Anti-inflammatory Diet May Affect Physical Functioning in RA

A new controlled crossover study found a diet based on anti-inflammatory foods did not have a significant impact on health-related quality of life (HRQoL) among patients with rheumatoid arthritis (RA). However, a sub-analysis of the data suggested the diet may make a difference in physical functioning.

Patients with RA can face a number of challenges in their daily lives. As the disease progresses, many patients experience difficulties dressing and grooming themselves, cooking their own meals, and walking. A number of studies in recent years have looked into questions of whether the nutrients in patients’ diets might have an impact on their disease outcomes.

One such study, the Anti-inflammatory Diet in Rheumatoid Arthritis (ADIRA) trial, specifically looked at the impact of a diet based on foods with anti-inflammatory properties, such as fish, legumes, grains, and potatoes. Patients in that trial, which took place between 2017 and 2018, were asked to either adopt the anti-inflammatory diet, or continue eating a typical diet, which in this case was a typical Swedish diet, since the study was conducted in Sweden. As patients continued their assigned diets, they were asked to complete a series of questionnaires to indicate how they felt and how the disease was impacting their lives. After 10 weeks, the control diet and intervention diet groups switched diets for another 10-week period.

A total of 47 patients completed at least one diet period, and 44 patients completed both.

Overall, according to corresponding author Anna Winkvist, PhD, MSc, of the University of Gothenburg, the anti-inflammatory diet did not significantly improve HRQoL.

Yet, Winkvist and colleagues dug further into the data and found meaningful differences in a sub-analysis. Their findings were published in PLoS One.

When investigators looked at results of the patient-reported 36-item Short Form, they noticed improvements in physical functioning among patients while on the anti-inflammatory diet compared to those on the control diet.

Furthermore, when they excluded patients who had pharmacological treatment changes during the study period, they found larger differences in a number of categories, especially those pertaining to physical domains.

The authors said their findings could be used to inform larger studies aimed at better understanding the impact of diet. They said their current findings are intriguing, though they are also subject to limitations. For instance, the findings were based on subjective, patient-reported data.

In addition, the scope of “health care-related quality of life” was limited by the particular assessments they used, and it is possible that the diet intervention had effects on other aspects of quality of life, such as sleep, sexual functioning, and self-esteem, they wrote. Winkvist and colleagues added they might have had clearer results if they did not allow patients in the study to switch medications; however, they said it is likely they would have had a higher drop-out rate if such a restriction were imposed.

On the positive side, Winkvist and colleagues said they had a high rate of fidelity to the study protocols, both in terms of diet compliance and survey participation.

“Larger studies with restrictions in medication changes conducted in study populations more affected by the disease are needed to confirm our results and to possibly detect significant changes in other HrQoL-outcomes as well,” they concluded.

Reference:

Wadell AT, Bärebring L, Hulander E, et al. Effects on health-related quality of life in the randomized, controlled crossover trial ADIRA (Anti-inflammatory Diet In Rheumatoid Arthritis). PLoS One. Published online October 14, 2021. doi:10.1371/journal.pone.0258716