The human body converts nitrate to nitric oxide (NO), which is a signaling molecule associated with several physiological functions involving blood pressure regulation, cardiovascular health, mitochondria production, calcium transport, oxidative stress, and skeletal muscle repair. It plays a prominent role as a vasodilator, which means it relaxes blood vessels and improves blood flow.
Nitrate supplementation, whether in its pure form (e.g. sodium/potassium nitrate), or via foods (e.g. beetroot juice/powder), may temporarily reduce the body’s oxygen demand during exercise. A decrease in oxygen demand may result in improved exercise and muscular performance.
The most accurate method of assessing NO levels is to measure plasma nitrate and nitrite in your blood. The half-life of NO is incredibly short, existing for less than 0.1 seconds before it breaks down into nitrate and nitrite. These two metabolites are measured as stand-in measures (i.e., surrogate markers) of NO production.
Researchers may not use this method due to inconvenience or cost concerns. Instead, they may opt to use indirect approaches.
It is not uncommon for researchers to test the effects of a nitrate-rich supplement on secondary endpoints affected by NO levels. Below is a list of frequently used endpoints.
Heart stroke volume
Graded exercise tests
Open-ended exercise tests
NO levels can be increased through direct nitrate ingestion. Obvious, right? But there’s a twist — nitrates do not exist as isolated dietary supplements due to the regulations surrounding high quantities of sodium nitrate. Instead, nitrate supplementation is typically achieved via nitrate-rich foods or beverages. Most studies deliver nitrates in the form of beetroot juice or powder.
The table below displays an analysis of human studies and indicates how supplements may affect NO levels and production.
Nitrates are found in various foods, notably beetroot and leafy green vegetables. Beetroot extract capsules do not provide enough nitrates to affect blood flow, but beetroot powder and juice are valid options.
Estrogen regulates blood flow by inducing the production of NO, a potent vasodilator made by endothelial cells, which is a specialized cell type lining all blood vessels. After being produced in the endothelium, NO diffuses into the underlying smooth muscle cells that regulate vascular tone, causing them to relax and subsequently increase blood flow through the body. This process is called vasodilation.