Question: of these foods which is the best source of niacin?
Answer: Liver. Liver is one of the best natural sources of niacin. ... 
Chicken Breast. Chicken, especially the breast meat, is a good source of both niacin and lean protein. ... 
Tuna. ... 
Turkey. ... 
Salmon. ... 
Anchovies. ... 
Pork. ... 
Ground Beef.