Effects of freeze-dried strawberry supplementation on metabolic biomarkers of atherosclerosis in subjects with type 2 diabetes: a randomized double-blind controlled trial

Abstract

Background: To our knowledge there has been no study investigating the impact of freeze-dried strawberry (FDS) supplementation on metabolic biomarkers of atherosclerosis in subjects with type 2 diabetes (T2D).

Objective: This study was carried out to determine the effects of FDS supplementation on glycemic control, biomarkers of oxidative stress, inflammation and serum total antioxidant status in subjects with T2D compared to matched control subjects.

Methods: Thirty-six subjects with T2D (23 females; mean body mass index 27.90 ± 3.7; mean age 51.57 ± 10 years) were randomly divided into two groups. The treatment group consumed 2 cups of FDS beverage (50 g of FDS is equivalent to 500 g of fresh strawberries) or macronutrient matched placebo powder with strawberry flavor daily for 6 weeks in a randomized double-blind controlled trial. Anthropometric measurements, dietary intakes, hemoglobin (Hb)A1c, antioxidant status, C-reactive protein and malondialdehyde (MDA) levels were assessed at baseline and 6 weeks post-intervention.

Results: FDS supplementation significantly decreased C-reactive protein levels as a biomarker of inflammation (2.5 vs. 2.04 mg/l, p < 0.05) and lipid peroxidation in the form of MDA (3.36 vs. 2.7 nmol/ml, p < 0.05) at 6 weeks compared to the baseline. Moreover, supplementation led to a decreasing trend in HbA1c (-5.7%, p < 0.05) and significant increase in total antioxidant status in the FDS group (1.44 vs. 1.26 mmol/l, p < 0.01) compared to the placebo group. No significant changes were observed in serum glucose concentrations and anthropometric indices.

Conclusions: FDS improved glycemic control and antioxidant status, and reduced lipid peroxidation and inflammatory response in patients with T2D. Supplementation with freeze-dried berry products, as natural sources of antioxidants with low glycemic index, could be considered as an adjunctive therapy in ameliorating metabolic complications of T2D.