Can an anti-inflammatory diet help with rheumatoid arthritis?

Rheumatoid arthritis:

Rheumatoid arthritis (RA for short) is a chronic autoimmune disease that occurs in relapses in many sufferers. The inflammatory disease affects the joints, with individuals requiring treatment suffering from reduced function, pain and stiffness. A current treatment method is based on immunosuppression, which is intended to avert further joint destruction and alleviate symptoms. However, not all sufferers are able to achieve a permanent reduction in pain.

Some patients also ask their doctors for specific recommendations regarding their diet. According to nutritional questionnaire studies, people undergoing treatment report improvement or worsening of disease symptoms with different food intake. For example, previous studies report that red meat and alcoholic beverages could worsen symptoms of RA. Fish and berries, on the other hand, could improve disease activity. While these studies have focused on specific foods, few analyses exist that have examined an overall anti-inflammatory diet.

Researchers in the current ADIRA (Anti-inflammatory Diet in Rheumatoid Arthritis) study are targeting a dietary portfolio of n-3 fatty acids, fiber and probiotics that can complement pharmacological treatment of RA to further reduce disease activity.

Swedish Study Design:

The single-blinded crossover study, published in 2020 in The American Journal of Clinical Nutrition, examined 50 patients* diagnosed with rheumatoid arthritis. These individuals were randomly assigned to two groups for 10 weeks. The first group followed an intervention diet with recommended anti-inflammatory foods, while the control group followed a control diet similar to an average food intake in Sweden. After this period, a washout period of 4 months was performed. Following this, the group participants switched diets.

Each week, food equivalent to approximately 50% of the daily energy requirement was delivered to the participants' homes - for the remaining meals, the participants were expected to independently consume the same type of food for which they were allocated at the time. The food was delivered to the study participants' homes by a grocery chain every week at a time/day of their choice. They were not to take any supplements unless prescribed by a physician.

The primary end goal, according to the researchers, was a change in disease activity scores on the DAS28 (i.e., Disease Activity Score 28) quantitative assessment system, which was developed and validated by the so-called EULAR (i.e., The European League Against Rheumatism). Secondary outcome measures were changes in individual components of the DAS28, such as painful and swollen joints, joint sedimentation rate, and subjectively perceived health status.

To participate in the study, an invitation letter was sent to all SRG (i.e., Swedish Quality Register of Rheumatology) participants aged 18-75 years with more than 2 years of disease in the Gothenburg region. Exclusion criteria were:

• allergies or food intolerance to foods included in the study
• other serious diseases
• pregnancy or lactation

The intervention diet consisted of approximately 1100 kcal/d:

• Breakfast(low-fat dairy products, whole grains, pomegranate, blueberry, nuts and 5x/week juice with probiotics such as Lactobacillus plantarum 299v)
• 1x snack(fruit)
• 1x main meal (3-4x/week fish, mostly salmon and 1-2x/week vegetarian with legumes, potatoes, whole grains, vegetables, yogurt and spices).

For non-delivered foods, the following rules applied:

• Meat consumption maximum 3x/week
• At least 5 servings of fruits, berries or vegetables per day (with the delivered products)
• Use oil/margarine for cooking
• Use low-fat dairy products and whole grains

Significant results?

The main analysis with participants* who went through the diet period at least once showed no particular difference in DAS28 between the two groups. However, the unadjusted analysis showed among participants* in both diet periods, DAS28 decreased significantly in the diet period and was significantly lower after the intervention than after the control period.

Conclusion:

According to the analysis of this study, no clinically relevant minimization of DAS28 or its parts could be recorded in the main analysis with an intervention diet, which includes foods with possible anti-inflammatory characteristics, compared to a classic Swedish diet. However, a non-adjusted analysis showed that an improvement during the study period and in the final results of each diet period was significant. According to researchers, these results suggest a positive effect of a possibly anti-inflammatory diet as supportive therapy in patients in relation to disease activity in individuals with RA.

In any case, further, more detailed clinical studies are needed to clearly establish exact, clinically relevant improvements in disease activity in individuals with RA.