BACKGROUND: Trivalent chromium is a trace element thought to have a beneficial effect on oxidative stress (OS) parameters and inflammation. This review aimed to investigate the dose-response of chromium and summarize the effects of chromium supplementation on OS parameters in the literature. METHODS: MEDLINE, Scopus, Web of Science and Cochrane CENTRAL databases were searched for RCTs published from inception to January 2021 evaluating the effect of chromium supplementation on OS parameters, namely MDA, TBARS, SOD, TAS, CAT, GPx, and GSH. A random-effects model was used to pool data and calculated standard mean difference and 95 % confidence intervals. Quantified heterogeneity among studies was assessed through Cochrane's I2 values. RESULTS: Nine studies enrolling 550 participants met the inclusion criteria. The obtained results indicate that chromium supplementation significantly increases TAC (SMD: 0.46; 95 % CI: 0.08, 0.84; I2 = 00.0 % n = 2) and significantly decreases MDA levels (SMD: -0.46; 95 % CI: -0.86, -0.07; I2 = 52.4 % n = 5). Supplementation did not significantly change CAT, GPx, GSH, SOD, TAS, and TBARS. CONCLUSION: Chromium supplementation may improve OS parameters, however, due to high heterogeneity observed in the included studies, these findings should be interpreted with caution. Large RCTs on various patient groups evaluating the impact of chromium supplementation are needed to allow an adequate generalization of the benefits of chromium on human health.
Dietary Supplements , Oxidative Stress , Chromium , Humans , Superoxide Dismutase/metabolism , Thiobarbituric Acid Reactive Substances
Oxidative stress (OS), the absence of equilibrium between prooxidants and antioxidants in the body, has been shown to play a pivotal role in the initiation and progression of many diseases. Saffron has been noted for its antioxidant capacity and can be used to improve OS parameters in unhealthy patients. Our aim was to evaluate the efficacy of saffron supplementation on OS parameters in unhealthy patients in randomized controlled trials (RCTs). We searched Medline, EMBASE, Cochrane CENTRAL, Scopus, and Web of Science without language restrictions for RCTs up until April 2021. Studies were included if they compared any form of saffron supplementation to placebo or no supplementation on OS parameters in unhealthy patients. Using a random-effects model with calculated standardized mean difference (SMD) and 95% confidence intervals (CI), we quantitatively synthesized the data. Heterogeneity was assessed using Cochrane's I 2 values. Ten randomized controlled trials were eligible for this review. Seven were included in the meta-analysis and indicated an association between saffron intake and a statistically significant decrease in malondialdehyde (MDA) levels (SMD: -0.40; 95% CI: -0.63, -0.17; I 2 = 32.6%) and a significant increase in total antioxidant capacity (TAC, SMD: 0.24; 95% CI: 0.05, 0.42; I 2 = 00.0%). Saffron intake was shown to significantly impact MDA and TAC, indicating its beneficial properties in improving OS in unhealthy patients. However, additional RCTs are required to evaluate the effect on other OS parameters.
