any Qxxxxxx is a Wikidata topic. (also called an entity) any Pxxxx is a Wikidata property.
that equivalent class = http://health-lifesci.schema.org/Diet needs to be removed and changed to
'external subclass' = http://health-lifesci.schema.org/Diet
The reason is that our definition in Schema.org is slightly different than https://www.wikidata.org/wiki/Q474191 which is the biological definition (a mixture of food sources that sustains a living thing) and from that derives the nutritional definition, the one Schema.org has, like a specific diet like 'Thad's Special Vegan Diet without olives :)
So we need a new 'external subclass' made available in Wikidata please.
Thad +ThadGuidry https://www.google.com/+ThadGuidry