“Carnitine is an unusual amino acid that is biosynthesized in the liver of humans and is found highest in muscle and organ meats in the human diet. {The most abundant source of carnitine is lamb.] Carnitine is not found in vegetable sources. In human metabolism, it is utilized as a material which transfers fatty acids across the membranes of the mitochondria where they can be used as a source of fuel to generate energy. In the absence of proper carnitine levels within the cell, the fatty acids are poorly metabolized and can build up within the cell or the surrounding medium, thereby leading to elevated fat and triglycerides and fatty acids.
Carnitine is manufactured in the body from the amino acids lysine and methionine but again not all levels adequate to meet the needs of all individuals, particularly if they are on a low lysine or methionine diet. The spermatozoa from lysine-depleted animals became infertile due to potential carnitine insufficiency. This is the first tissue to show deficiencies in the animals that have been deprived of carnitine or lysine.....There seems to be genetic limitations on the ability of some individuals to synthesize carnitine from lysine or methionine, and therefore in these individuals carnitine may be an essential nutrient.”
Jeffrey Bland, PhD
Octacosonal, Carnitine and Other “Accessory” Nutrients
Cool. I like that, a lot.
The NIH summarizes the current research on the topic, including the study referenced by Dr. Bowden. BTW, check his bio. Carnitine is not an essential nutrient. A vegan gets less carnitine than a red meat eater, but enough. I don't see Dr. Bland's reservations in the NIH summary. Neither of the two statements "Carnitine is a vital source of protein, and is only in red meat" are correct.