Blood doping increases red blood cell count and compensates for physiological changes which happen during an event like the Tour de France, it's disingenuous to call it nutrients.
Lance Armstrong and his Postal teammates routinely did blood doping during the Tour de France. They smuggled frozen blood in a hidden compartment and arranged secret transfusions in hotel rooms. All the sordid details are in "The Secret Race" by Tyler Hamilton.
https://www.penguinrandomhouse.com/books/212873/the-secret-r...