Effects of diet on the outcomes of rheumatic and musculoskeletal diseases (RMDs): systematic review and meta-analyses informing the 2021 EULAR recommendations for lifestyle improvements in people with RMDs
BMJ Publishing Group
Background A EULAR taskforce was convened to develop recommendations for lifestyle behaviours in rheumatic and musculoskeletal diseases (RMDs). In this paper, the literature on the effect of diet on the progression of RMDs is reviewed. Methods Systematic reviews and meta-analyses were performed of studies related to diet and disease outcomes in seven RMDs: osteoarthritis (OA), rheumatoid arthritis (RA), systemic lupus erythematosus, axial spondyloarthritis, psoriatic arthritis, systemic sclerosis and gout. In the first phase, existing relevant systematic reviews and meta-analyses, published from 2013 to 2018, were identified. In the second phase, the review was expanded to include published original studies on diet in RMDs, with no restriction on publication date. Systematic reviews or original studies were included if they assessed a dietary exposure in one of the above RMDs, and reported results regarding progression of disease (eg, pain, function, joint damage). Results In total, 24 systematic reviews and 150 original articles were included. Many dietary exposures have been studied (n=83), although the majority of studies addressed people with OA and RA. Most dietary exposures were assessed by relatively few studies. Exposures that have been assessed by multiple, well conducted studies (eg, OA: vitamin D, chondroitin, glucosamine; RA: omega-3) were classified as moderate evidence of small effects on disease progression. Conclusion The current literature suggests that there is moderate evidence for a small benefit for certain dietary components. High-level evidence of clinically meaningful effect sizes from individual dietary exposures on outcomes in RMDs is missing. Rheumatic and musculoskeletal diseases (RMDs) are a diverse range of conditions that primarily affect people’s joints, causing pain, disability and reductions in health-related quality of life (HR-QoL). 1–3 According to the Global Burden of Disease study, RMDs are one of the leading causes of global disability.4 5 Some RMDs have effective pharmacological treatments that limit disease progression (eg, rheumatoid arthritis (RA)6), whereas others have no effective disease modifying treatment options (eg, osteoarthritis (OA)7). However, in all RMDs there is room for additional improvement in outcomes. In the general population, lifestyle modifications have been shown to improve non-RMD related outcomes. For instance, diet (ie, specific food stuffs ingested as part of daily living, and supplements or nutrients ingested to improve health) has a significant impact on the risk of chronic disease8 and benefits to mental health.9 However, it is unclear whether lifestyle modifications, such as changes to diet, have a beneficial impact on RMD related outcomes (including disease activity, pain, function, HR-QoL, radiographic damage, fatigue and depression). In 2018, a EULAR Taskforce was convened to develop recommendations for lifestyle improvements in people with RMDs with regards to RMD progression (including both modifiable (eg, pain, fatigue) and irreversible (eg, joint damage) outcomes).10 The taskforce decided to focus on six lifestyle factors: diet, exercise, weight, alcohol, smoking and paid work, and seven diseases: RA, OA, axial spondyloarthritis (axSpA), psoriatic arthritis (PsA), systemic lupus erythematosus (SLE), systemic sclerosis (SSc) and gout (henceforth referred to collectively as RMDs). For each of these lifestyle factors, systematic reviews were performed, aiming to collate all relevant literature on each factor in order to formulate evidence based recommendations. This article reports the results of systematic reviews on the effect of diet on progression of RMDs.
What is already known about this subject? ⇒ People’s diet can influence health related outcomes, such as cardiovascular outcomes and mental health. ⇒ It is unclear whether dietary factors influence rheumatic and musculoskeletal disease (RMD) specific outcomes. What does this study add? ⇒ This study brings together the literature on diet and progression of seven RMDs, concluding that research on diet has largely focused on osteoarthritis and rheumatoid arthritis, and there is little evidence suggesting dietary factors can make large differences to the outcomes of people with RMDs. How might this impact on clinical practice or further developments? ⇒ Based on the current literature, health professionals can advise people with RMDs that consuming specific dietary components is unlikely to influence the progression of their RMD, but that it is important to maintain a healthy diet and healthy weight for general health reasons.