Dietary strawberry powder reduces blood glucose concentrations in obese and lean C57BL/6 mice, and selectively lowers plasma C-reactive protein in lean mice

The purpose of the present study was to test the anti-inflammatory and blood glucose (BG)-regulating capacity of strawberries in a mouse model of diet-induced obesity. A total of thirty-six male C57BL/6J mice were randomly divided into four groups (nine mice per group). Mice were fed a low-fat diet (LF, 13% fat), the LF supplemented with 2.6% freeze-dried strawberry powder (LFSB), a high-fat diet (HF, 44% fat) or the HF supplemented with 2.6% strawberry powder (HFSB). Blood samples were collected to measure BG, inflammation and systemic markers for endocrine function of pancreas and adipose tissue. Splenocytes were harvested at the end of the study and activated with either anti-cluster of differentiation (CD) 3/anti-CD28 antibodies or lipopolysaccharide to test immune responsiveness. The HF increased non-fasted BG, insulin, soluble intracellular adhesion molecule-1, E-selectin, leptin, resistin and plasminogen activator protein-1 (P<0.05). High dietary fat decreased IL-4 production from activated splenocytes (P<0.05). BG concentrations were lower in the mice supplemented with SB (10.64 mmol/l) compared to the non-supplemented mice (11.37 mmol/l; P=0.0022). BG values were approximately 6.5% lower in the supplemented mice. Additionally, SB lowered plasma C-reactive protein in the LFSB group compared to the other three groups (P<0.05). The dietary intake of SB approximated one human serving of strawberries. These results, although modest, support a promising role for dietary strawberries in reducing the risks associated with obesity and diabetes, and regulating the levels of inflammatory markers in non-obese individuals.