I want to start by saying that any research that begins to looks into nutrition and autoimmunity is a step in the right direction!

Having done research and published peer-reviewed studies myself, I know how difficult it can be to obtain funding, carry out the research, and present your results. This process can take years. For a more in-depth discussion of the difficulties of studying nutrition, see my blog post here.

I’m really happy that research into nutrition and autoimmune arthritis is seeing a revival from earlier studies in the 1990s. Nutrition research was more common then before the success of DMARDS (disease-modifying anti-rheumatic drugs). If you’ve read my blog before, you know that I dealt with a form of autoimmune arthritis for 12 years before using nutrition to heal. During this time, I relied on information published in the 1990s and early 2000s because new research on diet just wasn’t happening. 

Thankfully, this is beginning to change and there’s a brand new study out which looks directly at diet and arthritis…so let’s dive in!

 

New Study

The latest study on nutrition and arthritis by Vadell et al. (2020) out of Sweden is entitled, Anti-inflammatory Diet in Rheumatoid Arthritis (ADIRA) – a randomized, controlled crossover trial indicating effects on disease activity.

This is an experimental study, meaning the researchers came up with a question they wanted to test and devised a real-world scenario to test this question. They decided that they wanted to understand the impact of a particular anti-inflammatory diet on blood markers of inflammation in people with rheumatoid arthritis, a particular type of autoimmune disease that primarily impacts the joints.

A randomized cross-over trial means that subjects were randomly selected to eat either the intervention diet (anti-inflammatory) or control diet (typical Swedish diet). After a period of time, the participants stopped each diet and then switched diet groups, which is the “cross-over” part. This ensures that every subject gets access to each diet, which removes several confounding factors. 

 

Details of the Study

 

Participants:
  • 50 subjects
  • Between the ages of 18-75 yrs 
  • Had RA (rheumatoid arthritis) for at least 2 years
  • Had no change in medication/symptoms in preceding 8 weeks
  • Had no known allergies to the foods included in the study

 

Methods:
  • Participants were randomly selected to eat either an anti-inflammatory diet for 10 weeks, or the standard Swedish diet for the same length of time. 
  • After a period of time (washout period) of approximately 4 months, the groups were switched and given the opposite diet for an additional 10 weeks (approximately).
  • Breakfast, 1 snack, and 1 main meal per day was delivered to each subject. The remainder of the meals/snacks were expected to be prepared by the participants based on dietary recommendations.
  • No supplements were provided, except those prescribed by each subject’s physician. Participants were told not to vary weight throughout the study period.
  • Intervention diet (aka “anti-inflammatory diet”) included
    • fish (mainly salmon) 3-4x/week
    • vegetarian dishes with legumes 1-2x/week
    • whole grains (included gluten)
    • potatoes (white presumably?)
    • vegetables
    • low-fat dairy
    • fruit
    • probiotics
    • oil/margarine for cooking
  • Control diet (aka, “inflammatory”)
    • high-fat dairy
    • butter for cooking
    • meat/chicken and refined grains daily
    • fruit juices
    • white bread
    • avoidance of probiotics
  • Participants were “blinded” to the diets, meaning they didn’t know that they were receiving either an inflammatory or anti-inflammatory diet. They were told they were involved in a study looking at difference in “fibre” (intervention) vs. “protein” (control) diets.
  • Subjects were called mid-way through the diet period to determine if they were following the instructions and meal plans.
  • They were required to keep a 3-day food journal as an example of their diet throughout each period and to weigh each item recorded in the journal.
  • A lifestyle questionnaire was completed to understand confounding variables, such as smoking, education, and career. These variables were recorded because they could impact the outcome of the results.
  • Disease outcome was measured using ESR (erythrocyte sedimentation rate) and CRP (C-Reactive Protein) through blood tests. These are widely used measures of disease activity and inflammation in arthritis.
  • Blood was collected before and after each diet period.

 

Results:
  • Forty-four participants completed both diet periods.
  • Forty control and 43 intervention diets were completely successfully.
  • Food journals indicate that fibre and quality fat intake (high in omega-3s) was significantly higher in the intervention diet.
  • There were no changes in energy intake or weight between the two diets.
  • Seventy-seven percent of participants identified as women, 43% did not work, and 32% had a BMI corresponding to obesity.
  • Overall, when confounding variables were controlled for, there was no statistically significant difference between diet periods in regards to impact on disease activity.
  • Other statistical tests were run that did not account for confounding variables. Inflammation levels were compared before and after the introduction of the anti-inflammatory diet. When this was done, there was a significant decrease in inflammation following the diet. This did not happen for the control diet.
  • Although not statistically significant, there were fewer swollen/tender joints after the anti-inflammatory diet (56%) than after the control diet (39%) and lower CRP levels after the anti-inflammatory diet as well.There was also a trend towards higher ESR after the control diet. 

 

Their Discussion:
  • While there was no statistically significant difference in effects on joint markers between diets, there was a decrease in disease activity and inflammation directly following the intervention diet.
  • They posit that perhaps participants were too healthy to notice a statistically significant difference or were not provided with enough meals during the study. Another reason for this could be small sample size.
  • They distinguish their “anti-inflammatory” diet from a “Mediterranean” diet typically studied in autoimmune disease due to the use of probiotics. They chose to use probiotics because research points to less diverse gut bacteria present in individuals with RA.
  • Overall their study indicates positive effects of the use of an anti-inflammatory diet in RA and suggests that it could be used as a potential adjuvant therapy in the future.

 

Limitations/Strengths that they note:
  • They were only able to blind the participants and not the researchers.
  • Participants only received half of the meals they needed throughout the study.
  • Participants all resided in one location, which could bias results.
  • It was difficult to recruit men, although more women than men have RA in Sweden.
  • Pharmaceutical drug use was not restricted, making it difficult to compare participants.
  • The study design exposed participants to both diet patterns, which allows each subject to be their own control, effectively eliminating issues with individual background diet. 
  • The 4-month washout period reduced the potential for carry-over effects from each diet. This means that any effects from the diet protocols would be eliminated during this time and would not effect the second diet period.
  • Participants remained weight stable, which controls for this variable. 
  • Meals were easy to prepare,which is important when living with joint pain.

 

My Critique:

  • This study was a positive step forward to acknowledge that an overall anti-inflammatory diet, as opposed to a single nutrient or class of food, is likely beneficial for RA.
  • A longer study period would be more beneficial than the chosen 10 weeks. In reality, it takes time to adjust dietary habits and learn to cook all meals from scratch. 
  • Providing all meals and snacks would allow for more control in this experiment.
  • What was classified as an “anti-inflammatory” diet is questionable:
    • Why was low-fat dairy chosen? Research indicates that earlier recommendations to reduce intake of full-fat dairy are no longer warranted.
    • Margarine is not anti-inflammatory. Margarine is a highly processed food which often contains harmful trans-fats. Grass-fed butter and ghee are often healthier alternatives.
    • Why was dairy and gluten a part of the diet? Research indicates that these food groups are more likely to cause issues in those with autoimmunity.
    • Protein quality was not mentioned. For example, grass-fed vs conventional beef provide very different nutritional profiles, as do organic vs. conventional produce. This is important when considering the inflammatory effects of food. Pesticide exposure can increase the body’s inflammatory response. 
  • Foods were delivered through a food-delivery service, but it’s not clear if any processed foods were included. For example, sauces are often processed.
  • This was not a holistic approach to autoimmune nutrition. Factors such as sleep, stress, exercise, and hydration all contribute to how well nutrients are digestion and absorbed.
  • This study also has a very large age range in participants (18-75 years), who are mostly female. This could lead to several confounding variables in lifestyle and ability/knowledge of healthy eating.

 

What else could be included in an anti-inflammatory diet:

  • More variety of prebiotic and probiotic foods for overall gut health, including lots of leafy greens.
  • More quality sources of omega 3s, such as flax seeds.
  • Limited amounts of caffeine and preferably from green tea.
  • At least 2 litres of water per day and limited coffee/alcohol.
  • Cooking with grass-fed ghee or coconut oil instead of margarine and vegetable oils.
  • Legumes could be soaked for easier digestion.

 

Potential confounding factors that were not addressed:

  • Sleep
  • Stress
  • Side effects from medication
  • Difference in supplement use
  • Use of chemicals for household cleaning and personal care products

 

 

Take-away

No scientific study can address all relevant variables. Science is an ever-evolving and never-settled pursuit of truth. 

It’s great that research on nutrition and autoimmune disease is becoming a focus of current research. However, there is a long way to go and a never-ending list of potential hypotheses to be tested. 

This study made an important step forwards in terms of studying the impact of a specific ‘diet’ on disease activity. Determining what constitutes an ‘anti-inflammatory’ protocol is difficult. Nutrigenomics – the science of studying nutrition and genetics – suggests that this will differ on a case-by-case basis for each individual. Nevertheless, studying combinations of food, as opposed to single nutrients, is an important step in identifying which groups of food are likely to be less inflammatory than others. 

Clearly, this study suggests that a diet rich in plant-protein, fibre, antioxidant-rich fruits, and probiotics likely leads to a decrease in disease activity. I would argue that, by addressing the issues I outline above, a more comprehensive ‘anti-inflammatory’ diet could lead to more clear statistically significant results in the future. 

Nutrition and autoimmunity can no longer be ignored. If you have autoimmunity and are interested in the role of food, talk to your healthcare providers about your interest. The more we ask, the more likely it is that research will continue to try to answer our questions. Our voice is important!

As always, I’m hear (virtually) if you have any questions or want to take a deep-dive into personalized nutrition!

Katie