Intake of dietary fibre, red and processed meat and risk of late-onset Chronic Inflammatory Diseases: A prospective Danish study on the "diet, cancer and health" cohort

Association of Healthy Lifestyle Behaviours With Incident Inflammatory Bowel Disease: A Population-Based Prospective Cohort Study

BACKGROUND

The combined effects of some modifiable lifestyle factors on incident inflammatory bowel disease (IBD) are uncertain.

AIMS

To evaluate the combined association between healthy lifestyle behaviours and IBD incidence.

METHODS

This population-based prospective cohort study used data from the UK Biobank. We included 105,715 participants aged 40-70 who had no IBD diagnosis at baseline in the analyses. The five healthy lifestyle behaviours that we studied were never smoking, optimal sleep, high level of vigorous physical activity, high dietary quality, and moderate alcohol intake. The outcome was the overall incidence of IBD and individual incidences of Crohn's disease (CD) and ulcerative colitis (UC). We derived hazard ratios (HR) and 95% confidence intervals (CI) for associations.

RESULTS

The multivariable adjusted HRs (95% CI) associated with having 1, 2 and 3-5 healthy lifestyle behaviours for IBD incidence compared with those with none of these behaviours were 0.75 (0.59-0.97), 0.72 (0.56-0.92), and 0.50 (0.37-0.68), respectively (p for trend < 0.001). We observed similar findings for CD and UC. Only never smoking exhibited significant independent inverse associations with the overall incidence of IBD (HR 0.70, 95% CI 0.58-0.83, p < 0.001) and the incidence of UC (HR 0.58, 95% CI 0.48-0.72, p < 0.001).

CONCLUSIONS

Healthy lifestyle behaviours are significantly associated with lower IBD incidence in middle-aged and elderly individuals, suggesting the potential of lifestyle modifications as a primary prevention strategy for IBD.

Association Between Ultra-Processed Food Intake and Self-Reported Arthritis

INTRODUCTION

Ultra-processed foods are typically high in fat, salt, sugar, and food additives, which may contribute to the development of arthritis. This study examined the association between ultra-processed food intake and the presence of self-reported arthritis.

METHODS

The 2001-2018 U.S. National Health and Nutrition Examination Survey data was used to analyze the association between ultra-processed food intake and arthritis in 2025. Ultra-processed foods were identified by applying Nova classifications to 24-hour dietary recall data and expressed as a percentage of daily total energy intake. The outcomes were self-reported physician's diagnosis of arthritis, osteoarthritis, and rheumatoid arthritis. Survey-weighted logistic regressions were conducted to analyze associations between ultra-processed food intake and outcomes, controlling for age, gender, race/ethnicity, smoking status, health insurance status, and poverty-to-income ratio.

RESULTS

UPFs contributed 55.2% of the daily total energy intake in the U.S.

POPULATION

After adjusting for covariates, a positive association was found between daily total energy intake from ultra-processed foods and self-reported arthritis (AOR associated with each 10-percentage point increase in intake: 1.04; 95% CI=1.02, 1.06). For the second, third, and fourth quartiles of ultra-processed food intake, the AOR of arthritis was 1.14 (95% CI=1.04, 1.25), 1.22 (95% CI=1.10, 1.35), and 1.27 (95% CI=1.14, 1.41), respectively (p for linear trend <0.001). A positive association was also observed between ultra-processed food intake and rheumatoid arthritis (AOR=1.05; 95% CI=1.02, 1.09) but not for osteoarthritis.

CONCLUSIONS

In this nationally representative sample of U.S. adults, higher consumption of ultra-processed foods was associated with overall arthritis and rheumatoid arthritis.

Impact of Dietary Fiber on Inflammation in Humans

Cohort studies consistently show that a high intake of cereal fiber and whole-grain products is associated with a decreased risk of type 2 diabetes (T2DM), cancer, and cardiovascular diseases. Similar findings are also reported for infectious and chronic inflammatory disorders. All these disorders are at least partially caused by inflammaging, a chronic state of inflammation associated with aging and Metabolic Syndrome. Surprisingly, insoluble (cereal) fiber intake consistently shows stronger protective associations with most long-term health outcomes than soluble fiber. Most humans consume soluble fiber mainly from sweet fruits, which usually come with high levels of sugar, counteracting the potentially beneficial effects of fiber. In both observational and interventional studies, high-fiber diets show a beneficial impact on inflammation, which can be attributed to a variety of nutrients apart from dietary fiber. These confounders need to be considered when evaluating the effects of fiber as part of complex dietary patterns. When assessing specific types of fiber, inulin and resistant starch clearly elicit anti-inflammatory short-term effects, while results for pectins, beta-glucans, or psyllium turn out to be less convincing. For insoluble fiber, promising but sparse data have been published so far. Hypotheses on putative mechanisms of anti-inflammatory fiber effects include a direct impact on immune cells (e.g., for pectin), fermentation to pleiotropic short-chain fatty acids (for fermentable fiber only), modulation of the gut microbiome towards higher levels of diversity, changes in bile acid metabolism, a differential release of gut hormones (such as the glucose-dependent insulinotropic peptide (GIP)), and an improvement of insulin resistance via the mTOR/S6K1 signaling cascade. Moreover, the contribution of phytate-mediated antioxidative and immune-modulatory means of action needs to be considered. In this review, we summarize the present knowledge on the impact of fiber-rich diets and dietary fiber on the human inflammatory system. However, given the huge heterogeneity of study designs, cohorts, interventions, and outcomes, definite conclusions on which fiber to recommend to whom cannot yet be drawn.

Investigating causal associations between pork intake and multiple sclerosis using Mendelian randomization: Insights from large-scale GWAS data in European populations

BACKGROUND

Observational studies propose associations between dietary factors and multiple sclerosis (MS). However, the causal nature of these relationships remains unclear. This study aims to determine whether nutritional factors causally influence MS risk through Mendelian randomization (MR) analysis.

METHODS

Summary statistics for 15 common dietary factors were derived from the Genome-Wide Association Study (GWAS) conducted by the Medical Research Council Integrated Epidemiology Unit (MRC-IEU). The GWAS data of MS were sourced from the International Multiple Sclerosis Genetics Consortium (IMSGC), including 14,498 cases and 24,091 controls. The inverse-variance weighted (IVW) method was utilized as the primary analytical approach to estimate causality, while Cochran's Q test assessed heterogeneity. MR-Egger (MRE) and MR-Pleiotropy RESidual Sum and Outlier (MR-PRESSO) were employed to detect pleiotropy and conduct sensitivity analyses.

RESULTS

We executed univariable- and multivariable-adjusted MR analyses, incorporating adjustments for past tobacco smoking, particulate matter air pollution (PM2.5) and moderate to vigorous physical activity. The univariable Mendelian randomization (UVMR) analysis elucidated potential causal relationships concerning the risk of MS for only two dietary factors: pork intake (odds ratio [OR] = 6.764, 95% confidence interval [CI]: 1.772-25.814, p = 0.005 by IVW) and fish/liver oil dietary supplements (OR = 0.119, 95%CI: 0.032-0.444, p = 0.002 by IVW). In the multivariate Mendelian randomization (MVMR) analysis, the significant causal relationship between pork intake and MS remained robust even after adjusting for potential confounders. Conversely, after adjusting for these confounders, the initially observed causal associations between fish/liver oil dietary supplements and MS ceased to be statistically significant.

CONCLUSIONS

Our findings suggest that pork intake could increase the risk of MS. Other nutritional factors analyzed in this study did not exhibit significant correlations with MS.

Dose-Response Associations Between Diet and Risk of Rheumatoid Arthritis: A Meta-Analysis of Prospective Cohort Studies

To provide a systematic and quantitative summary of dietary factors and rheumatoid arthritis (RA) risk. A systematic review and meta-analysis included prospective cohort studies from 2000 to 2024 reporting relative risks (RRs) with 95% confidence intervals (CIs) for RA incidence relating to 32 different dietary exposures. Linear and non-linear dose-response analyses were conducted. Thirty studies were included, involving 2,986,747 participants with 9,677 RA cases. Linear dose-response analysis suggested that each 2-unit per week increase in total alcohol intake was linked to 4% risk reduction (RR (95%-CI), heterogeneity (I2), NutriGrade score: 0.96 (0.94, 0.98), 58%, moderate certainty), and beer consumption was associated with a 10% reduction per 2 units/week increase (0.90 (0.84, 0.97), 0%, very low certainty). Each 2-unit/week increase in total alcohol intake was associated with a 3% decrease in seropositive RA risk (0.97 (0.96, 0.99), 28%, moderate certainty). Increased intakes of fruit (per 80 g/day) and cereals (per 30 g/day) were associated with 5% (0.95 (0.92, 0.99), 57%, moderate certainty) and 3% (0.97 (0.96, 0.99), 20%, moderate certainty) reduced risk, respectively. Conversely, tea consumption showed a 4% increased risk per additional cup/day (1.04 (1.02, 1.05), 0%, moderate certainty). Non-linear associations were observed for total coffee, vegetables, oily fish, and vitamin D supplementation. Data on dietary patterns and specific micronutrients were limited. The findings suggest that moderate alcohol consumption and a higher intake of fruits, oily fish, and cereals are associated with a reduced risk of RA, while tea and coffee may be linked to an increased risk. Optimising dietary intake of certain food components may reduce RA risk, despite moderate-quality evidence.

Weissella paramesenteroides NRIC1542 inhibits dextran sodium sulfate-induced colitis in mice through regulating gut microbiota and SIRT1/NF-κB signaling pathway

Inflammatory bowel disease (IBD) is a kind of recurrent inflammatory disorder of the intestinal tract. The purpose of this study was to investigate the effects of Weissella paramesenteroides NRIC1542 on colitis in mice. A colitis model was induced by adding 1.5% DSS to sterile distilled water for seven consecutive days. During this process, mice were administered different concentrations of W. paramesenteroides NRIC1542. Colitis was assessed by DAI, colon length and hematoxylin-eosin staining of colon sections. The expressions of NF-κB signaling proteins and the tight junction proteins ZO-1 and occludin were detected by western blotting, and the gut microbiota was analyzed by 16S rDNA. The results showed that W. paramesenteroides NRIC1542 significantly reduced the degree of pathological tissue damage and the levels of TNF-α and IL-1β in colonic tissue, inhibiting the NF-κB signaling pathway and increasing the expression of SIRT1, ZO-1 and occludin. In addition, W. paramesenteroides NRIC1542 can modulate the structure of the gut microbiota, characterized by increased relative abundance of Muribaculaceae_unclassified, Paraprevotella, Prevotellaceae_UCG_001 and Roseburia, and decrease the relative abundance of Akkermansia and Alloprevotella induced by DSS. The above results suggested that W. paramesenteroides NRIC1542 can protect against DSS-induced colitis in mice through anti-inflammatory, intestinal barrier maintenance and flora modulation.

Role of diet in prevention versus treatment of Crohn's disease and ulcerative colitis

Diet is a modifiable risk factor for disease course and data over the past decade have emerged to indicate its role in Crohn's disease (CD) and ulcerative colitis (UC). However, literature is riddled with misinterpretation of data, often leading to unexpected or conflicting results. The key understanding is that causative factors in disease development do not always proceed to an opportunity to change disease course, once established. Here, we discuss the data on dietary influences in three distinct disease states for CD and UC-predisease, active disease and quiescent disease. We appraise the literature for how our dietary recommendations should be shaped to prevent disease development and if or how that differs for CD and UC induction therapy and maintenance therapy. In UC, principles of healthy eating are likely to play a role in all states of disease. Conversely, data linking dietary factors to CD prevention and treatment are paradoxical with the highest quality evidence for CD treatment being exclusive enteral nutrition, a lactose, gluten and fibre-free diet comprising solely of ultraprocessed food-all dietary factors that are not associated or inversely associated with CD prevention. High-quality evidence from dietary trials is much awaited to expand our understanding and ultimately lead our dietary recommendations for targeted patient populations.

Adherence to dietary guidelines, and the risk of developing rheumatoid arthritis: results from a nested case-control study

OBJECTIVES

To examine the relationship between adherence to dietary guidelines and the risk of developing RA.

METHODS

Participants in the Malmö Diet and Cancer Study (MDCS) cohort diagnosed with RA were identified through register linkage and validated in a structured review. Four controls per case were selected, matched for sex, year of birth, and year of inclusion in the MDCS. Diet was assessed at baseline (1991-1996) using a validated diet history method. A Diet Quality Index (DQI) based on adherence to the Swedish dietary guidelines including intakes of fibre, vegetables and fruits, fish and shellfish, saturated fat, polyunsaturated fat, and sucrose, was used. The associations between the DQI and its components and the risk of RA were assessed using conditional logistic regression analysis, adjusting for total energy intake, smoking, leisure time physical activity and alcohol consumption.

RESULTS

We identified 172 validated cases of incident RA in the cohort. Overall adherence to the dietary guidelines was not associated with the risk of RA. Adherence to recommended fibre intake was associated with decreased risk of RA in crude and multivariable-adjusted analyses, with odds ratios (ORs) 0.60 (95% CI 0.39, 0.93) and 0.51 (95% CI 0.29, 0.90), respectively, compared with subjects with non-adherence.

CONCLUSIONS

Reaching the recommended intake level of dietary fibre, but not overall diet quality, was independently associated with decreased risk of RA. Further studies are needed to assess the role of different food sources of dietary fibre in relation to risk of RA and the underlying mechanisms.

The impact of dietary interventions in psoriatic arthritis

PURPOSE OF REVIEW

Psoriatic arthritis (PsA) is a common form of inflammatory arthritis that affects people with psoriasis. Both psoriasis and PsA are associated with metabolic diseases including obesity, hypertension, hyperlipidaemia, diabetes mellitus, fatty liver disease, and cardiovascular disease including myocardial infarction. Dietary interventions for psoriatic disease have been of great interest, particularly among patients with PsA.

RECENT FINDINGS

Herein, we review the evidence for dietary intervention in psoriatic arthritis. To date, weight loss among patients who are obese has the greatest evidence for benefit. We also examine the evidence for fasting, nutrient supplementation, and specific diets as adjunct therapeutic strategies.

SUMMARY

While the data do not clearly support a single dietary intervention across the disease, weight loss among those who are obese results in improved PsA disease activity and physical function. Additional studies are needed to better understand the impact of diet on psoriatic arthritis.

Modifiable risk factors linked to the development of rheumatoid arthritis: evidence, immunological mechanisms and prevention

Rheumatoid Arthritis (RA) is a common autoimmune disease that targets the synovial joints leading to arthritis. Although the etiology of RA remains largely unknown, it is clear that numerous modifiable risk factors confer increased risk to developing RA. Of these risk factors, cigarette smoking, nutrition, obesity, occupational exposures and periodontal disease all incrementally increase RA risk. However, the precise immunological mechanisms by which these risk factors lead to RA are not well understood. Basic and translational studies have provided key insights into the relationship between inflammation, antibody production and the influence in other key cellular events such as T cell polarization in RA risk. Improving our general understanding of the mechanisms which lead to RA will help identify targets for prevention trials, which are underway in at-risk populations. Herein, we review the modifiable risk factors that are linked to RA development and describe immune mechanisms that may be involved. We highlight the few studies that have sought to understand if modification of these risk factors reduces RA risk. Finally, we speculate that modification of risk factors may be an appealing avenue for prevention for some at-risk individuals, specifically those who prefer lifestyle interventions due to safety and economic reasons.

Higher dietary fibre intake is associated with lower risk of inflammatory bowel disease: prospective cohort study

BACKGROUND

Limited prospective studies that have examined the association of dietary fibre with IBD have provided inconsistent evidence.

AIM

To examine any associations between dietary fibre intake and subsequent incidence of IBD, Crohn's disease (CD) and ulcerative colitis (UC) METHODS: We conducted a prospective cohort study of 470,669 participants from the UK Biobank and estimated dietary fibre intake from a valid food frequency questionnaire at baseline. Incident IBD was ascertained from primary care data and inpatient data. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between dietary fibre intake and the risk of IBD, CD and UC.

RESULTS

During an average follow-up of 12.1 years, we ascertained 1473 incident IBD cases, including 543 cases of CD and 939 cases of UC. Comparing the lowest quintiles, an inverse association was observed between dietary fibre intake and risk of IBD (HR 0.74, 95% CI 0.58-0.93, p = 0.011) and CD (HR 0.48, 95% CI 0.32-0.72, p < 0.001), but not UC (HR 0.92, 95% CI 0.69-1.24, p = 0.595). For specified sources, dietary fibre intake from fruit and bread decreased the risk of CD, while dietary fibre intake from cereal decreased the risk of UC.

CONCLUSIONS

Higher consumption of dietary fibre was associated with a lower risk of IBD and CD, but not UC. Our findings support current recommendations to increase the intake of dietary fibre.

Dietary Patterns and Their Associations with Symptom Levels Among People with Multiple Sclerosis: A Real-World Digital Study

INTRODUCTION

The objective of the study was to investigate long-term food intake patterns and establish possible associations between the inferred dietary habits and levels of reported symptoms among people with multiple sclerosis (MS) in Denmark.

METHODS

The present study was designed as a prospective cohort study. Participants were invited to register daily food intake and MS symptoms and were observed during a period of 100 days. Dropout and inclusion probabilities were addressed using generalized linear models. Dietary clusters were identified among 163 participants using hierarchical clustering on principal component scores. Associations between the dietary clusters and the levels of self-assessed MS symptoms were estimated using inverse probability weighting. Furthermore, the effect of a person's position on the first and second principal dietary component axis on symptom burden was investigated.

RESULTS

Three dietary clusters were identified: a Western dietary cluster, a plant-rich dietary cluster and a varied dietary cluster. Analyses further indicated a vegetables-fish-fruit-whole grain axis and a red-meat-processed-meat axis. The plant-rich dietary cluster showed reduction in symptom burden in nine pre-defined MS symptoms compared to the Western dietary cluster (between 19 and 90% reduction). This reduction was significant for pain and bladder dysfunction as well as across all nine symptoms (pooled p value = 0.012). Related to the two dietary axes, high intake of vegetables resulted in 32-74% reduction in symptom burden compared to low levels of vegetable intake. Across symptoms, this was significant (pooled p value = 0.015), also regarding walking difficulty and fatigue.

CONCLUSIONS

Three dietary clusters were identified. Compared to levels of self-assessed MS-related symptoms, and adjusted for potential confounders, the results suggested less symptom burden with increased intake of vegetables. Although the research design limits the possibilities of establishing causal inference, the results indicate that general guidelines for healthy diet may be relevant as a tool in coping with MS symptoms.

Neurodegenerative and Neurodevelopmental Diseases and the Gut-Brain Axis: The Potential of Therapeutic Targeting of the Microbiome

The human gut microbiome contains the largest number of bacteria in the body and has the potential to greatly influence metabolism, not only locally but also systemically. There is an established link between a healthy, balanced, and diverse microbiome and overall health. When the gut microbiome becomes unbalanced (dysbiosis) through dietary changes, medication use, lifestyle choices, environmental factors, and ageing, this has a profound effect on our health and is linked to many diseases, including lifestyle diseases, metabolic diseases, inflammatory diseases, and neurological diseases. While this link in humans is largely an association of dysbiosis with disease, in animal models, a causative link can be demonstrated. The link between the gut and the brain is particularly important in maintaining brain health, with a strong association between dysbiosis in the gut and neurodegenerative and neurodevelopmental diseases. This link suggests not only that the gut microbiota composition can be used to make an early diagnosis of neurodegenerative and neurodevelopmental diseases but also that modifying the gut microbiome to influence the microbiome-gut-brain axis might present a therapeutic target for diseases that have proved intractable, with the aim of altering the trajectory of neurodegenerative and neurodevelopmental diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, autism spectrum disorder, and attention-deficit hyperactivity disorder, among others. There is also a microbiome-gut-brain link to other potentially reversible neurological diseases, such as migraine, post-operative cognitive dysfunction, and long COVID, which might be considered models of therapy for neurodegenerative disease. The role of traditional methods in altering the microbiome, as well as newer, more novel treatments such as faecal microbiome transplants and photobiomodulation, are discussed.

Diet and the risk of rheumatoid arthritis - A systematic literature review

OBJECTIVES

Diet has received attention as a factor possibly contributing to the development of Rheumatoid arthritis (RA). Several dietary exposures have been examined in various populations using different diet assessment methods. The aim of this study was to systematically assess the literature on the relation between dietary patterns, different food and food groups, macronutrients, non-alcoholic beverages and the risk of developing RA.

METHODS

A systematic literature search was performed to identify relevant articles on diet and the risk of developing RA. The selection of articles and overall quality assessment of all included studies were performed independently by two examiners. Overall study quality was evaluated using the Newcastle-Ottawa Scales. We excluded all articles where the temporal relation between dietary data collection and time of RA diagnosis was not presented. Main findings were summarized for cohort-based studies and case-control studies separately.

RESULTS

A total of 984 articles were screened. Nineteen relevant cohort-based studies, and eight case-control studies, were included in our review. Two articles were excluded due to lacking data on the relation between RA diagnosis and time of dietary data collection and one due to incorrect outcome. Identified studies suggested protective effects of fish, vegetables and Mediterranean-style diets, although study results and methods were heterogenous. An issue in some case-control studies was that unvalidated diet assessment methods were used. A vast majority of the cohort-based studies used validated diet assessment methods, although the definitions of exposures studied varied.

CONCLUSION

There is lack of consistent evidence on the role of diet in the development of RA, partly due to differences in study quality and methodology Limited evidence suggests that some healthy eating habits may reduce the risk of RA. More high-quality studies in the area are needed for a deeper understanding of the effect of diet, and to enable strategies to prevent RA.

Dietary Patterns and Gut Microbiota Changes in Inflammatory Bowel Disease: Current Insights and Future Challenges

Inflammatory bowel disease (IBD) is a result of a complex interplay between genes, host immune response, gut microbiota, and environmental factors. As one of the crucial environmental factors, diet plays a pivotal role in the modulation of gut microbiota community and the development of IBD. In this review, we present an overview of dietary patterns involved in the pathogenesis and management of IBD, and analyze the associated gut microbial alterations. A Westernized diet rich in protein, fats and refined carbohydrates tends to cause dysbiosis and promote IBD progression. Some dietary patterns have been found effective in obtaining IBD clinical remission, including Crohn's Disease Exclusion Diet (CDED), Mediterranean diet (MD), Anti-Inflammatory Diet (AID), the low-"Fermentable Oligo-, Di-, Mono-saccharides and Polyols" (FODMAP) diet, Specific Carbohydrate Diet (SCD), and plant-based diet, etc. Overall, many researchers have reported the role of diet in regulating gut microbiota and the IBD disease course. However, more prospective studies are required to achieve consistent and solid conclusions in the future. This review provides some recommendations for studies exploring novel and potential dietary strategies that prevent IBD.

Clinical procedures used to diagnose inflammatory bowel disease: real-world evidence from a Danish nationwide population-based study

Objective

Although clinical guidelines exist, the diagnostic work-up for diagnosing inflammatory bowel disease (IBD) is complex and varies in clinical practice. This study used real-life data to characterise the current diagnostic procedures used to establish IBD diagnoses in a Danish nationwide setting.

Design

Person-level data on patients diagnosed with IBD between 1 January 2014 and 30 June 2018 were linked between Danish health registers. Information on age, sex, registration of other gastrointestinal diseases, and diagnostic procedures (endoscopies, biopsies, and imaging) performed in relation to the first IBD hospital admission was analysed for the total study population and was stratified by IBD type, sex, and age.

Results

The majority of the 12 871 patients with IBD included underwent endoscopy (84%), had a biopsy taken (84%), and/or underwent imaging procedures (44%). In total, 7.5% of the population (6% for Crohn’s disease and 8% for ulcerative colitis) were diagnosed with IBD despite not undergoing any of these diagnostic procedures. Patients with Crohn’s disease underwent more procedures than patients with ulcerative colitis (94% vs 92%, p<0.001). Children underwent slightly fewer diagnostic procedures than adults (92% vs 93%, p=0.004). Slightly more men underwent at least one procedure than women (92% vs 94%, p<0.001).

Conclusion

For 7.5% of patients with IBD, this study did not detect any registrations of the recommended diagnostic procedures for establishing an IBD diagnosis. Further research is needed to examine whether these findings are mainly explained by limitations of the register data or also indicate shortcomings of the general approach to IBD.

Improvement of Inflammation and Pain after Three Months' Exclusion Diet in Rheumatoid Arthritis Patients

Introduction: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease affecting the synovial joints and causing severe disability. Environmental and lifestyle factors, including diet, have been proposed to play a role in the onset and severity of RA. Dietary manipulation may help to manage the symptoms of RA by lowering inflammation and potentially decreasing pain. Methods: In 40 patients with long-standing RA with stable symptoms and treated with conventional (c-) and biological (b-) disease modifying anti-rheumatic drugs (DMARDs), the effect of a 3-month diet avoiding meat, gluten, and lactose (and all dairy products; privative diet) was evaluated in comparison with a control balanced diet including those foods. Both diets were designed to reduce weight since all patients were overweight or obese. Patients were randomly assigned to one of the diets, and RA was clinically assessed at Time 0 (T0), through the Visual Analogue Scale (VAS), for pain, and the Disease Activity Score of 28 joints (DAS 28) for RA activity. Patients were also administered the Short Form Health survey (SF-36) and the Health Assessment Questionnaire (HAQ). At T0, a blood sample was collected for laboratory tests and adipokines measurements, and anthropometric measurements were compared. These evaluations were repeated at the end of the 3 months’ dietary regimens. Results: A significant decrease in VAS and the improvement of the overall state of physical and mental health, assessed through SF-36, was observed in patients assigned to the privative diet. Both dietary regimens resulted in the improvement of quality of life compared to baseline values; however, the change was significant only for the privative diet. With either diet, patients showed significant decreases in body weight and body mass index, with a reduction in waist and hips circumference and lower basal glucose and circulating leptin levels. A privative diet was also able to significantly reduce systolic (p = 0.003) and diastolic (p = 0.025) arterial pressure. The number of circulating leukocytes and neutrophils, and the level of hs-C-Reactive Protein also decreased after 3 months of the meat-, lactose-, and gluten-free diet. Conclusions: Our results suggest that a privative diet can result in a better control of inflammation in RA patients under stable optimized drug treatment.

A systematic review and meta-analysis of observational studies on the association between animal protein sources and risk of rheumatoid arthritis

OBJECTIVE

The aim of this study was to investigate the linear and nonlinear dose-response associations of animal-based dietary protein intake and risk of developing rheumatoid arthritis (RA).

METHODS

A systematic search of MEDLINE, Scopus and Embase was conducted up to October 2020. Observational studies that report risk estimates of RA for animal-based protein consumption were included. We calculated pooled relative risks (RRs) by using a random-effects model. Linear and non-linear dose-response analyses were performed to examine the dose-response relations between animal-based protein consumption and RA.

RESULTS

Seven cohort studies (n = 457,554) with 3545 incident cases and six case-control studies with 3994 cases and 5252 controls were identified. Highest compared with the lowest category of fish consumption was inversely associated with risk of RA (RR: 0.89; 95% CI, 0.80 to 0.99; I² = 0%, n = 10). Also, a 100 g/day increment in fish intake was associated with a 15% decreased risk of RA. Dose-response analysis showed a modest U-shaped association between fish consumption and incidence of RA, with the lowest risk at a fish intake of 20-30 g/day (P_{non-linearity} = 0.04). We found no significant association between consumption of red meat, poultry or dairy and the risk of RA.

CONCLUSION

The present study revealed a significant reverse association between fish consumption and risk of RA. While we observed no association between red meat, dairy or poultry consumption and risk of RA. Further well-designed prospective studies are needed to support our findings.