BackgroundAn increasing prevalence of cognitive disorders warrants comprehensive systematic reviews on the effect of diet on cognitive health. Studies have suggested that the Mediterranean (MeDi) diet has protective effects against metabolic diseases. However, comprehensive systematic reviews on the effect of the MeDi diet on the cognitive decline are limited. We investigated whether adherence to the MeDi diet could lower the risk of the cognitive disorder or improve cognitive function in older adults.MethodsIn this systematic review and meta-analysis, PubMed, Web of Science, PsycINFO, Scopus, and Cochrane databases were searched from inception to June 2021. Cohort studies and randomized controlled trials (RCTs) were included. The effect sizes were estimated as log risk ratios and standard mean differences (SMDs) with 95% confidence intervals (CIs). The Newcastle–Ottawa score and Cochrane Collaboration’s tool were used to assess the risk of bias in cohort studies and RCTs, respectively.ResultsOf the 1,687 screened studies, 31 cohort studies and five RCTs met the eligibility criteria for qualitative analysis; 26 cohort studies and two RCTs were included in the meta-analysis. In the cohort studies, high adherence to the MeDi diet was associated with lower risk of mild cognitive impairment (MCI) [risk ratio (RR) = 0.75 (0.66–0.86)], and Alzheimer’s disease (AD) [RR = 0.71 (0.56–0.89)]. In the RCTs, high adherence to the MeDi diet was associated with better episodic [SMD = 0.20 (0.09–0.30)] and working memories [SMD = 0.17 (0.01–0.32)] than lowest group.ConclusionAdherence to the MeDi diet may reduce the risk of MCI and AD. However, other associations with cognitive outcomes (global cognition, working memory, and episodic memory) remain open to interpretation. Overall, the MeDi diet is recommended to prevent or delay cognitive disorders and improve cognitive function. Further, long-term RCTs are warranted to strengthen the evidence.Systematic review registration[https://www.crd.york.ac.uk], identifier [CRD42021276801].
ObjectivesDietary patterns can holistically provide insights into the association of food groups and nutrients with the disease. Several studies have evaluated the association of dietary patterns with the risk of non-alcoholic fatty liver disease (NAFLD) in Western populations. However, few studies focused on this topic were conducted on Korean adults. Therefore, in this cohort study, we aimed to investigate the association between dietary patterns and the risk of NAFLD among middle-aged Koreans.DesignThe survey was performed at general hospitals and health examination centres in Korea. Dietary intake was assessed using a validated Food Frequency Questionnaire. The dietary patterns were identified using principal component analysis. The HR and 95% CI for NAFLD for each of the quartiles of the three dietary patterns were estimated using a Cox proportional hazards model.SettingSouth Korean Community.Participants44 460 healthy Koreans (aged 40–69 years) who completed a follow-up survey from 2012 to 2016 in the Health Examinees study were included.ResultsMen and women following a prudent pattern showed a 22% and 36% lower NAFLD risk, respectively (men: HR=0.78; women: HR=0.64). Men and women who highly adhered to the flour-based food and meat pattern had a 29% and 55% higher NAFLD risk, respectively (men: HR=1.29; women: HR=1.55).ConclusionThe prudent pattern induced a lower NAFLD risk, whereas the flour-based food and meat pattern induced a higher NAFLD risk. No significant difference was found between the white rice pattern and NAFLD risk.
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