For patients with rheumatoid arthritis, diets matter

Foods factor in the management of symptoms of rheumatoid arthritis (RA), and several dietary approaches help by removing staples that promote inflammation or by adding more of anti-inflammatory edibles and altering the gut microbiota, according to a team of researchers.

“[B]ased on the available evidence … we advocate to use the Mediterranean diet (MD) and fish oil supplements in conjunction but not as a replacement of other nondietary interventions and pharmacotherapy,” said principal researcher Dr Elena Philippou from the University of Nicosia in Cyprus.

MD is a well-balanced, nonrestrictive diet with anti-inflammatory, antioxidant, and cardioprotective properties, Philippou noted. She stressed that any elimination of foods should be done under dietetic supervision to minimize the risk of an unbalanced or restricted macro- or micronutrient intake.

“[W]e also recommend a reduction in salt intake to <5 g/d, as supported by the World Health Organization’s Healthy Eating Guidelines, and routine assessment of vitamin D3 concentration as well as supplementation where necessary,” she added. [https://www.who.int/news-room/factsheets/detail/healthy-diet]

In the study, Philippou and colleagues conducted a systematic review to update the current knowledge on the effects of nutritional, dietary supplement, and fasting interventions on RA outcomes. They searched multiple online databases and identified 70 studies, the large majority of which involving 20–60 participants. The mean age of the population was 50–60 years, with most participants being female, as expected for RA patients.

Among supplement studies, 17 examined the effects of fish oil, nine of omega-3 polyunsaturated fatty acid (PUFA), and seven of other supplements (ie, evening primrose oil, vitamin D, vitamin K, selenium, or combination). A single study assessed sodium restriction. The remainder of the 36 studies investigated fasting or dietary modifications, such as fasting or calorie restriction, ketogenic diets, Ramadan fasting, vegetarian feeding, vegetarian or vegan diet, gluten-free vegan diet, elemental or peptide diets, and MD. The duration of interventions varied between 7 days and 13 months, with most studies (n=26) lasting >3 months. Controls used in some studies were other oils (eg, olive oil), placebo supplements in supplement studies, or normal/usual diet in feeding studies.

Pooled data showed that administration of omega-3 at high doses (≥2.7 g/d) led to a reduction in RA disease activity and a lower failure rate of pharmacotherapy. Vitamin D supplementation and dietary sodium restriction were beneficial on some RA outcomes. [Nutr Rev 2020;doi:10.1093/nutrit/nuaa033]

“Correction of vitamin D concentration in those deficient is imperative owing to the central role of vitamin D in calcium homeostasis, bone mineralization, and general preservation of musculoskeletal health, and thus should be advocated,” according to Philippou. “[T]he observed benefits of sodium restriction on RA inflammation were also as expected, since sodium chloride activates proinflammatory macrophages and T helper 17 cells and decreases regulatory T cells, as recently reviewed.” [RMD Open 2018;4:e000591]

MD produced overall modest improvements in stable and modestly active RA, while outcomes from vegetarian, elimination, peptide, or elemental diets indicated that responses were very individualized. Finally, fasting resulted in significant but transient subjective improvements.

“Total fasting for specified periods was the most effective type of fast; however, such fasting is unsustainable or even impossible in some cases—and thus we would not recommend it,” the researcher said.

Taken together, the findings highlight the importance of routinely addressing nutrition in RA patients by referral to registered dietitians, who are experts in identifying and addressing nutrition-related issues, Philippou said.

Further large, well-controlled randomized controlled trials on plausible and realistic dietary interventions, such as the MD with additional fatty fish or omega-3 PUFA supplements, are needed in order to assess both objective and subjective RA outcomes.