Athletes on a low-carbohydrate diet may benefit – in the first few weeks at least – from taking a supplement containing the amino acid L-carnitine. This is suggested by an animal study published by biochemists at the Defence Food Research Laboratory in India in the Journal of Physiology and Biochemistry. The human equivalent of the dose used would be 2-4 g L-carnitine daily.
When the mitochondria in our cells convert fatty acids into energy, they use L-carnitine to do it. That’s why supplements manufacturers have been marketing products that contain L-carnitine for decades. The idea is that they help slimmers to lose body fat faster and athletes to train more intensively.
The researchers gave rats a high-fat diet. The animals’ food consisted of 10 or 15 percent fat. For humans that would be a low fat diet, but rodents are not humans.
The researchers also got the rats to swim regularly, and measured how long it was until they could no longer keep their head above water. Some of the animals were given L-carnitine, and others were not. The human equivalent of the dose that the researchers used would be about 2-4 g L-carnitine a day.
The figure below shows that for the rats that were given food that contained 10 percent fat, their endurance capacity increased faster when they were also given L-carnitine.
The figure above shows that L-carnitine had the same effect on the animals that were given food consisting of 15 percent fat.
The researchers analysed the rats’ blood after their last swimming session and found that the animals that had been given L-carnitine had higher amounts of triglycerides and glucose, and less urea [PUN] than the animals that had not been given L-carnitine. It seemed that the L-carnitine supplementation had improved the energy supply to the muscle cells.
“The findings of the present study provide the basis for human use of L-carnitine as performance enhancers under exercise-induced oxidative stress”, the researchers summarised. “Further studies are required to understand the physiology, biochemistry, and pharmacology of L-carnitine supplementation in human volunteers.”
Ergogenic effect of dietary L-carnitine and fat supplementation against exercise induced physical fatigue in Wistar rats
L-carnitine (LC) plays a central role in fatty acid metabolism and in skeletal muscle bioenergetics. LC supplementation is known to improve physical performance and has become widespread in recent years without any unequivocal support to this practice. A scientific-based knowledge is needed, to understand the implications of LC supplementation on physical fatigue. In current study, we have explored synergistic effects of dietary LC and fat content against physical fatigue in rats. Ninety male Wistar rats were supplemented with different concentrations of LC (0.15, 0.3, and 0.5 %) and fat content (5, 10, and 15 %) through diet in different combinations. Our results elucidated that LC (0.5 %) along with 10 and 15 % fat diet supplemented rats showed significant ergogenic effect. The swimming time until exhaustion was increased by ~2- and ~1.5-fold in rats fed with 10 and 15 % fat diet containing LC (0.5 %). LC supplementation improved the energy charge by increasing the levels of ATP, tissue glycogen, reduced GSH, plasma triglyceride, plasma glucose levels, and enzymatic antioxidant status, i.e., superoxide dismutase, catalase, and glutathione peroxidase. LC supplementation also significantly reduced lipid peroxidation, lactic acid, plasma urea nitrogen, creatinine, creatinekinase, and lactate dehydrogenase levels in various tissues compared to its respective control group. Thus the present study indicates that LC ameliorates the various impairments associated with physical endurance in rats.