I finally see some people answering the original question. Kashrus organizations are for the purpose of determining that the ingredients don’t contain foods and/or byproducts of the foods (fish/meats etc) enumerated in Torah shebeK’sav and Baal Peh to be impure/unfit (in the common vernacular “treif”) as well as basar b’cholov.
If you want to know what’s healthy see a doctor.