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Dietary and circulating vitamin C, vitamin E, β-carotene and risk of total cardiovascular mortality: a systematic review and dose-response meta-analysis of prospective observational studies.
Jayedi, A, Rashidy-Pour, A, Parohan, M, Zargar, MS, Shab-Bidar, S
Public health nutrition. 2019;(10):1872-1887
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Abstract
OBJECTIVE The present review aimed to quantify the association of dietary intake and circulating concentration of major dietary antioxidants with risk of total CVD mortality. DESIGN Systematic review and meta-analysis. SETTING Systematic search in PubMed and Scopus, up to October 2017.ParticipantsProspective observational studies reporting risk estimates of CVD mortality across three or more categories of dietary intakes and/or circulating concentrations of vitamin C, vitamin E and β-carotene were included. A random-effects meta-analysis was conducted. RESULTS A total of fifteen prospective cohort studies and three prospective evaluations within interventional studies (320 548 participants and 16 974 cases) were analysed. The relative risks of CVD mortality for the highest v. the lowest category of antioxidant intakes were as follows: vitamin C, 0·79 (95 % CI 0·68, 0·89; I 2=46 %, n 10); vitamin E, 0·91 (95 % CI 0·79, 1·03; I 2=51 %, n 8); β-carotene, 0·89 (95 % CI 0·73, 1·05; I 2=34 %, n 4). The relative risks for circulating concentrations were: vitamin C, 0·60 (95 % CI 0·42, 0·78; I 2=65 %, n 6); α-tocopherol, 0·82 (95 % CI 0·76, 0·88; I 2=0 %, n 5); β-carotene, 0·68 (95 % CI 0·52, 0·83; I 2=50 %, n 6). Dose-response meta-analyses demonstrated that the circulating biomarkers of antioxidants were more strongly associated with risk of CVD mortality than dietary intakes. CONCLUSIONS The present meta-analysis demonstrates that higher vitamin C intake and higher circulating concentrations of vitamin C, vitamin E and β-carotene are associated with a lower risk of CVD mortality.
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[Meta-analysis of vitamin C, vitamin E and β-carotene levels in the plasma of Alzheimer's disease patients].
Dong, R, Yang, Q, Zhang, Y, Li, J, Zhang, L, Zhao, H
Wei sheng yan jiu = Journal of hygiene research. 2018;(4):648-654
Abstract
OBJECTIVE To systematically evaluate the levels of vitamin C, vitamin E and β-carotene in the plasma of Alzheimer's disease( AD) patients. METHODS In this study, literature of the levels of vitamin C, vitamin E and β-carotene in the plasma of AD patients were collected by retrieving the database of Pub Med, Science Direct, CNKI and Wan Fang( from they were built to July 2017). RESULTS Meta-analysis result showed that, compared with the control group, the level of vitamin E in the plasma of AD patients declined significantly( SMD =-1. 49 μmol/L, 95% CI-2. 08--0. 89 μmol/L, P <0. 001). However, no differences were determined in the levels of the plasma vitamin C and β-carotene between the two groups( vitamin C: SMD =-1. 43 μmol/L, 95% CI-3. 05-0. 19 μmol/L, P = 0. 083; β-carotene: SMD =-0. 61 μmol/L, 95% CI-1. 40-0. 18 μmol/L, P = 0. 131). CONCLUSION Increasing vitamin E level in the plasma through vitamin E riched diet may be useful to prevent AD. However it is not yet believed the benefical role on AD to increase vitamin C and β-carotene.
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Carotenoid intake and risk of non-Hodgkin lymphoma: a systematic review and dose-response meta-analysis of observational studies.
Chen, F, Hu, J, Liu, P, Li, J, Wei, Z, Liu, P
Annals of hematology. 2017;(6):957-965
Abstract
Carotenoids may play a protective role in the development of non-Hodgkin lymphoma (NHL), but findings from epidemiological studies on the associations between carotenoid intake and NHL risk are inconsistent. We therefore performed a meta-analysis to systemically evaluate the associations. Eligible studies were identified by a search of PubMed, Web of Science, Embase, and article reference lists. We pooled risk estimates from individual studies using a random-effect model to quantify the associations between intakes of specific carotenoids and NHL risk. A total of 10 (7 case-control and 3 cohort) studies met our inclusion criteria. In the highest versus lowest analyses, intakes of alpha-carotene, beta-carotene, and lutein/zeaxanthin, but not lycopene or beta-cryptoxanthin, were associated with a significant reduced risk of NHL. The estimated summary relative risks (95% confidence intervals) for alpha-carotene, beta-carotene, and lutein/zeaxanthin were 0.87 (0.78-0.97), 0.80 (0.68-0.94), and 0.82 (0.69-0.97), respectively. Subgroup analyses showed that evidence supporting these protective associations was mostly based on studies with a case-control design. In addition, intakes of alpha-carotene and beta-carotene were associated with a significant decreased risk of diffuse large B-cell lymphoma, but not follicular lymphoma or small lymphocytic lymphoma/chronic lymphocytic leukemia. There was a significant inverse dose-response relationship between alpha-carotene intake and NHL risk (13% lower risk per 1000 μg/day increment of intake). In conclusion, our findings suggest that higher intakes of alpha-carotene, beta-carotene, and lutein/zeaxanthin might protect against NHL development. Further cohort studies with a control of plausible confounding are needed to confirm these associations.
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Dietary, circulating beta-carotene and risk of all-cause mortality: a meta-analysis from prospective studies.
Zhao, LG, Zhang, QL, Zheng, JL, Li, HL, Zhang, W, Tang, WG, Xiang, YB
Scientific reports. 2016;:26983
Abstract
Observational studies evaluating the relation between dietary or circulating level of beta-carotene and risk of total mortality yielded inconsistent results. We conducted a comprehensive search on publications of PubMed and EMBASE up to 31 March 2016. Random effect models were used to combine the results. Potential publication bias was assessed using Egger's and Begg's test. Seven studies that evaluated dietary beta-carotene intake in relation to overall mortality, indicated that a higher intake of beta-carotene was related to a significant lower risk of all-cause mortality (RR for highest vs. lowest group = 0.83, 95%CI: 0.78-0.88) with no evidence of heterogeneity between studies (I(2) = 1.0%, P = 0.416). A random-effect analysis comprising seven studies showed high beta-carotene level in serum or plasma was associated with a significant lower risk of all-cause mortality (RR for highest vs. lowest group = 0.69, 95%CI: 0.59-0.80) with low heterogeneity (I(2) = 37.1%, P = 0.145). No evidence of publication bias was detected by Begg's and Egger's regression tests. In conclusion, dietary or circulating beta-carotene was inversely associated with risk of all-cause mortality. More studies should be conducted to clarify the dose-response relationship between beta-carotene and all-cause mortality.
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Meta-regression analyses, meta-analyses, and trial sequential analyses of the effects of supplementation with beta-carotene, vitamin A, and vitamin E singly or in different combinations on all-cause mortality: do we have evidence for lack of harm?
Bjelakovic, G, Nikolova, D, Gluud, C
PloS one. 2013;(9):e74558
Abstract
BACKGROUND AND AIMS Evidence shows that antioxidant supplements may increase mortality. Our aims were to assess whether different doses of beta-carotene, vitamin A, and vitamin E affect mortality in primary and secondary prevention randomized clinical trials with low risk of bias. METHODS The present study is based on our 2012 Cochrane systematic review analyzing beneficial and harmful effects of antioxidant supplements in adults. Using random-effects meta-analyses, meta-regression analyses, and trial sequential analyses, we examined the association between beta-carotene, vitamin A, and vitamin E, and mortality according to their daily doses and doses below and above the recommended daily allowances (RDA). RESULTS We included 53 randomized trials with low risk of bias (241,883 participants, aged 18 to 103 years, 44.6% women) assessing beta-carotene, vitamin A, and vitamin E. Meta-regression analysis showed that the dose of vitamin A was significantly positively associated with all-cause mortality. Beta-carotene in a dose above 9.6 mg significantly increased mortality (relative risk (RR) 1.06, 95% confidence interval (CI) 1.02 to 1.09, I(2) = 13%). Vitamin A in a dose above the RDA (> 800 µg) did not significantly influence mortality (RR 1.08, 95% CI 0.98 to 1.19, I(2) = 53%). Vitamin E in a dose above the RDA (> 15 mg) significantly increased mortality (RR 1.03, 95% CI 1.00 to 1.05, I(2) = 0%). Doses below the RDAs did not affect mortality, but data were sparse. CONCLUSIONS Beta-carotene and vitamin E in doses higher than the RDA seem to significantly increase mortality, whereas we lack information on vitamin A. Dose of vitamin A was significantly associated with increased mortality in meta-regression. We lack information on doses below the RDA. BACKGROUND All essential compounds to stay healthy cannot be synthesized in our body. Therefore, these compounds must be taken through our diet or obtained in other ways [1]. Oxidative stress has been suggested to cause a variety of diseases [2]. Therefore, it is speculated that antioxidant supplements could have a potential role in preventing diseases and death. Despite the fact that a normal diet in high-income countries may provide sufficient amounts of antioxidants [3,4], more than one third of adults regularly take antioxidant supplements [5,6].
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Dietary intakes of vitamin E, vitamin C, and β-carotene and risk of Alzheimer's disease: a meta-analysis.
Li, FJ, Shen, L, Ji, HF
Journal of Alzheimer's disease : JAD. 2012;(2):253-8
Abstract
In view of the vital role of oxidative stress in the pathogenesis of Alzheimer's disease (AD), the potential of antioxidant supplements to prevent AD have gained much interest, while there are conflicting results on this topic in recent years. The purpose of the present study is to comprehensively evaluate the association between dietary intakes, instead of supplements, of the most common three antioxidants (vitamin E, vitamin C, and β-carotene) and the risk of AD on the basis of the meta-analysis studies published up to October 2011 in Medline and Scopus databases. In total, seven articles were included in the meta-analysis. According to the pooled relative risk [(95% CI) 0.76 (0.67-0.84) for vitamin E, 0.83 (0.72-0.94) for vitamin C, and 0.88 (0.73-1.03) for β-carotene], dietary intakes of the three antioxidants can lower the risk of AD, with vitamin E exhibiting the most pronounced protective effects. The findings will be of significance to the prevention and interventional treatment of AD.
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Effects of beta-carotene supplements on cancer prevention: meta-analysis of randomized controlled trials.
Jeon, YJ, Myung, SK, Lee, EH, Kim, Y, Chang, YJ, Ju, W, Cho, HJ, Seo, HG, Huh, BY
Nutrition and cancer. 2011;(8):1196-207
Abstract
This meta-analysis aimed to investigate the effects of beta-carotene supplements alone on cancer prevention as reported by randomized controlled trials (RCTs). We searched PubMed, EMBASE, and CENTRAL. Among the 848 articles searched, 6 randomized controlled trials, including 40,544 total participants, 20,290 in beta-carotene supplement groups, and 20,254 in placebo groups, were included in the final analysis. In a meta-analysis of 6 RCTs, beta-carotene supplements had no preventive effect on either cancer incidence [relative risk (RR) = 1.08, 95% confidence interval (CI) = 0.99-1.18] or cancer mortality (RR = 1.00, 95% CI = 0.87-1.15). Similar findings were observed in both primary prevention trials and secondary prevention trials. Subgroup analyses by various factors revealed no preventive effect of beta-carotene supplementation on cancer prevention and that it significantly increased the risk of urothelial cancer, especially bladder cancer (RR = 1.52, 95% CI = 1.03-2.24) and marginally increased the risk of cancer among current smokers (RR = 1.07, 95% CI = 0.99-1.17). The current meta-analysis of RCTs indicated that there is no clinical evidence to support the overall primary or secondary preventive effect of beta-carotene supplements on cancer. The potential effects, either beneficial or harmful, of beta-carotene supplementation on cancer should not be overemphasized.
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Beta-carotene supplementation and cancer risk: a systematic review and metaanalysis of randomized controlled trials.
Druesne-Pecollo, N, Latino-Martel, P, Norat, T, Barrandon, E, Bertrais, S, Galan, P, Hercberg, S
International journal of cancer. 2010;(1):172-84
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Abstract
The effect of beta-carotene supplementation on cancer incidence has been investigated in several randomized controlled trials. The objective was to review the effect of beta-carotene supplementation on cancer incidence in randomized trials by cancer site, beta-carotene supplementation characteristics and study population. Relevant trials were retrieved by searching PubMed (up to April 2009). Authors involved in selected studies were contacted for additional information. Thirteen publications reporting results from 9 randomized controlled trials were included. Overall, no effect of beta-carotene supplementation was observed on the incidence of all cancers combined (RR, 1.01; 95% CI, 0.98-1.04), pancreatic cancer (RR, 0.99; 95% CI, 0.73-1.36), colorectal cancer (RR, 0.96; 95% CI, 0.85-1.09), prostate cancer (RR, 0.99; 95% CI, 0.91-1.07), breast cancer (RR, 0.96; 95% CI, 0.85-1.10), melanoma (RR, 0.98; 95% CI, 0.65-1.46) and non melanoma skin cancer (RR, 0.99; 95% CI, 0.93-1.05). The incidence of lung and stomach cancers were significantly increased in individuals supplemented with beta-carotene at 20-30 mg day(-1) (RR, 1.16; 95% CI, 1.06-1.27 and RR, 1.34; 95% CI, 1.06-1.70), in smokers and asbestos workers (RR, 1.20; 95% CI, 1.07-1.34 and RR, 1.54; 95% CI, 1.08-2.19) compared to the placebo group. Beta-carotene supplementation has not been shown to have any beneficial effect on cancer prevention. Conversely, it was associated with increased risk not only of lung cancer but also of gastric cancer at doses of 20-30 mg day(-1), in smokers and asbestos workers. This study adds to the evidence that nutritional prevention of cancer through beta-carotene supplementation should not be recommended.
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Intake of vitamin E, vitamin C, and carotenoids and the risk of Parkinson's disease: a meta-analysis.
Etminan, M, Gill, SS, Samii, A
The Lancet. Neurology. 2005;(6):362-5
Abstract
We studied the effect of vitamin C, vitamin E, and beta carotene intake on the risk of Parkinson's disease (PD). We did a systematic review and meta-analysis of observational studies published between 1966 and March 2005 searching MEDLINE, EMBASE, and the Cochrane Library. Eight studies were identified (six case-control, one cohort, and one cross-sectional). We found that dietary intake of vitamin E protects against PD. This protective influence was seen with both moderate intake (relative risk 0.81, 95% CI 0.67-0.98) and high intake (0.78, 0.57-1.06) of vitamin E, although the possible benefit associated with high intake of vitamin E was not significant. The studies did not suggest any protective effects associated with vitamin C or beta carotene. We conclude that dietary vitamin E may have a neuroprotective effect attenuating the risk of PD. These results require confirmation in randomised controlled trials.
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Dietary beta-carotene intake and the risk of epithelial ovarian cancer: a meta-analysis of 3,782 subjects from five observational studies.
Huncharek, M, Klassen, H, Kupelnick, B
In vivo (Athens, Greece). 2001;(4):339-43
Abstract
OBJECTIVE The etiology of epithelial ovarian cancer is unknown. Prior work suggests that high dietary beta-carotene intake is associated with a decreased risk of this tumor although this association remains speculative. A meta-analysis was performed to evaluate this suspected relationship. METHODS Using previously described methods, a protocol was developed for a meta-analysis examining the association between high dietary beta-carotene intake versus low intake and the risk of epithelial ovarian cancer. Literature search techniques, study inclusion criteria and statistical procedures were prospectively defined. Data from observational studies were pooled using a general variance based meta-analytic method employing confidence intervals previously described by Greenland. The outcome of interest was a summary relative risk (RRs) reflecting the risk of ovarian cancer associated with high beta-carotene intake versus low dietary intake. Sensitivity analyses were performed when necessary to evaluate any observed statistical heterogeneity. RESULTS Five observational studies enrolling 3,782 subjects were initially pooled in a meta-analysis subsequent to an analysis showing a lack of statistical heterogeneity. The meta-analysis showed a summary relative risk of 0.84 with a 95% confidence interval of 0.75-0.94, a statistically significant result. These data suggest that high (versus low) dietary intake of beta-carotene is associated with a sixteen percent decrease in ovarian cancer risk. Sensitivity analyses showed no impact of study design or differences in quantitative measure of beta-carotene intake across studies on the summary relative risk. CONCLUSIONS High dietary intake of beta-carotene appears to represent a protective factor for the development of ovarian cancer although its magnitude is modest. Further work is needed to clarify factors that may modify the effects of beta-carotene in vivo.