Antioxidant Responses in Hypertensive Postmenopausal Women after Acute Beetroot Juice Ingestion and Aerobic Exercise: Double Blind and Placebo-Controlled Crossover Trial

Abstract

This study is aimed to analyze the effect of different nitrate concentrations [NO3-] present in beetroot juice (BJ) on salivary oxidative stress markers after acute exercise performance in hypertensive postmenopausal women. Thirteen hypertensive postmenopausal women participated in three experimental sessions, taking different beverages: noncaloric orange flavored drink (OFD), low nitrate (low-NO3-) BJ, and high nitrate (high-NO3-) BJ. The participants performed aerobic exercise on a treadmill, at 65-70% of heart rate reserve (HRR), for 40 min. Saliva samples were collected after an overnight fast, 10 minutes before BJ ingestion at 7: 20 am (0′), 120 minutes after beverages ingestion (130′), immediately after exercise (170′), and 90 min after exercise (260′). Salivary total protein (TP), catalase activity (CAT), reduced glutathione (GSH), and total antioxidant capacity by ferric-reducing antioxidant power (FRAP) concentrations were analyzed. No interaction (session∗time) was found among three sessions over time. Catalase area under the curve (AUC) was lower after both low-NO3- and high-NO3- consumption (p<0.001), and GSH AUC was lower after high-NO3- (p<0.001) compared with OFD. So, the acute intake of BJ with aerobic exercise seems to decrease catalase (in high-NO3- and low-NO3-) and GSH (in high-NO3-), besides not interfering with FRAP in hypertensive postmenopausal women.