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The Associations of Plasma/Serum Carotenoids with Alzheimer's Disease: A Systematic Review and Meta-Analysis.
Qu, M, Shi, H, Wang, K, Wang, X, Yu, N, Guo, B
Journal of Alzheimer's disease : JAD. 2021;(3):1055-1066
Abstract
BACKGROUND Multiple lines of evidence indicate protective effects of carotenoids in Alzheimer's disease (AD). However, previous epidemiological studies reported inconsistent results regarding the associations between carotenoids levels and the risk of AD. OBJECTIVE Our study aims to evaluate the associations of six major members of carotenoids with the occurrence of AD by conducting a systematic review and meta-analysis. METHODS Following PRISMA guidelines, a comprehensive literature search of PubMed, Web of Science, Ebsco, and PsycINFO databases was conducted, and the quality of each included studies was evaluated by a validated scoring systems. Standardized mean differences (SMD) with 95% confidence intervals (CI) were determined by using a random effects model. Heterogeneity was evaluated by I2 statistics. Publication bias was detected using funnel plots and Egger's test. RESULTS Sixteen studies, with 10,633 participants were included. Pooled analysis showed significantly lower plasma/serum levels of lutein (SMD = -0.86, 95% CI: -1.67 to -0.05, p = 0.04) and zeaxanthin (SMD = -0.59; 95% CI: -1.12 to -0.06, p = 0.03) in patients with AD versus cognitively intact controls, while α-carotene (SMD = 0.21, 95% CI: -0.68 to 0.26, p = 0.39), β-carotene (SMD = 0.04, 95% CI: -0.57 to 0.65, p = 0.9), lycopene (SMD = -0.12, 95% CI: -0.96 to 0.72, p = 0.78), and β-cryptoxanthin (SMD = -0.09, 95% CI: -0.83 to 0.65, p = 0.81) did not achieve significant differences. CONCLUSION Of six major members of carotenoids, only lutein and zeaxanthin concentrations in plasma/serum were inversely related to the risk of AD. More high-quality longitudinal studies are needed to verify these findings.
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Carotenoids, vitamin A, and their association with the metabolic syndrome: a systematic review and meta-analysis.
Beydoun, MA, Chen, X, Jha, K, Beydoun, HA, Zonderman, AB, Canas, JA
Nutrition reviews. 2019;(1):32-45
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CONTEXT Modifiable factors that reduce the burden of the metabolic syndrome (MetS), particularly plant-derived biomarkers, have been a recent focus of rising interest. OBJECTIVE This systematic review and meta-analysis, which follows PRISMA guidelines, evaluates evidence from a period of 20 years that links vitamin A and carotenoids with the occurrence of MetS and following the PRISMA guidelines. DATA SOURCES PubMed and Cochrane databases (January 1997 through March 2017) were systematically assessed for studies, including case-control, cross-sectional, and cohort studies, that evaluated the associations of MetS with carotenoids and retinyl esters and retinol (vitamin A). DATA EXTRACTION Key measures of associations were harmonized into odds ratios (ORs) and 95% confidence intervals (95%CI) of MetS per 1 standard deviation (SD) of exposure using forest plots and random effects models that pooled data points from 11 cross-sectional studies. Begg's funnel and harvest plots were constructed. RESULTS An inverse association between total carotenoids and MetS was found [ORpooled, 0.66; 95%CI, 0.56-0.78; 1 SD ∼ 0.82 µmol/L; n = 5 studies]. This association was the strongest for β-carotene, followed by α-carotene and β-crypotoxanthin. No association was detected between retinol and MetS (ORpooled, 1.00; 95%CI, 0.88-1.13; 1 SD ∼ 2.14 µmol/L; n = 6 studies). Publication bias was absent, and harvest plots indicated consistency upon replication for β-carotene and total carotenoid exposures. CONCLUSIONS This review and meta-analysis suggests that, unlike retinol, total and individual carotenoids were inversely related to MetS.
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[Efficacy of lycopene intake in primary prevention of prostate cancer: a systematic review of the literature and meta-analysis.].
Cataño, JG, Trujillo, CG, Caicedo, JI, Bravo-Balado, A, Robledo, D, Mariño-Alvarez, AM, Pedraza, A, Arcila, MJ, Plata, M
Archivos espanoles de urologia. 2018;(2):187-197
Abstract
OBJECTIVE To evaluate the efficacy of lycopene intake in primary prevention of prostate cancer (PCa). METHODS A systematic search of the literature was conducted in March 2015 and the articles published between the years 1990-2015 were reviewed. The following search terms were used: prostate cancer, prostatic neoplasm, lycopene, prevention, effectiveness and efficacy (MeSH). Publications including research in humans, written in English and whose texts were accessible were reviewed. The types of studies included were: clinical trials, cohort and case-control studies. We found 343 articles; of these, 27 were included in the systematic review. After the latter were rigorously analyzed, 23 were included in the meta-analysis using the pooled odds ratios (OR) and risk ratios (RR) of case-control and cohort studies, respectively, and their confidence intervals (95% CI), using random-effects models with Review Manager 5.2. RESULTS Out of the 27 articles included in the systematic review, 22 were case-control and 5 were cohort studies. For the case-control studies, the total number of patients with PCa was 13,999 and the total number of controls 22,028. Cohort studies included 187,417 patients and PCa was diagnosed in 8,619 of these. The metaanalysis determined an OR = 0.94 (IC 95% 0.89-1.00) and RR = 0.9 (IC 95% 0.85-0.95) of PCa related with lycopene and/or raw or cooked tomatoes intake. CONCLUSIONS Although our study found that there is a statistically significant inverse association between lycopene intake and PCa, the magnitude of this association is weak and comes solely from observational studies, which do not allow recommending its use as a standard of practice. High-quality randomized clinical trials are required to clarify current evidence.
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Tomato and lycopene supplementation and cardiovascular risk factors: A systematic review and meta-analysis.
Cheng, HM, Koutsidis, G, Lodge, JK, Ashor, A, Siervo, M, Lara, J
Atherosclerosis. 2017;:100-108
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BACKGROUND AND AIMS Epidemiological evidence suggests an association between consumption of tomato products or lycopene and lower risk for cardiovascular diseases (CVD). Our aim was to evaluate the state of the evidence from intervention trials on the effect of consuming tomato products and lycopene on markers of cardiovascular (CV) function. We undertook a systematic review and meta-analysis on the effect of supplementing tomato and lycopene on CV risk factors. METHODS Three databases including Medline, Web of science, and Scopus were searched from inception to August 2016. Inclusion criteria were: intervention trials reporting effects of tomato products and lycopene supplementation on CV risk factors among adult subjects >18 years of age. The outcomes of interest included blood lipids (total-, HDL-, LDL-cholesterol, triglycerides, oxidised-LDL), endothelial function (flow-mediated dilation (FMD), pulse wave velocity (PWV)) and blood pressure (BP) inflammatory factors (CRP, IL-6) and adhesion molecules (ICAM-1). Random-effects models were used to determine the pooled effect sizes. RESULTS Out of 1189 publications identified, 21 fulfilled inclusion criteria and were meta-analysed. Overall, interventions supplementing tomato were associated with significant reductions in LDL-cholesterol (-0.22 mmol/L; p = 0.006), IL-6 (standardised mean difference -0.25; p = 0.03), and improvements in FMD (2.53%; p = 0.01); while lycopene supplementation reduced systolic-BP (-5.66 mmHg; p = 0.002). No other outcome was significantly affected by these interventions. CONCLUSIONS The available evidence on the effects of tomato products and lycopene supplementation on CV risk factors supports the view that increasing the intake of these has positive effects on blood lipids, blood pressure and endothelial function. These results support the development of promising individualised nutritional strategies involving tomatoes to tackle CVD.
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Plasma fat-soluble vitamin and carotenoid concentrations after plant sterol and plant stanol consumption: a meta-analysis of randomized controlled trials.
Baumgartner, S, Ras, RT, Trautwein, EA, Mensink, RP, Plat, J
European journal of nutrition. 2017;(3):909-923
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PURPOSE Plant sterols and stanols interfere with intestinal cholesterol absorption, and it has been questioned whether absorption and plasma concentrations of fat-soluble vitamins and carotenoids are also affected. We conducted a meta-analysis to assess the effects of plant sterol and stanol consumption on plasma fat-soluble vitamin and carotenoid concentrations. METHODS Forty-one randomized controlled trials involving 3306 subjects were included. Weighted absolute and relative changes of non-standardized and total cholesterol (TC)-standardized values (expressed as summary estimates and 95 % CIs) were calculated for three fat-soluble vitamins (α- and γ-tocopherol, retinol and vitamin D) and six carotenoids (β-carotene, α-carotene, lycopene, lutein, zeaxanthin and β-cryptoxanthin) using a random effects model. Heterogeneity was assessed using predefined subject and treatment characteristics. RESULTS Average plant sterol or stanol intake was 2.5 g/d. Relative non-standardized and TC-standardized concentrations of β-carotene decreased by, respectively, -16.3 % (95 % CI -18.3; -14.3) and -10.1 % (-12.3; -8.0), α-carotene by -14.4 % (-17.5; 11.3) and -7.8 % (-11.3; -4.3), and lycopene by -12.3 % (-14.6; -10.1) and -6.3 % (-8.6; -4.0). Lutein concentrations decreased by -7.4 % (-10.1; -4.8), while TC-standardized concentrations were not changed. For zeaxanthin, these values were -12.9 % (-18.9; -6.8) and -7.7 % (-13.8; -1.7) and for β-cryptoxanthin -10.6 % (-14.3; -6.9) and -4.8 % (-8.7; -0.9). Non-standardized α-tocopherol concentrations decreased by -7.1 % (-8.0; -6.2) and γ-tocopherol by -6.9 % (-9.8; -3.9), while TC-standardized tocopherol concentrations were not changed. Non-standardized retinol and vitamin D concentrations were not affected. Results were not affected by baseline concentrations, dose, duration and type of plant sterols/stanols, except for significant effects of duration (≤4 vs. >4 weeks) on TC-standardized lutein concentrations (1.0 vs. -5.6 %) and type of plant sterol/stanol on TC-standardized β-carotene concentrations (-8.9 vs. -14.2 %). CONCLUSIONS Plant sterol and stanol intake lowers TC-standardized hydrocarbon carotenoid concentrations, differently affects TC-standardized oxygenated carotenoid concentrations, but does not affect TC-standardized tocopherol concentrations or absolute retinol and vitamin D concentrations. Observed concentrations remained within normal ranges.
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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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Lycopene and risk of cardiovascular diseases: A meta-analysis of observational studies.
Song, B, Liu, K, Gao, Y, Zhao, L, Fang, H, Li, Y, Pei, L, Xu, Y
Molecular nutrition & food research. 2017;(9)
Abstract
SCOPE The aim of current meta-analysis was to investigate the relation between lycopene and risk of cardiovascular diseases (CVD). METHODS AND RESULTS Studies concerning about the association between lycopene and risk of CVD were searched on Pubmed, Embase, and Web of Science from inception to October 2016. A total of 14 eligible studies were identified. A significantly inverse association with a pooled risk ratio (RR) of 0.83 (95% CI: 0.76-0.90) was shown between lycopene exposure and risk of CVD. Findings were similar restricting to dietary studies (RR = 0.87, 95% CI = 0.79-0.96) and biomarker studies (RR = 0.74, 95% CI = 0. 62-0.87).Dietary lycopene intake was statistically significant for coronary heart disease (CHD) (RR: 0.87; 95% CI: 0.76-0.98) and stroke (RR: 0.83; 95% CI: 0.69-0.96).The pooled risk estimate was generally similar for lycopene biomarker concentrations, but the association was only statistically significant for stroke (RR: 0.65; 95% CI: 0.42-0.87). Subgroup analyses showed that retrospective and low quality studies were statistically significant sources of heterogeneity. CONCLUSION Higher lycopene exposure is inversely associated with a lower risk of CVD. Further well-designed randomized clinical trials are required to assess the role of lycopene on CVD.
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Blood concentrations of carotenoids and retinol and lung cancer risk: an update of the WCRF-AICR systematic review of published prospective studies.
Abar, L, Vieira, AR, Aune, D, Stevens, C, Vingeliene, S, Navarro Rosenblatt, DA, Chan, D, Greenwood, DC, Norat, T
Cancer medicine. 2016;(8):2069-83
Abstract
Carotenoids and retinol are considered biomarkers of fruits and vegetables intake, and are of much interest because of their anti-inflammatory and antioxidant properties; however, there is inconsistent evidence regarding their protective effects against lung cancer. We conducted a meta-analysis of prospective studies of blood concentrations of carotenoids and retinol, and lung cancer risk. We identified relevant prospective studies published up to December 2014 by searching the PubMed and several other databases. We calculated summary estimates of lung cancer risk for the highest compared with lowest carotenoid and retinol concentrations and dose-response meta-analyses using random effects models. We used fractional polynomial models to assess potential nonlinear relationships. Seventeen prospective studies (18 publications) including 3603 cases and 458,434 participants were included in the meta-analysis. Blood concentrations of α-carotene, β-carotene, total carotenoids, and retinol were significantly inversely associated with lung cancer risk or mortality. The summary relative risk were 0.66 (95% confidence interval [CI]: 0.55-0.80) per 5 μg/100 mL of α-carotene (studies [n] = 5), 0.84 (95% CI: 0.76-0.94) per 20 μg/100 mL of β-carotene (n = 9), 0.66 (95% CI: 0.54-0.81) per 100 μg/100 mL of total carotenoids (n = 4), and 0.81 (95% CI: 0.73-0.90) per 70 μg/100 mL of retinol (n = 8). In stratified analysis by sex, the significant inverse associations for β-carotene and retinol were observed only in men and not in women. Nonlinear associations were observed for β-carotene, β-cryptoxanthin, and lycopene, with stronger associations observed at lower concentrations. There were not enough data to conduct stratified analyses by smoking. In conclusion, higher blood concentrations of several carotenoids and retinol are associated with reduced lung cancer risk. Further studies in never and former smokers are needed to rule out confounding by smoking.
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Reinterpretation of the results of a pooled analysis of dietary carotenoid intake and breast cancer risk by using the interval collapsing method.
Bae, JM
Epidemiology and health. 2016;:e2016024
Abstract
OBJECTIVES A pooled analysis of 18 prospective cohort studies reported in 2012 for evaluating carotenoid intakes and breast cancer risk defined by estrogen receptor (ER) and progesterone receptor (PR) statuses by using the "highest versus lowest intake" method (HLM). By applying the interval collapsing method (ICM) to maximize the use of the estimated information, we reevaluated the results of the previous analysis in order to reinterpret the inferences made. METHODS In order to estimate the summary effect size (sES) and its 95% confidence interval (CI), meta-analyses with the random-effects model were conducted for adjusted relative risks and their 95% CI from the second to the fifth interval according to five kinds of carotenoids and ER/PR status. RESULTS The following new findings were identified: α-Carotene and β-cryptoxanthin have protective effects on overall breast cancer. All five kinds of carotenoids showed protective effects on ER- breast cancer. β-Carotene level increased the risk of ER+ or ER+/PR+ breast cancer. α-Carotene, β-carotene, lutein/zeaxanthin, and lycopene showed a protective effect on ER-/PR+ or ER-/PR- breast cancer. CONCLUSIONS The new facts support the hypothesis that carotenoids that show anticancer effects with anti-oxygen function might reduce the risk of ER- breast cancer. Based on the new facts, the modification of the effects of α-carotene, β-carotene, and β-cryptoxanthin should be evaluated according to PR and ER statuses.
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Lycopene Consumption and Risk of Colorectal Cancer: A Meta-Analysis of Observational Studies.
Wang, X, Yang, HH, Liu, Y, Zhou, Q, Chen, ZH
Nutrition and cancer. 2016;(7):1083-96
Abstract
A number of epidemiological studies have explored the association between lycopene or lycopene-rich food intake and the risk of colorectal cancer, but the results of these studies have not been consistent. We conducted a systematic review and meta-analysis of studies published in the PubMed and EMBASE databases to quantitatively assess the association between lycopene consumption and the risk of colorectal cancer. A total of 15 studies were included in the meta-analysis, and the summary relative risk (RR) for highest versus lowest category indicated no significant association between lycopene consumption and the risk of colorectal cancer [RR = 0.94, 95% confidence interval (CI): 0.80-1.10]. However, a significant inverse association was observed between lycopene consumption and the site of cancer in the colon (RR = 0.88, 95% CI: 0.81-0.96). We also found that the incidence of colon cancer and lycopene intake did not exhibit dose-response relationships. The Grades of Recommendations Assessment, Development and Evaluation (GRADE) quality in our study was very low. In conclusion, this meta-analysis indicates that lycopene consumption is not associated with the risk of colorectal cancer. Further research will be needed in this area to provide conclusive evidence.