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I’m pretty unclear about what you’re asking. So I’ll do my best to answer them as I read it.
Humans need salt. As far as I know, there is not chemical reaction in our cooking that transforming the molecules in salt (Na+ and Cl- for table salt).
With that said, I believe OP was answering of when to add salt for flavor maximization.
Since salt doesn’t transform the process of cooking, nutrient absorption is the same. Microwaving doesn’t alter food despite it being radiation. Microwaves heat your food by vibrating the water molecules.
Ohio. A perfect cretic (– ᴗ –).