Serum 25(OH)D Concentration, Vitamin D Supplementation, and Risk of Cardiovascular Disease and Mortality in Patients with Type 2 Diabetes or Prediabetes: a Systematic Review and Dose-Response Meta-Analysis.

BACKGROUND: Evidence is uncertain about the association between serum 25-hydroxyvitamin D (25(OH)D) concentration and health outcomes in people with type 2 diabetes. OBJECTIVES: We aimed to assess the association between vitamin D status and all-cause mortality and cardiovascular disease in people with type 2 diabetes. METHODS: We did a systematic search in PubMed, Scopus, CENTRAL, and Web of Science until May 2022. We selected 1) cohort studies investigating the association between serum 25(OH)D concentration and mortality or cardiovascular disease in people with type 2 diabetes or prediabetes and 2) randomized trials of vitamin D supplementation in these patients. We used random-effects pairwise meta-analyses to calculate summary relative risks (RRs) and 95% confidence intervals (CI). RESULTS: 21 cohort studies and 6 randomized trials were included. Compared with sufficient vitamin D status (≥50 nmol/L), the RR of all-cause mortality was 1.36 (95% CI: 1.23, 1.49; n = 11 studies, GRADE = moderate) for vitamin D insufficiency (25 to <50 nmol/L), and 1.58 (1.33, 1.83; n = 16, GRADE = moderate) for deficiency (<25 nmol/L). Similar findings were observed for cardiovascular mortality and morbidity but not for cancer mortality. The certainty of evidence ranged from very low to moderate. Dose-response meta-analyses indicated nonlinear associations, with the lowest risk at 25(OH)D ∼60 nmol/L for all-cause and cardiovascular mortality. Supplementation with vitamin D did not reduce the risk of all-cause mortality (RR: 0.96, 95% CI: 0.79, 1.16; risk difference per 1000 patients: 3 fewer, 95% CI: 16 fewer, 12 more; n = 6 trials with 7316 participants; GRADE = low) or the risk of cardiovascular mortality and morbidity (very low- to low-certainty evidence). CONCLUSIONS: Vitamin D deficiency and insufficiency are associated with a higher risk of all-cause and cardiovascular mortality in patients with type 2 diabetes or prediabetes. Vitamin D deficiency should be corrected in patients with type 2 diabetes to reach normal serum 25(OH)D concentrations, preferably 60 nmol/L. SYSTEMATIC REVIEW REGISTRATION: This systemic review was registered at PROSPERO as CRD42022326429 (=https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=326429).

Effect of Avena sativa (Oats) on cognitive function: A systematic review of randomized controlled trials.

BACKGROUND AND AIM: The effect of polyphenol-rich diets or supplements on cognitive function remains a contentious topic. The objective of this study was to investigate the effects of Avena sativa (oat extracts) on cognitive function among healthy adults. METHODS: A structured literature search was undertaken using PubMed, Web of Science, and Scopus from the database's establishment until March 17, 2022. Data on cognitive function, regarding accuracy and speed of performance, were gathered from randomized controlled trials (RCTs) that investigated the acute or chronic effects of Avena sativa in healthy subjects. The Cochrane Collaboration risk-of-bias tool was used to assess the quality of included studies. RESULTS: We included six RCTs, of which three were crossover designs, with a total of 287 individuals. Four studies investigated the acute effect of Avena sativa, while two investigated its chronic effect. Acute ingestion of Avena sativa appeared to positively influence the accuracy and speed of performance. While short-term chronic supplementation resulted in a significant improvement in cognitive function, long-term chronic supplementation did not. Overall, the evidence was of average quality. CONCLUSION: Acute supplementation with Avena sativa may improve cognitive function in healthy volunteers. Given the small number of trials included and the disparity of the intervention dose, the conclusions of this study should be interpreted with caution. More high-quality, long-term studies are warranted.

Efficacy and safety of oral alpha-lipoic acid supplementation for type 2 diabetes management: a systematic review and dose-response meta-analysis of randomized trials.

Objective: To examine the dose-dependent influence of oral alpha-lipoic acid (ALA) supplementation on cardiometabolic risk factors in patients with type 2 diabetes (T2D). Design: We followed the instructions outlined in the Cochrane Handbook for Systematic Reviews of Interventions and the Grading of Recommendations, Assessment, Development, and Evaluation Handbook to conduct our systematic review. The protocol of the study was registered in PROSPERO (CRD42021260587). Method: We searched PubMed, Scopus, and Web of Science to May 2021 for trials of oral ALA supplementation in adults with T2D. The primary outcomes were HbA1c, weight loss, and LDL cholesterol (LDL-C). Secondary outcomes included fasting plasma glucose (FPG), triglyceride (TG), C-reactive protein (CRP), and blood pressure. We conducted a random-effects dose-response meta-analysis to calculate the mean difference (MD) and 95% CI for each 500 mg/day oral ALA supplementation. We performed a nonlinear dose-response meta-analysis using a restricted cubic spline. Results: We included 16 trials with 1035 patients. Each 500 mg/day increase in oral ALA supplementation significantly reduced HbA1c, body weight, CRP, FPG, and TG. Dose-response meta-analyses indicated a linear decrement in body weight at ALA supplementation of more than 600 mg/day (MD600 mg/day: -0.30 kg, 95% CI: -0.04, -0.57). A relatively J-shaped effect was seen for HbA1c (MD: -0.32%, 95% CI: -0.45, -0.18). Levels of FPG and LDL-C decreased up to 600 mg/day ALA intake. The point estimates were below minimal clinically important difference thresholds for all outcomes. Conclusion: Despite significant improvements, the effects of oral ALA supplementation on cardiometabolic risk factors in patients with T2D were not clinically important.

Association of healthy beverage index with circadian rhythm and quality of sleep among overweight and obese women: a cross-sectional study.

PURPOSE: Circadian rhythm is a behavioral, physiological, and molecular change with a cycle length of approximately 24 h. Changes to the circadian rhythm can result in sleep difficulty. The healthy beverage index (HBI) is a holistic concept for evaluating the quality of overall beverage intake and its association with health-related outcomes in nutritional epidemiological studies. This study aimed to assess the relationship of HBI with circadian rhythm and sleep quality among overweight/obese women. METHODS: The current study was conducted among 208 overweight and obese women between 18-48 years in Tehran, Iran. We evaluated potential HBI with a valid food frequency questionnaire. Following standard procedures, trained personnel assessed anthropometric measures, blood samples, and other baseline characteristics. The Pittsburgh Sleep Quality Index and the morning-eveningness questionnaire were applied to evaluate sleep quality and circadian rhythm respectively. RESULTS: The mean (SD) BMI for this study was 30.8 (4.2) kg/m2. We observed that subjects in the least tertile had significantly high levels of triglyceride (p = 0.04) and low-density lipoprotein (p = 0.009). High-density lipoprotein was significantly different across the tertiles (p = 0.003). After adjusting for potential covariates, subjects in the second tertile of HBI had 5.07 odds of having the worst quality of sleep as compared to those in the third tertile, p < 0.05. We also observed a significant inverse association between the HBI and the "moderately evening type" participants (OR 0.86; 95% CI 0.68-0.99; p: 0.02) after adjusting for potential confounders. CONCLUSION: Healthy beverage consumption may have the potential of improving sleep quality among overweight and obese subjects. LEVEL OF EVIDENCE: Level IV, evidence obtained from a descriptive study.

Administration of dietary antioxidants for patients with inflammatory bowel disease: A systematic review and meta-analysis of randomized controlled clinical trials.

OBJECTIVE: Accumulating evidence has been reported regarding the effect of dietary antioxidants on clinical variables in IBD patients, however, findings are controversial. This systematic review and meta-analysis aimed to investigate effect of dietary antioxidants on clinical variables in patients with IBD or its subtypes. METHODS: We searched PubMed, Scopus, and ISI Web of Science from inception to January 2021 using relevant keywords. Data were pooled by using the random-effect model. All statistical analyses were done using STATA version 14. RESULTS: Our meta-analysis was exclusively done on studies about the effect of curcumin on IBD patients, because limited studies were done on other antioxidants. Curcumin administration resulted in significant increment of clinical remission in patients with IBD (SMD: 0.86%, 95% CI: 0.16, 1.56, p = 0.016), significant remission in clinical symptoms (SMD: -0.96 score, 95% CI: -1.34, -0.57, p < 0.001), and significant increment in endoscopic remission in IBD patients (SMD: 0.51%, 95% CI: 0.16, 0.85, p = 0.004), comparing to control group. Curcumin supplementation also made better clinical response than control group (SMD: 0.74%, 95% CI: 0.22, 1.26, p = 0.005) and also resulted in significant improvement in quality of life of patients with IBD, as compared to control group (SMD: 1.23 score, 95% CI: 0.72, 1.74, p < 0.001). CONCLUSIONS: Our meta-analysis showed that curcumin significantly improved clinical and endoscopic remissions in IBD patients. This supplementation also caused significant reduction in clinical symptoms of IBD patients along with better clinical response and the increased quality of life. Further researches with larger sample size and longer period of intervention are required to evaluate efficacy of dietary antioxidants on clinical variables in patients with IBD.

Effects of curcumin supplementation on inflammatory biomarkers in patients with Rheumatoid Arthritis and Ulcerative colitis: A systematic review and meta-analysis.

BACKGROUND: Although previous studies have examined the impact of curcumin supplementation on cytokine levels in patients with autoimmune disorders, we were unable to find a systematic review of the effect of curcumin supplementation on inflammatory biomarkers such as CRP and ESR in patients with rheumatoid arthritis or ulcerative colitis; therefore we conducted this systematic review and meta-analysis. METHODS: Relevant studies published from inception to December 2020 were systematically searched through the PubMed, SCOPUS, and google scholar databases. We conducted our systematic review and meta-analysis according to the 2020 PRISMA guidelines. The quality of the papers were assessed by using the Cochrane Collaboration's risk of bias tool. Included studies were randomized clinical trials on the effects of supplementation with curcumin or its derivative on inflammatory factors in patients with rheumatoid arthritis and ulcerative colitis. Pooled effect sizes were calculated using a random-effects model and reported as the weighted mean difference (WMD) and 95 % CI. RESULTS: In all, six studies met the inclusion criteria for this study. Curcumin supplementation in doses of 250-1500 mg/day over 8-12 weeks was observed to be associated with decreases in CRP and ESR in adult patients with rheumatoid arthritis and ulcerative colitis in comparison with the control group (WMD: -0.42; 95 % CI: -0.59, -0.26, I2 = 94.3 %; WMD: -55.96; 95 % CI: -93.74, -18.17, I2 = 99.7 %, respectively). Significant findings were also observed based on subgroup analyses by the study sample size, duration, participants' age, curcumin dosage, and type of disease. CONCLUSIONS: Curcumin supplementation was associated with significant reductions in levels of CRP and ESR in patients with rheumatoid arthritis and ulcerative colitis. Earlier studies reported curcumin as a safe complementary therapy for several diseases. However, a handful of studies were found on the effect of curcumin on autoimmune diseases despite our comprehensive search. Further studies are therefore warranted in this area.