Cholesterol-absorber status modifies the LDL cholesterol-lowering effect of a Mediterranean-type diet in adults with moderate cardiovascular risk factors

The role of the Mediterranean diet in reducing the risk of cognitive impairement, dementia, and Alzheimer's disease: a meta-analysis

Age-related cognitive impairment and dementia pose a significant global health, social, and economic challenge. While Alzheimer's disease (AD) has historically been viewed as the leading cause of dementia, recent evidence reveals the considerable impact of vascular cognitive impairment and dementia (VCID), which now accounts for nearly half of all dementia cases. The Mediterranean diet-characterized by high consumption of fruits, vegetables, whole grains, fish, and olive oil-has been widely recognized for its cardiovascular benefits and may also reduce the risk of cognitive decline and dementia. To investigate the protective effects of the Mediterranean diet on cognitive health, we conducted a systematic literature review using PubMed, Web of Science, and Google Scholar, focusing on studies published between 2000 and 2024. The studies included in the meta-nalysis examined the adherence to the Mediterranean diet and the incidence of dementia and AD. We applied a random-effects model to calculate pooled hazard ratios (HRs) with 95% confidence intervals (CIs) and assessed heterogeneity through I-square statistics. Forest plots, funnel plots, and Z-score plots were used to visualize study outcomes. Of the 324 full-text records reviewed, 23 studies met the inclusion criteria. The combined HR for cognitive impairment among those adhering to the Mediterranean diet was 0.82 (95% CI 0.75-0.89); for dementia, the HR was 0.89 (95% CI 0.83-0.95); and for AD, the HR was 0.70 (95% CI 0.60-0.82), indicating substantial protective effects. Significant heterogeneity was observed across studies, though Z-score plots suggested sufficient sample sizes to support reliable conclusions for each condition. In conclusion, this meta-analysis confirms that adherence to the Mediterranean diet is associated with an 11-30% reduction in the risk of age-related cognitive disorders, including cognitive impairment, dementia, and AD. These findings underscore the Mediterranean diet's potential as a central element in neuroprotective public health strategies to mitigate the global impact of cognitive decline and dementia and to promote healthier cognitive aging.

Impact of adherence to the Mediterranean diet on stroke risk

Stroke is a leading cause of morbidity and mortality worldwide, and dietary patterns have emerged as a significant modifiable factor in stroke prevention. The Mediterranean diet, characterized by high intake of fruits, vegetables, whole grains, nuts, olive oil, and fish, has been widely recognized for its cardiovascular benefits. However, its specific impact on stroke risk requires further elucidation. We conducted a comprehensive meta-analysis of 30 studies, including both cohort and case-control designs, to evaluate the relationship between adherence to the Mediterranean diet and the risk of stroke. A systematic search was performed across multiple databases, and a random-effects model was used to estimate pooled hazard ratios (HRs) with 95% confidence intervals (CIs). Heterogeneity was assessed using the I2 statistic, and publication bias was examined through funnel plots and Egger's regression test. Additionally, trial sequential analysis was conducted to determine the adequacy of the sample size. The meta-analysis revealed a significant reduction in stroke risk among individuals adhering to the Mediterranean diet, with a pooled HR of 0.88 (95% CI: 0.84-0.91). Notably, a significant heterogeneity was detected (I2 = 34%). The Z-score plot from trial sequential analysis confirmed that the sample sizes were sufficient to draw definitive conclusions. However, a potential publication bias was identified. The case-control studies confirmed a highly significant effect (HR = 0.54, 95% CI: 0.4-0.73). The funnel plots in both settings hinted at the presence of a potential publication bias, supported by a significant Egger's test. Our findings provide robust evidence supporting the protective effect of the Mediterranean diet against stroke. Despite the presence of some heterogeneity and potential publication bias, the cumulative evidence suggests that promoting the Mediterranean diet could serve as an effective public health strategy for stroke prevention. Further research is recommended to explore the underlying mechanisms and to assess the diet's impact across diverse populations.

Mediterranean diet intervention in overweight and obese subjects lowers plasma cholesterol and causes changes in the gut microbiome and metabolome independently of energy intake

OBJECTIVES

This study aimed to explore the effects of an isocaloric Mediterranean diet (MD) intervention on metabolic health, gut microbiome and systemic metabolome in subjects with lifestyle risk factors for metabolic disease.

DESIGN

Eighty-two healthy overweight and obese subjects with a habitually low intake of fruit and vegetables and a sedentary lifestyle participated in a parallel 8-week randomised controlled trial. Forty-three participants consumed an MD tailored to their habitual energy intakes (MedD), and 39 maintained their regular diets (ConD). Dietary adherence, metabolic parameters, gut microbiome and systemic metabolome were monitored over the study period.

RESULTS

Increased MD adherence in the MedD group successfully reprogrammed subjects' intake of fibre and animal proteins. Compliance was confirmed by lowered levels of carnitine in plasma and urine. Significant reductions in plasma cholesterol (primary outcome) and faecal bile acids occurred in the MedD compared with the ConD group. Shotgun metagenomics showed gut microbiome changes that reflected individual MD adherence and increase in gene richness in participants who reduced systemic inflammation over the intervention. The MD intervention led to increased levels of the fibre-degrading Faecalibacterium prausnitzii and of genes for microbial carbohydrate degradation linked to butyrate metabolism. The dietary changes in the MedD group led to increased urinary urolithins, faecal bile acid degradation and insulin sensitivity that co-varied with specific microbial taxa.

CONCLUSION

Switching subjects to an MD while maintaining their energy intake reduced their blood cholesterol and caused multiple changes in their microbiome and metabolome that are relevant in future strategies for the improvement of metabolic health.

Evidence-Based Guideline of the German Nutrition Society: Fat Intake and Prevention of Selected Nutrition-Related Diseases

As nutrition-related chronic diseases have become more and more frequent, the importance of dietary prevention has also increased. Dietary fat plays a major role in human nutrition, and modification of fat and/or fatty acid intake could have a preventive potential. The aim of the guideline of the German Nutrition Society (DGE) was to systematically evaluate the evidence for the prevention of the widespread diseases obesity, type 2 diabetes mellitus, dyslipoproteinaemia, hypertension, metabolic syndrome, coronary heart disease (CHD), stroke, and cancer through the intake of fat or fatty acids. The main results can be summarized as follows: it was concluded with convincing evidence that a reduced intake of total and saturated fat as well as a larger intake of polyunsaturated fatty acids (PUFA) at the expense of saturated fatty acids (SFA) reduces the concentration of total and low-density lipoprotein cholesterol in plasma. Furthermore, there is convincing evidence that a high intake of trans fatty acids increases risk of dyslipoproteinaemia and that a high intake of long-chain polyunsaturated n-3 fatty acids reduces the triglyceride concentration in plasma. A high fat intake increases the risk of obesity with probable evidence when total energy intake is not controlled for (ad libitum diet). When energy intake is controlled for, there is probable evidence for no association between fat intake and risk of obesity. A larger intake of PUFA at the expense of SFA reduces risk of CHD with probable evidence. Furthermore, there is probable evidence that a high intake of long-chain polyunsaturated n-3 fatty acids reduces risk of hypertension and CHD. With probable evidence, a high trans fatty acid intake increases risk of CHD. The practical consequences for current dietary recommendations are described at the end of this article.

Multilevel systems biology modeling characterized the atheroprotective efficiencies of modified dairy fats in a hamster model

We assessed the atheroprotective efficiency of modified dairy fats in hyperlipidemic hamsters. A systems biology approach was implemented to reveal and quantify the dietary fat-related components of the disease. Three modified dairy fats (40% energy) were prepared from regular butter by mixing with a plant oil mixture, by removing cholesterol alone, or by removing cholesterol in combination with reducing saturated fatty acids. A plant oil mixture and a regular butter were used as control diets. The atherosclerosis severity (aortic cholesteryl-ester level) was higher in the regular butter-fed hamsters than in the other four groups (P < 0.05). Eighty-seven of the 1,666 variables measured from multiplatform analysis were found to be strongly associated with the disease. When aggregated into 10 biological clusters combined into a multivariate predictive equation, these 87 variables explained 81% of the disease variability. The biological cluster "regulation of lipid transport and metabolism" appeared central to atherogenic development relative to diets. The "vitamin E metabolism" cluster was the main driver of atheroprotection with the best performing transformed dairy fat. Under conditions that promote atherosclerosis, the impact of dairy fats on atherogenesis could be greatly ameliorated by technological modifications. Our modeling approach allowed for identifying and quantifying the contribution of complex factors to atherogenic development in each dietary setup.