Nitric oxide (NO) is a gas that’s naturally produced by the body, used to deliver messages between cells. It relaxes and widens blood vessels and affects how efficiently cells use oxygen, giving it a key role in controlling the circulation of blood, which is why it’s so appealing to athletes. By increasing blood flow to muscles, NO delivers more nutrients to the muscles, helping them grow and recover.
To produce nitric oxide, enzymes in the body break down nitrates, like arginine. Arginine is naturally found in food such as spinach, sesame seeds, crab, shrimp and white meat turkey. Beetroot is another source of naturally occurring nitrates.
Due to its nitrate content, beetroot is believed to improve blood and oxygen flow in muscles during training and competition. This may help improve athletes’ ability to withstand muscle fatigue during an intense workout.
In fact, several studies have documented evidence of improved muscle oxygenation during exercise after the consumption of nitrate-rich supplements like beetroot juice.
One study, conducted at the Washington School of Medicine in St. Louis, found that patients given 140 milliliters of concentrated beet juice experienced an almost instantaneous increase in their muscle capacity by an average of 13 percent.
In two studies at the University of Exeter, researchers gave 15 cyclists a half liter of beet juice and discovered that they were able to ride up to 20% longer than the cyclists given a placebo. After the exercise, the riders were measured by a scanner that analyzes the amount of energy needed for a muscle to contract. The scan revealed that the cyclists given beet juice used less oxygen than usual.
Another experiment, at Penn State, started by giving participants either a placebo beetroot drink without nitrates or a relatively high dose of nitrate-rich beetroot juice. While their results were not as convincing as the first study mentioned, they theorized that the effect of dietary nitrate is most apparent during high intensity, fatiguing workouts. Why? The conditions during rigorous training favor the conversion of nitrite to nitric oxide.