Nitrate supplements wouldn't seem to meet the WADA criteria for inclusion on the prohibited substance list because they don't present a health risk to the athlete. A lot of endurance athletes are using beetroot supplements and so far there haven't been any adverse effects.

https://www.wada-ama.org/en/what-we-do/world-anti-doping-cod...

Where do you draw the line? (I know that the answer to that question is always 'somewhere') No one's getting significant levels of baking soda from their diet, and caffeine is a relatively recent cultural addition to most diets.

The gels are much the same. Getting the same nutiritional ratios used to require carefully controlled eating and certainly weighed vastly more than the gels adding both weight and complexity and likely being less performant.

Most(?) sports handle this by maintaining multiple leaderboards. The sub two hour 26.2 mile run was broken years ago, but the sub 2 marathon race was only recently completed, for instance. The difference being that the original was done much like this one in that it was paced, on a track, etc while the later was run in typical marathon conditions with other racers, variable winds etc.

There are off the shelf supplements that are widely used for this, e.g. BeetElite which contains nitric oxide derived from beet juice. I can testify that they do offer a real performance benefit - in my case I've found them beneficial when running at altitude as a (very) amateur. I'm not sure how/when something like this should become a banned PED.

You'd have to ban beets if you want to ban nitrates. Caffeine is more of a performance enhancer than nitrates, but they wouldn't ban it because everyone drinks coffee.

Sleep is the biggest performance enhancer. They should ban that.