Food & Disease: How Diet May Affect Rheumatic & Musculoskeletal Diseases

In a 2018 review on this subject, Petersson et al. noted the Mediterranean diet may reduce pain and swollen and tender joints in patients with RA. Moreover, the authors noted that n-3 polyunsaturated fat supplementation (i.e., fish oil supplements) may reduce inflammation and possibly slow the progression to pharmacotherapy in patients with RA.⁵

Comorbidities

In addition to managing rheumatic diseases, rheumatologists must be attuned to preventing common comorbidities in patients. Among these conditions is osteoporosis, and Dr. Nikiphorou said patients on particular diets, such as vegan diets, may be at risk of inadequate calcium and vitamin D intake. Other dietary considerations important to bone health include the intake of vitamin C, vitamin K, magnesium and potassium.

Focusing on vitamin D, evidence exists that deficiency of this vitamin may correlate with disease activity for patients with autoimmune disease. Fernandes et al. found, in patients with spondyloarthritis, vitamin D correlates with disease activity, structural damage and extra-articular manifestations, including gut inflammation and anterior uveitis.⁶

Evidence exists that vitamin D deficiency can also significantly affect disease activity in systemic lupus erythematosus (SLE). Gao et al. measured serum levels of 25-hydroxyvitamin D3 in 121 patients with SLE and in 150 healthy controls. They found severe deficiency (defined as a level less than 10 ng/mL) correlated with increased SLE Disease Activity Index scores (odds ratio [OR] 6.420; P=0.006).⁷

In a separate study, Petri et al. found that among 1,000 patients with SLE monitored over 128 weeks, a 20 ng/mL increase in 25-hydroxyvitamin D level was associated with a 21% decrease in the odds of having a high disease activity score and a 15% decrease in the odds of having clinically important proteinuria.⁸

Weight

On the subject of obesity, Dr. Nikiphorou referred to some of her own research. Using data from two consecutive, similarly designed, multicenter RA inception cohorts in the U.K., Dr. Nikiphorou and colleagues collected data on the BMI for more than 2,300 patients with newly diagnosed RA. The researchers found that being obese at baseline was associated with a 43% reduction in the odds of achieving a low EULAR Disease Activity Score in 28 Joints (DAS-28) on at least one occasion by year 2 compared with those in the normal/overweight category (OR 0.57; 95% confidence interval 0.61, 0.90). Also, scores on the Health Assessment Questionnaire (HAQ) and the 36-item Short Form Health Survey (SF-36) were significantly worse in year 2 of follow-up for patients who were obese at baseline.⁹