Effect of Short-Term Vitamin D Supplementation on the Alterations of Glycemic Variables in Response to Exhaustive Eccentric Exercise in Patients with Non-Alcoholic Fatty Liver

Exhaustive eccentric exercise (EEE), along with a positive role in weight loss and physiological adaptation, increases liver enzymes and disturbs glucose homeostasis. Many studies have been considered to neutralize the adverse effects of EEE, including vitamin D (Vit D) supplementation. The present study aimed to investigate the effect of short-term Vit D supplementation on the alteration of glycemic variables in response to EEE in patients with nonalcoholic fatty liver disease (NAFLD).

In this clinical trial, 22 overweight women with NAFLD were randomly assigned to control (C; n=11) and experimental (Exp; n=11) groups. C group received a lactose placebo daily with the same color, shape, and warmth percentage; Exp group received 2000 IU of Vit D daily for 6 weeks (42 days). Blood samples were taken to measure the liver enzymes, lipid profile, and Vit D levels alteration at four stages: Pre1(before the first EEE session), post 1 (after the first EEE session), pre 2 (before the second EEE session), and post 2 (after the second EEE session). Repeated measures ANOVA and independent t test were used to analyze the data using SPSS software (version 26) at a significance level of P < 0.05.

The results show a significant increase in glucose, insulin, and homeostatic model assessment for insulin resistance (HOMA-IR) levels in both C and Exp groups following the EEE (comparing pre 1 and post 1). Also, after 6 weeks of Vit D supplementation, glucose, insulin, and HOMA-IR increased significantly in both C (P = 0.001, P = 0.001, and P = 0.001, respectively) and Exp (P = 0.001, P = 0.001, and P = 0.001, respectively) groups following EEE (comparison of pre 2 and post 2). However, these increases were significantly lower in Exp group compared with the C group (comparing post 2).

Short-term Vit D supplementation downregulates the increased glucose, insulin, and insulin resistance induced by EEE in patients with NAFLD.