|SuppVersity reader Derek D. wants to know if 2013 study shows we are missing out if we don't use carnitine.|
If you are a long-term SuppVersity reader, you will be aware that this is not the first SuppVersity article discussing a study that points to the use of carnitine outside of dieting scenarios. In 2013, for example, I wrote about a study by Keller et al. (2013). A study that found significant increases in pro-anabolic hormones and proteins, and a 7% improvement in lean-to-total-mass ratio in rodents in response to a relatively low amount of carnitine in the diet.
Now, what's interesting about the study Derek asked about is that it was done in human. In only 12 healthy (the scientists planned for 16 which is not much better, but there were 4 drop-outs), non-vegetarian, male recreational athletes ("non-vegetarian" is important because vegetarians and vegans may benefit much more from carnitine supplements | learn more), to be specific. It's also noteworthy that Stephens et al. used dual-energy X-ray absorptiometry (DEXA) to assess the body composition of the subjects and incorporated a complex array of gene essays to assess what could drive the changes the UK researchers observed in response to the ingestion of a beverage containing 1.36 g of L-carnitine and 80 g of carbohydrate twice a day.
|Figure 1: The changes look to good to be true and may in fact be purely random (Stephens. 2013).|
It may thus have been a bit surprising for the researchers, when they realized that the subjects in the control group gained a significant amount of (trunk) fat over the 12-week study period - a pro-obesogenic effect that was prevented by the additional 2.72 g/day of carnitine which also increased the total energy expenditure (significantly) and the fatty acid oxidation (non-signifcantly) over Control.
- Keller J, Couturie A, Haferkamp M, Most E, Eder K. 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.
- Stephens, Francis B., et al. "Skeletal muscle carnitine loading increases energy expenditure, modulates fuel metabolism gene networks and prevents body fat accumulation in humans." The Journal of physiology 591.18 (2013): 4655-4666.