Impact of short‐term bilberry supplementation on glycemic control, cardiovascular disease risk factors, and antioxidant status in Chinese patients with type 2 diabetes

Abstract

Bilberry (Vaccinium myrtillus L.) is one of the richest natural sources of anthocyanins which are powerful antioxidants and reported to have antiinflammatory, antidyslipidemic, antihypertensive, and hypoglycemic effects. The objective of this study was to assess the effect of bilberry supplementation on biomarkers of glycemic control, lipid profile, antioxidant, and inflammatory status in patients with type 2 diabetes in a randomized, double-blind, placebo-controlled cross-over study. Twenty patients were randomized to receive either bilberry supplementation (1.4 g/day of extract) daily for 4 weeks followed by 6 weeks of washout and then an additional 4 weeks of matching placebo or vice versa. Blood pressure, metabolic parameters, antioxidant status, and oxidative stress were measured before and after each period.Results showed no effect on body weight, blood pressure, or lipid profile. HbA1c was reduced by 0.31 ± 0.58% during bilberry supplementation, but this change was not significantly different from that with placebo. Antioxidant status, oxidative stress, and inflammatory status showed no significant differences across treatments. This short-term study of bilberry supplementation did not show significant effects on cardiovascular risk factors or antioxidant status, but the tendency for improved glycemic control may suggest a longer treatment period may be effective in diabetic patients.

The effects of blueberry and cranberry supplementation on blood pressure in patients with cardiovascular diseases: A systematic review and meta‐analysis of randomized clinical trials

“…Cardiometabolic diseases ranged from hypertension, myocardial infarction, metabolic syndrome, overweight/obesity, and non‐alcoholic fatty liver disease. The length of intervention ranged from four (Chan et al, 2021; Dohadwala et al, 2011; Ruel et al, 2013) to 24 weeks (Curtis et al, 2019; Masnadi Shirazi et al, 2021). Fifteen studies were randomized, double‐blind, or triple‐blind, while two were only randomized (Arevström et al, 2019; Basu et al, 2010).…”

“…The sample size ranged from 20 (Lee et al, 2008) to 115 subjects (Curtis et al, 2019). Eight studies used cranberry as an intervention (Basu et al, 2011; Dohadwala et al, 2011; Eftekhari et al, 2016; Hsia et al, 2020; Lee et al, 2008; Masnadi Shirazi et al, 2021; Richter et al, 2021; Ruel et al, 2014), while the other nine used blueberry (Arevström et al, 2019; Basu et al, 2010; Chan et al, 2021; Curtis et al, 2019; Johnson et al, 2015; Rousseau et al, 2021; Stote et al, 2020; Stull et al, 2010. 2015).…”

The Role of Berry Consumption on Blood Pressure Regulation and Hypertension: An Overview of the Clinical Evidence

“…Three human interventions investigated the effect of bilberry consumption on BP. Daily administration of a 1.4 g dose of bilberry extract for four weeks to a group of 20 participants with T2DM, in a double-blind, placebo-controlled, crossover intervention, did not significantly affect SBP or DBP [72].…”

Bilberries: Curative and Miraculous – A Review on Bioactive Constituents and Clinical Research

“…However, other clinical studies have indicated that there were no significant differences in fasting plasma glucose between the treatment and the control groups after dietary supplementation with anthocyanins for 12 ( Qin et al, 2009 ) or 24 weeks ( Zhu et al, 2013 ), or after ingesting 400 g fresh bilberries daily for 2 months ( Kolehmainen et al, 2012 ). Even the newest clinical study on Chinese patients with T2DM using 1400 mg of bilberry extract per day did not report any significant differences compared to placebo in any of the measured biomarkers ( Chan et al, 2021 ).…”