Anti-Inflammatory Diets & The Mediterranean Diet

Though this material was generated for people with rheumatic conditions as part of Nutrition for People with Rheumatic Diseases, it is also relevant to the general public.  

There are many different definitions of an anti-inflammatory diet and it is unclear whether diets that claim to be anti-inflammatory actually decrease inflammation in people with autoimmune conditions [1, 2]. However, we know that certain food components and ingredients can increase or decrease inflammation by affecting blood sugar, antioxidant levels, and the bacteria that live in our gut. These helpful and harmful food components are discussed in the General Nutrition Recommendations section. Whereas the Mediterranean diet is an example of an anti-inflammatory diet, the Standard [North] American Diet (or SAD diet), which contains large amounts of calorically-dense processed foods, saturated fat, and added sugar, is pro-inflammatory and associated with increased risk of cardiovascular disease and death [3-6].  

The Mediterranean diet is a pattern of eating based on typical diets in countries near the Mediterranean Sea, such as Greece, Italy, and Spain. This diet contains lots of vegetables, fruit, olive oil, whole grains, and beans and moderate amounts of fish, chicken, low-fat dairy, and nuts. The diet limits red meat, sugary drinks (including fruit juice), salt, processed foods, and processed meats. The American Heart Association provides a great summary of this diet.

Two different randomized controlled trials have studied whether the Mediterranean diet decreases joint inflammation in people with RA. The first study found that the group eating a Mediterranean diet had a significant improvement in RA disease activity (reduced joint inflammation) after 12 weeks on the diet [7]. The amount of improvement in the Mediterranean diet group was large for a diet intervention and was about 1/3rd the size of the benefit seen in trials of methotrexate for RA (the most common RA medication). This version of the Mediterranean diet included olive oil, canola oil, margarine (based on canola oil), green vegetables, root vegetables, fish, fruit, low-fat yogurt, low-fat cheese, green tea, black tea, poultry, and sparing amounts of red meat. Notably, RA patients on the Mediterranean diet lost a significant amount of weight at the end of 12 weeks—about 7 pounds—so it’s possible that some of the improvement in RA symptoms was due to weight loss. 

Another trial that tested a 6-week Mediterranean-type diet for RA patients found that the group eating the Mediterranean diet had less pain and morning stiffness 6 months later, suggesting that it provided a long-lasting benefit [8]. The intervention included weekly Mediterranean diet cooking classes, and provided recipes, written materials about the diet, and information about local access to affordable ingredients. The Mediterranean-type diet was high in fruit, vegetables, legumes (beans), and olive oil. 

References

1. Bustamante, M.F., et al., Design of an anti-inflammatory diet (ITIS diet) for patients with rheumatoid arthritis. Contemp Clin Trials Commun, 2020. 17: p. 100524. 

2. Vadell, A.K.E., et al., Anti-inflammatory Diet In Rheumatoid Arthritis (ADIRA)-a randomized, controlled crossover trial indicating effects on disease activity. Am J Clin Nutr, 2020. 111(6): p. 1203-1213. 

3. Rico-Campa, A., et al., Association between consumption of ultra-processed foods and all cause mortality: SUN prospective cohort study. BMJ, 2019. 365: p. l1949. 

4. Manzel, A., et al., Role of "Western diet" in inflammatory autoimmune diseases. Curr Allergy Asthma Rep, 2014. 14(1): p. 404. 

5. Grotto, D. and E. Zied, The Standard American Diet and its relationship to the health status of Americans. Nutr Clin Pract, 2010. 25(6): p. 603-12. 

6. Srour, B., et al., Ultra-processed food intake and risk of cardiovascular disease: prospective cohort study (NutriNet-Sante). BMJ, 2019. 365: p. l1451. 

7. Skoldstam, L., L. Hagfors, and G. Johansson, An experimental study of a Mediterranean diet intervention for patients with rheumatoid arthritis. Ann Rheum Dis, 2003. 62(3): p. 208-14. 

8. McKellar, G., et al., A pilot study of a Mediterranean-type diet intervention in female patients with rheumatoid arthritis living in areas of social deprivation in Glasgow. Ann Rheum Dis, 2007. 66(9): p. 1239-43.