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.

Background There is a growing interest in the role of inflammageing for chronic disease development. Cytokines are potent soluble immune mediators that can be used as target biomarkers of inflammageing; however, their measurement in human samples has been challenging. This study aimed to assess the reliability of a pro- and anti-inflammatory cytokine panel in a sample of healthy people measured with a novel electrochemiluminescent multiplex immunoassay platform (Meso Scale Discovery, MSD), and to characterize their associations with metabolic and inflammatory phenotypes. Results Overall, the majority of cytokines were above the limit of detection (in at least 85.3% of the samples). Cytokines IL-6, IL-8, TNF-α, IL-10, IL-13, and IFN-γ showed overall good to fair reliability (ICC > 0.40), whereas IL-1β, IL-2, IL-4, and IL-12p70 showed poor reliability (ICC < 0.40). The reliability estimates were not substantially influenced by participants’ age, sex, obesity and C-reactive protein (CRP) levels. As expected, cytokine concentrations were elevated with advanced age most pronouncedly for IL-6, IL-8, Il-2, IFN- γ, and TNF-α. No major associations with metabolic phenotypes were observed for most cytokines, with the exception of a positive association between IL-6 and TNF-α with body mass index and CRP (ρ: 0.36; ρ: 0.20; ρ: 0.53; ρ: 0.22, respectively), and IFN-γ and IL-10 with CRP (ρ: 0.23 and ρ: 0.19, respectively). Conclusions Single measurements of selected cytokines using MSD platform, including IL-6, IL-8, IL-10, IL-13, TNF-α, and IFN-γ have shown to be representative of an individual’s average level over time and could be suitable for use in prospective epidemiological and clinical studies. Such studies are highly warranted to characterize associations of cytokines with phenotypes and diseases associated with ageing. Electronic supplementary material The online version of this article (10.1186/s12979-019-0151-1) contains supplementary material, which is available to authorized users.

Altered immune cell phenotype and chronic inflammation are key features shared by various chronic diseases. Evidence from nutritional interventions aimed at alleviating inflammation could be a promising approach for the prevention of adverse health outcomes. We therefore aimed to conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) to summarize the recent evidence on the effects of dietary patterns on inflammatory and immune-related biomarkers in humans. PubMed, Medline, and Web of Science databases were searched for publications up to October 2020. In total, 22 RCTs were included in the meta-analysis conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The Mediterranean diet appeared as the dietary pattern that showed the most prominent reductions of inflammatory biomarkers such as IL-6 [mean difference (MD): –1.07 pg/mL (95% CI: –1.94, –0.20); I2: 96%], IL-1β [MD: –0.46 pg/mL (95% CI: –0.66, –0.25); I2: 0%], and C-reactive protein [MD: –1.00 mg/L (95% CI: –2.02, 0.01); I2: 100%]. No substantial effects were observed for the additional dietary patterns studied in intervention research, including the Dietary Adherence to Stop Hypertension diet, and the vegetarian or vegan diets. Future large-scale multifactorial intervention studies are warranted to allow direct comparison of various dietary patterns in relation to a range of biomarkers reflecting multiple inflammatory and immune-related pathways.

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Nutritional interventions in morbidly obese individuals that effectively reverse a pro-inflammatory state and prevent obesity-associated medical complications are highly warranted. Our aim was to evaluate the effect of high (HP) or low (LP) protein diets on circulating immune-inflammatory biomarkers, including C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-a), interleukin-10 (IL-10), monocyte chemoattractant protein-1 (MCP-1), chemerin, omentin, leptin, total adiponectin, high molecular weight adiponectin, and fetuin-A. With this aim, 18 people with morbid obesity were matched into two hypocaloric groups: HP (30E% protein, n = 8) and LP (10E% protein, n = 10) for three weeks. Biomarkers were measured pre and post intervention and linear mixed-effects models were used to investigate differences. Consuming HP or LP diets resulted in reduced CRP (HP: −2.2 ± 1.0 mg/L, LP: −2.3 ± 0.9 mg/L) and chemerin (HP: −17.9 ± 8.6 ng/mL, LP: −20.0 ± 7.4 ng/mL), with no statistically significant differences by diet arm. Participants following the LP diet showed a more pronounced decrease in leptin (−19.2 ± 6.0 ng/mL) and IL-6 (−0.4 ± 0.1 pg/mL) and an increase in total adiponectin (1.6 ± 0.6 µg/mL). Changes were also observed for the remaining biomarkers to a smaller degree by the HP than the LP hypocaloric diet, suggesting that a LP hypocaloric diet modulates a wider range of immune inflammatory biomarkers in morbidly obese individuals.

Objective: Chemerin is a novel inflammatory biomarker suggested to play a role in the development of metabolic disorders, providing new avenues for treatment and prevention. Little is known about the factors that predispose elevated chemerin concentrations. We therefore aimed to explore a range of lifestyle-associated, dietary, and metabolic factors as potential determinants of elevated chemerin concentrations in asymptomatic adults. Design: We used cross-sectional data from a random subsample of 2,433 participants (1,494 women, 939 men) aged 42-58 years of the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam cohort. Methods: Random forest regression (RFR) was applied to explore the relative importance of 32 variables as statistical predictors of elevated chemerin concentrations overall and by sex. Multivariable-adjusted linear regression was applied to evaluate associations between selected predictors and chemerin concentrations. Results: Results from RFR suggested BMI, waist circumference, C-reactive protein, fatty liver index, and estimated glomerular filtration rate as the strongest predictors of chemerin concentrations. Additional predictors included sleeping duration, alcohol, red and processed meat, fruits, sugar sweetened beverages (SSB), vegetables, dairy and refined grains. Collectively, these factors explained 32.9% variation of circulating chemerin. Multivariable-adjusted analyses revealed linear associations of elevated chemerin with metabolic parameters, obesity, longer sleep, higher intakes of red meat and SSB, and lower intakes of dairy. Conclusions: These findings come in support of the role of chemerin as a biomarker characterizing inflammatory and metabolic phenotypes in asymptomatic adults. Modifiable dietary and lifestyle-associated determinants of elevated chemerin concentrations require further evaluation in a prospective study setting.

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Background:Nutritional interventions in morbidly obese individuals that effectively reverse pro-inflammatory state and prevent obesity-associated medical complications are highly warranted. Our aim was to evaluate the effect of high- (HP) or low- (LP) protein diets on circulating immune-inflammatory biomarkers, includingC-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-a), interleukin-10 (IL-10), monocyte chemoattractant protein-1 (MCP-1),chemerin, omentin, leptin, total adiponectin, high molecular weight adiponectin and fetuin-A.Methods:18 people with morbid obesity were matched into two hypocaloric diet groups: HP (30E% protein, n=8) and LP (10E% protein, n=10) for three weeks.Biomarkers were measured pre-post intervention.We used linear mixed-effects models to investigate differences of least squares means for biomarkers, adjusted for age, sex, BMI, and baseline value.Results:Consuming HP or LP diets resulted in reduced CRP(HP: -2.2 ± 1.0 mg/l, LP: -2.3 ± 0.9 mg/l) and chemerin (HP: -17.9 ± 8.6 ng/ml, LP: -20.0 ± 7.4 ng/ml). People following the LP diet showed decreased leptin (-19.2± 6.0 ng/ml), IL-6 (-0.4 ± 0.1pg/ml) and increased total adiponectin (1.6 ± 0.6µg/ml). Changes were observed for remaining biomarkers yetto a smaller degree.Conclusions:These data suggest LP dietsmodulatea wider range of immune-inflammatory biomarkers compared to HP diets in morbidly obese individuals.Larger trials are needed to allow firm conclusions on the suggested effects.Trial registration: DRKS00009509. Registered 25 January 2016 – Retrospectively registered, www.drks.de