Arthritis is characterized by inflammation of the joints. Rheumatoid arthritis (RA), differs from Osteoarthritis (OA) in that it is caused by an autoimmune reaction where the immune system attacks the lining surrounding the joints.
This results in inflammation, pain, swelling, and potential joint damage over time.
It mainly affects the joints, but it can also affect other parts of the body. Other symptoms include red, puffy hands, fatigue, loss of appetite, fever, and hard bumps under the skin near joints.
RA affects about 1% of the population and although the cause is not well understood, it seems to involve environmental, genetic, and hormonal factors.
RA treatments are generally designed to provide pain relief, reduce joint stiffness and inflammation, and suppress immune activity to limit further joint damage.
Medication and physical therapy are often essential components of this management.
Although there is a clear link between diet and the immune system, the specific effects on RA symptoms and pathology are currently unclear.
However, since inflammation is a central aspect of RA, some research suggests that dietary interventions addressing this may play a role in relieving certain symptoms.
There are also specific inflammatory molecules that are commonly involved in the joints and subsequent cartilage destruction, and therefore dietary interventions that target these show more positive outcomes.
To assess the efficacy of interventions related to rheumatoid arthritis, there are certain criteria that are commonly used.
As these are mentioned throughout this blog post (through mentioning results seen in studies), it’s important to understand what these are.
DAS28: Disease Activity Score at 28 Joints
A combined index providing a measure of disease activity, comprising:
- The number of swollen joints (of a possible 28);
- The number of tender joints (of a possible 28); and
- Either erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) level (these are both markers of inflammation).
VAS: Visual Analog Scale
A psychometric response scale for parameters that range across a continuum of values, such as pain. The VAS pain scale ranges from “no pain” to “worst pain,” and patients mark a line to indicate how they are feeling.
HAQ-DI: Health Assessment Questionnaire Disability Index
The physical function scale of the HAQ, including twenty items in eight categories representing activities including dressing, eating, walking, grip, and reach.
ACR20/50/70: American College of Rheumatology Response Criteria
At least a 20%, 50%, or 70% improvement in the number of tender and swollen joints, and at least a 20%, 50%, or 70% improvement in three of the following five criteria:
- patient global VAS;
- patient pain VAS;
- physician global VAS;
- HAQ score;
- acute-phase reactant value (ESR or CRP).
Vegetarian / Vegan Diets
Overall, the research shows positive outcomes in those with RA who implement a plant-based diet
It’s important to note that weight reduction also occurred and therefore may be hard to isolate whether these results came from the diet itself or the weight loss.
Similarly, a 1-year intervention tested the effects of a 7–10 day fast, followed by 3.5 months of a gluten-free vegan diet and then the adoption of just a vegetarian diet for the remainder of the study period.
This led to significant reductions in RA symptoms such as the total number of tender and swollen joints, pain, duration of morning stiffness, and inflammatory markers. These results occurred after one month and were sustained at the 1 year period.
A follow-up study was conducted one year after this trial and found that those who continued on a plant-based diet maintained these outcomes.
Another study compared a gluten-free vegan diet vs a balanced omnivorous diet for one year. 40.5% of the vegan group met the ACR20 improvement criteria compared with 4% of the non-vegan group.
Additionally, a 3-month study which excluded meat, gluten, and lactose, was evaluated against a group with no dietary restrictions.
Improvements in the DAS28, VAS, and HAQ scores were seen in both groups (which also may have occurred through weight loss seen in both groups) however these results were only statistically significant in the food exclusion group.
The improvements in RA symptoms from these may be explained through a few mechanisms.
Firstly, a diet high in plant sources typically offer more vitamin, and minerals and can provide anti-inflammatory benefits.
This is supported in other research where a vegan dietary intervention led to a 33% reduction in C-reactive protein, which is commonly elevated in RA.
Change in Fat intake
This dietary pattern may also change the types and quantity of fats being consumed, which can influence inflammation.
For example, it may lead to a decreased intake of arachidonic acid, a type of omega-6 primarily found in animal sources that derives pro-inflammatory cytokines and has been shown to promote joint inflammation.
Another study found that those who were placed on a diet low in arachidonic acid (<90mg/day) for 3 months decreased the number of tender and swollen joints by 14% compared to those on a standard Western diet.
These benefits were even greater with the addition of fish oil.
A higher intake of plant sources typically increases dietary fibre. This can also have anti-inflammatory effects and may lead to improvements in the health of the gut, another component that is strongly linked to RA symptoms.
Research suggests there is a potential link between the gut microbiome and RA.
One proposed mechanism is the connection between intestinal inflammation and joint inflammation. This is because certain species of gut bacteria that are responsible for joint inflammation are more abundant in those with RA.
These bacteria have also been shown to lower the amount of other beneficial species.
This increase in potentially pathogenic microbes and loss of beneficial bacteria presents a state of dysbiosis and results in chronic inflammation.
A lower diversity of the gut microbiome is also typically found in those with RA which can reduce the production of short chain fatty acids (SCFA).
Since these play a role in reducing inflammation and low amounts have been shown to increase the permeability of the intestinal barrier, this may partly be contributing to a heightened inflammatory state seen in RA patients.
Alternatively, a diet rich in fibre increases the amount of these SCFA and may therefore partly explain why those who follow a plant-based diet typically see improvements in symptoms.
A low ratio of omega-3:omega-6 fatty acids has been shown to promote inflammation, increasing the risk of RA.
This is because omega-3s decrease the production of pro-inflammatory molecules that can increase the severity of symptoms, whereas omega-6s stimulate the production of these.
A review of 22 studies (956 total participants) that tested supplements of omega-3s found a favorable effect on pain in patients with RA. Overall, the results translated to an 8% improvement on the VAS scale.
From this review, they recommend RA patients look for a marine omega-3 source with an EPA/DHA ratio >1.5.
Although there was no recommended dosage, an older review found RA symptoms were reduced at a total EPA and DHA dose of ≥2.6 g/day over ≥12 weeks, with the higher the resulting in less time needed to demonstrate benefits.
The Mediterranean diet primarily includes foods that may promote antioxidant and anti-inflammatory foods and has therefore been studied for its effect on RA.
A randomized control trial found that after the 12-week period, those following the Mediterranean-style diet had significant improvements in the DAS28 and HAQ, whereas the control group did not.
Similar results have been mimicked in other studies over different lengths.
Ultimately, those consuming a dietary pattern, like the Mediterranean diet, that is high in fibre, antioxidants, and healthy fats, seem to contribute to the reduction in inflammation in RA.
Fasting has been researched in relation to RA.
Overall, studies looking at 7-day fasts decrease inflammatory symptoms related to RA.
Other researchers speculate that it could be through the increased production of beta-hydroxybutyrate (BHB), a type of ketone body.
This is because BHB can decrease the activation of a certain protein (NLRP3 Infammasone) which is responsible for releasing pro-inflammatory molecules that have been shown to worsen joint inflammation and damage seen in RA. However, drugs that have targeted this have been shown to be ineffective.
It’s important to note that following these fasting protocols, inflammation returns when food is reintroduced. Therefore, fasting may limited benefits unless combined with other dietary interventions.
A systematic review found that being overweight or obese led to adverse effects on the onset, progression, and severity of RA symptoms.
This may be because excessive adipose tissue secretes pro-inflammatory molecules, which has been shown to increase inflammatory markers in those with RA.
Research also highlights that having excess body weight may be independently associated with a decreased chance of achieving sustained RA remission, with overweight and obese patients being 25 and 47% less likely to achieve sustained remission within 3 years, respectively.
Another study found that being overweight at 18 years of age was associated with a 35% increased risk of developing RA and a 50% risk of developing seropositive RA in adulthood.
In RA patients who are overweight, weight loss may be an important strategy to reduce RA disease activity.
One study found that those who lost ≥5 kg had a three-fold increased odds of disease activity improvement compared to those who lost <5 kg.
Another study looked at the effect of weight loss in RA patients after bariatric surgery. After 12 months post-surgery, 6% of patients had moderate/high disease activity compared to 57% at baseline and after 6 years, and 74% of patients were in remission compared to 26% at baseline.
In addition to marine omega-3s, there are other supplements that have been explored in relation to RA.
It’s important to note that there are limited studies for many of these.
Thunder God Vine
Thunder God Vine (or ‘Tripterygium Wilfordii’) is a traditional Chinese medicine that appears to be effective for the treatment of inflammatory and autoimmune diseases.
A meta-analysis found that supplementing with this plant + methotrexate (a common medication used in RA), improved the ‘treatment effective rate’ (>20% improvements in RA symptoms) by 15%, ‘partial remission rate’ (>50% improvement in RA symptoms) by 27%, and ‘remission rate’ (>75% improvement in RA symptoms) by 31% compared with taking just methotrexate alone.
The dose in the review suggests 30-60mg of the Thunder God Vine with 10mg of methotrexate for the greatest outcomes.
It’s very important to note that this herb has a very low therapeutic index, meaning there is a small difference between the effective dose and the toxic dose.
It reduces inflammation around the joints by decreasing the number of white blood cells. However, this also makes the body more susceptible to infections, sickness, and potentially death.
Subsequently, supplementation is usually avoided for this reason.
Due to its anti-inflammatory properties, curcumin has been studied in relation to its effect on RA.
A 2023 systematic review of 10 studies concluded that curcumin supplementation was beneficial for reducing inflammation levels and clinical symptoms in RA patients.
The effective dosages varied between studies.
One study had participants consume either 250mg or 500 mg of curcumin twice daily or a placebo for 90 days. The percentage changes from baseline for the high-dose curcumin group resulted in decreases of 66% and 72% for DAS28 and VAS, respectively, while the low-dose group had decreases of 53% and 62%, respectively. There were no significant changes in the placebo group.
Another study looked at recent clinical trials with patients taking 250-1500 mg/day over 8 weeks to 3 months and found reductions in the clinical symptoms in all cases.
Type II Collagen
Type II collagen is a major component in joint cartilage and has been studied in its effect on reducing RA symptoms.
A randomized control trial showed a decrease in the number of swollen and tender joints in those given collagen after 3 months of supplementation whereas the placebo group did not.
One study compared four different dosages (20, 100, 500 and 2,500 ug/day), administered for 24 weeks. The greatest effects were observed with CII at the lowest dosage tested.
8 out of 10 participants in another study showed an average reduction from baseline in swollen and tender joint counts was 61% and 54% respectively after 3 months of supplementation.
Rosehip is the accessory fruit of the various species of rose plant and has been used in herbal medication due to its anti-inflammatory properties.
The research is mixed, however, there may be some potential benefits.
One study found that taking 10g/day for 28 days showed no benefit.
Another one that was conducted over 6 months with 5g/day did find benefits joint symptoms.
The same dosage for 3 months has also been shown to reduce pain and stiffness in osteoarthritis.
The research for saffron is also currently mixed.
A double-blind randomized control trial had participants take 100mg per day or a placebo for 12 weeks.
Those supplementing saffron found significant reductions in the number of tender joints (-1.28 vs 0.10), swollen joints (-2.12 vs 0.63), had a reduction in pain intensity using the VAS (-18.36 vs -2.33) and decreased DAS28 (0.75 vs 0.26) at the end of intervention compared with placebo.
Saffron supplementation has also been shown to reduce joint-related inflammatory markers in animal models induced with RA.
However other studies found no differences in improvement of disease activity by taking 100mg/day for 90 days in addition to standard therapy.
Overall, protocols such as the use of medications and physical therapy are a part of the standard effective treatment for RA.
However, from the research, it seems possible that dietary interventions may play a small role in reducing symptoms.
The benefits seem to come from being in the healthy weight range and having a diet rich in fibre, antioxidants, and foods that provide anti-inflammatory effects.
Some supplements may help through similar mechanisms, with some being fairly promising, whereas others being mixed.
Subsequently, as there were no adverse effects seen in the studies (apart from the ‘Thunder God Vine)’, they could be worth trialing on an individual basis.