Elements of Mediterranean diet improve oxidative status in blood of kidney graft recipients

Exploring the nexus: The place of kidney diseases within the cardiovascular-kidney-metabolic syndrome spectrum

Cardiovascular-kidney-metabolic (CKM) syndrome and chronic kidney disease (CKD) are two significant comorbidities affecting a large proportion of the general population with considerable crosstalk. In addition to substantial co-incidence of CKD and CKM syndrome in epidemiological studies, clinical and pre-clinical studies have identified similar pathophysiological pathways leading to both entities. Patients with CKM syndrome are more prone to develop acute kidney injury and CKD, while therapeutic alternatives and their success rates are considerably lower in such patient groups. Nevertheless, the association between CKM syndrome and CKD or ESKD is bidirectional rather than being a cause-effect relationship as patients with CKD are also prone to develop peripheral insulin resistance, high blood pressure, and dyslipidemia. Furthermore, such patients are less likely to receive kidney transplantation in addition to the higher allograft dysfunction risk. We hereby aim to evaluate the association in-between kidney diseases and CKM syndrome, including epidemiological data, pre-clinical studies with pathophysiological pathways, and potential therapeutic perspectives.

Chronic Kidney Disease Diets for Kidney Failure Prevention: Insights from the IL-11 Paradigm

Nearly every fifth adult in the United States and many older adults worldwide are affected by chronic kidney disease (CKD), which can progress to kidney failure requiring invasive kidney replacement therapy. In this review, we briefly examine the pathophysiology of CKD and discuss emerging mechanisms involving the physiological resolution of kidney injury by transforming growth factor beta 1 (TGFβ1) and interleukin-11 (IL-11), as well as the pathological consequences of IL-11 overproduction, which misguides repair processes, ultimately culminating in CKD. Taking these mechanisms into account, we offer an overview of the efficacy of plant-dominant dietary patterns in preventing and managing CKD, while also addressing their limitations in terms of restoring kidney function or preventing kidney failure. In conclusion, this paper outlines novel regeneration strategies aimed at developing a reno-regenerative diet to inhibit IL-11 and promote repair mechanisms in kidneys affected by CKD.

Effect of anti-inflammatory diets on inflammation markers in adult human populations: a systematic review of randomized controlled trials

CONTEXT

Chronic inflammation, characterized by prolonged elevated inflammation markers, is linked to several chronic conditions. Diet can influence the levels of inflammation markers in the body.

OBJECTIVE

The aim of this systematic review was to assess the effects of anti-inflammatory diets on 14 different inflammation markers in adults.

DATA SOURCES

This systematic review conducted searches using Medline, PubMed, EMCare, Cochrane, and CINAHL, to locate randomized controlled trials (RCTs).

DATA EXTRACTION

Two researchers independently screened 1537 RCTs that measured changes in inflammation markers after prescription of an intervention diet.

DATA ANALYSIS

In total, 20 RCTs were included and assessed qualitatively. The results demonstrated that a Mediterranean diet can bring about statistically significant and clinically meaningful between-group differences in interleukins -1α, -1β, -4, -5, -6, -7, -8, -10, and -18, interferon γ, tumor necrosis factor α, C-reactive protein, and high-sensitivity C-reactive protein, as compared with a control diet.

CONCLUSIONS

There may be a link between diet, inflammation markers, and disease outcomes in various adult populations. However, further research using consistent RCT protocols is required to determine correlations between diet, specific inflammation markers, and clinically relevant outcomes.

Polyphenols and Novel Insights Into Post-kidney Transplant Complications and Cardiovascular Disease: A Narrative Review

Kidney transplantation is the preferred treatment for end-stage kidney disease. It is, however, not devoid of complications. Delayed graft function related to ischemia-reperfusion injury (IRI), calcineurin inhibitor (CNI) nephrotoxicity, diabetes, and a particularly high-rate cardiovascular disease (CVD) risk, represent important complications following kidney transplantation. Oxidative stress and chronic low-grade inflammation are mechanisms of disease incompletely abrogated in stable kidney transplant recipient (KTR), contributing to the occurrence of these complications. Polyphenols, bioactive compounds with recognized antioxidant and anti-inflammatory properties have been strongly associated with prevention of CVD in the general population and have been shown to decrease IRI and antagonize CNI nephrotoxicity in animal experimental models, therefore they may have a role in prevention of complications in KTR. This narrative review aims to summarize and discuss current evidence on different polyphenols for prevention of complications, particularly prevention of CVD in KTR, pointing toward the need of further studies with potential clinical impact.

Mediterranean Diet Adherence and Nutritional Status in Dalmatian Kidney Transplant Recipients-Are They Related?

The aim of this study was to evaluate adherence to Mediterranean diet (MeDi) and possible correlation of MeDi adherence and nutritional status parameters in Dalmatian kidney transplant recipients (KTRs). One hundred and sixteen KTRs were included in this study. Data about Mediterranean Diet Serving Score (MDSS), body mass composition, anthropometric parameters, clinical and laboratory parameters were collected for each study participant. The results showed 25% adherence to the MeDi in Dalmatian KTRs. MDSS showed association with higher serum albumin and phosphorus level and higher skeletal muscle mass. Also, significant association between diabetic status and MDSS was found. Adherence to olive oil intake suggested by the MeDi showed significant association with lower level of triglycerides and adherence to nuts suggestions was associated with lower level of fat mass. Following MeDi recommendations for consumption of other foods (cereals, potato, eggs, vegetables, fruits and dairy) were also associated with body mass composition parameters and laboratory findings. In conclusion, low adherence to the MeDi in Dalmatian KTRs raises high concerns. The results showed that MeDi can have favorable effects on nutritional status in KTRs. A structured nutritional approach is needed to enhance adherence to the MeDi and prevent possible adverse effects in this patient population.

A Narrative Review of Dietary Approaches for Kidney Transplant Patients

A healthy eating pattern has proven to lower the risk of metabolic and cardiovascular diseases. However, there are sparse dietary recommendations for kidney transplant recipients, and the ones available focus only on single nutrients intake, such as sodium, potassium, and proteins, and not on the overall eating pattern. Considering that individuals do not typically consume nutrients in isolation, but as part of a complete dietary pattern, it is challenging for the average transplanted patient to understand and implement specific dietary recommendations. Also, single-nutrient interventions demonstrate largely inconclusive effects, and it seems improbable that they could have a strong enough impact on transplant outcomes. Dietary trends such as plant-based diets, intermittent fasting, low-carb diet/keto-diet, and juicing, have gained major attention from the media. Herein, we review the potential risks and benefits of these diets in kidney transplant recipients and provide an updated dietary recommendation for this population with consideration of current nutritional trends. Overall, the Mediterranean and DASH diets have demonstrated to be the most beneficial dietary patterns to the post kidney transplant population by focusing on less meat and processed foods, while increasing the intake of fresh foods and plant-based choices. We believe that to maintain a healthy lifestyle posttransplant, patients should be educated about the scientific evidence of different diets and choose a dietary pattern that is sustainable long-term.

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.

Dietary interventions with dietitian involvement in adults with chronic kidney disease: A systematic review

BACKGROUND

A comprehensive evidence base is needed to support recommendations for the dietetic management of adults with chronic kidney disease (CKD). The present study aimed to determine the effect of dietary interventions with dietitian involvement on nutritional status, well-being, kidney risk factors and clinical outcomes in adults with CKD.

METHODS

Cochrane Central Register of Controlled Trials, CINAHL, MEDLINE, PsycINFO and EMBASE.com were searched from January 2000 to November 2019. Intentional weight loss and single nutrient studies were excluded. Risk of bias was assessed using the Cochrane risk-of-bias tool. Effectiveness was summarised using the mean difference between groups for each outcome per study.

RESULTS

Twelve controlled trials (1906 participants) were included. High fruit and vegetable intake, as well as a multidisciplinary hospital and community care programme, slowed the decline in glomerular filtration rate in adults with stage 3-4 CKD. Interventions addressing nutrition-related barriers increased protein and energy intake in haemodialysis patients. A Mediterranean diet and a diet with high n-3 polyunsaturated fatty acids improved the lipid profile in kidney transplant recipients.

CONCLUSIONS

A limited number of studies suggest benefits as a result of dietary interventions that are delivered by dietitians and focus on diet quality. We did not identify any studies that focussed on our primary outcome of nutritional status or studies that examined the timing or frequency of the nutritional assessment. This review emphasises the need for a wider body of high-quality evidence to support recommendations on what and how dietetic interventions are delivered by dietitians for adults with CKD.

KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update

The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for nutrition in kidney diseases since 1999. Since the publication of the first KDOQI nutrition guideline, there has been a great accumulation of new evidence regarding the management of nutritional aspects of kidney disease and sophistication in the guidelines process. The 2020 update to the KDOQI Clinical Practice Guideline for Nutrition in CKD was developed as a joint effort with the Academy of Nutrition and Dietetics (Academy). It provides comprehensive up-to-date information on the understanding and care of patients with chronic kidney disease (CKD), especially in terms of their metabolic and nutritional milieu for the practicing clinician and allied health care workers. The guideline was expanded to include not only patients with end-stage kidney disease or advanced CKD, but also patients with stages 1-5 CKD who are not receiving dialysis and patients with a functional kidney transplant. The updated guideline statements focus on 6 primary areas: nutritional assessment, medical nutrition therapy (MNT), dietary protein and energy intake, nutritional supplementation, micronutrients, and electrolytes. The guidelines primarily cover dietary management rather than all possible nutritional interventions. The evidence data and guideline statements were evaluated using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.

Dietary interventions for adults with chronic kidney disease

BACKGROUND

Dietary changes are routinely recommended in people with chronic kidney disease (CKD) on the basis of randomised evidence in the general population and non-randomised studies in CKD that suggest certain healthy eating patterns may prevent cardiovascular events and lower mortality. People who have kidney disease have prioritised dietary modifications as an important treatment uncertainty.

OBJECTIVES

This review evaluated the benefits and harms of dietary interventions among adults with CKD including people with end-stage kidney disease (ESKD) treated with dialysis or kidney transplantation.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register (up to 31 January 2017) through contact with the Information Specialist using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE, and EMBASE; handsearching conference proceedings; and searching the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-randomised RCTs of dietary interventions versus other dietary interventions, lifestyle advice, or standard care assessing mortality, cardiovascular events, health-related quality of life, and biochemical, anthropomorphic, and nutritional outcomes among people with CKD.

DATA COLLECTION AND ANALYSIS

Two authors independently screened studies for inclusion and extracted data. Results were summarised as risk ratios (RR) for dichotomous outcomes or mean differences (MD) or standardised MD (SMD) for continuous outcomes, with 95% confidence intervals (CI) or in descriptive format when meta-analysis was not possible. Confidence in the evidence was assessed using GRADE.

MAIN RESULTS

We included 17 studies involving 1639 people with CKD. Three studies enrolled 341 people treated with dialysis, four studies enrolled 168 kidney transplant recipients, and 10 studies enrolled 1130 people with CKD stages 1 to 5. Eleven studies (900 people) evaluated dietary counselling with or without lifestyle advice and six evaluated dietary patterns (739 people), including one study (191 people) of a carbohydrate-restricted low-iron, polyphenol enriched diet, two studies (181 people) of increased fruit and vegetable intake, two studies (355 people) of a Mediterranean diet and one study (12 people) of a high protein/low carbohydrate diet. Risks of bias in the included studies were generally high or unclear, lowering confidence in the results. Participants were followed up for a median of 12 months (range 1 to 46.8 months).Studies were not designed to examine all-cause mortality or cardiovascular events. In very-low quality evidence, dietary interventions had uncertain effects on all-cause mortality or ESKD. In absolute terms, dietary interventions may prevent one person in every 3000 treated for one year avoiding ESKD, although the certainty in this effect was very low. Across all 17 studies, outcome data for cardiovascular events were sparse. Dietary interventions in low quality evidence were associated with a higher health-related quality of life (2 studies, 119 people: MD in SF-36 score 11.46, 95% CI 7.73 to 15.18; I2 = 0%). Adverse events were generally not reported.Dietary interventions lowered systolic blood pressure (3 studies, 167 people: MD -9.26 mm Hg, 95% CI -13.48 to -5.04; I2 = 80%) and diastolic blood pressure (2 studies, 95 people: MD -8.95, 95% CI -10.69 to -7.21; I2 = 0%) compared to a control diet. Dietary interventions were associated with a higher estimated glomerular filtration rate (eGFR) (5 studies, 219 people: SMD 1.08; 95% CI 0.26 to 1.97; I2 = 88%) and serum albumin levels (6 studies, 541 people: MD 0.16 g/dL, 95% CI 0.07 to 0.24; I2 = 26%). A Mediterranean diet lowered serum LDL cholesterol levels (1 study, 40 people: MD -1.00 mmol/L, 95% CI -1.56 to -0.44).

AUTHORS' CONCLUSIONS

Dietary interventions have uncertain effects on mortality, cardiovascular events and ESKD among people with CKD as these outcomes were rarely measured or reported. Dietary interventions may increase health-related quality of life, eGFR, and serum albumin, and lower blood pressure and serum cholesterol levels.Based on stakeholder prioritisation of dietary research in the setting of CKD and preliminary evidence of beneficial effects on risks factors for clinical outcomes, large-scale pragmatic RCTs to test the effects of dietary interventions on patient outcomes are required.

Healthy Dietary Patterns and Risk of Mortality and ESRD in CKD: A Meta-Analysis of Cohort Studies

BACKGROUND AND OBJECTIVES

Patients with CKD are advised to follow dietary recommendations that restrict individual nutrients. Emerging evidence indicates overall eating patterns may better predict clinical outcomes, however, current data on dietary patterns in kidney disease are limited.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This systematic review aimed to evaluate the association between dietary patterns and mortality or ESRD among adults with CKD. Medline, Embase, and reference lists were systematically searched up to November 24, 2015 by two independent review authors. Eligible studies were longitudinal cohort studies reporting the association of dietary patterns with mortality, cardiovascular events, or ESRD.

RESULTS

A total of seven studies involving 15,285 participants were included. Healthy dietary patterns were generally higher in fruit and vegetables, fish, legumes, cereals, whole grains, and fiber, and lower in red meat, salt, and refined sugars. In six studies, healthy dietary patterns were consistently associated with lower mortality (3983 events; adjusted relative risk, 0.73; 95% confidence interval, 0.63 to 0.83; risk difference of 46 fewer (29-63 fewer) events per 1000 people over 5 years). There was no statistically significant association between healthy dietary patterns and risk of ESRD (1027 events; adjusted relative risk, 1.04; 95% confidence interval, 0.68 to 1.40).

CONCLUSIONS

Healthy dietary patterns are associated with lower mortality in people with kidney disease. Interventions to support adherence to increased fruit and vegetable, fish, legume, whole grain, and fiber intake, and reduced red meat, sodium, and refined sugar intake could be effective tools to lower mortality in people with kidney disease.

Effect of plant-based diets on obesity-related inflammatory profiles: a systematic review and meta-analysis of intervention trials

Plant-based dietary interventions have been proposed to reduce obesity induced chronic low-grade inflammation and hence prevent chronic disease risk; however, human evidence remains unclear. This systematic review and meta-analysis of intervention trials aimed to assess the effect of plant-based diets on obesity-related inflammatory biomarker profiles. Medline, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for articles published until January 2016 and mean differences in biomarkers of inflammatory status were assessed for: C-reactive protein (CRP), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-ɑ), soluble intercellular adhesion molecule 1 (sICAM), leptin, adiponectin and resistin. Of initially identified 2,583 publications, 29 met the meta-analysis inclusion criteria [a total of 2,689 participants]. Consumption of plant-based diets was associated with a reduction in the mean concentrations of the following biomarkers: CRP [effect size, -0.55 mg/l, 95% confidence intervals (CI): -0.78; -0.32, I²  = 94.4%], IL-6 [effect size, -0.25 ng/l, 95% CI: -0.56; 0.06, I²  = 74%], and, to some degree, sICAM (-25.07 ng/ml [95% CI: -52.32; 2.17, I²  = 93.2%]). No substantial effects were revealed for TNF-ɑ, resistin, adiponectin and leptin. Plant-based diets are associated with an improvement in obesity-related inflammatory profiles and could provide means for therapy and prevention of chronic disease risk.

The Effect of the Mediterranean Diet on Serum Total Antioxidant Capacity in Obese Patients: A Randomized Controlled Trial

OBJECTIVE

The aim of this work was to evaluate the combined effect of physical activity and 1 and 12 months' adherence to Mediterranean diet (MD) on serum total antioxidant capacity (TAC) in obese patients, as well as factors contributing to TAC.

METHODS

One hundred twenty-four patients were randomly assigned to either MD combined with physical activity or standard hypolypemic diet (SHD) with physical activity. Both groups received counseling and education during the initial week and were invited for the follow-up visits, where data on body weight and blood samples were collected. TAC was determined by Trolox equivalent antioxidant capacity and urate was determined using a uricase spectrophotometric method at the initial visit and after 1 and 12 months.

RESULTS

Eighty-four patients finished the 12-month program and were analyzed. The baseline and 1- and 12-month mean (±SD) TAC values in the MD group (n = 40) were 2.38 ± 0.48, 2.51 ± 0.47, and 2.47 ± 0.45 mmol Trolox equivalent (TE)/L, respectively. In the SHD group (n = 44), TAC values were 2.37 ± 0.49, 2.48 ± 0.49, and 2.31 ± 0.51 mmol TE/L, respectively. There was a statistically significant main effect for time (p < 0.001), as well as statistically significant time-diet interaction effect (p = 0.009). There was no statistically significant correlation between TAC and uric acid after 1 month (p = 0.733) or 12 months (p = 0.844) of the intervention. Based on the regression model, which included gender, diet, physical activity level, and percentage body weight change, the type of diet was the only significantly contributing factor to TAC change after the 12-month period, F = 3.867, df = 3, p = 0.012, R = 0.358, R(2) = 0.128.

CONCLUSION

This randomized controlled trial with diet and physical activity intervention and TAC as a primary outcome demonstrated initial antioxidant improvement in both MD and SHD groups and a long-term beneficial effect of MD. The results imply that diet composition-olive oil, nuts, and fish in particular-combined with physical activity modify antioxidant capacity.

Recent findings of studies on the Mediterranean diet: what are the implications for current dietary recommendations?

There is evidence from epidemiologic studies and clinical trials demonstrating that the Mediterranean dietary pattern reduces the risk of many chronic diseases, including cardiovascular disease (CVD), and the attendant risk factors. A Mediterranean-style diet reflects most food and nutrient goals in current dietary guidelines. Minor modifications to reduce sodium and saturated fat intake can be made to further meet recommendations. Including the Mediterranean diet in the list of recommended evidence-based dietary patterns offers an additional strategy for improving dietary habits, which may help individuals achieve better long-term adherence to dietary guidelines and sustain optimal reductions in CVD risk.

Mediterranean diet, kidney function, and mortality in men with CKD

BACKGROUND AND OBJECTIVES

Adherence to a Mediterranean diet may link to a better preserved kidney function in the community as well as a favorable cardiometabolic profile and reduced mortality risk in individuals with manifest CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Dietary habits were determined by 7-day dietary records in a population-based cohort of 1110 Swedish men (age 70 years) from 1991 to 1995, 506 of whom were considered to have CKD because of a GFR<60 ml/min per 1.73 m(2). A Mediterranean Diet Score was calculated, and participants were categorized as having low, medium, or high adherence. Adequate dietary reporters were identified with Goldberg cutoffs (n=597). Deaths were registered during a median follow-up of 9.9 years.

RESULTS

Compared with low adherents, medium and high adherents were 23% and 42% less likely to have CKD, respectively (adjusted odds ratio [95% confidence interval]=0.77 [0.57 to 1.05] and 0.58 [0.38 to 0.87], respectively, P for trend=0.04). Among those individuals with CKD, phosphate intake and net endogenous acid production were progressively lower across increasing adherence groups. No differences were observed regarding other cardiometabolic risk factors across adherence groups. As many as 168 (33%) CKD individuals died during follow-up. Compared with low adherents, proportional hazards regression associated medium and high adherents to a 25% and 23% lower mortality risk, respectively (adjusted hazard ratio [95% confidence interval]=0.75 [0.52 to 1.06] and 0.77 [0.44 to 1.36], respectively, P for trend=0.10). Sensitivity analyses showed significant and stronger associations when only adequate dietary reporters were considered.

CONCLUSIONS

Adherence to a Mediterranean dietary pattern is associated with lower likelihood of CKD in elderly men. A greater adherence to this diet independently predicted survival in those patients with manifest CKD. Clinical trials are warranted to test the hypothesis that following such a diet could improve outcomes (independent of other healthy lifestyles) in CKD patients.

Postprandial antioxidant gene expression is modified by Mediterranean diet supplemented with coenzyme Q(10) in elderly men and women

Postprandial oxidative stress is characterized by an increased susceptibility of the organism towards oxidative damage after consumption of a meal rich in lipids and/or carbohydrates. We have investigated whether the quality of dietary fat alters postprandial gene expression and protein levels involved in oxidative stress and whether the supplementation with coenzyme Q(10) (CoQ) improves this situation in an elderly population. Twenty participants were randomized to receive three isocaloric diets each for 4 weeks: Mediterranean diet supplemented with CoQ (Med + CoQ diet), Mediterranean diet (Med diet), saturated fatty acid-rich diet (SFA diet). After 12-h fast, volunteers consumed a breakfast with a fat composition similar to that consumed in each of the diets. Nrf2, p22(phox) and p47(phox), superoxide dismutase 1 and 2 (SOD1 and SOD2), glutathione peroxidase 1 (GPx1), thiorredoxin reductase (TrxR) gene expression and Kelch-like ECH associating protein 1 (Keap-1) and citoplasmic and nuclear Nrf2 protein levels were determined. Med and Med + CoQ diets induced lower Nrf2, p22(phox), p47(phox), SOD1, SOD2 and TrxR gene expression and higher cytoplasmic Nrf2 and Keap-1 protein levels compared to the SFA diet. Moreover, Med + CoQ diet produced lower postprandial Nrf2 gene expression and lower nuclear Nrf2 protein levels compared to the other diets and lower GPx1 gene expression than the SFA diet. Our results support the antioxidant effect of a Med diet and that exogenous CoQ supplementation has a protective effects against free radical overgeneration through the lowering of postprandial oxidative stress modifying the postprandial antioxidant protein levels and reducing the postprandial expression of antioxidant genes in peripheral blood mononuclear cells.

Levels of TBARS are inversely associated with lowest oxygen saturation in obese patients with OSAS

PURPOSE

The aim of this study was to investigate the most important factors that determine lipid peroxidation in obese patients with obstructive sleep apnoea syndrome (OSAS).

METHODS

Twenty-one obese patients with OSAS based on overnight attended polysomnography were included. Thiobarbituric acid reactive substances (TBARS) were measured in serum. Anthropometric measurements were carried out. Dietary habits were assessed by a standardised food frequency questionnaire.

RESULTS

Spearman's correlation analysis showed significant positive correlations between TBARS and apnoea-hypopnoea index and desaturations/hour while negative between TBARS and mean/lowest oxygen saturation. The most significant predicting factor in the multiple linear regression model was lowest oxygen saturation.

CONCLUSIONS

This study has revealed an independent association between lowest oxygen saturation and TBARS levels after controlling for age, gender, diet and obesity in predominantly male patients with moderate to severe OSAS.

Postprandial antioxidant effect of the Mediterranean diet supplemented with coenzyme Q10 in elderly men and women

Postprandial oxidative stress is characterized by an increased susceptibility of the organism towards oxidative damage after consumption of a meal rich in lipids and/or carbohydrates. We have investigated whether the quality of dietary fat alters postprandial cellular oxidative stress and whether the supplementation with coenzyme Q(10) (CoQ) lowers postprandial oxidative stress in an elderly population. In this randomized crossover study, 20 participants were assigned to receive three isocaloric diets for periods of 4 week each: (1) Mediterranean diet supplemented with CoQ (Med+CoQ diet), (2) Mediterranean diet (Med diet), and (3) saturated fatty acid-rich diet (SFA diet). After a 12-h fast, the volunteers consumed a breakfast with a fat composition similar to that consumed in each of the diets. CoQ, lipid peroxides (LPO), oxidized low-density lipoprotein (oxLDL), protein carbonyl (PC), total nitrite, nitrotyrosine plasma levels, catalase, superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities and ischemic reactive hyperaemia (IRH) were determined. Med diet produced a lower postprandial GPx activity and a lower decrease in total nitrite level compared to the SFA diet. Med and Med+CoQ diets induced a higher postprandial increase in IRH and a lower postprandial LPO, oxLDL, and nitrotyrosine plasma levels than the SFA diet. Moreover, the Med+CoQ diet produced a lower postprandial decrease in total nitrite and a greater decrease in PC levels compared to the other two diets and lower SOD, CAT, and GPx activities than the SFA diet.In conclusion, Med diet reduces postprandial oxidative stress by reducing processes of cellular oxidation and increases the action of the antioxidant system in elderly persons and the administration of CoQ further improves this redox balance.

Relações da dieta ovo-lácteo-vegetariana com o exercício físico e as enzimas antioxidantes superóxido dismutase e catalase

OBJETIVO: O objetivo deste trabalho foi estudar a influência da dieta ovo-lácteo-vegetariana e do exercício físico extenuante sobre as atividades das enzimas catalase e superóxido dismutase em dez indivíduos masculinos, jovens e saudáveis. MÉTODOS: O controle alimentar aplicou-se por quatro meses. Antes disso, foram recolhidas amostras de sangue em estado basal e cinco minutos após o exercício físico extenuante efetuado em esteira rolante. O mesmo procedimento foi aplicado após o controle alimentar. RESULTADOS: Os resultados mostraram que a dieta ovo-lácteo-vegetariana, em condições de repouso, reduziu de forma significativa a atividade da enzima catalase em 18,98% (p<0,05) e aumentou, também de forma significativa, a atividade da enzima superóxido dismutase em 77,84% (p<0,001). Depois do exercício físico extenuante, a dieta ovo-lácteo-vegetariana reduziu a atividade da enzima catalase de forma significativa em 26,11% (p<0,05) e não alterou a atividade da enzima superóxido dismutase. CONCLUSÃO: Os resultados indicam que tanto as atividades da catalase como da superóxido dismutase são sensíveis a uma dieta ovo-lácteo-vegetariana adequada.

The effect of L-ascorbic acid and/or tocopherol supplementation on electrophysiological parameters of the colon of rats chronically exposed to lead

Background

The aim of this study was to assess the effect of diet supplementation with L-ascorbic acid (500 mg/L), tocopherol (3 mg/kg b.w.), and/or a water soluble analog of tocopherol (Trolox) (48 mg/L) on ion transport in the colon of rats subjected to a chronic exposure (9 months) to 0.1% lead acetate in drinking water.

Material/Methods

The electrophysiological parameters of the colon wall were measured with Ussing methods. Lead content in the whole blood was analyzed by graphite furnace atomic absorption spectrometry (GFAAS) using Zeeman correction. L-ascorbic acid and tocopherol in plasma was measured by high performance liquid chromatography. Immunohistochemical reaction was carried out for visualization of occludin, the intracellular tight junction protein.

Results

We showed a strong inhibitory effect of lead on the electrophysiological parameters, changes in intestinal permeability, disappearance of junctional occludin, decreased amount of mucus covering the colon surface, and the accumulation of PAS-positive substance in the apical region of the cytoplasm in the absorptive cells.

Conclusions

Supplementation with tocopherol or Trolox did not exert a beneficial influence on the studied parameters. L-ascorbic acid positively influenced the examined electrophysiological parameters, as it cancelled the inhibitory influence of lead on ion transport in the rat colon. L-ascorbic acid also protected against tight junction disruption of epithelial cells in the colon of the lead-treated rats. A similar effect was observed in the group of rats receiving lead and supplemented with L-ascorbic acid plus Trolox.

Postprandial oxidative stress is modified by dietary fat: evidence from a human intervention study

Previous evidence supports the concept that increased oxidative stress may play an important role in MetS (metabolic syndrome)-related manifestations. Dietary fat quality has been proposed to be critical in oxidative stress and the pathogenesis of the MetS. In the present study, we investigated whether oxidative stress parameters are affected by diets with different fat quantity and quality during the postprandial state in subjects with the MetS. Patients were randomly assigned to one of four isoenergetic diets distinct in fat quantity and quality for 12 weeks: a high-saturated-fatty-acid (HSFA) diet, a high-mono-unsaturated-fatty-acid (HMUFA) diet and two low-fat/high-complex carbohydrate diets [supplemented with 1.24 g/day of long-chain n−3 polyunsaturated fatty acid (LFHCC n−3) or with 1 g/day of sunflower oil high in oleic acid (LFHCC) as placebo]. The HMUFA diet enhanced postprandial GSH (reduced glutathione) levels and the GSH/GSSH (oxidized glutathione) ratio, compared with the other three diets. In addition, after the HMUFA-rich diet postprandial lipid peroxide levels, protein carbonyl concentrations, SOD (superoxide dismutase) activity and plasma H2O2 levels were lower compared with subjects adhering to the HSFA-rich diet. Both LFHCC diets had an intermediate effect relative to the HMUFA and HSFA diets. In conclusion, our data support the notion that the HMUFA diet improves postprandial oxidative stress in patients with the MetS. These findings suggest that the postprandial state is important for understanding the possible cardioprotective effects associated with mono-unsaturated dietary fat, particularly in subjects with the MetS.

Association between adherence to the Mediterranean diet and oxidative stress

BACKGROUND

The cardioprotective property of the Mediterranean diet has been attributed to its antioxidant capacity, but direct investigation of this mechanism has been limited.

OBJECTIVE

We examined the association between the Mediterranean diet and an established plasma marker of oxidative stress, the ratio of reduced to oxidized glutathione (GSH/GSSG), in a well-controlled study of twins.

DESIGN

We administered the Willett food-frequency questionnaire to 138 monozygotic and dizygotic twin pairs and to 21 unpaired twins and derived a score measuring adherence to the Mediterranean diet. Fasting plasma GSH and GSSG concentrations were measured to calculate the GSH/GSSG ratio. The higher the ratio, the lower the oxidative stress. Mixed-effect regression analysis was used to partition the association into between- and within-twin pair differences. When within-pair effects are examined, twins are matched for sociodemographic and familial factors.

RESULTS

A one-unit increment in the diet score was associated with a 7% higher GSH/GSSG ratio (P = 0.03) after adjustment for energy intake, other nutritional factors, cardiovascular disease risk factors, and medication use. The association persisted within twin pairs: a one-unit within-pair absolute difference in the diet score was associated with a 10% (95% CI: 2.7, 18.0) higher GSH/GSSG ratio in the twin with the higher score than in the co-twin with the lower score (P = 0.007). Results were similar in monozygotic and dizygotic twin pairs.

CONCLUSIONS

The association between the Mediterranean diet and plasma oxidative stress is robust and is not confounded by genetic or shared environmental factors. Decreased oxidative stress is a plausible mechanism linking the Mediterranean diet to reduced cardiovascular disease risk.

Dieta afro-bahiana, estrés oxidativo y ejercício físico

OBJETIVO: El objetivo de este trabajo fue estudiar el efecto de la dieta afro-bahiana sobre el estrés oxidativo inducido por el ejercicio físico extenuante en 17 individuos jóvenes y saludables. MÉTODOS: La dieta afro-bahiana se compone principalmente de carne roja, aceite de palma, zumo de frutas, raíces, harina de mandioca y cereales. El control alimenticio se extendió por 4 meses. Antes del control alimenticio, se retiraron muestras de sangre en estado basal y cinco minutos después de un ejercicio físico extenuante en tapiz rodante. El mismo procedimiento fue seguido después del control alimenticio. Para analizar el efecto de la dieta y del ejercicio físico extenuante se compararon los indicadores antioxidantes, catalasa y superóxido dismutasa y el estrés oxidativo por la peroxidación lipídica, determinada por el análisis del malonaldeído en eritrocitos. RESULTADOS: Los resultados muestran que la dieta, en condición de reposo, no influenció significativamente el estatus antioxidante de las enzimas catalasa y superóxido dismutasa ni la concentración de análisis del malonaldeído. Se observa, no obstante, que después de un ejercicio físico extenuante, la actividad de la catalasa, tanto con dieta libre como después de la dieta afro-bahiana, aumentó de forma significativa (p<0,05) en 19,49 y 11,74%, respectivamente. La actividad del superóxido dismutasa y concentración de análisis del malonaldeído no se alteraron. La actividad de la catalasa después del ejercicio físico extenuante fue significativamente menor (p<0,05) después de la dieta afro-baiana (26,11%). CONCLUSIONES: Estos datos sugieren la presencia de antioxidantes en la dieta afro-bahiana capaces de interferir en el aumento de la actividad de la catalasa inducida por el ejercicio físico extenuante.

The use of neural networks in evaluation of the direction and dynamics of changes in lipid parameters in kidney transplant patients on the Mediterranean diet

OBJECTIVE

The objective of the study was to assess whether neural networks can be a tool useful in the evaluation of the effect of the Mediterranean diet (MD) on the direction and dynamics of selected parameters.

DESIGN

Randomized, prospective study.

SETTING

Outpatient Clinic of the Department of Nephrology, Transplantology, and Internal Medicine.

PATIENTS AND INTERVENTION

The study group consisted of 21 patients after kidney transplantation whose diet complied with the MD; the control group included 16 patients (also after transplantation) on a low-fat diet, isocaloric with the study diet.

MAIN OUTCOME MEASURES

Anthropometry, plasma lipids, chromatography of triacylglycerols and fatty acids, and activity of superoxide dismutase and catalase were measured in both groups. Statistical analysis was done with the SNN (Statistica Neural Networks) StatSoft software package.

RESULTS

The advantage of neural networks is the possibility of the dynamic presentation of a process taking place in a biological system. In the MD group in the first months of use of the diet, the cholesterol level was reduced only in the group of young and middle-aged patients. This tendency was not observed among elderly patients, among whom a small reduction of the total cholesterol level was noted only at the end of the observation period. In control group at the beginning of the observation, the plasma total cholesterol level was proportional to the patient's age. After 6 months, the total cholesterol increased in young patients and redacted in the group of elderly patients.

CONCLUSIONS

We concluded that the MD diet would be ideal for posttransplantation patients without serious pathologic dyslipidemia. In the case of patients with substantial dyslipidemia, appropriate pharmacologic treatment lowering proatherosclerotic lipid levels should be used in combination with the MD. Artificial neural networks (ANNs) were a useful tool in modeling biological parameters, showing dynamics of the studied interactions in a very detailed way. ANN is the most suitable method for investigations with many variables, interconnected nonlinearly; therefore, this method allows for a more general approach to biological problems. However, it should be noted that considerable data sets are required to obtain a satisfactory fit to the data. Moreover, to ensure the predictive power of this method for new cases, the representative database is indispensable. In spite of these demands, ANN is a prospective tool for reliable, quick assessments and predictions.