Last year, two Welsh athletes missed the Commonwelath Games after testing positive for banned substances.
An independent tribunal recently cleared Rhys Williams and Gareth Warburton of cheating, and found a contaminated energy drink was the reason for the steroids traced in their bodies.
This week, Y Byd ar Bedwar investigates the sports supplement industry, asking who was to blame for the steroids in their supplements? And does the industry need to be better regulated?