True. According to the Washington Post, "scientists have discovered a surprisingly simple way to potentially peer inside the body, using a common yellow food dye found in Doritos to create see-through mice. In a series of experiments that could have been plucked from the pages of science fiction, researchers at Stanford University massaged a solution containing tartrazine, the chemical found in the food dye known as 'yellow No. 5,' onto the stomachs, scalps and hind legs of mice. About five minutes later, the opaque skin of the mice transformed temporarily into a living window, revealing branching blood vessels, muscle fibers and contractions of the gut, they reported Thursday in the journal Science."
https://www.washingtonpost.com/science/2024/09/05/see-through-transparent-mice-food-dye/