A Dutch pediatrician studied children with celiac who became healthier while they were starving to death because Nazis blocked food shipments. Thanks to his dedication to his patients, we now know that celiac disease is caused by gluten. He saved many lives.
Because of his work, Europe takes celiac disease very seriously and children are screened as a routine practice. During the same time, an American doctor was touting an "all banana diet" for children with celiac (which was effective only because bananas are gluten-free), and claimed this was curative, so children could grow into adults who could eat gluten (consequently getting very sick again).
The Dutch pediatrician was never taken seriously in the U.S. because of Dr. Banana's fame, and this is likely why the U.S. is so far behind in celiac testing and treatment compared to Europe.
He was being considered for a Nobel prize for this work, but unfortunately passed away before the winners were announced, and prizes are not awarded posthumously.