For example, plasma and red blood cells are two different metabolic compartments of carnitine that can and should be analyzed. When Supplemental Carnitine Is Needed Carnitine is not a vitamin. Data do not indicate a need for dietary carnitine by healthy young adults. However, there is a great deal of data consistent with the hypothesis that supplemental carnitine is required under special physiological circumstances. Parenteral nutrition is probably one of those conditions where supplemental carnitine is beneficial.
More data are available for newborns than for adults.
But the data are not sufficient for proof, so we are getting into the realm of opinion. If parenteral nutrition solutions are supplemented, data are clear that it is critical that the supplement be pure L-carnitine. Available data do not show a need to supplement parenteral nutrition solutions with pharmacological doses of carnitine unless there is an inborn error of metabolism being treated. It is my opinion that parenteral nutrition solutions should be supplemented with carnitine at a dose that is similar to the dietary intake of most western countries. I suggest that plasma and red blood cell carnitine be monitored before supplementation and at four months after supplementation.