Discussion
irritable bowel syndrome, anxiety, NAFLDIn, reduction in blood pressure, depression
IRRITABLE BOWEL SYNDROME
The findings of this double-blind, randomized and placebo-controlled study demonstrated that daily intake of 500 mg Iranian propolis extract in subjects with MeS for 12 weeks could lead to a significant reduction in WC, increase in physical functioning, general health, and the overall score of SF-36. While, propolis supplementation had no effects on other anthropometric indices and biochemical parameters compared to the placebo group.In the propolis group, compared with baseline, at the end of the study, a significant reduction was observed in anthropometric indices including WC, BMI, and body weight. Nonetheless, significant differences were observed between two groups for WC, but not regarding BMI and body weight. In three previous interventional studies that assessed the effects of propolis on WC measurementWe found that propolis supplementation for 12 weeks had no effects on FBG, serum insulin, and HOMO-IR among subjects with MeS. Consist with our study, the result of a trial indicated that intake 500 mg/day of propolis extract for four months did not improve FBG, serum insulin, and HOMO-IR in patients with NAFLDIn our study, no significant effect was found on lipid profile after taking propolis in subjects with MeS. Our finding is in agreement with the results of two meta-analyses that indicated propolis supplementation had no effects on lipid indicesIn this study, we observed no difference in the concentration of serum CRP between two groups after propolis intake, which is accordance with the data from studies performed by Fukuda et al.Some animal studies have shown a significant reduction in blood pressure following consumption of propolis through decreasing the tyrosine hydroxylase activity which involved in biosynthesis of catecholamine. The presence of antioxidant components in propolis might play a role in vasorelaxation through down-regulation of nicotinamide adenine dinucleotide phosphate oxidase (NOX) and increase nitric oxide synthase (NOS) activityWe observed that the mean score of anxiety reduced significantly in the intervention group. However, there was no significant difference in three subscales of DASS-21 including, stress, anxiety and depression between the two groups. In six weeks randomized trial, Miryan et al. found that daily supplementation of 900 mg propolis improved anxiety and quality of life among irritable bowel syndrome patientsSome limitations should be noted in our study. The effect of propolis alone could not be investigated, due to ethical issues. The main limitation of the current study is that it was conducted during the Covid-19 pandemic. Covid-19 has caused a stressful condition upon the major of individuals which has negative effects on different aspects of life. Probably, this tissue can distort our results. The strength points of our study included the following: firstly, the present study is a parallel randomized double-blind clinical trial that has been performed for the first time among subjects with MeS. Third, the control and intervention groups were matched in terms of baseline values.