A recent study published in Antioxidants examined the effects of freeze-dried strawberries (FDS) on antioxidant status, fasting glucose, and vascular inflammation in adults with prediabetes. The results showed that 12 weeks of daily FDS consumption lowered inflammation markers and fasting glucose while improving multiple antioxidant biomarkers.
Prediabetes is characterized by mild hyperglycemia that promotes oxidative stress and inflammation, contributing to endothelial dysfunction and progression to type 2 diabetes. Elevated glucose increases reactive oxygen species, which impair insulin activity and damage β-cells. Polyphenols and other dietary antioxidants may counteract these processes, though absorption and bioavailability vary. Strawberries are rich in anthocyanins and ellagic acid, compounds linked to improved antioxidant enzyme activity and insulin sensitivity.
The randomized controlled crossover trial was conducted at the University of Nevada, Las Vegas, involving 25 adults meeting the American Diabetes Association's criteria for prediabetes. Each participant completed both 12-week phases of the study: one with daily intake of 32 g of FDS powder (equivalent to 2.5 servings of fresh strawberries) and one control phase without supplementation, separated by a four-week washout. Participants maintained their regular diet and physical activity.
Compliance exceeded 85%, confirmed by plasma ellagic acid levels. Blood samples collected at baseline, 12, 16, and 28 weeks were analyzed for fasting glucose, antioxidant enzymes, and vascular markers, including intercellular adhesion molecule (ICAM) and vascular cell adhesion molecule (VCAM).
During the FDS phase, superoxide dismutase, glutathione (GSH), total antioxidant capacity, and β-carotene levels increased compared to the control. No changes were noted in catalase, glutathione reductase, glutathione peroxidase, or α-carotene. Fasting glucose decreased during FDS intake, and ICAM and VCAM concentrations were reduced, indicating lower vascular inflammation. Correlation analysis showed inverse relationships between antioxidant and inflammation markers. Minor side effects such as mild gastrointestinal discomfort and headaches were reported.
The study concluded that a realistic dietary dose of FDS improved antioxidant defense, reduced inflammation, and supported glycemic regulation in adults with prediabetes. These effects are attributed to strawberry polyphenols enhancing glutathione synthesis and antioxidant enzyme activity, and carotenoids reducing oxidative stress.
Researchers noted limitations, including the small sample size, lack of a placebo, and recruitment from a single site, which may limit broader applicability. The study was funded by the California Strawberry Commission.
Source: News Medical Life Sciences
