As part of the “Plants for Joints” study, the diet intervention study recently published in the British Medical Journal, improvements were also noted for individuals with autoimmune rheumatoid arthritis.

In the RA study, 77 patients with mild to moderate RA were randomized to follow either the PFJ (plants for joints) diet plus usual care or only usual care (control group). Out of them, 48 from both the intervention and control groups also finished the 2-year follow-up. The same details for the OA study were used in the PFJ intervention and extension study for RA patients.

Study investigator Wagenaar noted that her team tried to individualize the exercise portion of the study. "We noticed many of the RA patients asked too much of their body, while in contrast, those with OA were too hesitant," she said. "We decided to focus on people's own physical barriers, and we wanted to protect these. Sometimes, people needed to move more, and at other times, we had to tell people to slow down. Often, we advised people to move more by integrating exercise into their daily life."

It was requested that RA subjects try to avoid changing their medications during the 16-week study, similar to the OA study. They were encouraged to reduce medication use in the extension study, while collaborating with their doctors, explained Wagenaar.

Changes were measured based on medication groups including rheumatic medications, pain, blood pressure, blood sugar lowering, and cholesterol medications. Changes were captured as increased, stable, or decreased/stopped.

Subjects were primarily women (92%) aged 55 years on average, BMI of 26 kg/m2, and DAS28 (Disease Activity Score) of 3.85 at baseline. Reasons for dropout were similar to those for OA. More than 85% of participants were on medications.

The DAS28 changed more in the intervention participants during the 16-week trial period than in the controls. After 2 years of follow-up, DAS28 was significantly lower than baseline with a mean difference of −0.9 (95% CI, −1.2 to −0.6; P < .0001). The drop is a significant reduction, notes Wagenaar.

Other improvements noted included a drop in mean tender joint count from 3 to 0. General health components of the DAS28 also improved significantly over the intervention and in the 2-year follow-up. There was no significant difference in the previously low erythrocyte sedimentation rate and swollen joint count compared to the baseline. C-reactive protein (CRP) dropped from 3.2 to 1.3 mg/L over the 2-year follow-up. High-density lipoprotein increased from 1.6 to 1.8 mmol/L.

A total of 44% of patients using antirheumatic medication decreased or stopped their use after the 2-year extension.

Wagenaar further noted, "participants were very enthusiastic about the program despite it largely involving lifestyle change, and this is reflected in our low dropout rates after the trial and 1-year extension [20% for OA and RA]." More dropouts were seen in year 2 of the extension.

"People in the program felt like they had more control over their disease, and they felt listened to”, she noted in a recent interview.

Why PFJ Worked

Wagenaar and her team wanted to discover possible mechanisms behind the clinical effects of the plant-based diet on RA. "With RA, we have the mucosal origins hypothesis, which suggests RA is triggered at the mucosal site [of the gut] in genetically predisposed individuals, and this consequently transfers to the synovial [fluid in] joints," she said.

She noted, “Fiber protects our gut barrier and therefore reduces inflammation. The PFJ intervention is a very high-fiber program, so our hypothesis is that it might help [strengthen] the barrier.”

Fecal samples from subjects were collected and levels of albumin and calprotectin were evaluated. These are indicators of gut barrier function. Metabolic data was analyzed and researchers found that fecal albumin dropped significantly in the intervention group. In those with RA, the improvement was associated with an improvement in DAS28.

"Patients who had the greatest improvement in their gut barrier function also showed the greatest improvement in the DAS28 score, suggestive of a possible link between gut barrier improvement and clinical effects."

No change in calprotectin, a marker of inflammation, was seen in the intervention group after 4 months but CRP was reduced after a year. A lentil intake biomarker, known as lenticin considered protective from inflammation also increased while tryptophan was reduced in those in the PFJ group.

Wagenaar’s research was applauded by Fernando Estevez-Lopez, PhD, a sports scientist at Harvard University, Boston, who specializes in physical activity and behavioral change in rheumatology patients. "In this study, they did a brilliant job with encouraging participants to follow the program. The design and methods were really good — the sample size was good, and they followed people up. Also, these researchers come from Reade [a medical research center in Amsterdam University Medical Center] where they are well known for applying their research findings to the clinic”.

Wagenaar’s team emphasized increasing time spent moving through gentle activities like walking in patients with OA or RA. They don’t want them to experience more pain afterward. 1

Tips for those with RA:

·         Reduce red meat intake if you’re at risk for RA as it’s been linked with the early onset of RA.2

·         Include more beans and lentils in your diet given their high fiber content and anti-inflammatory effects, according to research. 3

·         Consider a vegetarian or vegan diet as both are considered anti-inflammatory. Include plenty of vegetables and limit ultra-processed foods. 4

·         Incorporate coaching to encourage better adherence to a Mediterranean diet and physical activity in those with RA. 5

·         Consider limiting sodium as this has been found to be helpful in some individuals with RA. 6

·         Add spices to your food such as cinnamon, curcumin (turmeric) and ginger as these have anti-inflammatory properties. They’re also calorie-free. 7

·         Increase intake of foods containing omega-3 fatty acids such as salmon, mackerel, walnuts, and ground flaxseeds.

·         Include seasonal fruit for dessert in place of ultra-processed sugary treats.

·         Obtain adequate calcium and vitamin D for bone health as individuals with RA are at higher risk for osteoporosis.

·         Work with a personal trainer to find exercise that’s right for you. Staying active is key to managing mobility and joint pain.

Lisa Andrews, MEd, RD, LD

References:

1.   https://ard.bmj.com/content/83/Suppl_1/737.2

2.   Jin J, Li J, Gan Y, Liu J, Zhao X, Chen J, Zhang R, Zhong Y, Chen X, Wu L, Xiang X, Zhou Y, He J, Guo J, Liu X, Li Z. Red meat intake is associated with early onset of rheumatoid arthritis: a cross-sectional study. Sci Rep. 2021 Mar 11;11(1):5681. doi: 10.1038/s41598-021-85035-6. PMID: 33707573; PMCID: PMC7952581.

3.   Alexander R, Khaja A, Debiec N, Fazioli A, Torrance M, Razzaque MS. Health-promoting benefits of lentils: Anti-inflammatory and anti-microbial effects. Curr Res Physiol. 2024 Mar 5;7:100124. doi: 10.1016/j.crphys.2024.100124. PMID: 38501131; PMCID: PMC10945126.

4.   Schönenberger KA, Schüpfer AC, Gloy VL, Hasler P, Stanga Z, Kaegi-Braun N, Reber E. Effect of Anti-Inflammatory Diets on Pain in Rheumatoid Arthritis: A Systematic Review and Meta-Analysis. Nutrients. 2021 Nov 24;13(12):4221. doi: 10.3390/nu13124221. PMID: 34959772; PMCID: PMC8706441.

5.   Papandreou P, Gioxari A, Daskalou E, Grammatikopoulou MG, Skouroliakou M, Bogdanos DP. Mediterranean Diet and Physical Activity Nudges versus Usual Care in Women with Rheumatoid Arthritis: Results from the MADEIRA Randomized Controlled Trial. Nutrients. 2023 Jan 28;15(3):676. doi: 10.3390/nu15030676. PMID: 36771382; PMCID: PMC9919932.

6.   Philippou E, Petersson SD, Rodomar C, Nikiphorou E. Rheumatoid arthritis and dietary interventions: systematic review of clinical trials. Nutr Rev. 2021 Mar 9;79(4):410-428. doi: 10.1093/nutrit/nuaa033. PMID: 32585000.

7.   Nelson J, Sjöblom H, Gjertsson I, Ulven SM, Lindqvist HM, Bärebring L. Do Interventions with Diet or Dietary Supplements Reduce the Disease Activity Score in Rheumatoid Arthritis? A Systematic Review of Randomized Controlled Trials. Nutrients. 2020 Sep 29;12(10):2991. doi: 10.3390/nu12102991. PMID: 33003645; PMCID: PMC7600426.

8.   Liu YQ, Liu Y, Chen ZY, Li H, Xiao T. Rheumatoid arthritis and osteoporosis: a bi-directional Mendelian randomization study. Aging (Albany NY). 2021 May 18;13(10):14109-14130. doi: 10.18632/aging.203029. Epub 2021 May 18. PMID: 34015765; PMCID: PMC8202858.