The Effect of a Ketogenic Diet versus Mediterranean Diet on Clinical and Biochemical Markers of Inflammation in Patients with Obesity and Psoriatic Arthritis: A Randomized Crossover Trial

The effect of different diet patterns on psoriasis (PSO) and psoriatic arthritis (PSA) is unknown. Τhe aim of our study was to evaluate the effectiveness of a Mediterranean diet (MD) and Ketogenic diet (KD), in patients with PSO and PSA. Twenty-six patients were randomly assigned to start either with MD or KD for a period of 8 weeks. After a 6-week washout interval, the two groups were crossed over to the other type of diet for 8 weeks. At the end of this study, MD and KD resulted in significant reduction in weight (p = 0.002, p < 0.001, respectively), in BMI (p = 0.006, p < 0.001, respectively), in waist circumference (WC) (p = 0.001, p < 0.001, respectively), in total fat mass (p = 0.007, p < 0.001, respectively), and in visceral fat (p = 0.01, p < 0.001, respectively), in comparison with baseline. After KD, patients displayed a significant reduction in the Psoriasis Area and Severity Index (PASI) (p = 0.04), Disease Activity Index of Psoriatic Arthritis (DAPSA) (p = 0.004), interleukin (IL)-6 (p = 0.047), IL-17 (p = 0.042), and IL-23 (p = 0.037), whereas no significant differences were observed in these markers after MD (p > 0.05), compared to baseline. The 22-week MD–KD diet program in patients with PSO and PSA led to beneficial results in markers of inflammation and disease activity, which were mainly attributed to KD.