New evidence highlights how the Mediterranean diet’s anti-inflammatory nutrients, like extra-virgin olive oil and omega-3-rich fish, can help manage both joint and thyroid autoimmune disorders, offering a low-cost lifestyle intervention with clinical benefits.

Study: Unlocking the Power of the Mediterranean Diet: Two in One—Dual Benefits for Rheumatic and Thyroid Autoimmune Diseases. Image Credit: monticello / Shutterstock.com

A recent study published in the journal Nutrients reviews the effects of the Mediterranean diet (MD) on both systemic and organ-specific autoimmune disorders, particularly rheumatic and thyroid diseases.

What are autoimmune diseases?

Autoimmune diseases are systemic or organ-specific diseases that are associated with the development of anomalous immune responses against self-antigens. Systemic autoimmune diseases may include rheumatoid arthritis (RA), seronegative spondyloarthritis (SpA), and autoimmune connective tissue diseases (CTDs), whereas Hashimoto’s thyroiditis (HT), type 1 diabetes mellitus (T1D), and Graves’ disease (GD) are considered organ-specific diseases.

Autoimmune diseases are triggered by genetic and environmental factors that activate the immune system through various mechanisms, including the production of interferon type I, molecular mimicry, epitope spreading, post-translational modification of proteins, or the presentation of superantigens.

T- and B-lymphocytes are involved in the manifestation of autoimmune diseases, as demonstrated by the synthesis of autoantibodies against self-antigens. Non-immune cells, such as epithelial, endothelial, and fibroblast cells, also damage tissues through the synthesis of pro-inflammatory cytokines.

The potential of the Mediterranean diet in managing autoimmune diseases

The MD is rich in fiber, olive oil, fruits, grains, legumes, nuts, and vegetables, as well as a moderate intake of fish, poultry, and wine. In comparison to Western dietary habits, the MD recommends a moderate consumption of red meat, processed foods, and refined sugar.

Previous studies have highlighted the potential of MD in modulating inflammation due to its antioxidant and anti-inflammatory properties. The MD has also been shown to promote the growth of beneficial bacteria, including Lactobacillus, Bifidobacterium, and Faecalibacterium prausnitzii, which exerts anti-inflammatory effects.

Several studies have reported the beneficial effects of various MD components on rheumatoid arthritis (RA), chronic widespread arthritis (CTD), spondyloarthritis (SpA), and autoimmune thyroiditis. Moreover, the intake of oily fish rich in ω-3 polyunsaturated fatty acids (PUFAs), as well as various fruits and vegetables containing different classes of bioactive compounds, has been shown to mitigate the effects of certain autoimmune diseases.

The high intake of fiber enhances the proliferation of fermenting bacteria, which produce short-chain fatty acids (SCFAs) such as butyrate, acetate, and propionate. Multiple studies have confirmed the anti-inflammatory properties of SCFAs and their ability to alleviate oxidative stress and chemotaxis of immune cells by enhancing the number of Treg cells and the release of interleukin-10 (IL-10).

Furthermore, a recent clinical trial also revealed that ω-3 PUFA supplementation could positively impact the progression of RA by suppressing the levels of inflammatory cytokines, such as IL-1β, modulating T-cell differentiation, and reducing the production of leukotriene B4 (LTB4) by neutrophils.

Extra virgin olive oil (EVOO) contains a wide range of bioactive compounds, such as carotenoids, phenolics, sterols, and triterpenic alcohols. Several preclinical studies have investigated the potential anti-inflammatory properties of extra-virgin olive oil (EVOO) and its components.

For example, oleocanthal (OL), a typical phenolic component of extra-virgin olive oil (EVOO), exhibits preventive effects against rheumatoid arthritis (RA). Likewise, a mouse model of pristane-induced systemic lupus erythematosus (SLE) showed that EVOO consumption inhibited the release of nitric oxide (NO) and the production of pro-inflammatory cytokines.

The National Health and Nutrition Examination Survey (NHANES) recently reported that individuals who consume a pro-inflammatory diet had higher levels of total T4 and total T3. Similarly, HT patients adhering to an anti-inflammatory diet exhibited lower TSH levels, higher free T4 levels, and lower body mass index (BMI) values. Higher adherence to MD also improved thyroid autoimmunity and related dysfunction.

Recently, a randomized clinical trial (RCT) revealed that patients with RA who underwent the MD intervention for 12 weeks exhibited a significant reduction in their disease activity score on 28 joints (DAS28) compared to controls. These patients also experienced improvements in cardiometabolic parameters, including body composition, body weight, blood glucose levels, and plasma vitamin D levels.

Encouraging adherence to the MD could serve as an effective, cost-efficient lifestyle approach to reduce the burden of autoimmune disorders in modern societies.”

Conclusions

The synergistic effect of individual MD components may be sufficient to mitigate the inflammatory processes that occur during autoimmune conditions, thus supporting the incorporation of this dietary approach into the management of autoimmune diseases and their complications. In vitro and in vivo studies, along with clinical trial data, have confirmed the potential of MD as a complementary tool for managing rheumatic and thyroid autoimmune diseases; however, combining MD with exercise has the potential to provide more robust and durable improvements.