Mediterranean diet in axial spondyloarthritis: an observational study in an Italian monocentric cohort

BACKGROUND: Little evidence is available about the impact of diet on disease activity of axial spondyloarthritis (axSpA). This study evaluated the impact of a 6-month nutritional advice based on the Mediterranean diet on the disease activity of axSpA. METHODS: We prospectively collected the information of a group of axSpA patients who were offered nutritional advice for a 6-month period, who were compared to axSpA patients followed at the same center who were not on a specific diet. A nutritionist gave suggestions for dietary modification at baseline and thereafter every 2 months until month 6. Adherence to the Mediterranean diet was evaluated with the PREDIMED questionnaire ranging from 0 (no adherence) to 10 (optimal adherence); disease activity was evaluated with ASDAS-CRP. A multivariable regression analysis was conducted to identify independent predictors of PREDIMED and of ASDAS-CRP improvement (improvement ≥ 20% of each score). RESULTS: A total of 161 patients were included: 81 receiving nutritional advice and 80 controls; 47 in the nutritional group and 63 controls had complete information until month 6. Overall, 40 (36.4%) were females, the mean age was 51.7 ± 1.3 years, and 58 (52.7%) were affected with psoriasis. No relevant change of anthropometric or laboratory measures was observed in either group. Adherence to the Mediterranean diet was moderate (PREDIMED score 6.7 ± 1.8 at baseline; 7.6 ± 2.1 at month 6) and improved more in the nutritional group compared to controls (p = 0.020). Predictors of a PREDIMED improvement ≥ 20% were receiving nutritional advice (OR 4.53, 1.36–15.1, p = 0.014), age (per 10-year increase OR 1.05, 1.02–1.68, p = 0.007), and BMI (OR 0.77, 0.63–0.9, p = 0.006). An ASDAS-CRP improvement ≥ 20% was more frequent in the nutritional group compared to controls (p = 0.020). A PREDIMED improvement ≥ 20% was associated with a ASDAS-CRP improvement ≥ 20% (OR 6.75,1.8–25.3, p = 0.005). Psoriasis and disease duration were negatively but not significantly associated to the ASDAS-CRP improvement. CONCLUSIONS: Improving adherence to the Mediterranean diet may have a beneficial impact on the activity of axSpA. Patients with a lower BMI and older patients are less prone to modify their diet towards the Mediterranean diet following nutritional advice. Patients with psoriasis may have a limited benefit from dietary improvement. STUDY REGISTRATION: Protocol No. 52723, Padova Hospital Medical Ethical Committee (October 11, 2010). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13075-021-02600-0.