>>512226711 (OP)>the only actual answer is to get your appropriate spread of nutrients in reasonable post-digestion amounts without going significantly over your adjusted calorie output.That's it, it's that simple.
Eat enough of XYZ that your body gets what it needs by the end of digestion, and don't overeat.
>eat something blocking proper absorption of something else then complain?You're an idiot, split them up or swap something.
>don't digest something well but keep eating it as a primary food?You're an idiot, you have thousands of alternatives.
>some stuff is hard to get in your country?You're an idiot, use supplements and don't overdo them.
>purge all of something despite not having an allergy or reaction to it?You're an idiot, use the tools at your disposal and be happy you're not diseased.