Have a marking on things "is essential"
For example vitamin b12 doesnt sound interesting. But if you just went vegan and just be like "meh what is this weird vitamin b12 even gonna do" and then you'd feel all weak and stuff but dont want to hurt animals or something of that sort...well then u might end up being dead.
okay rare today since almost everyone is aware of it but that one odd one that uses cronometer but has never heard of social media where they mention vitamin b12 might benefit from it.
but this is just one example (protein being another one: 0.8g/kg bodyweight is "recommended" but somewhere between 0.5 and 0.6g/kg bodyweight is essential iirc (looking at you fruitarians!)...and probably many other nutrients too)