Mirriam- Webster defines food as, " material consisting essentially of protein, carbohydrate, and fat used in the body of an organism to sustain growth, repair, and vital processes and to furnish energy; also : such food together with supplementary substances (as minerals, vitamins, and condiments). By that definition, a wide range of consumable items qualify as food.
The folks at Oxford Dictionary define food as, "any nutritious substance that people or animals eat or drink or that plants absorb in order to maintain life and growth." With the addition the word nutritious, the meaning of food changes.
In the last several years, we've added a value qualifier to the word food. There's an argument made that products which are designed for consumer to consume don't meet the definition of food. That's one of Pollan's key arguments in his Food Rules concept. Pollan argues that these "food like substances" are not real food. They are chemical concoctions designed by scientists, not designed by nature.
Yet depending on the definition you chose, these designer consumables are indeed food. They combine protein, carbohydrates, fats, vitamins and minerals into a substance used to sustain growth, repair the body, and support various vital processes. After all, the commercially designed feed that goes into pigs, cows and chickens does indeed fulfill those requirements.
So if we proceed to add the word nutritious into the mix, it appears on face to change things up. Nutritious comes from the word nourish, meaning to "nutrure or rear, or to promote the growth of." So nutritious leads us to look at food types as foods which promote growth or encourage. There's a positive value associated with them.
So how do we associate these values with the things we eat? Is blowfish, a fish valued for the toxin it produces, better for you than a cheeseburger from McDonald's? Why? The blowfish requires minimal preparation, yet prepared incorrectly it can lead to major illness or even death. The McDonald's cheeseburger won't kill you with the first bite. Are both items food? Are both items nutritious? What changes between the two?
There's no easy answer. At what point does human manipulation of an edible item change it from a nutritious food item to something else? Where do we draw the line?