, Brazilian researchers found.
Earlier research has reported that weight loss improves the symptoms of PsA.
Improvement in the Brazilian DIETA study was linked to both better eating patterns and better quality of diet, and while omega-3 supplementation caused relevant body composition changes, it did not improve disease activity, according to Beatriz F. Leite of the division of rheumatology at the Federal University of São Paulo and colleagues.
“The DIETA trial, a nonpharmacologic approach, is an inexpensive, suitable, and efficient approach that could be combined with standardized drug therapy,” the investigators wrote online in Advances in Rheumatology.
Dietary counseling aimed at losing or controlling weight could therefore be part of the global protocol for PsA patients, the researchers added. They conceded, however, that nonpharmacologic interventions traditionally have a low rate of adherence.
This recommendation aligns with a systematic review by the National Psoriasis Foundation, which found evidence of benefit with dietary weight reduction via a hypocaloric diet in overweight and obese patients with psoriasis and/or PsA.
The DIETA trial
The 12-week randomized, double-blind, placebo-controlled study, conducted at three hospitals in São Paulo from September 2012 to May 2014, assessed whether dietary changes, antioxidant supplementation, or weight loss of 5%-10% could improve skin and joint activity in 97 enrolled PsA patients.
Participants were randomized into the following supervised dietary groups:
- Diet-placebo (hypocaloric diet plus placebo supplementation).
- Diet-fish (hypocaloric diet plus 3 g/day of omega-3 supplementation).
- Placebo (with habitual diet).
Diets were carefully tailored to each individual patient. The regimen for overweight and obese patients included a 500-kcal restriction, while for eutrophic patients, diets were calculated to maintain weight with no caloric restriction.
In the 91 patients evaluable by multiple measures at 12 weeks, Ms. Leite and colleagues observed the following:
- The Disease Activity Score 28 (DAS28) for Rheumatoid Arthritis with C-Reactive Protein and the Bath Ankylosing Spondylitis Disease Activity Index improved, especially in the diet-placebo group (−0.6 ± 0.9, P = .004 and −1.39 ± 1.97, P = .001, respectively).
- Minimal disease activity improved in all groups.
- The diet-fish group showed significant weight loss (−1.79 ± 2.4 kg, P = .004), as well as reductions in waist circumference (−3.28 ± 3.5 cm, P < .001) and body fat (−1.2 ± 2.2 kg, P = .006).
Other findings from this study showed the following:
- No significant correlation was seen between weight loss and disease activity improvement.
- Each 1-unit increase in the Healthy Eating Index value reduced the likelihood of achieving remission by 4%.
- Each 100-calorie increase per day caused a 3.4-fold impairment on the DAS28-Erythrocyte Sedimentation Rate score.
The fact that no changes in PsA, medications, or physical activity were made during the study period reinforces the role of diet in the context of immunometabolism, the authors said. Supervised exercise, however, could contribute to weight loss, lean muscle mass, and better disease activity control.
The authors stressed that the data suggest “increased energy intake and worse diet quality may negatively affect joint activity and reduce the likelihood of achieving disease remission, regardless of weight loss or body composition changes.”
“There are other studies that have looked at the effect of weight loss from a very low-calorie diet, and they’ve suggested that PsA symptoms can improve, said rheumatologist Eric. M. Ruderman, MD, a professor of medicine at Northwestern Medicine in Chicago, in an interview. “The unique piece here is that they found that the improvement was really independent of weight loss.”
Dr. Ruderman, who was not involved in DIETA, cautioned, however, that the study is small and saw improvement in the placebo group as well, which could suggest that some of the improvement was related to the extra attention and regular communication with the nutritionist that came with participation in the study.
“Also, the absolute improvement was small, and the dietary restriction was pretty aggressive, so I’m not sure how generalizable this really is. While there are lots of benefits to maintaining a healthy diet and exercising, I don’t think that the results of this small study would justify taking an aggressive [dietary] approach as part of the clinical playbook for all PsA patients.”
This study was supported by the São Paulo Research Foundation and the Coordination for Improvement in Higher Education Foundation of the Ministry of Education, Brazil.
The authors had no competing interests to declare.
Dr. Ruderman disclosed no relevant competing interests.