L-carnitine supplementation is indicated in weight management or in recovery after exercise.
L-carnitine is naturally found in the human diet in a variety of foods, particularly red meat. The western diet contains approximately 100-300 mg of L-carnitine per day. However, in Europe and the United States, dietary intake of L-carnitine has decreased by about 20% over the last decade, mainly due to the decrease in beef consumption.
We can easily summarise the role L-carnitine plays in fat metabolism: it transforms fat into energy. More specifically, L-carnitine is needed to transport long-chain fatty acids across the mitochondrial membrane so that they can breakdown fat and generate energy.
What's more, when they possess a sufficiently high concentration of free L-carnitine, mitochondria can sustain energy-generating processes that depend on the availability of the free coenzyme A. If only a small amount of free coenzyme A is available, L-carnitine can bind acetyl units temporarily and ensure that more energy is generated.
In addition, L-carnitine can support acid excretion, a function that can be important after intense exercise or for certain metabolic conditions.
Due to the key role it plays in energy metabolism, L-carnitine is typically
used by the body to support functions with high energy requirements.
In this sense, L-carnitine supplementation plays an important role in heart health, male fertility, healthy ageing, as well as for infants, pregnant women, and vegetarians.
L-carnitine supplementation has been found to increase fatty acid oxidation in healthy humans. In two different studies, trial participants were given fatty acids with a meal, before and after supplementing their diet with L-carnitine (3g/day) for ten days. As a decomposition product, fatty acids, labelled as CO2, were measured in the air exhaled by the participants. The group that was given carnitine tartrate recorded a significant increase in marked CO2 exhalation, indicating a large increase in fatty acid oxidation (fig. 1). This leads us to conclude that carnitine may be useful in weight management programmes.
Recovery after exercise
Studies show that carnitine supplementation can aid recovery after exercise. Researchers recorded a decrease in free radical production, less tissue damage, and reduced muscle pain after exercise in amateur athletes after three weeks of carnitine supplementation.
Carnitine supplementation has been found to increase muscle oxygen consumption, providing a potential mechanism for reducing hypoxia after endurance exercise.