Medical professionals actively resisted Goldberger’s correct pellagra model because the intuitive one was wrong.

Evidence

One man, Dr. Joseph Goldberger, investigated orphanages, performed controlled experiments on prisoners, and had begun to construct the right causal model by 1915. However, at the time, the medical community was convinced that pellagra must be an infectious disease, so Goldberger was ineffective and his ideas thought “absurd.” Goldberger even injected his wife and friends with blood from people suffering from pellagra to demonstrate the noninfectious nature of the condition. These studies were dismissed by asserting that Goldberger’s staff must have been “constitutionally resistant” to the disease. … Thus, not only did people—Europeans and Americans in this case—not figure out the right causal model, but they actively resisted it when it was presented to them by Goldberger. Instead, they preferred to hold firmly to the wrong causal model, probably because the right model was rather less intuitive. … Spoiled food and contamination were, and are, relatively “easy to think” about with regard to food compared to the concept of chemical reactions initiated by the introduction of nonfoods, like burnt seashells, into culinary recipes. Cultural evolution had produced a rather nonintuitive fix for the pellagra challenge. — Joseph Henrich, The Secret of Our Success, 340