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Liu XX, Wang XX, Cui LL. Association between Oral vitamin C supplementation and serum uric acid: A meta-analysis of randomized controlled trials. Complement Ther Med 2021; 60:102761. [PMID: 34280483 DOI: 10.1016/j.ctim.2021.102761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 06/01/2021] [Accepted: 07/15/2021] [Indexed: 10/20/2022] Open
Abstract
INTRODUCTION Results from recent trials assessing the effect of oral vitamin C supplementation on serum uric acid (SUA) have been inconsistent. OBJECTIVES The purpose of this study was to explore the association between oral vitamin C supplementation and serum uric acid. METHODS PUBMED, EMBASE, CNKI, Web of Science, and CENTRAL of Cochrane library databases were searched to identify relevant articles published up to February 2020. Heterogeneity was evaluated using I-square (I2) statistics. Random-effects model was used to pool weighted mean differences (WMD) and 95 % confidence interval (CI) as summary effect sizes. RESULTS The total sixteen eligible randomized controlled trials (RCTs) containing 1,013 participants were included in this meta-analysis. The pooled findings showed that vitamin C supplementation had a significant effect of lowering SUA. The subgroup analyses showed that the effect of vitamin C supplementation on SUA has positive association with mean age of participants <65 years old, the use of placebo or blank control, duration of trials <1 month and high-quality studies. In addition, sensitivity analysis showed that the results of this study were stable. Both Egger's test and Begg's test demonstrated that no evidence of significant publication bias. CONCLUSIONS The results of present meta-analysis have demonstrated that vitamin C supplementation could make a reduction of SUA. The use of placebo, duration of intervention, age of the subjects and study quality have an impact on the effect of oral vitamin C, but the baseline of SUA not.
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Affiliation(s)
- Xin-Xin Liu
- Department of Nutrition and Hygiene, College of Public Health, Zhengzhou University, Henan, 450001, China.
| | - Xiao-Xue Wang
- Department of Nutrition and Hygiene, College of Public Health, Zhengzhou University, Henan, 450001, China.
| | - Ling-Ling Cui
- Department of Nutrition and Hygiene, College of Public Health, Zhengzhou University, Henan, 450001, China.
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Effects of the Consumption of Low-Fat Cooked Ham with Reduced Salt Enriched with Antioxidants on the Improvement of Cardiovascular Health: A Randomized Clinical Trial. Nutrients 2021; 13:nu13051480. [PMID: 33925704 PMCID: PMC8146046 DOI: 10.3390/nu13051480] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/22/2021] [Accepted: 04/24/2021] [Indexed: 12/12/2022] Open
Abstract
The aim of the study was to analyze how cardiovascular risk factors can be modified using nutritionally improved cooked ham enriched with a pool of antioxidants to influence relevant metabolic targets. Sixty-five untreated subjects (49.2% males, 50.8% females, mean age 40.92 ± 9.03 years) with total cholesterol level ≥180 mg/dL or LDL cholesterol ≥130 mg/dL participated in a 8-weeks randomized, double-blind controlled trial. Participant in the intervention group (51.5% males, 48.5% females, mean age 41.6 ± 9.8 years and mean BMI 25.1 ± 3.6 kg/m2) consumed cooked ham enriched with antioxidants (100 g/d) and controls (49.9% males, 53.1% females, mean age 40.2 ± 8.3 years and mean BMI 26.3 ± 3.2 kg/m2) received placebo. At 8 weeks, oxidized LDL decreased significantly between experimental and placebo groups (p < 0.036). Experimental group differences were also significant (p < 0.05). Similar findings in malondialdehyde, total cholesterol, high-sensitivity C-reactive protein, and interleukin 6 were observed in the intervention group. Significant between-group differences in these variables were also found, except for total cholesterol and interleukin 6. The effects on inflammation and oxidation support the direct action of these antioxidants on the etiopathogenic factors of atheromatous plaque. We also observed an improvement in the lipid profiles among the subjects.
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Vitamin C and Cardiovascular Disease: An Update. Antioxidants (Basel) 2020; 9:antiox9121227. [PMID: 33287462 PMCID: PMC7761826 DOI: 10.3390/antiox9121227] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 11/24/2020] [Accepted: 11/27/2020] [Indexed: 02/07/2023] Open
Abstract
The potential beneficial effects of the antioxidant properties of vitamin C have been investigated in a number of pathological conditions. In this review, we assess both clinical and preclinical studies evaluating the role of vitamin C in cardiac and vascular disorders, including coronary heart disease, heart failure, hypertension, and cerebrovascular diseases. Pitfalls and controversies in investigations on vitamin C and cardiovascular disorders are also discussed.
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Protection of natural antioxidants against low-density lipoprotein oxidation. ADVANCES IN FOOD AND NUTRITION RESEARCH 2020. [PMID: 32711864 DOI: 10.1016/bs.afnr.2020.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
This chapter reports essential information about the protective action of antioxidants against LDL oxidation. The activity of individual compounds (tocopherols, vitamin C, phenolic compounds) as well as extracts obtained from plant material (cereals, fruits, legumes, nuts, mushrooms, by-products of food industry) is reported. The structure-antioxidant activity relationship of phenolic compounds is discussed. This article summarizes the findings to date of both in vitro and in vivo studies using foods or phenolic extracts isolated from foodstuffs at inhibiting the incidence of LDL oxidation. This chapter summarizes also the reportings to date of in vivo studies using foods or beverages at inhibiting the incidence of LDL oxidation.
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Winklhofer-Roob BM, Faustmann G, Roob JM. Low-density lipoprotein oxidation biomarkers in human health and disease and effects of bioactive compounds. Free Radic Biol Med 2017; 111:38-86. [PMID: 28456641 DOI: 10.1016/j.freeradbiomed.2017.04.345] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 04/16/2017] [Accepted: 04/18/2017] [Indexed: 12/14/2022]
Abstract
Based on the significance of oxidized low-density lipoprotein (LDL) in health and disease, this review focuses on human studies addressing oxidation of LDL, including three lines of biomarkers, (i) ex vivo LDL resistance to oxidation, a "challenge test" model, (ii) circulating oxidized LDL, indicating the "current in vivo status", and (iii) autoantibodies against oxidized LDL as fingerprints of an immune response to oxidized LDL, along with circulating oxysterols and 4-hydroxynonenal as biomarkers of lipid peroxidation. Lipid peroxidation and oxidized LDL are hallmarks in the development of various metabolic, cardiovascular and other diseases. Changes further occur across life stages from infancy to older age as well as in athletes and smokers. Given their responsiveness to targeted nutritional interventions, markers of LDL oxidation have been employed in a rapidly growing number of human studies for more than 2 decades. There is growing interest in foods, which, besides providing energy and nutrients, exert beneficial effects on human health, such as protection of DNA, proteins and lipids from oxidative damage. Any health claim, however, needs to be substantiated by supportive evidence derived from human studies, using reliable biomarkers to demonstrate such beneficial effects. A large body of evidence has accumulated, demonstrating protection of LDL from oxidation by bioactive food compounds, including vitamins, other micronutrients and secondary plant ingredients, which will facilitate the selection of oxidation biomarkers for future human intervention studies and health claim support.
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Affiliation(s)
- Brigitte M Winklhofer-Roob
- Human Nutrition & Metabolism Research and Training Center, Institute of Molecular Biosciences, Karl-Franzens University of Graz, Austria.
| | - Gernot Faustmann
- Human Nutrition & Metabolism Research and Training Center, Institute of Molecular Biosciences, Karl-Franzens University of Graz, Austria; Clinical Division of Nephrology, Department of Internal Medicine, Medical University of Graz, Austria
| | - Johannes M Roob
- Clinical Division of Nephrology, Department of Internal Medicine, Medical University of Graz, Austria
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Systematic review and meta-analysis of randomised controlled trials testing the effects of vitamin C supplementation on blood lipids. Clin Nutr 2015; 35:626-37. [PMID: 26164552 DOI: 10.1016/j.clnu.2015.05.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 05/21/2015] [Accepted: 05/30/2015] [Indexed: 12/28/2022]
Abstract
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/.
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Kim KM, Lee DJ, Joo NS. Reduction of the nailfold capillary blood velocity in cigarette smokers. Korean J Fam Med 2012; 33:398-405. [PMID: 23267426 PMCID: PMC3526723 DOI: 10.4082/kjfm.2012.33.6.398] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2012] [Accepted: 10/11/2012] [Indexed: 02/03/2023] Open
Abstract
Background Cigarette smoking causes cardiovascular disease and activates markers of endothelial dysfunction or injury. We investigated the nailfold capillary blood velocity (NCV) in cigarette smokers compared to non-smokers. Methods Forty-eight men (eighteen non-smokers and thirty smokers) were recruited. We measured NCV using nailfold capillary microscopy and exhaled carbon monoxide (ECO) concentration three times (before smoking; NCV0min and ECO0min, and after smoking; NCV5min, ECO5min, NCV30min, and ECO30min), in a condition of fasting in the case of smokers. In non-smokers, the same measurements were taken without smoking. Additionally, personal cigarette smoking and alcohol drinking history were acquired by a self-administrated questionnaire. Results Mean age, waist circumference, ECO0min, ECO5min, and ECO30min was higher and NCV5min and NCV30min were significantly lower in smokers compared to non-smokers. Total smoking years were negatively correlated with NCV5min. Average pack of the daily smoking, total pack-years, as well as total smoking years were also negatively correlated with NCV30min by regression analysis. After adjustment of significantly different variables, NCV30min was significantly lower in smokers. In the subgroup analysis, the interleukin-6 level was significantly increased in subjects with a long period of cigarette smoking compared with non-smokers. Conclusion Reduction of NCV in smokers is associated with personal smoking history, not with body composition or certain oxidative stress markers.
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Affiliation(s)
- Kwang-Min Kim
- Department of Family Practice and Community Health, Ajou University School of Medicine, Suwon, Korea
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Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane Database Syst Rev 2012; 2012:CD007176. [PMID: 22419320 PMCID: PMC8407395 DOI: 10.1002/14651858.cd007176.pub2] [Citation(s) in RCA: 296] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Our systematic review has demonstrated that antioxidant supplements may increase mortality. We have now updated this review. OBJECTIVES To assess the beneficial and harmful effects of antioxidant supplements for prevention of mortality in adults. SEARCH METHODS We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to February 2011. We scanned bibliographies of relevant publications and asked pharmaceutical companies for additional trials. SELECTION CRITERIA We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. DATA COLLECTION AND ANALYSIS Three authors extracted data. Random-effects and fixed-effect model meta-analyses were conducted. Risk of bias was considered in order to minimise the risk of systematic errors. Trial sequential analyses were conducted to minimise the risk of random errors. Random-effects model meta-regression analyses were performed to assess sources of intertrial heterogeneity. MAIN RESULTS Seventy-eight randomised trials with 296,707 participants were included. Fifty-six trials including 244,056 participants had low risk of bias. Twenty-six trials included 215,900 healthy participants. Fifty-two trials included 80,807 participants with various diseases in a stable phase. The mean age was 63 years (range 18 to 103 years). The mean proportion of women was 46%. Of the 78 trials, 46 used the parallel-group design, 30 the factorial design, and 2 the cross-over design. All antioxidants were administered orally, either alone or in combination with vitamins, minerals, or other interventions. The duration of supplementation varied from 28 days to 12 years (mean duration 3 years; median duration 2 years). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects model meta-analysis (21,484 dead/183,749 (11.7%) versus 11,479 dead/112,958 (10.2%); 78 trials, relative risk (RR) 1.02, 95% confidence interval (CI) 0.98 to 1.05) but significantly increased mortality in a fixed-effect model (RR 1.03, 95% CI 1.01 to 1.05). Heterogeneity was low with an I(2)- of 12%. In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. Meta-regression analysis did not find a significant difference in the estimated intervention effect in the primary prevention and the secondary prevention trials. In the 56 trials with a low risk of bias, the antioxidant supplements significantly increased mortality (18,833 dead/146,320 (12.9%) versus 10,320 dead/97,736 (10.6%); RR 1.04, 95% CI 1.01 to 1.07). This effect was confirmed by trial sequential analysis. Excluding factorial trials with potential confounding showed that 38 trials with low risk of bias demonstrated a significant increase in mortality (2822 dead/26,903 (10.5%) versus 2473 dead/26,052 (9.5%); RR 1.10, 95% CI 1.05 to 1.15). In trials with low risk of bias, beta-carotene (13,202 dead/96,003 (13.8%) versus 8556 dead/77,003 (11.1%); 26 trials, RR 1.05, 95% CI 1.01 to 1.09) and vitamin E (11,689 dead/97,523 (12.0%) versus 7561 dead/73,721 (10.3%); 46 trials, RR 1.03, 95% CI 1.00 to 1.05) significantly increased mortality, whereas vitamin A (3444 dead/24,596 (14.0%) versus 2249 dead/16,548 (13.6%); 12 trials, RR 1.07, 95% CI 0.97 to 1.18), vitamin C (3637 dead/36,659 (9.9%) versus 2717 dead/29,283 (9.3%); 29 trials, RR 1.02, 95% CI 0.98 to 1.07), and selenium (2670 dead/39,779 (6.7%) versus 1468 dead/22,961 (6.4%); 17 trials, RR 0.97, 95% CI 0.91 to 1.03) did not significantly affect mortality. In univariate meta-regression analysis, the dose of vitamin A was significantly associated with increased mortality (RR 1.0006, 95% CI 1.0002 to 1.001, P = 0.002). AUTHORS' CONCLUSIONS We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.
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Affiliation(s)
- Goran Bjelakovic
- Department of InternalMedicine,Medical Faculty, University ofNis,Nis, Serbia.
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Juraschek SP, Miller ER, Gelber AC. Effect of oral vitamin C supplementation on serum uric acid: a meta-analysis of randomized controlled trials. Arthritis Care Res (Hoboken) 2011; 63:1295-306. [PMID: 21671418 DOI: 10.1002/acr.20519] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To assess the effect of vitamin C supplementation on serum uric acid (SUA) by pooling the findings from published randomized controlled trials (RCTs). METHODS A total of 2,082 publications identified through systematic search were subjected to the following inclusion criteria: 1) RCTs conducted on human subjects, 2) reported end-trial SUA means and variance, 3) study design with oral vitamin C supplementation and concurrent control groups, and 4) trial duration of at least 1 week. Trials that enrolled children or patients receiving dialysis were excluded. Two investigators independently abstracted trial and participant characteristics. SUA effects were pooled by random-effects models and weighted by inverse variance. RESULTS Thirteen RCTs were identified in the Medline, EMBase, and Cochrane Central Register of Controlled Trials databases. The total number of participants was 556, the median dosage of vitamin C was 500 mg/day, trial size ranged from 8-184 participants, and the median study duration was 30 days. Pretreatment SUA values ranged from 2.9-7.0 mg/dl (Système International d'Unités [SI units]: 172.5-416.4 μmoles/liter). The combined effect of these trials was a significant reduction in SUA of -0.35 mg/dl (95% confidence interval -0.66, -0.03 [P = 0.032]; SI units: -20.8 μmoles/liter). Trial heterogeneity was significant (I(2) = 77%, P < 0.01). Subgroup analyses based on trial characteristics indicated larger reductions in uric acid in trials that were placebo controlled. CONCLUSIONS In aggregate, vitamin C supplementation significantly lowered SUA. Future trials are needed to determine whether vitamin C supplementation can reduce hyperuricemia or prevent incident and recurrent gout.
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Affiliation(s)
- Stephen P Juraschek
- Johns Hopkins University School of Medicine, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21224, USA
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The efficacy of vitamin C supplementation on reducing total serum cholesterol in human subjects: a review and analysis of 51 experimental trials. J Chiropr Med 2011; 5:2-12. [PMID: 19674666 DOI: 10.1016/s0899-3467(07)60127-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE Observational studies in humans have shown an inverse relationship between plasma vitamin C concentration and total serum cholesterol. However, experimental studies have shown inconsistent results regarding the ability of vitamin C to reduce total serum cholesterol. METHODS Published reports of trials studying the effects of vitamin C on serum lipids were identified by a search of Medline from 1966 to 2004. Data from 51 experimental studies comprising of 1666 pooled subjects were selected for analysis. RESULTS A very strong negative association was observed between baseline total serum cholesterol and the percent change in cholesterol (r = -0.585, p<0.001). When subjects were divided into 4 groups based on their baseline total serum cholesterol levels, the following weighted mean percent changes in cholesterol from baseline were observed: normal cholesterol (<199mg/dl): 0.91+/-6.8% (n=508); borderline high cholesterol (200-239mg/dl): 3.90+/-5.78% (n=605); high cholesterol (240-279mg/dl): 11.40+/-7.96% (n=300); severe cholesterol (>280mg/dl): 14.30+/-8.36% (n=253). A significant inverse relationship was found between the baseline plasma vitamin C concentrations and mean percent change in total cholesterol from baseline (r = -0.500, p<0.005). It was also observed that the high and severe baseline cholesterol groups possessed lower baseline plasma vitamin C concentrations than those in the normal cholesterol groups (0.79 and 0.55 versus 1.24 mg/dl respectively). CONCLUSION This finding strengthens the hypothesis that the cholesterol lowering and cardio-protective benefit of vitamin C supplementation may be in its ability to elevate plasma vitamin C concentrations in those patients who initially possess lower than normal vitamin C plasma concentrations.
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Mohiti-Asli M, Zaghari M. Does dietary vitamin E or C decrease egg yolk cholesterol? Biol Trace Elem Res 2010; 138:60-8. [PMID: 20127202 DOI: 10.1007/s12011-010-8612-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Accepted: 01/11/2010] [Indexed: 10/19/2022]
Abstract
An experiment was conducted to determine the effect of dietary vitamin E and C on serum metabolites, yolk cholesterol, egg quality, and performance of layer hens. One hundred sixty-eight commercial Hy-Line W-36 layer hens were randomly divided into seven groups and six replicates with four hens in each. Dietary treatments were introduced after the pre-experimental period (10 days) to adjust egg production. Treatments were levels of vitamin E or C (100, 200, and 400 mg/kg diet) supplementation to the basal diet for 4 weeks, whereas the control group received no supplementation. Egg production, egg weight, and feed consumption were recorded during the study. Shell thickness, Haugh unit score, yolk color, yolk weight, yolk cholesterol, and blood parameters were measured at the end of experiment. There was no significant effect of dietary vitamin E or C on hen performance. Egg yolk cholesterol concentrations decreased linearly by antioxidant vitamin supplementation (P < 0.01). Egg yolk cholesterol reduction did not have any negative effect on egg production rate. Antioxidants, especially vitamin C, increased serum glucose concentration (P < 0.05). Serum total cholesterol content did not change by vitamin supplementation but cholesterol in high-density lipoprotein (HDL-C) decreased and cholesterol in low-density lipoprotein (LDL-C) increased (P < 0.05), as dietary vitamin E or C supplementation increased in diets. These results are in conflict with the previous hypothesis that antioxidants have a role in LDL-C removal from the blood or increasing HDL-C. Vitamin E was more effective than vitamin C in this case and if these results are confirmed by further studies, they may result to revision in researchers' point of view about antioxidant especially in human medicine.
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Affiliation(s)
- Maziar Mohiti-Asli
- Department of Animal Science, Faculty of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
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Kelly RP, Poo Yeo K, Isaac HB, Lee CYJ, Huang SH, Teng L, Halliwell B, Wise SD. Lack of effect of acute oral ingestion of vitamin C on oxidative stress, arterial stiffness or blood pressure in healthy subjects. Free Radic Res 2008; 42:514-22. [PMID: 18484415 DOI: 10.1080/10715760802087431] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Vitamin C is a potent antioxidant in vitro and has been reported to act as a vasodilator, possibly by increasing nitric oxide bioavailability. This study examined the antioxidant and vascular effects of a single large oral dose of vitamin C in 26 healthy human volunteers. Haemodynamic and oxidative DNA and lipid damage markers were measured for 8 h following an oral dose of 2 g vitamin C or placebo. Vitamin C had no effect on vasodilation (measured by augmentation index (mean change=0.04%, 90% CI=- 2.20% to 2.28%) or forearm blood flow (-0.19%/min (-0.68, 0.30)), in comparison to placebo) or on several markers of oxidative stress including DNA base oxidation products in blood cells, 8-hydroxy-2'-deoxyguanosine (8O HdG) in urine (0.068 (-0.009, 0.144)) or urinary or plasma total F(2)-isoprostanes (-0.005 ng/ml (-0.021, 0.010), -0.153 ng/mg (-0.319, 0.014), respectively).
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Affiliation(s)
- Ronan P Kelly
- Lilly-NUS Centre for Clinical Pharmacology, Level 6, Clinical Research Centre (MD 11), National University of Singapore, Singapore.
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Robert L, Narcy A, Rayssiguier Y, Mazur A, Rémésy C. Lipid metabolism and antioxidant status in sucrose vs. potato-fed rats. J Am Coll Nutr 2008; 27:109-16. [PMID: 18460489 DOI: 10.1080/07315724.2008.10719682] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Consumption of high levels of simple carbohydrates is associated with several metabolic disorders in humans and in laboratory animals, including symptoms of an early stage of metabolic syndrome (syndrome X). This disorder has several cardiovascular risk factors, such as hypertriglyceridemia, and is associated with an increase in oxidative stress. In contrast to sucrose, potato, a source of complex carbohydrates and antioxidant micronutrients, was thought to improve lipid metabolism and antioxidant protection. METHODS We investigated the effects of diets containing i) complex dietary carbohydrates and antioxidant micronutrients (potato Solanum tuberosum L.), ii) complex carbohydrates (starch) and iii) a simple carbohydrate (sucrose) on lipid metabolism and antioxidant status in rats. RESULTS An increase in short chain fatty acid (SCFA) pools was observed in the cecum of rats fed a potato-based diet, resulting from an increase in all SCFAs, especially propionate (+360%, P < 0.0001). Feeding rats a potato-based diet for 3 weeks led to a decrease in cholesterol (-37%, potato vs. control and -32%, potato vs. sucrose) and triglycerides (-31%, potato vs. control and -43%, potato vs. sucrose) concentrations in triglyceride-rich lipoproteins (TGRLP) fractions. The antioxidant status was decreased by sucrose consumption and improved by potato consumption. CONCLUSIONS Our present results suggest that consumption of complex carbohydrates (provided as cooked potatoes), in combination with different antioxidant micronutrients, may enhance the antioxidant defences and improve lipid metabolism, when compared with starch (complex carbohydrates) and to sucrose consumption (source of simple sugar). These effects limit oxidative stress and reduce the risk of developing the associated degenerative diseases, including cardiovascular disease, and could have potential in cardiovascular disease prevention.
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Affiliation(s)
- Laëtitia Robert
- INRA, Unité de Nutrition Humaine, Equipe Stress Métabolique et Micronutriments, Centre de Clermont-Ferrand/Theix, 63122 Saint-Genès Champanelle, France
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Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane Database Syst Rev 2008:CD007176. [PMID: 18425980 DOI: 10.1002/14651858.cd007176] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Animal and physiological research as well as observational studies suggest that antioxidant supplements may improve survival. OBJECTIVES To assess the effect of antioxidant supplements on mortality in primary or secondary prevention randomised clinical trials. SEARCH STRATEGY We searched The Cochrane Library (Issue 3, 2005), MEDLINE (1966 to October 2005), EMBASE (1985 to October 2005), and the Science Citation Index Expanded (1945 to October 2005). We scanned bibliographies of relevant publications and wrote to pharmaceutical companies for additional trials. SELECTION CRITERIA We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. Included participants were either healthy (primary prevention trials) or had any disease (secondary prevention trials). DATA COLLECTION AND ANALYSIS Three authors extracted data. Trials with adequate randomisation, blinding, and follow-up were classified as having a low risk of bias. Random-effects and fixed-effect meta-analyses were performed. Random-effects meta-regression analyses were performed to assess sources of intertrial heterogeneity. MAIN RESULTS Sixty-seven randomised trials with 232,550 participants were included. Forty-seven trials including 180,938 participants had low risk of bias. Twenty-one trials included 164,439 healthy participants. Forty-six trials included 68111 participants with various diseases (gastrointestinal, cardiovascular, neurological, ocular, dermatological, rheumatoid, renal, endocrinological, or unspecified). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects meta-analysis (relative risk [RR] 1.02, 95% confidence interval [CI] 0.99 to 1.06), but significantly increased mortality in a fixed-effect model (RR 1.04, 95% CI 1.02 to 1.06). In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. In the trials with a low risk of bias, the antioxidant supplements significantly increased mortality (RR 1.05, 95% CI 1.02 to 1.08). When the different antioxidants were assessed separately, analyses including trials with a low risk of bias and excluding selenium trials found significantly increased mortality by vitamin A (RR 1.16, 95% CI 1.10 to 1.24), beta-carotene (RR 1.07, 95% CI 1.02 to 1.11), and vitamin E (RR 1.04, 95% CI 1.01 to 1.07), but no significant detrimental effect of vitamin C (RR 1.06, 95% CI 0.94 to 1.20). Low-bias risk trials on selenium found no significant effect on mortality (RR 0.91, 95% CI 0.76 to 1.09). AUTHORS' CONCLUSIONS We found no evidence to support antioxidant supplements for primary or secondary prevention. Vitamin A, beta-carotene, and vitamin E may increase mortality. Future randomised trials could evaluate the potential effects of vitamin C and selenium for primary and secondary prevention. Such trials should be closely monitored for potential harmful effects. Antioxidant supplements need to be considered medicinal products and should undergo sufficient evaluation before marketing.
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Affiliation(s)
- G Bjelakovic
- Copenhagen University Hospital, Rigshospitalet, Department 3344,Copenhagen Trial Unit, Centre for Clinical Intervention Research, Blegdamsvej 9, Copenhagen, Denmark, DK-2100.
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Robert L, Narcy A, Rock E, Demigne C, Mazur A, Rémésy C. Entire potato consumption improves lipid metabolism and antioxidant status in cholesterol-fed rat. Eur J Nutr 2006; 45:267-74. [PMID: 16586150 DOI: 10.1007/s00394-006-0594-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Accepted: 02/01/2006] [Indexed: 11/26/2022]
Abstract
BACKGROUND Vegetables and fruits are rich sources of a variety of nutrients, including vitamins (E and C), trace minerals, and dietary fibers, and many other classes of biologically active compounds such as carotenoids and polyphenols, which are often assumed to protect against degenerative pathologies such as cardiovascular diseases. Although potato is considered as a starchy food, it is also included in the category of vegetables by its micronutrient content. AIM OF THE STUDY In the present study, we investigated in the rat the effect of a potato-enriched diet on lipid metabolism and antioxidant protection. RESULTS Feeding rats a potato-enriched diet for 3 weeks led to a significant decrease in cholesterol and triglyceride levels in plasma (respectively, -30%, P<0.0001 and -36%, P<0.05) and cholesterol level in liver (-42%, P<0.0001). Antioxidant status was also improved by potato consumption. TBARS levels in heart were decreased and vitamin E/triglycerides ratio in plasma was improved. CONCLUSIONS Our present results suggest that consumption of cooked potatoes (consumed with skin) may enhance antioxidant defense and improve the lipid metabolism. These effects could be interesting for prevention of cardiovascular disease.
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Affiliation(s)
- Laëtitia Robert
- Unité des Maladies Métaboliques et Micronutriments Institut National de Recherche Agronomique Centre de Clermont-Ferrand/Theix, 63122 Saint-Genès Champanelle, France
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