The results of a study conducted in 2008 showed that the ingestion of one , 250mL can of sugar-free Red Bull , in a sample of 30 healthy young adults , had an immediate detrimental effect on both endothelial function , and normal blood coagulation . The results of a study showed that the ingestion of one , 250mL can of sugar-free Red Bull , in a sample of 30 healthy young adults , had an immediate detrimental effect on both endothelial function , and normal blood coagulation .