try searching for grass-fed with no dash: "grass fed" (don't put in the quotes), in other words, enter grass fed
that way if the person spells it "grass fed" instead of "grass-fed", you will pick that up too. It will also pick up anything that has both words "grass" and "fed", whether they are together or not.
try arthriti (this will pick up arthritis, arthritic)
and allerg (this will pick up allergy, allergies, allergic, allergens)
Let me know what you think!