Who knows most about nutrition? Doctor or dietician

Dietician. In my experience, physicians do have some knowledge of nutrition especially if they have studied it or are interested in it. A dietician spends their training learning all facets of nutrition and are very impressive in their knowledge. Working together and utilizing each others knowledge is very beneficial.
Neither. A nutritionist knows best. Doctors are unfortunately very poorly trained (if at all in some medical schools) in nutrition in medical school. And i speak from experience having completed medical school this century. Also, the american dietetic association (which represents most registered dieticians) do not provide good, unbiased information for general nutrition.