If you want to plan a healthy diet, get some advice from a registered dietian. Someone who has verified crudentials, preferably some kind of doctorate in their field from an acknowledged university. These days it's far too easy for anyone with a doctorate in anything to give medical advice, and it's not always right.
Most dairy cattle in Australia are feed on grass. Just grass. Beef cattle are grain fed. Just grain. European and North American cattle often have their diets enhanced with all kinds of crap -- offal, poultry products, etc. which is why they are so susceptible to disease and can cause disease in humans, and it's also why Australian beef is regarded as the best and healthiest in the world.
If you want to explore various diets, go ahead, but get advice from more than one person! If you don't have your health, you might as well have nothing.