Nutritional Information Data Model
If your intention is that you want to have multiple equivalent units of measure, all of which share the identical nutrition information, then you should flip things around and make nutrition_facts either a child of food directly.  The serving_sizes would then be a child of your nutrition facts, not of food (except as a grand child through nutrition facts.  Something like this:

food -+-----&lt; nutrition_facts -+-----&lt; serving_sizes

This would let you have multiple sets of nutrition facts, say for "box of cookies" and "two cookies" each stored only once, with these units of measure stored as either cookie units or equivalent grams.

If you only want to have one set of nutrition facts... such as would appear on a nutrition label, then you have a 1:1 between food and nutrition facts, which gives you the option of moving the columns from nutrition_facts into the food table as an alternative design.  This may or may not appeal to you, depending on your design inklings.