Carnitine is one of the leading ingredients in weight loss supplements. This is due to the virtues attributed to it for its potential action on energy metabolism and the transport of fatty acids.
Discover this amino acid.
Carnitine
Carnitine is an amino acid synthesised by the liver and kidneys. It is produced from the precursors that are two other amino acids: lysine and methionine. The synthesis requires the presence of other molecules: iron, vitamins 83 and 86 as well as vitamin C.
This is a non-essential amino acid. In fact, the body is able to synthesise the quantity it needs.
It is also a molecule of endogenous type, because it is produced by the body itself. Carnitine is present in food absorbed through the digestive tract. It then enters the bloodstream. Its main food source is red meat, followed by white meat and fish.
From a terminological point of view, this carnitine is referred to as L-carnitine (L for Levo, left) as opposed to D-camitine (D for Dextro, right), depending on the spatial conformation of the atoms. Only L-carnitine is active in the body.
Acetyl-L-carnitine is also present in the body. It is a different molecule from simple carnitine due to the presence of its acetyl chemical group.
Function of carnitine in the body
Carnitine plays an important role in metabolism. Its main role is to transport fatty acids into the mitochondria, which are the essential components of a cell in the body, to provide energy.
The fatty acids are then used to supply ATP, the key cellular energy molecule, to the cell. In the body, carnitine plays a lesser role in carbohydrate metabolism. It is used more as a supplement for sports and for overall health.
In the presence of oxygen, i. e. aerobic metabolism, the efficiency of the process is much higher than in its absence.
The different forms of carnitine and their effects on the body
There are two main forms of carnitine: the first is simple L-carnitine, and the second is acetyl-L-camitine. Both forms are sold as supplements, in powder or capsule form.
The second form of carnitine is acetyl-L-camitine. As mentioned above, this is fat-soluble.
These two forms of carnitine have different effects on the body.
Firstly, L-carnitine. At the muscular level, scientific studies have shown that, compared to a placebo, taking carnitine improves oxygenation through a vasodilator action.
It also allows, as mentioned above, an increase in the use of lipids as fuel, to the detriment of glycogen, during physical effort.
Finally, for men, carnitine is said to have an anabolic action, thanks to an increase in the number of androgen receptors on the muscle cells. But for this, it must be combined with a post-training meal. It is also necessary for catabolism and muscle soreness to decrease.
However, this last effect is not yet considered, clinically speaking, because the studies were all done in vitro. Indeed, even if the number of androgen receptors increases, it is not at all certain that this will result in a clinically significant increase in muscle value. On the other hand, the clinical studies carried out have not shown any difference with a placebo.
Similarly, for the health effects of carnitine, clinical studies remain controversial. Carnitine is reputed to have a beneficial effect on the cardiovascular system, due to its anti-oxidant effect and its action on the heart muscle.
However, in experiments carried out, the administration of camitine in patients with cardiovascular diseases did not show statistically significant results.
It is also thought that taking carnitine causes an increase in the life expectancy of patients, which led to a meta-analysis (merging several studies to increase the number of participants). This meta-analysis showed a significant benefit on various clinical parameters, including mortality after a heart attack and recurrence of a heart attack. However, again, the results of the experiments were not significant.
Carnitine has been shown to improve sperm quality!
Acetyl-L-carnitine, on the other hand, acts on the brain. According to research, it has a protective effect on neurons, cognitive decline and memory impairment linked to ageing or degenerative diseases. This effect is explained by an anti-oxidant effect on neurons and blood circulation. Again, as mentioned in the previous paragraphs, the limitations of scientific studies are the same.
to conclude
In conclusion, while camitine has been shown to play an important role in fat transport for energy metabolism, its other benefits to the body are not recognised, despite the experiments and scientific research undertaken. Researchers still need to experiment a little more before they can conclude. In the meantime, there is nothing to stop the use of carnitine.
