Diet and rheumatoid arthritis: investigating the impact of a Mediterranean diet on patient-reported outcome measures

Background: Rheumatoid Arthritis (RA) is a chronic inflammatory autoimmune disease with an estimated global prevalence of 0.46%. Chronic low-grade inflammation is central in the pathogenesis and progression of RA. With no cure, the treatment goals of RA are to control symptoms, prevent joint damage and improve quality of life and ability to function. Accumulating evidence suggests that diet may play an important role in RA management and even remission. However, to date, there is a lack of evidence supporting a preferred diet. The Mediterranean diet (MedDiet), recognised for its anti-inflammatory properties, is one the most researched diets for prevention and management of chronic diseases. However, very few trials have assessed a MedDiet with RA specific outcomes and in non-Mediterranean countries. Improving the evidence base for diet in people with RA could serve to inform the development of dietary guidelines for this patient population and ultimately improve patient outcomes.

Aims: The primary aim of this doctorate is to investigate the impact of a MedDiet in the management of RA.

Methods: To achieve the aims, the research strategy undertaken involves; (i) A systematic review on the effectiveness of dietary interventions in RA (Chapter 2); (ii) A RCT examining the effects of a MedDiet compared to the Irish Healthy Eating Guidelines (HEG) on physical function and quality of life in adults with RA in Ireland (MEDRA, Chapter 3); (iii) A qualitative exploration of participants’ experiences following the 12-week telehealth-delivered dietary intervention (Chapter 4); (iv) A cross-sectional study investigating the self-perceived levels of adherence and the barriers, and enablers toward adherence to a MedDiet in the general Irish population (Chapter 5).

Results: Key findings from this programme of research:

• The systematic review of dietary interventions found that diets with an anti-inflammatory basis such as the MedDiet may be an effective strategy in the management of RA. An anti-inflammatory diet supplemented with omega-3 polyunsaturated fatty acids may provide additional benefits.

• The MEDRA RCT found that both a MedDiet and adhering to the Irish HEG significantly improved physical function and quality of life in adults with RA. Improving dietary quality irrespective of dietary prescription is beneficial in an RA population.

• The telehealth component of the intervention was positively received by adults with RA. The MedDiet was well accepted by an Irish population with RA.

• The observational study indicated low adherence to the MedDiet in a healthy population residing in Ireland.

Conclusion: Diet must be considered as part of the overall management of people with RA. Adherence to a MedDiet is feasible in an Irish population. Larger observational and interventional studies are required to confirm and expand upon these findings.