Blueberry Supplementation Alters Biomarkers of Oxidative Stress in High‐fat Fed Rats

Abstract

Obesity is associated with enhanced inflammation and oxidative stress. Blueberries contain high levels of anthocyanins, which may mitigate oxidative stress through direct antioxidant activity and/or alterations to antioxidant enzyme activities. Our objective was to determine if blueberry supplementation would decrease systemic, hepatic, and colonic oxidative stress in high fat fed rats. Wistar rats (n= 8/group) were fed low‐fat (LF, 10% fat), high‐fat (HF, 45% fat) or high‐fat with 10% blueberry (HF_BB) diets for 8 wks. HF and HF_BB diets were isocaloric and all diets were matched for sugar and fiber content. Levels of urinary F2‐isoprostanes, a marker of systemic lipid peroxidation, and hepatic and colonic malondialdehyde (MDA) were assessed. Activities of glutathione peroxidase (GPx) and glutathione reductase (GR), antioxidant enzymes that may be altered by anthocyanins, were also measured in liver. Unexpectedly, blueberry supplementation resulted in a small but significant increase in urinary F2‐isoprostanes in high fat fed rats. Hepatic MDA was elevated by HF feeding but was significantly lower in HF_BB fed animals compared to HF fed animals. Blueberry supplementation did not enhance hepatic GPx or GR activities, suggesting these enzymes did not account for the reduction in hepatic MDA. Although colonic MDA was lower in HF_BB animals compared to HF animals, the difference was not significant. These results suggest that blueberry supplementation may alter oxidative stress in high fat fed animals in a tissue‐specific manner.Support or Funding InformationThis material is based on work that is supported by the National Institute of Food and Agriculture, USDA, under award number 2014‐67017‐21757 & GA Agricultural Experiment Station.