As early as the 1920s, the Mayo Clinic included a “balanced diet” among the therapeutic modalities used to treat patients admitted for what was then called “chronic arthritis.”1 Today, questions about whether dietary factors might trigger rheumatoid arthritis (RA) — and whether diet could play a role in relieving symptoms — are of keen interest to patients affected by the disease, and are frequently asked of rheumatologists.2
In a recent study led by Jeffrey Sparks, MD, a rheumatologist and clinical researcher at Brigham and Women’s Hospital and Harvard Medical School in Boston, Massachusetts, women from 2 Nurses’ Health Study cohorts — 79,988 in the Nurses’ Health Study (NHS), that was conducted from 1984 to 2014 and 93,572 women in the NHSII, which was conducted from 1991 to 2013 — were followed prospectively to determine whether an inflammatory diet pattern was associated with the risk for incident RA.3 At baseline and at 4-year intervals, participants in the NHS completed food frequency questionnaires that assessed the intake of a variety of foods and beverages over the previous year and ranked the frequency of each one on a scale from never or <1 per month to ≥6 servings per day.
Dr Sparks and colleagues used data from the food frequency questionnaires to determine each woman’s Empirical Dietary Inflammatory Pattern (EDIP) score, a measure that had been developed previously by identifying the food and beverage groups most strongly associated with 3 circulating inflammatory markers implicated in numerous diseases: interleukin-6, C-reactive protein, and tumor necrosis factor-α receptor 2.4 Processed meat, red meat, organ meat, non-dark meat fish, vegetables other than green leafy and dark-yellow vegetables, refined grains, high-energy beverages, low-energy beverages, and tomatoes were positively associated with the inflammatory markers and thus identified as pro-inflammatory food groups, whereas beer, wine, tea, coffee, dark-yellow vegetables, leafy green vegetables, snacks, fruit juice, and pizza were inversely associated with the markers and thus identified as anti-inflammatory food groups. High EDIP scores are indicative of pro-inflammatory diets, and low EDIP scores are indicative of anti-inflammatory diets.
Dr Sparks and colleagues documented 1185 cases of incident RA over 4,425,434 person-years of follow-up. An inflammatory dietary pattern was not associated with overall RA risk or RA risk among women older than 55 years; however, it did increase the risk for seropositive RA in women younger than 55 years, leading the authors to conclude that “metabolic/dietary lifestyle factors may affect RA risk differently based on age of onset as well as serologic status.”
Rheumatology Advisor asked Dr Sparks about the counterintuitive inclusion of pizza as an anti-inflammatory food group. “We were surprised about that, too,” Dr Sparks said. “There are some interesting thoughts about whether processed tomatoes might actually have anti-inflammatory properties. This study was done in a cohort of older nurses. So the type of pizza they may be eating may be relatively more healthy. It’s not clear that this is generalizable to other populations.”
The study adds to the growing body of literature examining the influence of diet on RA. In a recent narrative review, researchers from Wrocław Medical University, Poland, wrote that RA, “develops in the course of an autoimmune inflammatory process triggered by environmental factors in a genetically predisposed person. One such environmental factor, which may either increase or decrease the risk of RA incidence, as well as having an immunomodulatory (exacerbating or attenuating) influence on disease activity, is the diet.”
The review authors summarized current research on influence of diet on RA development and disease activity. With varying degrees of evidence, many components of diet have been implicated as possible risk factors for RA, including high fat diets; sugary drinks rich in fructose; dietary lectins commonly found in cereal grains, beans, and legumes; and a Western dietary pattern involving the high consumption of red and processed meats, sugary foods, and drinks.5-7 Conversely, studies have shown that that omega-3 polyunsaturated fatty acids, healthy eating patterns based on the US Dietary Guidelines for Americans, and the consumption of citrus fruits, dairy, and mushrooms may attenuate the risk of developing RA.5,6
“I don’t know that our research points to an optimal diet that can prevent [RA],” Dr. Sparks told Rheumatology Advisor. “The important thing is that our study, among others, does suggest that diet does play a role in the pathogenesis of [RA]. As far as how much it could reduce risk and how long you need to be on a diet before we see these effects, I think those are a bit more unclear. But at the end of the day, there is more evidence showing that healthier diet choices can lower blood inflammation and that probably does have an impact on diseases such as [RA].” He cautioned that the effects of diet on RA are relatively modest. “It’s very unlikely that diet will ever be able to replace the drugs that are having much more powerful effects on outcome.”
“I think it’s fascinating that while we still don’t know what causes [RA], we are getting to the point where we can define a lifestyle that will alter your risk either positively or negatively,” Dr Sparks noted. “So when people are concerned about their RA risk, there are lifestyle changes that you could talk to them about. Certainly, diet and smoking cessation and weight loss all seem to have a positive impact.”
Dr Sparks said that researching the effect of physical activity on RA risk was the next step in understanding the metabolic effects that go on prior to the development of RA. “That’s a lifestyle factor that there’s relatively less literature about. We’d also like to understand some of the biological effects of obesity prior to [RA], particularly how the actual molecules secreted by adipose cells could impact RA risk.”
- Hunder GG, Matteson EL. Rheumatology practice at Mayo Clinic: The first 40 years–1920 to 1960. Mayo Clin Proc. 2010;85(4):e17-e30.
- Salminen E, Heikkilä S, Poussa T, Lagström H, Saario R, Salminen S. Female patients tend to alter their diet following the diagnosis of rheumatoid arthritis and breast cancer. Prev Med. 2002;34(5):529-535.
- Sparks JA, Barbhaiya M, Tedeschi SK, et al. Inflammatory dietary pattern and risk of developing rheumatoid arthritis in women [published online August 14, 2018]. Clin Rheumatol. doi:10.1007/s10067-018-4261-5
- Tabung FK, Smith-Warner SA, Chavarro JE, et al. Development and validation of an empirical dietary inflammatory index. J Nutr. 2016;146(8):1560-1570.
- Hu Y, Sparks JA, Malspeis S, et al. Long-term dietary quality and risk of developing rheumatoid arthritis in women. Ann Rheum Dis. 2017;76(8):1357-1364.
- Skoczyńska M, Świerkot J. The role of diet in rheumatoid arthritis. Reumatologia. 2018;56(4):259-267.
- Cordain L, Toohey L, Smith MJ, Hickey MS. Modulation of immune function by dietary lectins in rheumatoid arthritis. Br J Nutr. 2000;83(3):207-217.