Associating the blood vitamin A, C, D and E status with tuberculosis: a systematic review and meta-analysis of observational studies.

Vitamins may play an important role in preventing tuberculosis. The purpose of this work is to associate the vitamin A, C, D and E status with tuberculosis through a systematic review and meta-analysis of observational studies. Web of Science, Pubmed and Scopus were searched from the earliest date of the database to May 2021. The standardized mean differences (SMDs) of blood vitamin concentrations and odds ratios (ORs) of vitamin deficiency between the tuberculosis patients and the control subjects were used as the main effect sizes. The effect sizes were pooled by a random-effects model using the Stata software (Version 11). The vitamin A concentration was significantly lower in the tuberculosis group than in the control group [SMD (95% CI): -0.96 (-1.31, -0.61), p < 0.01]. Only two case-control studies reported the vitamin C concentrations in the tuberculosis group versus the control group, and the difference was not significant. The blood vitamin D concentration was significantly lower in the tuberculosis group than in the control group [SMD (95% CI): -0.53 (-0.75, -0.32), p < 0.01]. Consistently, the number of people with vitamin D deficiency was significantly higher in the tuberculosis group [OR (95% CI): 2.29 (1.55, 3.37), p < 0.01]. The vitamin E concentration was significantly lower in the tuberculosis group than in the control group [SMD (95% CI): -0.34 (-0.61, -0.08), p = 0.01]. The current meta-analysis suggested a negative association between the vitamin A, D and E status and tuberculosis, and the association between the vitamin C status and tuberculosis was inconclusive due to the limited studies available.

Blood retinol and retinol-binding protein concentrations are associated with diabetes: a systematic review and meta-analysis of observational studies.

PURPOSE: The associations between blood retinol, retinol-binding protein (RBP) concentrations and diabetes mellitus were inconsistent in literature. The objective is to investigate these associations by a systematic review and meta-analysis and provide basis for clinical intervention. METHODS: PubMed, Web of science, and Cochrane databases were searched from the beginning to July 1, 2021. A total of 13 studies on retinol and 31 studies on RBP are included in the current meta-analysis. RESULTS: The blood retinol concentration was significantly lower in the type I diabetes mellitus (T1DM) [standardized mean difference (SMD) (95% CI): - 0.59 (- 0.81, - 0.37), P < 0.01] and gestational diabetes mellitus (GDM) patients [SMD (95% CI): - 0.54 (- 0.87, - 0.20), P < 0.01] than in the controls. However, the difference was not significant between the type II diabetes mellitus (T2DM) patients and the controls. The RBP concentration was significantly higher in the diabetic patients than in the controls [SMD (95% CI): 0.24 (0.12, 0.35), P < 0.01]. Particularly, the RBP concentration was significantly higher in the T2DM and GDM patients. CONCLUSION: The blood retinol concentration was negatively associated with T1DM and GDM, while the blood RBP concentration was positively associated with T2DM and GDM. Future work should use a more sensitive retinol measurement method like retinol isotope dilution method to confirm whether blood retinol concentration differs between the diabetes patients and the controls.

Astaxanthin supplementation mildly reduced oxidative stress and inflammation biomarkers: a systematic review and meta-analysis of randomized controlled trials.

Previous in vitro and animal studies showed that astaxanthin improved oxidative stress and inflammation biomarkers. We hypothesized the same effects of astaxanthin in humans and conducted a systematic review and meta-analysis of previous randomized controlled trials to test this hypothesis. The literature search was performed on PubMed, Cochrane Library, and Scopus databases from January 1970 to April 2021. Main eligibility criteria include: intervention using astaxanthin for at least 1 week; inclusion of placebo control; and measuring at least 1 of the common oxidative stress and inflammation biomarkers before and after intervention. Twelve randomized controlled trials including 380 participants were included. Compared with placebo, astaxanthin significantly reduced blood malondialdehyde concentration (standardized mean difference [SMD]: -0.95; 95% CI, -1.67 to -0.23; P = .01). The lowering effect of astaxanthin supplementation on malondialdehyde was particularly significant in type 2 diabetes mellitus (T2DM) patients (SMD: -0.64; 95% CI, -1.26 to -0.01; P < .05). A limited number of trials were available for the effects of astaxanthin on other oxidative stress biomarkers. Astaxanthin supplementation appeared to improve superoxide dismutase activity and reduce serum isoprostane concentration in overweight subjects. Astaxanthin significantly reduced blood interleukin-6 concentration in T2DM patients (weighted mean difference: -0.70 pg/mL; 95% CI, -1.29 to -0.11 pg/mL; P = .02). The effects of astaxanthin on blood C-reactive protein and tumor necrosis factor-α concentrations were not significant. The current work indicated that astaxanthin supplementation may be beneficial for improving oxidative stress and certain inflammation biomarkers, particularly in T2DM patients. Future work should investigate the effects of astaxanthin on T2DM.

Effects of resistant starch supplementation on oxidative stress and inflammation biomarkers: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND AND OBJECTIVES: Animal experiments showed that resistant starch (RS) had an antioxidant and antiinflammatory effect. However, clinical studies showed both insignificant and significant effects of RS on inflammation and oxidative stress. The purpose of this work is to conduct a systematic review and meta-analysis of previous randomized controlled trials (RCTs) to investigate these effects. METHODS AND STUDY DESIGN: A systematic literature search was conducted on Web of Science, Scopus, PubMed and Cochrane electronic databases, which included studies from the earliest date of the database to September 2021. Key inclusion criteria were: RCTs; reporting at least one inflammatory or oxidative stress biomarker as endpoint; more than seven day intervention. Key exclusion criteria were: using a mixture of RS and other functional food ingredients as intervention substance; inappropriate controls. RESULTS: A total of 16 RCTs including 706 subjects were included. RS supplementation significantly improved total antioxidant capacity [standard mean difference (SMD) (95% CI): 2.64 (0.34, 4.94), p=0.03], and significantly reduced blood malondialdehyde concentration [SMD (95% CI): -0.55 (- 0.94, -0.17), p=0.01]. RS supplementation significantly reduced blood C-reactive protein concentration in type 2 diabetes mellitus (T2DM) patients [SMD (95% CI): -0.35 (-0.65, -0.05), p=0.02]. RS consumption significantly reduced blood interlukin-6 and tumor necrosis factor- concentration if removing one distinct trial. CONCLUSIONS: RS supplementation may significantly reduce a few oxidative-stress and inflammation biomarkers such as malondialdehyde and C-reactive protein, particularly in T2DM patients. Future work should investigate the optimal dosage of RS supplementation for modulating oxidative stress and inflammation biomarkers related to T2DM.