This is incorrect. There are much fewer contradictions than the average person can solve. The problem is the financial factor that hinders the spread of true knowledge. But if you start reading the academic publications personally (PubMed will help you), you will see that everything is quite simple.
Fortunately, some people devote their entire lives to this and create, for example, the non-profit information portal NutritionFacts. org.
I think that's why it is in advertising theory. Such a misfortune occurs when the experimenter is, as a rule, vitally interested in some particular result of the experiment. And, usually, this is the result.