One of the most important complications of obesity is non-alcoholic fatty liver disease (NAFLD). The most important assumption regarding the pathogenesis of NAFLD is the “multiple shock” assumption, according to which insulin resistance leads to increased hepatic lipogenesis, decreased hepatic oxidation of fatty acids and decreased fat excretion from the liver, resulting in accumulation of fat in the liver.
Tumor necrosis factor- alpha (TNF-α) is one of the most important proinflammatory cytokines released by helper T lymphocytes in Kupffer cells and macrophages, and by affecting the activity of insulin receptor tyrosine kinase, it plays an important role in developing insulin resistance. Interferon gamma (IFN-γ) is another cytokine that stimulates the immune system and increases the body›s resistance to pathogens. It upregulates proinflammatory parameters such as TNF-α, the over-release of which is associated with the pathogenesis of chronic autoimmune and inflammatory diseases.
Regarding the effectiveness of resistance exercise on NAFLD, studies have shown that it improves liver fat content and causes favorable changes in body composition. In this study, it was hypothesized that resistance training may be associated with decreased production of the proinflammatory cytokines INF-γ and TNF-α.
Zataria multiflora (Shirazi thyme) contains phenolic compounds such as carvacrol, thymol and gamma terpinin with anti-inflammatory and antioxidant properties. Its use may have a protective role on liver cells in various conditions. In this regard, this study aims to evaluate the effect of 8 weeks of resistance exercise combined with Shirazi thyme supplementation on INF-γ and TNF-α levels in men with NAFLD.

This is a quasi-experimental study with pre-test/post-test design. Participants were 60 non-athlete men with NAFLD aged 35-45 years living in Sari, Iran who voluntarily participated in this study and selected using purposive and convenience sampling methods and after declaring written consent. After conducting initial screening, they were randomly divided into four groups: control (n=15), exercise (n=15), supplementation (n=15), and exercise + supplementation (n=15). Exercise program was resistance exercise for 8 weeks, 3 sessions per week each for 70-90 minutes. Each session consisted of three sets of 12-8 repetitions, which started with an intensity of 50% of one repetition maximum and increased to 80% of one repetition maximum. To administer Shirazi thyme in the intervention groups, a 20 mg soft capsule (Barij gastrolith) was used three times a day and a half an hour before meals for eight weeks according to Vafaarani et al. [14]. In the control group, placebo (starch powder in the form of 20 mg capsules) was used. In the fasting state, 10 CC of blood samples were taken from the brachial vein in two stages, before the start of the exercise program and 48 hours after the last exercise session and were poured into tubes containing EDTA and then quickly centrifuged. Collected data were analyzed in SPSS v.20 software using descriptive and inferential statistics. One-way analysis of variance (ANOVA) was used to determine the differences between the groups and Tukey’s post hoc test was used to determine between which groups the difference was found (Table 1).


 

The results presented in Table 1 showed no significant difference in the levels of INF-γ and TNF-αbetween the exercise group and the control group. Moreover, there was no significant decrease in the levels of INF-γ and TNF-alpha in the exercise + supplementation group compared to the control, supplementation and exercise groups. In overall, the findings indicated that resistance exercise alone or in combination with Shirazi thyme supplementation can modulate body weight in men with NAFLD. However, it had no significant effect on proinflammatory cytokines INF-γ and TNF-α in these individuals.

The effectiveness of resistance training and the consumption of thyme on inflammatory markers and cytokines needs more research. In this study, there were limitations such as lack of control over the subjects' nutrition, daily physical activity, and circadian rhythm, as well as the small number of issues and the short duration of the exercise program, which can affect the results obtained.

This study was approved by the Research Council and the University Ethics Committee (Code: IRCT.REC.1397.S523). 

This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors. 

All authors equally contributed to preparing this article.

The authors declare no conflict of interest.
 

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