L-Carnitine Supplementation Benefits Low Carb/High Fat Diets
Carnitine is biosynthesized from the amino acids lysine and methionine. L-carnitine can be found in red meat, fish, poultry, and milk. Carnitine helps move fatty acids through the body, allowing the cells to break down fat and use fat deposit stores. The highest concentrations of L-carnitine can be found in red meat. As a result, those on a vegan/ vegetarian diet or those who restrict red meat intake will be most likely to have a deficiency. For example, 100g of beef steak has 94mg of L-carnitine, 100g of chicken breast has 3.9mg of L-carnitine, and 100g of asparagus has 0.195mg of L-carnitine. Additionally, carnitine also has potent antioxidant properties similar to vitamin C and vitamin E by reducing free radical damage.
Earlier studies reported that free-carnitine content in skeletal muscle is reduced during high-intensity exercise or when skeletal muscle glycogen content is elevated, and this reduction in carnitine might be rate-limiting for β- oxidation and also demonstrated a rise in free- carnitine pool intern increases long-chain fatty acid oxidation. A recent study reported that carnitine can also improve sprinting capacity by lowering lactic acid production and preventing fatigue. Some studies hypothesized that L-Carnitine supplementation improves exercise performance through various mechanisms, including enhanced muscle fatty acid oxidation, spares glycogen, and altered muscle fatigue resistance or postpones fatigue during exercise.
A new study published in the Journal of Physiological Biochemistry reported that low carb, high fat dieters may benefit from carnitine supplementation. Ninety male rats were supplemented with different concentrations of L-carnitine supplementation (0.15, 0.3, and 0.5 %) and fat content (5, 10, and 15 %) through diet in various combinations.
Animals in each diet group were further subdivided into five subgroups:
(c) L-Carnitine 0.15 %,
(d) L-Carnitine 0.3 %, and
(e) L-Carnitine 0.5 %
The researchers made the rats exercise to complete exhaustion, so how do you get a rat motivated? The researchers kept the rats in the water and measured how long it was until they could no longer keep their head above water. The rats would be so tired they would start sinking to the bottom…yikes!! 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.
At the end of the study, the rats that were given L-Carnitine had increased endurance capacity compared to those that were not given L-Carnitine on a high fat diet. The rats that were given L-Carnitine had spared muscle glycogen levels and increased fat oxidation which may have contributed to the improved endurance performance. The rats consuming L-carnitine also had reduced lactic acid levels during exercise as well. Another interesting finding was that the groups taking L-carnitine had lower markers of muscle damage and also greater anti-oxidant protection compared to the control group. The L-carnitine supplementation increased the levels of endogenous antioxidant status as well. Thus, L-carnitine can act as a potent antioxidant and interact with endogenous antioxidants for synergistic effects to defend against fatigue.
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