Dose-response effect of dietary nitrate on muscle function in older individuals
The purpose of this study is to see if drinking beetroot juice (BRJ) is beneficial for aging subjects.
The study will take a minimum of 19 days to complete. The study begins from the time you sign this informed consent document. This study consists of a screening visit followed by 3 study visits with 5-15 days between visits.
The purpose of the screening visit is to explain all aspects of the study. We will also determine if you can participate in the study. You will undergo a complete medical history and physical exam and a resting EKG. You will have your blood drawn (about 1.5 teaspoons). You will also practice the entire neuromuscular function exercise test. During this test, the strength of your muscles will be determined by having you kick, push and/or pull back as hard as you can while your leg is strapped to an exercise device.
During the study you will be instructed to consume your normal diet. However, you will be asked to avoid eating foods high in nitrate such as beets, spinach, and collard greens the evening before each study visit. You will be asked to refrain from the use of antibacterial mouthwash, such as Listerine or Cepacol, during the study. Chewing gum, alcohol, and food and drinks containing caffeine (coffee, tea, chocolate, and soft drinks) should be avoided 24 hours prior to each visit. You will be asked to fast for 12 hour prior to each study visit.
Study Visit Two – Approximately 5 hours At the beginning of your visit a catheter (small, flexible, sterile plastic tube) will be placed through a vein in one of your arms. This is for collection of blood samples. Your blood will be drawn four times during this visit. Each draw will be 6mL or about 1.2 teaspoons. Your first blood draw will check nitrate and nitrogen levels. You will then have a breath test to check nitric oxide. You will then drink about 280 mL (about 1 cup) of BRJ containing either 0 (placebo), about 12 mmol (about 0.03 ounces), or about 24 mmol (about 0.06 ounces) of nitrate. The smaller dose is roughly equivalent to about 3-4 whole beets or about 2 cups of cooked spinach, whereas the larger dose is twice that.
Blood and breath samples will be obtained every hour. Your heart rate and blood pressure will be measured at the same times the blood and breath samples are obtained. You will then rest quietly in a private room for about 2 hours after ingestion of BRJ (or placebo) then you will perform the neuromuscular function test that was practiced during the screening visit. One final blood and breath sample will then be obtained.
Washout After visit two, you will undergo a 5-15 day washout period where you will not drink the BRJ (or placebo).
Study Visit Three You will return to the research center and undergo the same procedures as you did in Study Visit Two.
Washout After visit three, you will undergo a 5-15 day washout period where you will not drink the BRJ (or placebo).
Study Visit Four You will then repeat Study Visits Two and Three again
Participants will be paid for their participation.
- IRB Number: 1712606816
- Research Study Identifier: TX8673
- Principal Investigator: Andrew Coggan