Questions:
- should recipes have a reference to a food with its computed nutrition?
    - or the other way around-- store a
- how should ingredients-that-are-recipes be linked to recipes?




Options:
1.  - ingredients just store a food_id
    - foods store an optional recipe_id

    Problems:
      - all recipes have to have an associated food entry
      - foods have to have a recipe_id-- shouldn't this be the other way around?

2.  - ingredients just store a food_id
    - recipes store a food_id

    Problems:
      - all recipes have to have an associated food entry
      - can't tell which ingredients are recipes without doing an indexed search


3.  - ingredients store a food_id and a recipe_id, only one is valid
    Implications: recipes and foods can be connected in any way

    Problems:
      - joining is more complicated