The effects of omega-3 plus vitamin E and zinc plus vitamin C supplementation on cardiovascular risk markers in postmenopausal women with type 2 diabetes

Can omega-3 fatty acids and vitamin E co-supplementation affect obesity indices?

Background: Studies have shown that vitamin E as an antioxidant protects omega-3 fatty acids (FAs) from oxidation. Several studies have evaluated the effect of omega-3 FAs and vitamin E co-supplementation on obesity indices; however, the results are inconsistent. The present systematic review and meta-analysis was conducted to address the role of omega-3 FAs plus vitamin E on obesity indices. Methods: Cochrane Library, PubMed, Scopus, Embase, and Web of Science databases were searched up to February 2022. Among all of the qualified studies, 10 articles were selected. The effect size was presented as weighted mean difference (WMD) and 95% confidence interval (CI). Fixed-effects model was employed to perform meta-analysis. Subgroup analysis and publication bias assessment were carried out. Results: Ten eligible randomized controlled trials comprising 558 participants were included. The average dose of omega-3 FAs and vitamin E co-supplementation in studies was 1000-4000 mg/day and 400 IU, respectively. Intervention duration varied from 6 to 16 weeks. There was no significant effect of omega-3 and vitamin E co-supplementation on body weight (BW) (WMD=0.14 kg; 95% CI: -0.13 to 0.42; p=0.297), and body mass index (BMI) (WMD=0.08, 95% CI: -0.01 to 0.16, p=0.073). However, subgroup analysis showed that it might increase BMI in women over 50 years and if the intervention lasted more than 8 weeks. Conclusion: There was no significant impact of combined omega-3 FAs and vitamin E supplementation on BW and BMI; however, it should be noted that the intervention has an increasing impact when supplementation duration was >8 weeks and in individuals with type 2 diabetes mellitus, >50 years old, and BMI>25 kg/m2.

Effect of zinc supplementation on blood sugar control in the overweight and obese population: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Although overweight and obese people have a higher risk of type 2 diabetes incidence than normal-weight individuals, the efficacy of zinc supplementation in blood sugar control in overweight and obese people remained unknown. This meta-analysis attempted to address this issue.

METHODS

Databases including PubMed, Embase, and the Cochrane Library were searched from inception until May 2022 to identify randomized controlled trials (RCTs) investigating the effects of zinc supplementation among participants who were overweight or obese without language restriction. It is a random-effect meta-analysis that analyzed the impact of zinc supplementation on fasting glucose (FG) (i.e., primary outcome) and other variables including fasting insulin (FI), homeostasis model assessment-insulin resistance index (HOMA-IR), glycated hemoglobin (HbA1c), high-sensitivity C-reactive protein (hs-CRP), and 2-hour postprandial glucose (2 h- PG).

RESULTS

Analysis of 12 eligible RCTs involving 651 overweight/obese participants demonstrated that zinc supplementation significantly improves FG (weighted mean difference [WMD]: -8.57 mg/dL; 95% confidence interval [CI]: -14.04 to -3.09 mg/dL, p = 0.002), HOMA-IR (WMD: -0.54; 95% CI: -0.78 to -0.30, p < 0.001), HbA1c (WMD: -0.25%; 95% CI: -0.43% to -0.07%, p = 0.006), and 2 h-PG (WMD: -18.42 mg/dL; 95% CI: -25.04 to -11.79 mg/dL, p < 0.001) compared to those in the control group. After conducting subgroup analyses, we found that the primary outcome, FG, showed more significant results in the subgroups with Asia, Zinc supplementation alone, higher dose (≥30 mg) and patients with diabetes.

CONCLUSION

Our meta-analysis indicated that zinc supplementation benefits blood sugar control in overweight and obese populations, with an especially significant reduction in FG.

Double-Blind Controlled Trial of Vitamin E Effects on Serum Lipid Profile in Menopausal Women

BACKGROUND

Menopause is associated with changes in lipid profile and is a known risk factor for oxidative stress. Different therapeutical strategies have been used to control menopause complications. Vitamin E, an important anti-oxidant, can possibly affect lipid peroxidation in menopausal women. Thus, we aimed to evaluate the effect of vitamin E supplementation on the lipid profile of menopausal women.

MATERIALS AND METHODS

This double-blind, placebo-controlled, randomized, cross-over, phase I/II trial study was designed in two 4-week intervention phases with an 8-day washout period in between. Eighty-three natural menopause women participated in the study. Randomized block allocation was used to divide women into group A (n = 41) and group B (n = 42). In phase I, one group received vitamin E capsule (400 IU/day) and another group received placebo capsule for 4 weeks. After an 8-day washout period, phase II was initiated for a period of 4 weeks, where the group that received vitamin E capsule was given placebo (E-P) and the group that received placebo was given vitamin E (P-E). Plasma lipid profile levels (LDL-C, HDL-C, TC, and TG) were assessed before and after intervention separately in each phase and in each group. Lipid profile was measured by enzymatic colorimetric method. Data were analyzed according to the intention-to-treat principle. All statistical analyses were performed using SPSS software.

RESULTS

The analysis indicated no significant difference in plasma TC, LDL-C, HDL-C, and TG levels between P-E and E-P groups before intervention in phase I and II (P > 0.05). There was no significant difference in plasma lipid profile levels within the P-E and E-P groups before and after intervention in phase I and II. There was a significant difference in plasma TG within the E-P group before [141.74 ± 53.52, 138.50 (94-195)] and after [167.47 ± 71.32, 170 (108-202)] intervention in phase II (P = 0.010). There was no significant difference in terms of the mean changes in plasma lipid profile between the P-E and E-P groups in phase I and II (P > 0.05).

CONCLUSION

The study results revealed that vitamin E supplementation had no remarkable effect on the lipid profile in menopausal women.

Zinc supplementation improves glycemic control for diabetes prevention and management: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Although many studies have shown that low zinc status is associated with diabetes, the putative effects of zinc supplementation on glycemic control are inconclusive.

OBJECTIVES

The aim of this meta-analysis of randomized controlled trials was to assess the effects of zinc supplementation in preventing and managing diabetes.

METHODS

PubMed, Embase, and the Cochrane Library were searched for articles that were published through February 10, 2019 and contained estimates for the outcomes of interest. The pooled results were then analyzed with the use of a random-effects model.

RESULTS

Thirty-two placebo-controlled interventions were extracted from 36 publications, involving a total of 1700 participants in 14 countries. Overall, compared with their respective control groups, the subjects in the zinc-supplementation group had a statistically significant reduction in fasting glucose [FG, weighted mean difference (WMD): -14.15 mg/dL; 95% CI: -17.36, -10.93 mg/dL], 2-h postprandial glucose (WMD: -36.85 mg/dL; 95% CI: -62.05, -11.65 mg/dL), fasting insulin (WMD: -1.82 mU/L; 95% CI: -3.10, -0.54 mU/L), homeostasis model assessment for insulin resistance (WMD: -0.73; 95% CI: -1.22, -0.24), glycated hemoglobin (WMD: -0.55%; 95% CI: -0.84, -0.27%), and high-sensitivity C-reactive protein (WMD: -1.31 mg/L; 95% CI: -2.05, -0.56 mg/L) concentrations. Moreover, subgroup analyses revealed that the effects of zinc supplementation on FG are significantly influenced by diabetic status and the formulation of the zinc supplement.

CONCLUSIONS

Our analysis revealed that several key glycemic indicators are significantly reduced by zinc supplementation, particularly the FG in subjects with diabetes and in subjects who received an inorganic zinc supplement. Together, these findings support the notion that zinc supplementation may have clinical potential as an adjunct therapy for preventing or managing diabetes. This trial was registered at PROSPERO as CRD42018111838.

Effect of Omega-3 and vitamin E co-supplementation on serum lipids concentrations in overweight patients with metabolic disorders: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Results of the studies assessed the effect of omega-3 and vitamin E co-supplementation on lipid profile in patients with metabolic syndrome (MS) are contradictory. Therefore, we carried out a systematic review and meta-analysis of randomized controlled trials (RCTs), to assess the effect of omega-3 and vitamin E co-supplementation on total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) in patients with MS.

METHODS

A systematic search was performed to find the related articles, up to April, 2019. There was no language and time limitation. Meta-analyses were carried out using both the random and fixed effects model where appropriate, and I2 index was used to evaluate the heterogeneity.

RESULTS

Search yielded 1236 publications. Five RCTs with 254 patients were eligible. Results of the meta-analysis indicated that omega-3 and vitamin E co-supplementation significantly reduced the serum concentrations of TG and LDL, whereas, it had no significant effect on the serum levels of TC and HDL in overweight patients with MS.

CONCLUSION

Present systematic review and meta-analysis revealed that omega-3 and vitamin E co-supplementation have beneficial effects on lipid profile of overweight patients with MS. It significantly reduced the serum levels of TG and LDL in such patients.

Effect of omega-3 fatty acid plus vitamin E Co-Supplementation on lipid profile: A systematic review and meta-analysis

BACKGROUND

Dyslipidemia is linked to chronic inflammation, which in return leads to a set of chronic disorders. Omega-3 fatty acids have been reported to reduce inflammation. Furthermore, Vitamin E is a fat-soluble vitamin which has antioxidant and anti-inflammatory effects. Vitamin E and omega-3 fatty acids co-supplementations may be more effective than the single supplementation in control dyslipidemia. Therefore, we designed and conducted the current systematic review and meta-analysis to investigate the effect of co-supplementation of vitamin E and omega-3 fatty acids on the lipid profile.

METHODS

A comprehensive search for studies published between January 1990 and July 2018 was performed. The initial search extracted 3015 potentially relevant articles. After studying these publications, 9 RCTs were potentially eligible and retrieved in full text.

RESULTS

The meta-analysis indicate that on total cholesterol, HDL, LDL and triglyceride individually did not show any significant difference between intervention and control groups, but vitamin E an omega-3 fatty acids co-supplementations significantly reduce VLDL levels.

CONCLUSIONS

Based on the available evidence, omega-3 fatty acid and vitamin E co-supplementation can reduce VLDL, although its effect on other lipid profile parameters requires more well-designed studies.