Should I Use - Carnitine
2022-08-17
Table of Contents
01 - The Science
Carnitine (AKA L-carnitine) has been extensively researched in the last few decades. Supplementation is used in order to improve aerobic capacity and reduce lactate production by utilising more fat during exercise and sparing muscle glycogen. Secondly, athletes and the general population may take it as a fat ‘burner’ to improve body composition.
Carnitine is mostly obtained from red meats and dairy in a mixed diet, ~98% of this is stored in skeletal muscle. Within the muscle carnitine has two main actions. Firstly, to assist in the transportation of long-chain fatty acids into the mitochondria to be used as fuel or secondly, to mop up excess acetyl-CoA during intense exercise, this will reduce the likelihood of pyruvate dehydrogenase enzyme being inhibited.
02 - How to use
Taking a daily dose of carnitine is said it improve levels within the muscle. By doing so it allows a greater transportation of long-chain fatty acids into the mitochondria to be oxidized. This process is inhibited by the availability of carnitine so in theory, increasing the amount in the muscle leads to a greater fat use and burn, resulting in a leaner athlete.
Usual recommended intakes are to ingest 2-3 grams per day, typically split over meal time. However, many studies have shown that neither acute or chronic intakes of carnitine elevate muscle carnitine levels. This was also consistent with the ingestion of either low or high doses.
Wachter and colleagues (2002) investigated the effects of 4 grams of carnitine per day over the course of 3 months in 8 males. Their findings indicated that there were no percieved benefits to mitochondrial functioning or muscle concentrations.
03 - Practical Significance
The proposed use of carnitine would suggest any athlete looking to change their body composition or that competes in an event where glycogen may become limiting. However, these studies have not shown any meaningful changes in body composition, muscle concentration or performance.
Due to the majority of the literature showing no change in either muscle concentration or performance outcomes, the use of carnitine remains controversial and probably not required. However, recent literature has shown that concentrations can be increased, but this will require an ingestion of carbohydrate alongside the supplement, somewhere in the region of ~350 grams!
04 - Take Home
Carnitine supplementation on its own may not be relevant currently. However, emerging research has shown to increase muscle concentrations with high doses of carbohydrate alongside. Yet, this may also increase calories in the diet and athletes should be mindful of the consequences of such high intakes of carbohydrate.