In the NutrionProduct resource description there is the following sentence: "Oral intake of food, fluids, oral nutritional supplements (i.e. Ensure), or enteral nutrition should be recorded using the NutritionIntake resource.".

The NutritionIntake resource is not available in the resource list (http://hl7.org/fhir/2021May/resourcelist.htm) as well as a link in the NutrionProduct resource page (http://hl7.org/fhir/2021May/nutritionproduct.htm).