Beetroot extract or juice and the amino acid L-citrulline are both supplements associated with improving athletic performance. Both play a role in creating nitric oxide (NO), which improves blood flow to working muscles. Though they create similar outcomes, they each work a little differently. Depending on your goals, one might be better than the other, or you might want to take both at the same time.
How Nitric Oxide Forms In Your Body
When you take L-citrulline, your body turns it into L-arginine. L-arginine then helps your body build proteins, improve muscle function, and produce NO. Because of how your body processes the different amino acids, it is more effective to take L-citrulline than to take L-arginine directly.
Beets are rich in nitrate. This is a compound made of nitrogen and oxygen. When you eat beets, supplement with beetroot powder, or drink beet juice, your saliva converts the nitrate into nitrite and NO.
Evidence on Beetroot and L-citrulline
There is an abundance of evidence showing that beetroot improves athletic performance. It can improve endurance, shorten recovery time, and boost muscle strength.
Evidence for L-citrulline’s benefits is mixed. Some studies show an increase in oxygen uptake and muscle oxygenation, and others suggest improvements for aerobic exercise. Other studies, however, show no effect.
There are some studies on taking beetroot and L-citrulline together (Burgos et al., 2021; Viribay et al., 2024). Both studies divided athletes into four groups to compare the effects of a placebo, beetroot on its own, L-citrulline on its own, and beetroot combined with L-citrulline. Both studies showed improved benefits to taking both beetroot and L-citrulline together.
Supplementing with Beetroot and L-citrulline
L-citrulline is found naturally in watermelon and a few other foods. Watermelon contains the highest concentration, with about 365 mg of L-citrulline in one cup of diced seedless watermelon. You can also get L-citrulline as a supplement, though there is no standard recommended daily dose. The studies looking at L-citrulline and beetroot together used 3 g or 6 g of L-citrulline per day.
Beetroot is typically taken in powder, extract, or juice form when supplementing for athletic performance. The amount of nitrite in beetroot supplements can vary widely. Studies on beetroot and L-citrulline together used 3.5 g or 2.1 g per day of beetroot extract.
As always, talk with your doctor before beginning any supplement. Beetroot is generally recognized as safe, but beets are high in oxalates, and this can make it more likely that your body will form kidney stones. You can also talk with a nutrition coach to develop a personalized supplement routine that will support your specific health and fitness goals.