P-246: Total antioxidant capacity, an important factor affecting blood pressure responses to diet?

Objective: The DASH (Dietary Approaches to Stop Hypertension) Diet effectively lowers BP. However, the mechanism is unknown. The DASH Diet is high in antioxidants, potassium, magnesium, and calcium, which may all contribute to lower BP. Recent evidence suggests the antioxidant content of the diet may be especially important in the BP response. We studied the impact of a high antioxidant (HAO), comparable to the DASH Study Diet, and a low antioxidant (LAO) diet, similar to the usual diet, on blood pressure, total antioxidant capacity (TAC) of plasma, 24-hour urine sodium, potassium, calcium, and magnesium in obese hypertensive with the risk factor cluster (OHT) and in lean normotensives (LNT) subjects. Design and Methods: Eleven obese hypertensives (35±2 years, 5 female / 6 male, 6 African Americans, 5 white, body mass index 34±2 kg/m2) and 12 healthy controls (39±2 years, 6 female, 6 African Americas, 5 white, body mass index 23±0.5) were evaluated. After the screening and qualifying visits, subjects were studied on their usual diets. They were randomized to a high antioxidant or a low antioxidant diet for 4 weeks then crossed over to the other diet for 4 weeks. BP, weight, urinary sodium, potassium, calcium, magnesium were measured and repeated every week for 4-weeks. The TAC was measured after 4-weeks on each diet by assaying the ferric reducing/antioxidant power (FRAP) of plasma. Results: BP declined 8 – 9/6 – 7 mmHg in OHT during the 3rd and 4th weeks of the HAO compared to usual and LAO diets, p