Olympians and amateurs alike swear by legal products such as probiotics and creatine for improving their performance – but does the evidence back them up? We ask the experts about four favourites

In August, Keely Hodgkinson won Great Britain’s only Olympic gold medal on the track. The foundation of the 800m star’s world-beating performance came from a regime that comprises intensity over mileage, cross-training, sand-dune workouts and a £15 supplement that has been around for years but has enjoyed a breakthrough year in 2024. Hodgkinson uses sodium bicarbonate – AKA baking powder – to power up her training and races, specifically Maurten’s “bicarb system” that, according to one leading coach, was used by 80% of endurance athletes in Paris. “I couldn’t recommend it strongly enough,” said Hodgkinson’s coach, Trevor Painter. But why? What is it about sodium bicarbonate and the Maurten system that’s had it labelled “gold dust” by another leading coach? And beyond the bicarb, what other legal supplements are used? The industry is currently valued at $17.61bn (£13.15bn) – that’s an awful lot of pills, powders and potions that purport to improve sporting performance. Here we look at the evidence on four of them.