ARS | Publication request: Dietary strawberry powder reduces blood glucose concentrations in obese and lean C57BL/6 mice and selectively lowers plasma C-reactive protein in lean mice

Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 16, 2011
Publication Date: February 1, 2012
Citation: Parelman, M.A., Storms, D.H., Kirschke, C.P., Huang, L., Zunino, S.J. 2012. Dietary strawberry powder reduces blood glucose concentrations in obese and lean C57BL/6 mice and selectively lowers plasma C-reactive protein in lean mice. British Journal of Nutrition. 1-11. DOI: 10.1017/S0007114512000037.

Interpretive Summary: Obesity is a public health problem in the United States and is often accompanied by high blood glucose levels, resistance to insulin, and low grade inflammation. Strawberries contain nutrients with anti-inflammatory potential. The purpose of this study was to test the anti-inflammatory and blood glucose lowering capacity of strawberries in a mouse model of obesity. Thirty-six male C57BL/6J mice were divided into 4 groups (n = 9 / group). The mice were fed either a low fat diet (13% fat), a low fat diet supplemented with 2.6% freeze-dried strawberry powder, a high fat diet (44% fat), or a high fat diet supplemented with 2.6% strawberry powder. Non-fasted blood glucose levels was tested periodically, and blood samples were collected at the beginning of the experiment and at 10, 18, and 24 weeks on the special diets to meaure markers of inflammation. As expected, the high fat diet significantly increased overall non-fasted blood glucose concentrations, glucose intolerance, insulin levels, intracellular adhesion molecule-1, E-selectin, leptin, resistin, and plasminogen activator protein-1. Strawberry supplementation did not have any effect on these outcomes. However, mice fed diets supplemented with strawberry powder had significantly lower overall blood glucose levels than mice fed unsupplemented diets. Additionally, the group of mice fed low fat diet supplemented with strawberry powder had significantly lower blood C-reactive protein compared to the other 3 groups. C-reactive protein is a marker for cardiovascular disease risk. Therefore, these data suggest dietary strawberries may reduce health risks associated with long-term consumption of a diet high in fat and the resulting obesity, as well as have potential health benefits for normal weight individuals.

Technical Abstract: Obesity is a public health problem in the United States and is often accompanied by hyperglycemia, insulin resistance, and low grade systemic inflammation. Strawberries contain polyphenols with anti-inflammatory potential. The purpose of this study was to test the anti-inflammatory and blood glucose (BG) lowering capacity of strawberries in a mouse model of diet-induced obesity. Thirty-six male C57BL/6J mice were divided into 4 groups (n = 9 / group). Mice were fed either a low fat diet (LF, 13% fat), a low fat diet supplemented with 2.6% freeze-dried strawberry powder (LFSB), a high fat diet (HF, 44% fat), or a high fat diet supplemented with 2.6% strawberry powder (HFSB). Non-fasted BG was tested periodically, and blood samples were collected at baseline, 10, 18, and 24 wk to examine systemic markers of inflammation. The high fat diet increased overall non-fasted BG concentrations, glucose intolerance, soluble insulin, intracellular adhesion molecule-1, E-selectin, leptin, resistin, and plasminogen activator protein-1 (P > 0.05). Strawberry supplementation did not ameliorate these outcomes. However, mice fed diets supplemented with strawberry powder (LFSB + HFSB) had lower overall BG levels than unsupplemented mice (P < 0.01). Additionally, strawberry powder lowered plasma C-reactive protein in the LFSB group compared to the other 3 groups (P < 0.05). These data suggest dietary strawberries may reduce health risks associated with long-term consumption of a diet high in fat and the resulting obesity, as well as have potential health benefits for normal weight individuals.