The UCI has announced that it "does not recommend" the use of ketones in cycling, but will not restrict their use, it was revealed on Monday.
In a statement, a spokesperson for cycling's governing body said that the UCI's position was there is "no reason for them to be used".
Cycling Weekly reported earlier this year that the UCI was set to approve the use of ketone supplements in the peloton, after a multi-year study into the product has concluded that they are safe and do not offer a significant performance enhancement to users.
Monday's statement does not suggest a full-throated endorsement, but there is no move towards banning them, as some have urged. The recommendation against them comes because the UCI says they do not have an effect, rather than because they are performance-enhancing. This recommendation is not legally-binding, and riders and teams are allowed to continue to employ them.
Ketones are naturally produced by the liver when the body burns fat instead of glucose for energy, and synthetic ketones are widely available; it is argued that they aid recovery, and are used by multiple WorldTour teams. Some squads have official ketone sponsors.
The Movement for Credible Cycling (MPPC) – a voluntary body that fights against doping and aims to improve the crediblity of the sport – recommends that its members do not use the supplement.
The UCI spokesperson said: "The use of dietary supplements containing ketone bodies (ketones) has become popular in endurance sports, particularly road cycling, since the publication of scientific findings of a study carried out in 2016. Results of the study suggested that ketones taken before or during exercise could improve cycling performance. However, these results were not confirmed by subsequent studies, and there is now a consensus that such supplements have no effect on performance during endurance exercise.
"However, several ensuing studies then drew attention to the potential benefits of ketones when it comes to the rapidity and quality of post-exercise recovery. Ketones were found to have added value in terms of the speed of muscle glycogen resynthesis and endogenous EPO production.
"More recently, research has now contradicted these earlier findings. The results of a very comprehensive, high-quality study show that taking ketones after competition or high-intensity training sessions has no effect on the quality of recovery."
"As there is no compelling evidence that ketone supplements enhance performance or recovery, the UCI sees no reason for them to be used. Therefore, the UCI does not recommend the inclusion of such supplements in riders' nutritional plans."
