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 ${}^{\prime }$ ), 120 minutes after beverages ingestion (130 ${}^{\prime }$ ), immediately after exercise (170 ${}^{\prime }$ ), and 90 min after exercise (260 ${}^{\prime }$ ). 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 $\ast$ 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.