Skipping the Middle Animal: coming to terms with the fact that plants are the source of all our nutrients.

We're told we need to eat animals and their secretions to obtain certain nutrients, such as calcium, iron, B12, Omega 3 fatty acids, but what we're not told is why the animals' flesh and secretions contain these nutrients in the first place. Here are a few clues. Calcium = mineral found in the ground. (Cows [are supposed to] eat grass, which contains calcium.) Iron = mineral found in the ground. B12 = grows on bacteria. (Bacteria is attracted to, well, corpses.) Omega 3 fatty acid = a type of polyunsaturated fat found in plant foods. (Fish eat algae, which contains Omega 3s.) See where I'm going with this?