Well of course the manufacturer would endorse them and present their own slightly biased evidence - it would be poor marketing if they didn't
If you're happy with the ingredient list then that is up to you
Ingredients: Rice flour, wheat starch, glycerin, calcium carbonate, gelatin, gum arabic, cellulose powder, natural poultry flavor, sodium tripolyphosphate, salt, potassium chloride, potassium sorbate (a preservative), vitamins [choline chloride, d-calcium pantothenate, vitamin B12 supplement, vitamin A supplement, niacin, riboflavin (vitamin B2), pyridoxine hydrochloride (vitamin B6), dl-alpha tocopherol acetate (source of vitamin E), folic acid], smoke flavor, turmeric, iron oxide, copper sulfate.
Personally I think there are better ways