No short-term effects of calorie-controlled Mediterranean or fast food dietary interventions on established biomarkers of vascular or metabolic risk in healthy individuals

A Mediterranean diet improves glycation markers in healthy people and in those with chronic diseases: a systematic review of clinical trials

CONTEXT

Consumption of the Mediterranean diet (MedDiet) has beneficial effects on cardiometabolic health and aging.

OBJECTIVE

This systematic review aimed to critically investigate the effect of the MedDiet on glycation markers in healthy or overweight individuals with type 2 diabetes or cardiovascular disease.

DATA SOURCES

MEDLINE, EMBASE, Web of Science, and the Cochrane Library were searched, using the terms "Mediterranean diet" AND "glycation end products, advanced".

DATA EXTRACTION

Three randomized and 3 nonrandomized clinical trials, containing data on 2935 adult and elderly individuals with normal weight or overweight, were included. All extracted data were compiled, compared, and critically analyzed.

DATA ANALYSIS

The authors of most of the studies demonstrated a reduction in serum concentrations of advanced glycation end products (AGEs), such as εN-carboxymethyllysine and methylglyoxal, and in skin autofluorescence levels after at least 4 weeks of adherence to the MedDiet. The MedDiet also led to positive effects on gene expression of receptors for AGEs, as RAGE and AGER1, and an enzyme involved in detoxification (glyoxalase I). There is no evidence that short-term adherence affects glycation markers.

CONCLUSIONS

Glycation markers improved in response to the MedDiet. The possible mechanisms involved may be related to the low AGE and refined sugars content of the diet, as well as its high monounsaturated fatty acid, phenolic compound, and dietary fiber contents.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021284006.

Dietary Patterns, Oxidative Stress, and Early Inflammation: A Systematic Review and Meta-Analysis Comparing Mediterranean, Vegan, and Vegetarian Diets

BACKGROUND

Dietary habits influenced by lifestyle and cultural factors play a critical role in health by modulating oxidative stress and inflammation. While diets offer significant benefits, they may also pose risks, such as nutrient deficiencies, emphasizing the need for a balanced approach. Exploring Mediterranean and plant-based diet effects on oxidative stress and inflammation biomarkers may help improve health outcomes and disease prevention strategies.

METHODS

This study analyzed 65 studies following PRISMA guidelines to evaluate the effects of Mediterranean and plant-based diets on biomarkers of oxidative stress and inflammation in healthy individuals.

RESULTS

The Mediterranean diet was weakly associated with reductions in oxidative stress markers, including MDA (ROM: 0.80; 95% CI: 0.57-1.13; p = 0.2092) and 8OHdG (ROM: 0.81; 95% CI: 0.59-1.11; p = 0.1847), as well as inflammation markers such as CRP (ROM: 0.72; 95% CI: 0.42-1.23; p = 0.1545) and IL-6 (ROM: 1.23; 95% CI: 0.97-1.55; p = 0.08). The vegetarian diet significantly reduced CRP (ROM: 0.82; 95% CI: 0.69-0.98; p = 0.0297), while the vegan diet showed a borderline reduction (ROM: 0.81; 95% CI: 0.56-1.17; p = 0.2544), suggesting lower systemic inflammation compared to omnivorous diets.

CONCLUSIONS

Although all three diets demonstrate potential in reducing oxidative stress and inflammation, the antioxidant effects-especially for the Mediterranean diet-are lower than anticipated, indicating alternative mechanisms. Further research is essential to confirm these findings and clarify the underlying mechanisms to enhance preventive health strategies.

Dietary patterns and biomarkers of oxidative stress and inflammation: A systematic review of observational and intervention studies

INTRODUCTION

Oxidative stress and inflammation are known to play a critical role in ageing and chronic disease development and could therefore represent important targets for developing dietary strategies for disease prevention. We aimed to systematically review the results from observational studies and intervention trials published in the last 5 years on the associations between dietary patterns and biomarkers of oxidative stress and inflammation.

METHODS

A systematic search of the PubMed, MEDLINE and Web of Science (January 2015 to October 2020) was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Methodological quality of selected studies was evaluated based on the NUTRIGRADE and BIOCROSS assessment tools.

RESULTS

In total, 29 studies among which 16 observational studies and 13 intervention studies were found eligible for review. Overall, results indicated an inverse association between plant-based diets - the Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diet - and oxidative stress and proinflammatory biomarkers. In observational studies, inverse associations were further revealed for the vegetarian diet, the USDA Healthy Eating Index (HEI) - based diet and the paleolithic diet, whereas a positive association was seen for western and fast food diets. Quality assessment suggested that majority of dietary intervention studies (n = 12) were of low to moderate quality.

CONCLUSIONS

This study provides evidence that the plant-based dietary patterns are associated with lowered levels of oxidative stress and inflammation and may provide valid means for chronic disease prevention. Future large-scale intervention trials using validated biomarkers are warranted to confirm these findings.

Immunomodulatory effect of Noni fruit and its isolates: insights into cell-mediated immune response and inhibition of LPS-induced THP-1 macrophage inflammation

Morinda citrifolia L. is a plant of the family Rubiaceae and is known as Indian mulberry or Noni in India. It is a perennial herb native to Southeast Asia and has been used over the years as a food supplement and medicinal plant. Noni fruits are reported to possess anticancer, fungicidal, antiviral and antiarthritic effects. The objective of our study is the screening of the immunomodulatory activity of the total extract, fractions, and isolated compounds of Noni fruits to identify their bioactive compounds. To achieve our goal, an ethanol extract (EE) was prepared from Noni fruits. Fractionation and purification of the EE were accomplished. The cell-mediated immune (CMI) response in prednisolone-induced immunosuppression rats was evaluated. The toxicity of the EE, fractions and isolated compounds on the differentiated THP-1 macrophage was assessed using the MTT viability assay. Moreover, the inflammation-related immune responses in lipopolysaccharide (LPS)-induced THP-1 macrophage activation were evaluated. Fractionation of the EE gave three fractions, dichloromethane (DCMF), water (WF) and methanol (MF). Purification of DCMF yielded stigmast-7-ene-3-ol (M1), 28-hydroxy-3β-acetoxy-9-dehydrogramisterol (M2), 3β-acetoxy-taraxast-20(30)-ene-21-ol (M3), 22-dehydroclerosterol (M4) and 22-dehydroclerosterol-3-O-β-d-glucopyranoside (M5), while purification of MF yielded quercetin (M6), hesperidin (M7), naringin (M9) and gallic acid (M8). The results revealed that DCMF elicited an increase in paw edema to the extent of 35.8%. All the tested samples had no cytotoxic effect on THP-1 macrophages. Co-treatment of the LPS-induced macrophages with DCMF, M2, M3, and M6 decreased the production of TNF-α, IL-1β, and IL-6/IL-10. The expression of iNOS, COX-2, and NF-κB decreased to 0.14 ± 0.02, 0.15 ± 0.02, and 0.17 ± 0.03, respectively, after co-treatment with LPS and DCMF. M2 attenuated the expression of iNOS and NF-κB to 0.18 ± 0.03 and 0.17 ± 0.03, respectively. Additionally, M3 attenuated the expression of iNOS to 0.18 ± 0.03, and after co-treatment with M6 and LPS, the expression of COX-2 and NF-κB was down-regulated to 0.2 ± 0.03. Our study proves the immunomodulatory effect of Noni fruits and specifies for the first time the compounds responsible for their activity.

The Effect of the Mediterranean Diet on Metabolic Health: A Systematic Review and Meta-Analysis of Controlled Trials in Adults

The Mediterranean diet (MD) may provide metabolic benefits but no systematic review to date has examined its effect on a multitude of outcomes related to metabolic health. This systematic review with meta-analysis (International Prospective Register of Systematic Reviews, PROSPERO; number CRD42019141459) aimed to examine the MD’s effect on metabolic syndrome (MetSyn) incidence, components and risk factors (primary outcomes), and incidence and/or mortality from MetSyn-related comorbidities and receipt of pharmacologic treatment for MetSyn components and comorbidities (secondary outcomes). We searched Pubmed, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Web of Science for controlled trials published until June 2019, comparing the MD with no treatment, usual care, or different diets in adults. Studies not published in English and not promoting the whole MD were excluded. Two authors independently extracted data and assessed risk of bias using the Cochrane Collaboration’s and Risk of Bias in non-randomised studies (ROBINS-I) tools. Reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Random-effects meta-analyses, subgroup analyses and meta-regressions were performed, and heterogeneity was quantified using the I² statistic. We identified 2654 reports and included 84 articles reporting 57 trials (n = 36,983). In random effects meta-analyses, the MD resulted in greater beneficial changes in 18 of 28 MetSyn components and risk factors (body weight, body mass index, waist circumference, systolic and diastolic blood pressure, glucose, insulin, homeostatic model assessment of insulin resistance (HOMA-IR) index, total-, low-density lipoprotein (LDL)- and high-density lipoprotein (HDL)-cholesterol, triglycerides, alanine transaminase, hepatic fat mass, C-reactive protein, interleukin-6, tumour necrosis factor-a, and flow-mediated dilatation) and lower risk of cardiovascular disease incidence (risk ratio (RR) = 0.61, 95% confidence intervals (CI) 0.42–0.80; I² = 0%), and stroke (RR = 0.67, 95% CI 0.35–0.98; I² = 0%). Only six studies reported effects on pharmacotherapy use, and pooled analysis indicated no differences between diet groups. Lack of consistency in comparator groups and other study characteristics across studies resulted in high heterogeneity for some outcomes, which could not be considerably explained by meta-regressions. However, a consistent direction of beneficial effect of the MD was observed for the vast majority of outcomes examined. Findings support MD’s beneficial effect on all components and most risk factors of the MetSyn, in addition to cardiovascular disease and stroke incidence. More studies are needed to establish effects on other clinical outcomes and use of pharmacotherapy for MetSyn components and comorbidities. Despite the high levels of heterogeneity for some outcomes, this meta-analysis enabled the comparison of findings across studies and the examination of consistency of effects. The consistent direction of effect, suggesting the MD’s benefits on metabolic health, supports the need to promote this dietary pattern to adult populations.

Genetic and nutritional factors determining circulating levels of lipoprotein(a): results of the "Montignoso Study"

Increasing evidence shows an association between high lipoprotein(a) [Lp(a)] levels and atherothrombotic diseases. Lp(a) trait is largely controlled by kringle-IV type 2 (KIV-2) size polymorphism in LPA gene, encoding for apo(a). Environmental factors are considered to determinate minor phenotypic variability in Lp(a) levels. In the present study, we investigated the possible gene-environment interaction between KIV-2 polymorphism and Mediterranean diet adherence or fish weekly intake in determining Lp(a) levels. We evaluated Lp(a), KIV-2 polymorphism, fish intake and Mediterranean diet adherence in 452 subjects [median age (range) 66 (46-80)years] from Montignoso Heart and Lung Project (MEHLP) population. In subjects with high KIV-2 repeats number, influence of Mediterranean diet adherence in reducing Lp(a) levels was observed (p = 0.049). No significant difference in subjects with low KIV-2 repeats according to diet was found. Moreover, in high-KIV-2-repeat subjects, we observed a trend towards influence of fish intake on reducing Lp(a) levels (p = 0.186). At multivariate linear regression analysis, high adherence to Mediterranean diet remains a significant and independent determinant of lower Lp(a) levels (β = - 64.97, standard error = 26.55, p = 0.015). In conclusion, this study showed that only subjects with high KIV-2 repeats can take advantage to lower Lp(a) levels from correct nutritional habits and, in particular, from Mediterranean diet.

The HDL lipidome is widely remodeled by fast food versus Mediterranean diet in 4 days

INTRODUCTION

HDL is associated with increased longevity and protection from multiple chronic diseases. The major HDL protein ApoA-I has a half-life of about 4 days, however, the effects of diet on the composition of HDL particles at this time scale have not been studied.

OBJECTIVES

The objective of this study is to investigate the short term dietary effect on HDL lipidomic composition.

METHODS

In this randomized order cross-over study, ten healthy subjects consumed a Mediterranean (Med) and a fast food (FF) diet for 4 days, with a 4-day wash-out between treatments. Lipidomic composition was analyzed in isolated HDL fractions by an untargeted LC-MS method with 15 internal standards.

RESULTS

HDL phosphatidylethanolamine (PE) content was increased by FF diet, and 41 out of 170 lipid species were differentially affected by diet. Saturated fatty acids (FAs) and odd chain FA were enriched after FF diet, while very-long chain FA and unsaturated FA were enriched after Med diet. The composition of phosphatidylcholine (PC), triacylglycerol (TG) and cholesteryl ester (CE) were significantly altered to reflect the FA composition of the diet whereas the composition of sphingomyelin (SM) and ceramides were generally unaffected.

CONCLUSION

Results from this study indicate that the HDL lipidome is widely remodeled within 4 days of diet change and that certain lipid classes are more sensitive markers of diet whereas other lipid classes are better indicators of non-dietary factors.

A prospective study of frequency of eating restaurant prepared meals and subsequent 9-year risk of all-cause and cardiometabolic mortality in US adults

Restaurant prepared foods are known to be energy-dense and high in fat and sodium, but lower in protective nutrients. There is evidence of higher risk of adiposity, type II diabetes, and heart disease in frequent consumers of restaurant meals. However, the risk of mortality as a long-term health consequence of frequent consumption of restaurant meals has not been examined. We examined the prospective risk of all-cause and coronary heart disease, cerebrovascular disease and diabetes (cardiometabolic) mortality in relation to frequency of eating restaurant prepared meals in a national cohort. We used frequency of eating restaurant prepared meals information collected in the National Health and Nutrition Examination Surveys, conducted from 1999-2004, with mortality follow-up completed through Dec. 31, 2011 (baseline age ≥ 40y; n = 9107). We estimated the relative hazard of all-cause and cardiometabolic mortality associated with weekly frequency of eating restaurant meals using Cox-proportional hazards regression methods to adjust for multiple covariates. All analyses accounted for complex survey design and included sample weights. Over 33% of all respondents reported eating ≥3 restaurant prepared meals/week. In this cohort, 2200 deaths due to all causes and 665 cardiometabolic deaths occurred over a median follow-up of 9 years. The covariate-adjusted hazard ratio of all cause or cardiometabolic mortality in men and women reporters of <1 or 1-2 restaurant prepared meals did not differ from those reporting ≥3 meals/week (P>0.05). The results were robust to effect modification by baseline BMI, years of education, and baseline morbidity. Expectedly, the 24-h dietary intakes of whole grains, fruits, dietary fiber, folate, vitamin C, potassium and magnesium at baseline were lower, but energy, energy density, and energy from fat were higher in more frequent restaurant meal reporters (P<0.05). Baseline serum HDL cholesterol, folate, and some carotenoids were inversely associated with the frequency of eating restaurant prepared meals (P<0.05); however, serum concentrations of total cholesterol, triglycerides, fasting glucose, insulin, glycated hemoglobin, and c-reactive protein were unrelated (P<0.05). The weekly frequency of eating restaurant prepared meals and prospective risk of mortality after 9 years were not related in this cohort.

Uric Acid for Cardiovascular Risk: Dr. Jekyll or Mr. Hide?

Uric acid (UA) is a potent endogenous antioxidant. However, high concentrations of this molecule have been associated with cardiovascular disease (CVD) and renal dysfunction, involving mechanisms that include oxidative stress, inflammatory processes, and endothelial injury. Experimental and in vitro results suggest that this biomarker behaves like other antioxidants, which can shift from the physiological antioxidant action to a pro-oxidizing effect according to their level and to microenvironment conditions. However, data on patients (general population or CAD cohorts) are controversial, so the debate on the role of hyperuricemia as a causative factor for CVD is still ongoing. Increasing evidence indicates UA as more meaningful to assess CVD in women, even though this aspect needs deeper investigation. It will be important to identify thresholds responsible for UA “biological shift” from protective to harmful effects in different pathological conditions, and according to possible gender-related differences. In any case, UA is a low-tech and inexpensive biomarker, generally performed at patient’s hospitalization and, therefore, easily accessible information for clinicians. For these reasons, UA might represent a useful additive tool as much as a CV risk marker. Thus, in view of available evidence, progressive UA elevation with levels higher than 6 mg/dL could be considered an “alarm” for increased CV risk.