The relationship between oxygen radical absorbance capacity (ORAC) index and elevated blood pressure in overweight or obese subjects compared to normal-weight subjects

Obesity is an important preventable disease and increases the chance of developing some chronic diseases like hypertension which is related to many factors including oxidative stress. Dietary antioxidants protect the body against oxidative stress. The purpose of this study was to evaluate the potential association of dietary oxygen radical absorbance capacity (ORAC) index with blood pressure in overweight or obese subjects compared to normal-weight subjects. In a cross-sectional study on 157 adult females and males from students and staff of Science and Research Branch of Islamic Azad University (SRBIAU) of Tehran that classified in two groups of normal weight and overweight or obese were evaluated. Demographic and validated food frequency questionnaires (FFQ) were completed and individuals' weight and height information were measured using the BIA. The systolic and diastolic pressure was recorded by the Automatic Blood Pressure monitor. Dietary antioxidant was estimated based on the ORAC index of selected foods reported by the Nutrient Data Laboratory of the United States Department of Agriculture (USDA). The results showed that there was a significant difference between the normal and overweight or obese groups in terms of body mass index, systolic and diastolic pressure (p=0.0001).  Also, the ORAC index was higher in normal individuals than the case group, but it was not significant (p=0.222). There was also an inverse correlation between dietary ORAC, systolic and diastolic pressure in both groups, and only in the normal weight group, the association between systolic pressure and the dietary ORAC index was significant (p=0.04). The findings of the present study suggested that the dietary ORAC index was inversely associated with systolic and diastolic pressure in both subjects.