METHODS: A systematic search was performed across online databases including Scopus, Web of Science, and PubMed/Medline to identify relevant randomized controlled trials (RCTs) published until July 2022. A random-effects model was applied for the meta-analysis.
RESULTS: The present meta-analysis included a total of 22 RCTs with 1447 patients diagnosed with T2DM.A pooled analysis revealed a significant decrease in levels of serum hemoglobin A1c (HbA1c), fasting insulin, and fasting blood glucose (FBG) in vitamin C-treated T2DM patients compared with their untreated counterparts. The dose-response evaluation displayed a substantial linear association between the intervention duration and changes in serum HbA1c levels. However, the analysis did not demonstrate any significant effect of vitamin C on serum values of homeostasis model assessment of insulin resistance(HOMA-IR) in diabetic patients. Subgroup analyses indicated that high-dose vitamin C administration (≥1000 mg/d) considerably decreased serum HOMA-IR levels.
CONCLUSION: These findings suggest that long-term (≥12 weeks) and high-dose vitamin C supplementation (≥1000 mg/d) may ameliorate glycemic profile in T2DM patients. However, additional high-quality RCTs are necessary to validate these results.
DATA SOURCES: Systematic search of MEDLINE, EMBASE, CINAHL, and the Cochrane Register of Controlled Trials.
STUDY SELECTION: Randomized controlled trials testing IV vitamin C in critically ill patients.
DATA ABSTRACTION: Two independent reviewers abstracted patient characteristics, treatment details, and clinical outcomes.
DATA SYNTHESIS: Fifteen studies involving 2,490 patients were identified. Compared with placebo, IV vitamin C administration is associated with a trend toward reduced overall mortality (relative risk, 0.87; 95% CI, 0.75-1.00; p = 0.06; test for heterogeneity I2 = 6%). High-dose IV vitamin C was associated with a significant reduction in overall mortality (relative risk, 0.70; 95% CI, 0.52-0.96; p = 0.03), whereas low-dose IV vitamin C had no effect (relative risk, 0.94; 95% CI, 0.79-1.07; p = 0.46; test for subgroup differences, p = 0.14). IV vitamin C monotherapy was associated with a significant reduction in overall mortality (relative risk, 0.64; 95% CI, 0.49-0.83; p = 0.006), whereas there was no effect with IV vitamin C combined therapy. No trial reported an increase in adverse events related to IV vitamin C.
CONCLUSIONS: IV vitamin C administration appears safe and may be associated with a trend toward reduction in overall mortality. High-dose IV vitamin C monotherapy may be associated with improved overall mortality, and further randomized controlled trials are warranted.
METHODS: One hundred and twenty posterior teeth had their occlusal enamel removed, then the specimens were divided into two main groups according to dentin substrates; SoD and CID, three subgroups according to pretreatments protocols control (no pretreatment), NaOCl-treated, and Er, Cr:YSGG-treated and two divisions according to antioxidant application (with and without sodium ascorbate (SA) application). All-Bond Universal (ABU) universal adhesives was applied in self-etch (SE) mode then resin composite discs were built. The specimens were stored in distilled water for 24-hr at 37°C before SBS testing. Three-way ANOVA and Tukey HSD tests were used for data analysis (a = 0.05).
RESULTS: 6% NaOCl resulted in a significant reduction in SBS in SoD without antioxidant application. 10% SA application showed significant increase in SBS for 6% NaOCl group only in SoD. Laser application recorded a significantly higher SBS compared to 6% NaOCl group without or with antioxidant application, while 10% SA application revealed a significant increase in SBS for control group only.
CONCLUSIONS: Er, Cr:YSGG laser irradiation followed by antioxidant application has the potential to enhance the bonding quality of both tested dentin substrates. NaOCl application has significantly compromised the bonding to SoD and CID substrates.
OBJECTIVE: This study evaluated the associations of plasma carotenoid, retinol, tocopherol, and vitamin C concentrations and risk of breast cancer.
DESIGN: In a nested case-control study within the European Prospective Investigation into Cancer and Nutrition cohort, 1502 female incident breast cancer cases were included, with an oversampling of premenopausal (n = 582) and estrogen receptor-negative (ER-) cases (n = 462). Controls (n = 1502) were individually matched to cases by using incidence density sampling. Prediagnostic samples were analyzed for α-carotene, β-carotene, lycopene, lutein, zeaxanthin, β-cryptoxanthin, retinol, α-tocopherol, γ-tocopherol, and vitamin C. Breast cancer risk was computed according to hormone receptor status and age at diagnosis (proxy for menopausal status) by using conditional logistic regression and was further stratified by smoking status, alcohol consumption, and body mass index (BMI). All statistical tests were 2-sided.
RESULTS: In quintile 5 compared with quintile 1, α-carotene (OR: 0.61; 95% CI: 0.39, 0.98) and β-carotene (OR: 0.41; 95% CI: 0.26, 0.65) were inversely associated with risk of ER- breast tumors. The other analytes were not statistically associated with ER- breast cancer. For estrogen receptor-positive (ER+) tumors, no statistically significant associations were found. The test for heterogeneity between ER- and ER+ tumors was statistically significant only for β-carotene (P-heterogeneity = 0.03). A higher risk of breast cancer was found for retinol in relation to ER-/progesterone receptor-negative tumors (OR: 2.37; 95% CI: 1.20, 4.67; P-heterogeneity with ER+/progesterone receptor positive = 0.06). We observed no statistically significant interaction between smoking, alcohol, or BMI and all investigated plasma analytes (based on tertile distribution).
CONCLUSION: Our results indicate that higher concentrations of plasma β-carotene and α-carotene are associated with lower breast cancer risk of ER- tumors.