Are L Carnitine and L Carnosine the Same? Anti Aging Systems All You Need To Know About L Carnitine HealthKart Did you know L carnitine, a vital amino acid, is naturally produced by your body and found in various foods? While acetyl L carnitine (ALCAR) can be a beneficial supplement for some, most people get Doctor's Best Acetyl L Carnitine, 120 Veggie Caps (500 mg per Cap) Walmart.com L carnitine is a naturally occurring amino acid structure that is made in the human brain, liver, and kidneys. L carnitine plays a critical role in energy production, as it converts fat into energy.