test-L-Carnitine and Acetyl L-Carnitine Question
L-Carnitine and Acetyl L-Carnitine Question
Vitamins and Supplements FAQs • April 22, 2013

Dear Swanson Vitamins,

I read your Explanation of the Difference Between L-Carnitine and Acetyl L-Carnitine. There is a new study by the Cleveland Clinic stating that Carnitine may contribute to preventing the body from excreting excess cholesterol.

I regularly take an Acetyl-L-Carnitine + Alpha Lipoic Acid Supplement. My question is: will the Acetyl-L-Carnitine also be damaging, or would that only be the L-Carnitine? Would the Acetyl group prevent the reaction in the gut with the bacteria? This supplement seems to help my cognitive function a great deal and I would like to continue to take it, but do not want to damage my heart.

Thanks very much for any information you may have.

There are multiple animal, as well as human studies, which demonstrate the beneficial effects of L-Carnitine. The results of this study indicate more research is necessary to determine if there is truly a causal link between L-carnitine and cardiovascular risk. With any research, it is possible that further research may change or disprove early conclusions. This study was performed using the diets of the animals, and not carnitine supplements. The researchers themselves stated that one could not conclude that the same study using a carnitine supplement would produce the same results. There are several human scientific research studies over the past several years that contradict the latest study’s findings and support l-carnitine’s beneficial role in supporting cardiovascular health. 

We should also remember that the human body naturally produces L-Carnitine in addition to obtaining carnitine from the diet, especially red meats and dairy products. It can also synthesize carnitines from the amino acids, lysine and methionine.

In regards to your question about acetyl-L-carnitine, unfortunately we don't have much to add... in the bigger picture, we don't know if it is appropriate to use that one study you mentioned as a cause for concern when there has been numerous other studies that show the safety and benefits of l-carnitine, and at the very least we don’t think that this study sheds any light on how the human body uses acetyl l-carnitine.