Comparison analysis of FFs and their impact on antioxidant, anti-inflammatory, and glycemic indices in T2DM patients.
| Functional food/ingredient | Dose and dosage form | Glycemic control effects | Impacton lipids | Inflammatory markers | Oxidative stress | Cardiovascular outcomes | Study limitations and strength of evidence |
|---|---|---|---|---|---|---|---|
| Green tea | ~200 mg/day (extract) or 9 g/day (leaves). | Data were conflicting; some studies show no effect, but recent studies reported improvements in FBG, HbA1c, and insulin resistance. | Not reported. | No significant improvement in CRP, IL-6, or TNF-, slight improvement in IL-1. | Significant reduction in MDA; increased TAC, SOD, and GPX. | Not reported | Significant heterogeneity due to product, dose, treatment period, and patient population. High risk of publication bias, low to very low quality of RCTs. A small number of studies and subjects. Long-term effectiveness was reduced after 8 weeks due to variations in participant health. |
| Flaxseed | 10–100 g/day (13–40 g/day for glucose reduction); whole/ground seed superior to oil. | Significant reduction in HbA1c (especially if baseline > 7%); conflicting results for FBG and insulin unless baseline FBG is > 8 mmol/L. | Reduced lipid profiles. | No significant effect on CRP levels. | Significant reduction in MDA. | Not reported | Significant heterogeneity due to a wide range of doses and dosage forms, and patient characteristics. High risk of bias, small number of studies, and subjects. HOMA-IR results inconclusive due to small sample sizes; modest clinical weight loss. |
| Resveratrol (RES) | High dose > 1000 mg/day only | Significantly reduced FBG, HbA1c, and fasting insulin levels; improved HOMA-IR in T2DM patients. | No significant effect on TC, TG, LDL-C, or HDL-C. | Significantly reduced CRP levels and pro-inflammatory cytokines. | Reduced lipid peroxides and increased antioxidant enzyme activity (catalase and GPX). | Reduced SBP (> 7 mm Hg) and DBP (> 3 mm Hg). | Significant heterogeneity due to variations in dosage and treatment duration. High risk of bias due to small numbers of studies and subjects, and low-quality studies included in meta-analyses. |
| ACNs | Median dose of 320 mg/day for at least 8 weeks; fruit extracts and powders tested better than purified ACNs. | Reduced HbA1c (~0.31%), FBG (0.63 mmol/L), and 2h-PPG (~1.6 mmol/L). | Reduced LDL-C and TG. | Reduced markers of systemic inflammation. | Reduced markers of systemic oxidation. | Improved endothelial function, but no effective reduction in existing high blood pressure. | Significant heterogeneity in products, dose, and patient population. High risk of bias, and due to data from specific countries, may not be generalizable to all T2DM patients. A small number of studies and subjects. Low to moderate quality of included RCTs. Conflicted results for insulin resistance (HOMA-IR vs. fasting insulin). |
| Turmeric/curcumin | > 1g/day. Bioavailability-enhanced products(nanocurcumin/phytosomal) were superior. | Significantly reduced FBG and HbA1c; improved HOMA-IR. | Increased HDL; significant reductions in TG, LDL, and TC. | Reduced TNF and CRP. | Significant reduction in MDA. | Lowered DBP (~3 mmHg); inconsistent effect on SBP. | Significant heterogeneity due to products, dose, and methods. High risk of bias due to the small number of studies and subjects used in some meta-analyses. Low to moderate quality in RCTs. Magnitude of effects dependent on dose and formulation. |
| Ginger | 1.6 g to 3 g/day of powder in capsules; doses > 1 g/day. | Conflicting results in T2DM patients. Four studies show a reduction in HbA1c, three show a reduction in FBG, and two reported no difference in either. | No significant effects on TG, TC, LDL, or HDL. | Reduced hs-CRP, TNF-, and IL-6. | Inhibited ROS and NO production; enhanced free radical scavenging. | Significant reductions in SBP and DBP. | Significant heterogeneity in products and a wide range of doses used. High risk of bias due to small sample sizes, limited generalizability due to study populations, and variations in extraction/storage. |
ACNs: anthocyanins; CRP: C-reactive protein; DBP: diastolic blood pressure; FBG: fasting blood glucose; FFs: functional foods; GPX: glutathione peroxidase; HbA1c: glycated hemoglobin; HDL-C: high-density lipoprotein cholesterol; HOMA-IR: homeostasis model assessment of insulin resistance; LDL-C: low-density lipoprotein cholesterol; MDA: malondialdehyde; NO: nitric oxide; PPG: postprandial glucose; RCTs: randomized controlled trials; ROS: reactive oxygen species; SOD: superoxide dismutase; T2DM: type 2 diabetes mellitus; TAC: total antioxidant capacity; TC: total cholesterol; TG: triglycerides.
The supplementary material for this article is available at: https://www.explorationpub.com/uploads/Article/file/101474_sup_1.pdf.
SMW: Investigation, Writing—original draft, Writing—review & editing. TOL: Validation, Writing—review & editing. BAA: Investigation, Validation, Writing—original draft, Writing—review & editing. GPA: Investigation, Writing—review & editing. GBM: Conceptualization, Investigation, Writing—original draft, Writing—review & editing. All authors read and approved the submitted version.
The authors declare that they have no conflicts of interest.
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All information and data in this review are in the public domain. The primary data for this systematic review were sourced online from databases listed in the methods. Referenced articles are accessible on Cochrane Library, PubMed Central/Medline, Embase, Google Scholar, and the Scopus electronic databases. Additional supporting data are available from the corresponding author upon request.
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