L-CARNITINE

What is Carnitine?

Carnitine is a generic term for several highly related compounds, such as L-carnitine, acetyl-L-carnitine, and propionyl-L-carnitine. As a nutrient, carnitine is comprised of two essential amino acids, lysine and methionine [^[1]]. We get carnitine from foods, especially animal products, and we can also get it from supplements [^[2]]. Carnitine deficiency creates fatigue, tiredness, and lethargy [^[1]].

Within the cell, L-carnitine and acetyl-l-carnitine are virtually identical, as one can be converted to the other easily. Acetyl-carnitine has better gut absorption than carnitine and can cross the blood-brain barrier, which gives it some advantages from a drug delivery standpoint [^[3]].

What does carnitine do in the body?

L-carnitine and a similar compound, acetyl-l-carnitine, both work to improve mitochondrial function [^[4]]. Mitochondria are the cell’s powerhouse, generating chemical energy to fuel the cell’s processes. Mitochondrial damage is linked to early aging and neurodegeneration. Carnitine and acetyl-l-carnitine have an important mitochondrial function [^[5]].

How can carnitine help alleviate certain Long COVID symptoms and pathophysiology? 

Fatigue is a feature of Long COVID, and previous studies of carnitine have shown that it can reduce fatigue in people with chronic diseases such as cancer and multiple sclerosis [^[1]]. This leads researchers to believe carnitine can also help relieve fatigue in Long COVID [^[6]].

Carnitine’s antioxidant properties are also relevant to Long COVID. Supplementing carnitine, CoQ10, and lipoic acid can lower inflammatory markers, which can be elevated in Long COVID. Lastly, carnitine can boost anti-inflammatory and antioxidant mechanisms along with its anti-fatigue characteristics. Potentially, carnitine can also regulate the formation of acetylcholine, a substance in the brain that is involved in memory [^[1]].