Carnitine
Carnitine is an amino-acid derivative found naturally in all body tissues and fluids; the body produces about one-quarter of requirements and obtains the rest from dietary red meat.
Role
Carnitine helps protect cells from oxidative damage by reducing the effects of activated oxygen species released during energy metabolism. It acts as an antioxidant.
Evidence in Hyperthyroidism
A clinical trial of carnitine in patients with hyperthyroidism found it improved many symptoms, particularly irregular heartbeat (palpitations).
No evidence of benefit in hypothyroidism.