Effect of kiwifruit on metabolic health in patients with cardiovascular risk factors: a systematic review and meta-analysis

BACKGROUND: Kiwifruit seems to have beneficial effect on metabolic health because it contains abundant phytochemicals and antioxidants. This study aimed to assess the effect of kiwifruit on metabolic health in participants with cardiovascular risk factors. METHODS: Literature was searched from PubMed, CENTRAL, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Scopus, Proquest, Latin American and Carib-bean Health Sciences Literature, International Clinical Trials Registry Platform, Australia New Zealand Clinical Trials Registry, https://clinicaltrials.gov/, China National Knowledge Infrastructure, Wanfang Standards Database, European Association for the Study of Diabetes, and American Diabetes Association conferences up to August 2018. Citing references were manually searched. Randomized controlled trials were selected if they evaluated the effect of kiwifruit in patients with cardiovascular risk factors and reported SBP, DBP, total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), glycated hemoglobin (A1C), fasting plasma glucose (FPG), homeostasis model assessment of insulin resistance (HOMA-IR), 2-hour postprandial glucose, or body weight (BW). Data extraction and study quality assessment were performed independently by two investigators. Any inconsistencies were resolved by a third investigator. Treatment effect was estimated with mean difference (MD). Effect estimates were pooled using inverse-variance weighted method. Heterogeneity was assessed by the I(2) and Q statistic. RESULTS: Five randomized controlled trials involving 489 participants met the inclusion criteria. These included hypercholesterolemia, hypertension, type 2 diabetes mellitus, and male smokers. There was no effect of kiwifruit on SBP (MD, −1.72 mmHg; 95% CI: −4.27 to 0.84); DBP (MD, −2.35 mmHg; 95% CI: −5.10 to 0.41); TC (MD, −0.14 mmol/L; 95% CI: −0.71 to 0.43); TG (MD, −0.23 mmol/L; 95% CI: −0.66 to 0.20); LDL-C (MD, −0.41 mmol/L; 95% CI: −0.99 to 0.18); HDL-C (MD, 0.15 mmol/L; 95% CI: −0.18 to 0.48); FPG (MD, −0.08 mmol/L; 95% CI: −0.37 to 0.21); HOMA-IR (MD, −0.29; 95% CI: −0.61 to 0.02), and BW (MD, −1.08 kg; 95% CI: −4.22 to 2.05). CONCLUSION: This meta-analysis suggested no effect of kiwifruit on metabolic health in patients with cardiovascular risk factors, although there seemed to be a trend of improvement after kiwifruit intervention.