Dutch anti-doping boss says he’s ‘uncomfortable’ with use of ketones in Jumbo-Visma Cycling by el-admin - January 29, 2020 0632 Jumbo-Visma at the 2019 Tour de France (Sunada) A Dutch anti-doping boss has said the use of ketones within Jumbo-Visma makes him “uncomfortable.” Share this: Jumbo-Visma rider forced to retire due to injury, aged 26DateMay 2, 2019In relation toCyclingDaring to dream: How Jumbo Visma built their Tour challengeDateJuly 19, 2019In relation toCyclingTom Dumoulin’s departure from Sunweb ‘far from settled’DateJuly 30, 2019In relation toCycling