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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].