Nutritional is the adjective for things that have to do with the goodness in food — the vitamins, the protein, the rest of what keeps you well. A nutritional label is the little table on a packet. Nutritional advice is what a teacher or a doctor says about eating. Nutritional value means how much this food actually gives your body. People also say “this meal is not very nutritional,” meaning it does not feed you well; though actually, some careful speakers keep nutritious for “this food is good for you,” and keep nutritional for “about nutrition.” In real life both happen, especially on packaging. The word is ordinary in health class and on boxes; it is not slang and not posh. It is simply nutrition with -al stuck on, “of or about nutrition.”