From Ruth Chepng'etich Wikipedia page:
""Chepng'etich's world record was partially met with criticism and accusations of doping. Robert Johnson of LetsRun.com directly asked Chepng'etich her thoughts on the criticisms. The Kenyan National Assembly considered Johnson's question "disrespectful". Her improvement has been attributed to the use of a Maurten carbohydrate mix, a special combination of sodium, carbs, and sugar, and the Nike Alphafly 3 shoe."