Rheumatic diseases and lifestyle
Rheumatic diseases, including rheumatoid arthritis (REA), ankylosing spondylitis (ASP), and psoriatic arthritis (PsA), pose a significant medical and social challenge. These chronic autoimmune disorders are characterized by persistent inflammation and considerable consequences for patients’ quality of life. The primary mechanism underlying these diseases involves dysregulation of the immune response, leading to the release of proinflammatory cytokines, that exacerbate the inflammatory process and contribute to tissue damage, particularly in articular cartilage and bone. Oxidative stress is closely associated with the progression of rheumatic diseases and their systemic complications, including atherosclerosis and metabolic syndrome.
Current treatment strategies include pharmacotherapy based on disease-modifying antirheumatic drugs (DMARDs), steroids and common nonsteroidal anti-inflammatory drugs (NSAIDs). However, their efficacy is often limited by adverse effects and variable patient responses. Consequently, growing attention is being directed toward alternative interventions (most notably dietary modifications) that can influence inflammatory and oxidative processes. Diet is a key environmental factor in the pathogenesis of rheumatic diseases. Particular interest has focused on dietary patterns such as the Mediterranean diet, low-starch diets, and hypocaloric regimens.
Evidence suggests that appropriate dietary habits may exert protective effects by reducing inflammation, oxidative stress and improving gut microbiota function. The gut microbiota, which plays a pivotal role in immune system modulation, is also closely linked to diet. Gut dysbiosis—characterized by reduced levels of probiotic bacteria and an overrepresentation of proinflammatory species—is frequently observed in patients with REA, ASP and PsA. Dietary interventions can alter the composition of the gut microbiota, promoting the production of short-chain fatty acids (SCFAs) that exhibit anti-inflammatory properties and support the integrity of the intestinal barrier.
Diet as a conditioning outer factor
PsA, like psoriasis, is strongly associated with obesity and metabolic syndrome. Visceral adipose tissue acts as a reservoir for proinflammatory cytokines, such as leptin, TNF-α and IL-6, which reinforce systemic inflammation. Weight reduction through hypocaloric diets, has been shown to significantly reduce disease activity in PsA patients, as demonstrated in clinical trials such as the DIETA trial. A diet rich in omega-3 fatty acids, fiber and antioxidants can modulate inflammatory and oxidative processes in PsA. Omega-3 fatty acids inhibit the IL-23/IL-17 pathway, while antioxidants (e.g., vitamin C and polyphenols) neutralize ROS, thereby reducing oxidative stress.
The gut microbiota plays a pivotal role in regulating the immune system. Dysbiosis, defined by an increased abundance of proinflammatory bacteria and a decreased diversity of probiotic species, is frequently observed in rheumatic diseases. Such dysbiosis can enhance intestinal permeability and promote the translocation of endotoxins, triggering an inflammatory response. Notably, a link between dysbiosis and the IL-23/IL-17 pathway has been reported in ASP. Internal factors may compromise this barrier; hence, maintaining a healthy gut microbiota is critically important. Diet emerges as a significant modifiable factor in this context: the composition of the gut microbiota can change within as little as two days in response to dietary modifications.
A Mediterranean-style (MED) diet has been shown to induce favorable shifts in gut microbiota composition, largely due to an increased intake of vegetables, fruits, legumes—rich in vitamins, minerals and dietary fiber—and fermented dairy products. Fiber and polyphenols stimulate the growth of commensal microbes, while limiting meat consumption further supports a healthier microbiome. Non-digestible polysaccharides, which are fermented in the large intestine, are among the main drivers of beneficial microbial proliferation. In ASP, gut barrier dysfunction can precede disease onset, underscoring the importance of preserving gut barrier integrity and functionality in autoimmunities.
Microbiota and rheumatic diseases
In rheumatic diseases such as REA, ASP and PsA, significant alterations in gut microbiota composition ave been documented. Dysbiosis can amplify inflammatory and oxidative processes by disrupting the interplay between the gut microbiota and the immune system while also increasing intestinal permeability. Dietary strategies are of considerable importance in regulating microbiota composition and function. High-fiber diets support the proliferation of SCFA-producing probiotic species, bolstering the intestinal barrier and mitigating inflammation. Polyphenol-rich foods—such as fruits, vegetables and green tea—promote microbial diversity while reducing the abundance of proinflammatory bacteria.
Mediterranean diet fosters the growth of beneficial gut bacteria, including Lactobacillus and Bifidobacterium, and stimulates the production of SCFAs. This supports the integrity of the intestinal barrier and limits endotoxin translocation. Clinical studies have demonstrated that following MED for 12 weeks in patients with REA results in reduced CRP levels, improved DAS28 scores, and a decrease in the number of tender joints. In ASP and psoriatic arthritis, this dietary pattern lessens disease activity and slows joint damage progression, underscoring its potential role as an adjunct to pharmacotherapy Restricting saturated fats and simple sugars further diminishes bacterial endotoxin translocation, attenuating the inflammatory response.
Clinical findings show that in ASP and PsA patients, dietary regimens rich in fiber and prebiotics are associated with lower CRP and IL-6 levels, improved disease activity indices (including the Bath Ankylosing Spondylitis Disease Activity Index [BASDAI] and Disease Activity Score [DAS28]), and a reduction in pain. Prebiotic-containing foods have shown promising effects in modulating gut microbiota composition and, consequently, reducing inflammation in rheumatic diseases. Dietary prebiotics can promote the growth of beneficial bacteria which are associated with anti-inflammatory effects through the production of SCFAs like butyrate. Yogurt and kefir (enriched with Lactobacillus, Streptococcus and Bifidobacterium strains) are easy to get, economic and safe.
Studies have demonstrated that in conditions like rheumatoid arthritis and psoriatic arthritis, gut dysbiosis often coincides with decreased microbial diversity and an imbalance between proinflammatory and anti-inflammatory bacterial populations. By enriching the gut with prebiotics, it may be possible to restore microbial balance, enhance intestinal barrier integrity, and reduce systemic inflammation, offering a supportive strategy alongside conventional therapies. A hypocaloric diet, by reducing body weight, reduces levels of proinflammatory adipokines and reduces systemic inflammation. In the DIETA trial, patients with PsA who followed a hypocaloric diet for 12 weeks had significant improvements in DAS28-CRP and reduced their number of swollen joints.
These effects were seen regardless of the degree of weight loss, suggesting that changes in diet quality may have an independent effect on disease activity. A hypocaloric diet also affects lipid and carbohydrate metabolism, which may limit the development of metabolic syndrome in patients with PsA. Improving insulin sensitivity and lowering triglyceride levels reduce the activation of inflammatory pathways in adipocytes and endothelial cells. Clinical studies confirm that patients who follow this diet experience reduced fatigue and improved physical fitness. However, it is worth noting that the effectiveness of this diet depends on its quality, not only on a reduction in calorie intake.
Antinflammatory molecules in foods
The inclusion of anti-inflammatory ingredients, such as omega-3 acids and polyphenols, may additionally increase its effectiveness in the treatment of PsA. Diet therapy in rheumatoid diseases is based on the use of nutrients with proven anti-inflammatory and antioxidant properties. Omega-3 fatty acids, fiber, polyphenols, and antioxidant vitamins play a key role in reducing inflammation and neutralizing reactive oxygen species, which are significant factors exacerbating pathological processes in these diseases. Omega-3 fatty acids, like EPA and DHA, have strong anti-inflammatory effects. They are mainly present in oily fish such as salmon, mackerel and sardines, as well as in chia seeds and linseed.
Their mechanism of action is based on the regulation of eicosanoid production, which are key mediators of inflammation. Omega-3s also modulate T cell function by reducing the activation of the IL-23/IL-17 pathway, which is key in ASP and PsA. Additionally, EPA and DHA reduce the expression of inflammatory genes activated by NF-κB, which limits the production of TNF-α and IL-6. In clinical studies, omega-3 supplementation at doses of ≥3 g/day led to a reduction in the number of swollen joints, an improvement in the DAS28 score, and a decrease in CRP levels in patients with REA. In patients with ASP and PsA, reduced pain and improved quality of life were observed.
Catechins present in green tea and cocoa improve the function of endothelial cells, which is important in the context of reducing the risk of cardiovascular complications, which often occur in rheumatoid diseases. Vitamin C, found in citrus fruits, berries, peppers and broccoli, is a potent ROS scavenger, while Vitamin E, found in nuts, seeds, and vegetable oils, protects cell membranes from lipid peroxidation. In clinical studies, vitamin E supplementation led to a reduction in disease activity in patients with REA. The combination of vitamins C + E has been shown to synergize in protecting against oxidative stress, which may be particularly beneficial in ASP and PsA, where ROS play a key role.
Education and challenges for personalized medicine
One of the key challenges in diet therapy for rheumatoid diseases is the need to personalize dietary recommendations. Each patient is characterized by individual characteristics, such as the diversity of the gut microbiota, genetic polymorphisms related to nutrient metabolism and comorbidities that may affect the effectiveness of nutritional interventions. An example is the diverse response of patients with AS to a low-starch diet, which may be more effective in people with an excess of Klebsiella pneumoniae in the gut microbiota. In turn, in patients with PsA, a hypocaloric diet may bring the greatest benefits in the case of coexisting obesity or metabolic syndrome. Personalization requires the identification of biomarkers of response to dietary interventions. Examples of biomarkers include fecal SCFA levels, intestinal permeability indicators, and inflammatory markers such as CRP and IL-6. Microbiome analysis is also becoming increasingly important.
Another challenge is the lack of appropriate education on the role of diet in the treatment of rheumatoid diseases. Many patients are not aware of the potential benefits of changing their eating habits, and medical professionals often do not have sufficient knowledge about dietary therapy. The introduction of educational programs for patients could increase their involvement in the treatment process and improve the results of therapy. The education of specialists, including rheumatologists and dietitians, is equally important. Training on the mechanisms of action of dietary components such as omega-3, fiber and polyphenols, and their impact on inflammatory and oxidative processes, could help to more effectively implement dietary recommendations in everyday clinical practice. Diet should be viewed as a complement to pharmacological therapy, not a substitute for it.
Optimizing treatment requires cooperation between different specialists, including rheumatologists, dietitians, and psychologists. Dietary interventions can increase the effectiveness of disease-modifying antirheumatic drugs (DMARDs) and reduce the risk of adverse effects. For example, a diet rich in omega-3 may enhance the effects of biologics such as TNF-α inhibitors by additionally modulating inflammatory pathways. Dietary changes can be difficult to implement due to cultural differences, dietary habits, and economic constraints. The Mediterranean diet, despite its proven benefits, can be difficult to implement in regions where access to fresh fruits, vegetables, and fish is limited. In such cases, it is necessary to adapt recommendations to local conditions and patient preferences, taking into account available resources.
- EDited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
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