When to take L carnitine: Dosage, forms, and side effects Early research into L carnitine was often cited as underwhelming, showing negligible changes in muscle carnitine content and fat loss outcomes. However, these findings may have been limited by a short study window L Theanine Vs L Carnitine: Can We Combine Them? Vinatura Supplements The Role of L Carnitine in Kidney Disease and Related Metabolic Dysfunctions