For someone who worked as a nutritionist and in the supplement industry, I don’t take a lot of supplements on a regular basis. I try to get what I need from food, but sometimes either for myself or for my athletes I will recommend a few of the supplements I think are excellent. One of those supplements is carnitine.


Enabling the use of fat for fuel is one important role that carnitine plays. It’s a critical link in the chain of fat loss, and as such might be a performance enhancer for sport. I even knew a guy who said it made him more aggressive, and he’s not the type prone to exaggeration. It’s an interesting nutrient, and its effects don’t end there. A study this month in Nutrition and Metabolism examined the effects of carnitine on protein turnover.


carnitine, carnitine studies, protein turnover, catabolic vs anabolicProtein turnover is a necessary aspect of biology for athletes. It’s the fine balance between how much protein is created in the body versus how much is broken down into amino acids. Altering this balance is a big part of what training is about, and in general we shoot to increase protein synthesis while minimizing protein degradation. You may have heard the terms “anabolic” and “catabolic.” These are complex states of the human body that essentially amount to the synthesis of new tissue and the degradation of tissue respectively. For example, the term “anabolic steroid” refers to a sex hormone (in this case either natural or synthetic testosterone) that promotes the creation of new protein.


As it turns out, carnitine can affect your protein turnover. In this study researchers examined the effects of carnitine supplementation on rats. They wanted to see if there was a change in the major processes that impact protein turnover, with a specific focus on reducing protein degradation after four weeks. They also examined the fat and protein content of the muscles.


In the end, the rats taking carnitine were clearly lighter in bodyweight and had less fat. They had greater protein content in their muscles, but only the protein content of one of the studied muscles had statistical significance. Nevertheless, the trend seems obvious and compelling, and I’d be interested to see a study longer than four weeks. The amount of carnitine in the muscles, blood, and organs was much higher in that group.


As for what researchers were looking for specifically, they found it. Carnitine suppressed the gene expression of rate-limiting chemicals in the process of muscle degradation. This means that the key portions of the process that result in muscle breakdown were suppressed by carnitine. Also of interest was the greater presence of IGF-1 in the group taking carnitine. While the researchers were only interested in IGF-1’s tendency to reduce muscle breakdown, it should also be noted that the “GF” in IGF-1 stands for growth factor, and it has known anabolic properties as well.


After this study, my reasons for supporting carnitine supplementation have become even more robust. As a substance with potential fat-burning, muscle-sparing, and maybe even aggression-inducing properties (that are hopefully limited to the weight room), this is one to check out.



1. Janine Keller, et. al., “Supplementation of carnitine leads to an activation of the IGF-1/PI3K/Akt signalling pathway and down regulates the E3 ligase MuRF1 in skeletal muscle of rats,” Nutrition & Metabolism 2013, 10:28


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