According to the present invention, acquired metabolic derangements or fatty acid disorders in humans that are manifested by a deficiency in at least one enzyme involved in fatty acid metabolism are treated with a five carbon or a fifteen carbon fatty acid source. Rapid nutritional supplementation can also be provided to a mammalian cell by providing either a five carbon or fifteen carbon fatty acid source. Dietary formulations suitable for human consumption comprising either a five carbon fatty acid, a fifteen carbon fatty acid or triglycerides thereof is also disclosed.