Dietary formulations in the form of an oil emulsion providing total enteral or parenteral nutrition, or in the form of food oil suitable for oral administration is provided. The formulations include about 2-60% by calories of a C20 or longer omega-3 fatty acid and about 0.05% to 1% by calories of arachidonic acid, where the formulation provides less than 1% of total calories from linoleic acid and alpha-linolenic acid, and where the fatty acids provide 5-60% of the total calories of said dietary formulation. Methods for treatment of diseases and disorders using the dietary formulations are also provided.