Beetroot juice helps you last longer, not race faster

Beetroot juice and other inorganic nitrate supplements have attracted serious interest as endurance aids, but individual studies have pointed in different directions. Whether nitrate genuinely improves performance, in which kinds of exercise test, and how it is best taken were all unsettled questions. Pooling the controlled human studies is the cleanest way to size the true effect, separate real benefit from noise, and check whether the format of the test changes the answer. It also allows a look at who benefits: everyday exercisers, or highly trained athletes chasing small margins.

The authors searched four electronic databases and cross-referenced reference lists for controlled human studies of inorganic nitrate supplementation and exercise performance, ending with 17 studies that met their inclusion criteria. Beetroot juice and sodium nitrate were the most common supplements, at doses ranging from 300 to 600 mg of nitrate, given in protocols spanning a single bolus to 15 days of regular ingestion. Performance outcomes were grouped into three formats, time to exhaustion tests, time trials and graded exercise tests, and the results were pooled statistically alongside a qualitative reading of the patterns across studies.

The clear result was for time to exhaustion: nitrate produced a significant moderate improvement in how long people could keep going at a constant workload. For time trials, the format closest to actual racing, the effect was small and did not reach statistical significance, and the same held for graded exercise tests. Reading across the studies, benefits appeared more often in inactive to recreationally active individuals than in trained athletes, and more often when nitrate was loaded chronically over several days rather than taken as a one-off dose before exercise.

This pooled analysis brings order to a mixed body of individual trials: nitrate reliably helps sustained fixed-intensity efforts, while the case for faster race times remains suggestive rather than proven. The authors point out that the small, non-significant time trial effect could still be meaningful in elite sport, where outcomes turn on tiny margins, but the data here could not confirm it. Open questions remain around the optimal dose, duration and timing of supplementation, and whether well-trained athletes, who showed less benefit in these studies, respond much at all.

This is a reason to see beetroot juice as a supplement with genuine evidence behind it, with an important footnote: the strongest proof concerns lasting longer at a steady effort, not clocking a faster time over a set distance. The pattern in the data suggests newer and recreational exercisers have more to gain than seasoned competitors, and that regular intake over several days showed benefits more often than a single dose. As with any pooled result, the average effect is not a personal guarantee.