induce MS after AA (3 g) or placebo (PL, 0.9% NaCl) intravenous infusions. Venous blood samples were collected at baseline and the last minute of MS to measure nitrite concentration (chemiluminescence), protein carbonylation, thiobarbituric acid reactive substances (TBARS) and catalase activity (colorimetric assays), superoxide dismutase (SOD; immunoenzymatic assay), activities of active/inactive (pro) forms of metalloproteinases-9 and -2 (MMP; zymography) and its respective tissue inhibitors concentration (TIMP-1 and TIMP-2; immunoenzymatic assays). RESULTS At baseline, MMP-9 activity (p < 0.01), the MMP-9/proMMP-9 ratio (p = 0.02) and TIMP-1 concentration (p = 0.05) were reduced, whereas proMPP-9 activity was increased (p = 0.02) after AA compared to PL infusion. After PL infusion, MS increased protein carbonylation (p < 0.01), catalase (p < 0.01), and the MMP-9/proMMP-9 ratio (p = 0.04) when compared to baseline. AA infusion reduced protein carbonylation (p = 0.02), MMP-9 activity (p < 0.01), and MMP-9/pro-MMP-9 ratio (p < 0.01), while SOD (p = 0.04 vs baseline), proMPP-9 (p < 0.01 vs PL), MMP-2 (p < 0.01 vs PL) and TIMP-2 (p = 0.02 vs baseline) remained elevated during MS. CONCLUSIONS AA appears to minimize the oxidative imbalance and vascular remodeling induced by MS.
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Plasma Cortisol, Aldosterone, and Ascorbic Acid Concentrations in Patients with Septic Shock Do Not Predict Treatment Effect of Hydrocortisone on Mortality. A Nested Cohort Study.
Cohen, J, Bellomo, R, Billot, L, Burrell, LM, Evans, DM, Finfer, S, Hammond, NE, Li, Q, Liu, D, McArthur, C, et al
American journal of respiratory and critical care medicine. 2020;(5):700-707
Abstract
Rationale: Whether biomarkers can identify subgroups of patients with septic shock with differential treatment responses to hydrocortisone is unknown.Objectives: To determine if there is heterogeneity in effect for hydrocortisone on mortality, shock resolution, and other clinical outcomes based on baseline cortisol, aldosterone, and ascorbic acid concentrations.Methods: From May 2014 to April 2017, we obtained serum samples from 529 patients with septic shock from 22 ICUs in Australia and New Zealand.Measurements and Main Results: There were no significant interactions between the association with 90-day mortality and treatment with either hydrocortisone or placebo for total cortisol (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.02-1.16 vs. OR, 1.07; 95% CI, 1.00-1.13; P = 0.70), free cortisol (OR, 1.20; 95% CI, 1.04-1.38 vs. OR, 1.16; 95% CI, 1.02-1.32; P = 0.75), aldosterone (OR, 1.01; 95% CI, 0.97-1.05 vs. OR, 1.01; 95% CI, 0.98-1.04; P = 0.99), or ascorbic acid (OR, 1.11; 95% CI, 0.89-1.39 vs. OR, 1.05; 95% CI, 0.91-1.22; P = 0.70), respectively. Similar results were observed for the association with shock resolution. Elevated free cortisol was significantly associated with 90-day mortality (OR, 1.13; 95% CI, 1.00-1.27; P = 0.04), but total cortisol, aldosterone, and ascorbic acid were not.Conclusions: In patients with septic shock, there was no heterogeneity in effect of adjunctive hydrocortisone on mortality, shock resolution, or other clinical outcomes based on cortisol, aldosterone, and ascorbic acid concentrations. Plasma aldosterone and ascorbic acid concentrations are not associated with outcome.
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The Role of Vitamin C in Two Distinct Physiological States: Physical Activity and Sleep.
Otocka-Kmiecik, A, Król, A
Nutrients. 2020;(12)
Abstract
This paper is a literature overview of the complex relationship between vitamin C and two opposing physiological states, physical activity and sleep. The evidence suggests a clinically important bidirectional association between these two phenomena mediated by different physiological mechanisms. With this in mind, and knowing that both states share a connection with oxidative stress, we discuss the existing body of evidence to answer the question of whether vitamin C supplementation can be beneficial in the context of sleep health and key aspects of physical activity, such as performance, metabolic changes, and antioxidant function. We analyze the effect of ascorbic acid on the main sleep components, sleep duration and quality, focusing on the most common disorders: insomnia, obstructive sleep apnea, and restless legs syndrome. Deeper understanding of those interactions has implications for both public health and clinical practice.
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Manipulation of Ascorbate Biosynthetic, Recycling, and Regulatory Pathways for Improved Abiotic Stress Tolerance in Plants.
Broad, RC, Bonneau, JP, Hellens, RP, Johnson, AAT
International journal of molecular sciences. 2020;(5)
Abstract
Abiotic stresses, such as drought, salinity, and extreme temperatures, are major limiting factors in global crop productivity and are predicted to be exacerbated by climate change. The overproduction of reactive oxygen species (ROS) is a common consequence of many abiotic stresses. Ascorbate, also known as vitamin C, is the most abundant water-soluble antioxidant in plant cells and can combat oxidative stress directly as a ROS scavenger, or through the ascorbate-glutathione cycle-a major antioxidant system in plant cells. Engineering crops with enhanced ascorbate concentrations therefore has the potential to promote broad abiotic stress tolerance. Three distinct strategies have been utilized to increase ascorbate concentrations in plants: (i) increased biosynthesis, (ii) enhanced recycling, or (iii) modulating regulatory factors. Here, we review the genetic pathways underlying ascorbate biosynthesis, recycling, and regulation in plants, including a summary of all metabolic engineering strategies utilized to date to increase ascorbate concentrations in model and crop species. We then highlight transgene-free strategies utilizing genome editing tools to increase ascorbate concentrations in crops, such as editing the highly conserved upstream open reading frame that controls translation of the GDP-L-galactose phosphorylase gene.
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Zinc Supplementation Reduces Common Cold Duration among Healthy Adults: A Systematic Review of Randomized Controlled Trials with Micronutrients Supplementation.
Wang, MX, Win, SS, Pang, J
The American journal of tropical medicine and hygiene. 2020;(1):86-99
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The common cold had resulted in significant economic and social burden worldwide. The effect of vitamin C on preventing common cold in healthy adults has been investigated extensively, but not that of other micronutrients. Thus, we aim to assess the effects of providing micronutrients singly through oral means, on cold incidence, and/or management (in terms of cold duration and symptom severity) in healthy adults from systematically searched randomized controlled trials. From four electronic databases, 660 identified studies were screened and data were extracted from 20 studies (zinc, 10; vitamin D, 8; and vitamins A and E, 2). The quality of selected studies was assessed using the Cochrane risk of bias tool and certainty in the outcomes was assessed with the Grading of Recommendations Assessment, Development and Evaluation approach. The review found that micronutrients supplementation, except vitamin C, may not prevent cold incidence or reduce symptom severity among healthy adults. However, zinc supplementation was observed to potentially reduce cold duration by 2.25 days (when zinc is provided singly, 95% CI: -3.39, -1.12). This suggests that zinc supplementation may reduce the overall burden due to common cold among healthy adults.
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Effects of inorganic nitrate and vitamin C co-supplementation on blood pressure and vascular function in younger and older healthy adults: A randomised double-blind crossover trial.
Ashor, AW, Shannon, OM, Werner, AD, Scialo, F, Gilliard, CN, Cassel, KS, Seal, CJ, Zheng, D, Mathers, JC, Siervo, M
Clinical nutrition (Edinburgh, Scotland). 2020;(3):708-717
Abstract
BACKGROUND Vitamin C and inorganic nitrate have been linked to enhanced nitric oxide (NO) production and reduced oxidative stress. Vitamin C may also enhance the conversion of nitrite into NO. AIMS We investigated the potential acute effects of vitamin C and inorganic nitrate co-supplementation on blood pressure (BP) and peripheral vascular function. The secondary aim was to investigate whether age modified the effects of vitamin C and inorganic nitrate on these vascular outcomes. METHODS Ten younger (age 18-40 y) and ten older (age 55-70 y) healthy participants were enrolled in a randomised double-blind crossover clinical trial. Participants ingested a solution of potassium nitrate (7 mg/kg body weight) and/or vitamin C (20 mg/kg body weight) or their placebos. Acute changes in resting BP and vascular function (post-occlusion reactive hyperemia [PORH], peripheral pulse wave velocity [PWV]) were monitored over a 3-h period. RESULTS Vitamin C supplementation reduced PWV significantly (vitamin C: -0.70 ± 0.31 m/s; vitamin C placebo: +0.43 ± 0.30 m/s; P = 0.007). There were significant interactions between age and vitamin C for systolic, diastolic, and mean arterial BP (P = 0.02, P = 0.03, P = 0.02, respectively), with systolic, diastolic and mean BP decreasing in older participants and diastolic BP increasing in younger participants following vitamin C administration. Nitrate supplementation did not influence BP (systolic: P = 0.81; diastolic: P = 0.24; mean BP: P = 0.87) or vascular function (PORH: P = 0.05; PWV: P = 0.44) significantly in both younger and older participants. However, combined supplementation with nitrate and vitamin C reduced mean arterial BP (-2.6 mmHg, P = 0.03) and decreased PWV in older participants (PWV: -2.0 m/s, P = 0.02). CONCLUSIONS The co-administration of a single dose of inorganic nitrate and vitamin C lowered diastolic BP and improved PVW in older participants. Vitamin C supplementation improved PWV in both age groups but decreased systolic and mean BP in older participants only. CLINICAL TRIAL REGISTRATION Current Controlled Trials (ISRCTN98942199).
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Effects of the Lysulin™ supplementation on pre-diabetes: A randomized double-blind, placebo-controlled clinical trial.
Ranasinghe, P, Jayawardena, R, Chandrasena, L
Diabetes & metabolic syndrome. 2020;(5):1479-1486
Abstract
BACKGROUND AND AIMS Diabetes is a leading cause of morbidity and mortality worldwide. Recent studies have demonstrated that nutraceutical products have beneficial effects in diabetes. Present study aims to investigate whether a product (Lysulin™) containing amino acid lysine, micronutrient zinc and vitamin C will have beneficial effects in pre-diabetes. METHODS A randomized, double-blind, placebo-controlled trial was conducted for a period of 6 months. The two parallel groups (1:1) were Lysulin™ (Interventional group-IG) and placebo (control group-CG). Evaluations were done at baseline, 1, 3 and 6 months. Primary outcome was defined as change in glycaemic control measured by HbA1c from baseline. Other outcomes included change in; fasting plasma glucose (FPG), 2-h OGTT plasma glucose and lipid profile from baseline. Three multiple regression analyses were performed, where change in FPG, 2-h OGTT, and HbA1c post intervention from baseline respectively were the continuous dependent variable with other independent variables. RESULTS One hundred and ten participants were recruited, 50% (n = 55) were males and mean age (±SD) was 46.7 ± 9.9 years. A significantly higher percentage of participants in CG (25.4%, n = 14) developed diabetes in comparison to IG (7.3%, n = 4) (p = 0.018). FPG, 2-h OGTT and HbA1c significantly reduced in the IG only. Both total cholesterol and LDL cholesterol decreased significantly from baseline only in the IG. In all three regression models the best predictor of respective dependent variable was Lysulin™ treatment. CONCLUSIONS Lysulin™ improved glycaemic control, with reduced progression to diabetes, in those with pre-diabetes. Treatment also showed a beneficial reduction in total and LDL cholesterol levels. TRIAL REGISTRATION Sri Lanka Clinical Trials Registry, identifier: SLCTR/2018/022 (http://slctr.lk/trials/1290). Registered on 13th July 2018; Study protocol version 2.0 (23rd March 2018).
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The effect of β-carotene on the mortality of male smokers is modified by smoking and by vitamins C and E: evidence against a uniform effect of nutrient.
Hemilä, H
Journal of nutritional science. 2020;:e11
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A previous analysis of the Alpha-Tocopherol Beta-Carotene (ATBC) Study on male smokers found that β-carotene supplementation increased the risk of pneumonia 4-fold in those who started smoking at the age of ≥21 years and smoked ≥21 cigarettes/d (a subgroup of 7 % of the study population). The present study hypothesised that β-carotene increases mortality in the same subgroup. The ATBC Study (1985-1993) recruited 29 133 Finnish male smokers (≥5 cigarettes/d) aged 50-69 years. Cox regression models were constructed to estimate the effect of β-carotene supplementation in subgroups. β-Carotene increased mortality (risk ratio 1·56; 95 % CI 1·06, 2·3) in those who started to smoke at ≥21 years and smoked ≥21 cigarettes/d. Within this subgroup, there was strong evidence of further heterogeneity. The effect of β-carotene supplementation was further modified by dietary vitamin C intake, fruit and vegetable intake (P = 0·0004), and by vitamin E supplementation (P = 0·011). Thus, harm from β-carotene was not uniform within the study population. Interactions between β-carotene and vitamins C and E were seen only within a subgroup of 7 % of the ATBC participants, and therefore should not be extrapolated to the general population. Heterogeneity of the β-carotene effect on mortality challenges the validity of previous meta-analyses that have pooled many diverse antioxidants for one single estimate of effect using the assumption that a single estimate equally applies to all antioxidants and all people. Trial registration: ClinicalTrials.gov NCT00342992.