Your body produces L-carnitine from the amino acid lysine, and while healthy people are typically able to synthesize enough, certain conditions — like pregnancy — may cause your body's need for carnitine to exceed its ability to produce it. For this reason, carnitine is considered a conditionally essential nutrient.1

L-carnitine and acetyl-L-carnitine are forms of carnitine found in dietary supplements. While your body absorbs carnitine from animal foods such as grass fed beef better than carnitine in dietary supplements,2 some research suggests L-carnitine supplements may benefit certain conditions.

Carnitine for Brain Health

Your body needs carnitine for energy production. It helps transport long-chain fatty acids into your mitochondria where they're oxidized and turned into energy in the form of adenosine triphosphate (ATP),3 which is needed by your cells for life, repair and regeneration. Carnitine may also help remove toxins from the mitochondria.4

Acetyl-L-carnitine (ALCAR) is more easily absorbed in your gut than L-carnitine, and also crosses the blood-brain barrier.5 ALCAR has many beneficial effects on brain metabolism, protects against neurotoxic insults and has been shown to benefit certain forms of depression. In one study,6 healthy mice given ALCAR for 25 days at a dose of about half a gram per kilo were found to have increased levels of the neurotransmitters noradrenaline and serotonin.

According to the authors, this is "consistent with ALCAR's potential efficacy for depressive symptoms." In another study, ALCAR was found to improve the clinical condition of patients with degenerative cerebellar ataxia, a condition resulting in the loss of control of bodily movements.7 According to the authors, "statistically significant improvement of some symptoms and a slow progression of the disease in both groups of patients" were observed.