OBJECTIVES: Habitual diet plays a major role in shaping the composition of the gut microbiota, and also determines the repertoire of microbial metabolites that can influence the host. The typical Western diet corresponds to that of an omnivore; however, the Mediterranean diet (MD), common in the Western Mediterranean culture, is to date a nutritionally recommended dietary pattern that includes high-level consumption of cereals, fruit, vegetables and legumes. To investigate the potential benefits of the MD in this cross-sectional survey, we assessed the gut microbiota and metabolome in a cohort of Italian individuals in relation to their habitual diets.
DESIGN AND RESULTS: We retrieved daily dietary information and assessed gut microbiota and metabolome in 153 individuals habitually following omnivore, vegetarian or vegan diets. The majority of vegan and vegetarian subjects and 30% of omnivore subjects had a high adherence to the MD. We were able to stratify individuals according to both diet type and adherence to the MD on the basis of their dietary patterns and associated microbiota. We detected significant associations between consumption of vegetable-based diets and increased levels of faecal short-chain fatty acids, Prevotella and some fibre-degrading Firmicutes, whose role in human gut warrants further research. Conversely, we detected higher urinary trimethylamine oxide levels in individuals with lower adherence to the MD.
CONCLUSIONS: High-level consumption of plant foodstuffs consistent with an MD is associated with beneficial microbiome-related metabolomic profiles in subjects ostensibly consuming a Western diet.
TRIAL REGISTRATION NUMBER: This study was registered at clinical trials.gov as NCT02118857.
BACKGROUND: Adherence to a healthy lifestyle is associated with substantially lower risks of mortality from all causes, cardiovascular diseases, and cancer in white populations. However, little is known about the health benefits among non-white populations. Also, no previous studies have focused on respiratory disease mortality in both white and non-white populations. We assessed the relationships between a combination of healthy lifestyle factors and multiple death outcomes in Chinese adults.
METHODS: This study included 487,198 adults aged 30-79 years from the China Kadoorie Biobank without heart disease, stroke, and cancer at study enrolment. We defined five healthy lifestyle factors as never smoking or smoking cessation not due to illness; non-daily drinking or moderate alcohol drinking; median or higher level of physical activity; a diet rich in vegetables, fruits, legumes and fish, and limited in red meat; a body mass index of 18.5 to 27.9 kg/m(2) and a waist circumference < 90 cm (men)/85 cm (women). Cox regression was used to produce adjusted hazard ratios (HRs) relating these healthy lifestyle factors to all-cause and cause-specific mortality.
RESULTS: During a median follow-up of 10.2 years (IQR 9.2-11.1), we documented 37,845 deaths. After multivariable adjustment, the number of healthy lifestyle factors exhibited almost inverse linear relationships with the risks of all-cause and cause-specific mortality. Compared with participants without any healthy factors, the hazard ratio of participants with five healthy factors was 0.32 [95% confidence interval (CI): 0.28, 0.37] for all-cause mortality. The corresponding HRs in specific cause of death were 0.42 (95% CI: 0.26, 0.67) for ischaemic heart disease, 0.21 (95% CI: 0.09, 0.49) for ischaemic stroke, 0.37 (95% CI: 0.22, 0.60) for haemorrhage stroke, 0.36 (95% CI: 0.29, 0.45) for cancer, 0.26 (95% CI: 0.14, 0.48) for respiratory diseases, and 0.29 (95% CI: 0.22, 0.39) for other causes. Theoretically, 38.5% (95% CI: 33.0, 43.8%) of all-cause mortality was attributable to nonadherence to a healthy lifestyle, and the proportions of preventable deaths through lifestyle modification ranged from 26.9 to 47.9% for cause-specific mortality.
CONCLUSIONS: Adherence to a healthy lifestyle was associated with substantially lower risks of all-cause, cardiovascular, respiratory, and cancer mortality in Chinese adults. Promotion of a healthy lifestyle may considerably reduce the burden of non-communicable diseases in China.
A previous meta-analysis provided convincing evidence for an inverse association between adherence to a Mediterranean diet (MedDiet) and the risk of all-cause mortality. Since then, 19 prospective studies have been published. We updated the evidence from these prospective studies and conducted a dose-response meta-analysis to test the linear and potential nonlinear dose-response associations between adherence to a MedDiet and the risk of all-cause mortality.
The PubMed, Scopus, ISI Web of Knowledge, and Embase bibliographic databases were systematically searched up to August 24, 2018. Summary HRs were estimated with the use of a random-effects meta-analysis to assess the association between a 2-point increment in MedDiet adherence and the risk of all-cause mortality. Sensitivity and subgroup analyses were performed and potential publication bias was tested. Twenty-nine prospective studies with 1,676,901 participants and 221,603 cases of all-cause mortality were included in the final analysis.
The pooled HR of all-cause mortality was 0.90 (95% CI: 0.89, 0.91; I2 = 81.1%) for a 2-point increment in adherence to a MedDiet. Subgroup analyses showed that a significant inverse association was stronger in participants who lived in the Mediterranean region compared with non-Mediterranean areas (HRs: 0.82 compared with 0.92, respectively), and in studies that used the Panagiotakos MedDiet score.
A nonlinear dose-response meta-analysis indicated that the risk of all-cause mortality linearly decreased with the increase in adherence to a MedDiet. The robustness of findings was confirmed in the sensitivity analyses. In conclusion, low-quality evidence from prospective cohort studies suggests an inverse association between adherence to a MedDiet and the risk of all-cause mortality, especially in Mediterranean regions. An inverse linear dose-response relation was also observed between adherence to a MedDiet and the risk of all-cause mortality.
Alzheimer's disease (AD) risk increases with age and lacks efficacious pharmacological options. Summaries of the existing evidence reveal an association between Mediterranean-style diet adherence and reduced AD incidence; however, no review has investigated this relationship with respect to the hallmark AD biomarkers (tau and beta-amyloid) that manifest decades before clinical symptomatology. MEDLINE, PubMed, PsycINFO, Google Scholar, and SCOPUS databases were systematically searched to identify peer-reviewed articles investigating diet and AD biomarkers in the last 2 decades.
Two thousand seven hundred twenty-six records were extracted, quality assessed, and double-blind screened by 2 authors. Fifteen studies met the inclusion criteria and 13 studies found a significant relationship. Of these, 4 studies found a high-glycemic load was related to an increase in AD biomarker burden; 6 found adherence to a Mediterranean or "AD-protective" dietary pattern conferred a reduction in AD biomarker burden. Meta-analysis revealed a small but significant effect of diet on AD biomarkers (β = 0.11 [95% CI 0.04-0.17], p = 0.002). This systematic review supports the notion that diet and nutrition display potential for nonpharmacological AD prevention.