Mediterranean diet, selenium and Graves' ophthalmopathy: a prospective, randomized, single-center study.

Abstract

Purpose: Graves' ophthalmopathy (GO) is an autoimmune-inflammatory condition affecting about 25% of patients with Graves' disease (GD). Oxidative stress (OS) increases the production of inflammatory cytokines, the production of free radicals (ROS) and insulin resistance modulating IGF-1r/TSHr cross-talk in GO. Selenium is a component of selenoproteins and promotes the suppression of ROS production. We aim to evaluate the effects of the Mediterranean diet (MD) naturally enriched with selenium in patients with GD and active mild GO on thyroid function parameters, nutritional state, autoimmunity and the clinical course of GO.

Methods: 40 GD patients with untreated mild active GO and stable thyroid function were randomly assigned to the Mediterranean diet (MD) naturally enriched with selenium (MD group) or a free diet (FD group). The selenium content of the MD was increased by approximately 30% according to the reference levels of nutrient and energy intake for the Italian population (LARN 2014). The combined endocrinological-ophthalmological evaluation was carried - out at baseline and after 12 and 24 weeks from the beginning of the MD or FD.

Results: The MD contained 178.1 ± 15.1 mcg of SE, and the diet was balanced with respect to the macronutrient composition. The Clinical Activity Score (CAS) improved significantly at visit 1 in the MD group compared to the FD group (p = 0.03). Hertel measurements and eyes motility were not different at visits 1 and 2 in either group of patients. Soft tissue involvement improved in the MD group compared to the FD group at visit 1 and 2 (p = 0.03 and 0.04). The absolute value (mm) of the eyelid aperture was significantly lower at visit 2 in the MD group than in the FD group (9.3 ± 0.6 vs. 10.5 ± 0.5, p = 0.01). The relative change in BMI was significantly lower in the MD group than in the FD group at visit 2 (2.5 [(-9.4) -10.1)] vs. 5.1 [(-0.4) -15)] kg, p = 0.04). TRABs values and thyroid function did not differ and decreased to a similar degree in both groups of patients during the observation period. No cases of GO exacerbation were observed in the two groups of patients.

Conclusions: The MD is a versatile dietary style and should be a component of the dietary treatment plan in patients with GD and mild GO to reduce weight regain and the inflammation and insulin resistance, which in turn contribute to the autoimmune-inflammatory processes of GO.