Effect of dietary interventions on nutritional status in patients with rheumatoid arthritis and spondyloarthritis - A systematic review and meta-analysis

Patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA) have an increased risk of developing altered body composition, such as low muscle mass, and an increased risk of developing cardiovascular diseases (CVD). Thus, investigating how to improve body composition and CVD risk factors is a relevant topic to improve management of RA and SpA. The aim of this study was to identify dietary interventions that can improve body composition, as well as reduce CVD risk factors in RA and SpA.

We searched the databases Medline, Embase and Cochrane. Duplicates were removed using Endnote and records were screened through Rayyan. The primary outcomes were muscle mass (kg) and fat mass (kg). Secondary outcomes were body weight (kg), body mass index (BMI: kg/m²), waist circumference (cm) and lipid profile (total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, mmol/L).

A total of 4965 articles were identified, and 17 articles were included in this review, of which 15 were suitable for meta-analysis. We found a reduction in TC and LDL-C, (Mean difference, [95%CI]: -0.36, [-0.63, -0.10], I² = 43%, and -0.20, [-0.35, -0.05], I² = 0% respectively). Otherwise, no other significant effect was seen in either primary or secondary outcomes. The evidence was graded as moderate for TC and low for LDL-C.

Dietary interventions might reduce the levels of blood lipids, and consequently, the risk of cardiovascular diseases. However, body composition did not change significantly after a 2-4 month dietary intervention. Both short intervention period and lack of reliable methods to assess body composition are possible explanations for this finding. Further studies of longer duration are needed.