Carnitine: The Ultimate Supplement
We will use injectable L-carnitine, which can be administered either intramuscularly (IM) or subcutaneously (Subq). The minimum recommended dose is 400 mg daily, while the upper limit remains undefined—I personally take 800mg. To enhance its absorption, consume 60-90g of simple carbohydrates or inject 8-10 IU of fast-acting insulin.
What does Carnitine mean?
Carnitine is an amine synthesized in the liver, kidneys, and brain from the essential amino acids lysine and methionine
How Does Carnitine Work?
Carnitine plays a crucial role once fatty acids are mobilized and ready for energy production. This process, known as beta-oxidation, occurs within the mitochondria and requires oxygen. Without carnitine, fatty acid metabolism cannot take place in the mitochondria. This is one of the most popular fat burner for sale you can start using.
Acting as a transporter, carnitine facilitates the movement of newly freed fatty acids across mitochondrial membranes for oxidation. This process, referred to as fatty acid activation, is essential for efficient energy production. If fatty acids are not transported or metabolized, they will simply return to triglyceride storage.
Research supports a strong link between free carnitine levels and beta-oxidation efficiency:
- Putman et al. (1993) found that depleting glycogen before exercise increased free carnitine levels, leading to enhanced beta-oxidation.
- Roepstorff et al. (2005) observed a 2.5-fold reduction in beta-oxidation when free carnitine levels dropped by 50% due to glycogen loading before exercise.
- Stephens et al. (2001) reported a 75% decrease in free carnitine during high-intensity interval training (HIIT), which regulated beta-oxidation levels. They also showed that carnitine infusion restored basal acetyl-CoA levels and increased beta-oxidation while reducing pyruvate dehydrogenase activity by 40%.
* Beta-oxidation increases acetyl-CoA levels, which in turn raises citrate and glucose-6-phosphate levels. This regulates carbohydrate metabolism by inhibiting key enzymes involved in glucose breakdown.
Carnitine Bioavailability
Carnitine has poor oral bioavailability, making intravenous or injectable administration more effective. Studies by Watcher (2002), Barnet (1994), Vulkovich (1994), and Brass (1994) indicate that oral bioavailability is less than 15%, with a maximum absorption limit of 3g in humans.
Carnitine and Insulin
Carnitine must be actively transported into the cell; without this process, increasing cellular carnitine levels is impossible. The organic cation transporter N2 (OCTN2) is responsible for moving carnitine into cells.
One way to enhance the activity of this transporter is through insulin. Insulin positively regulates the Na/K pump, and since OCTN2 is a cotransporter of carnitine and sodium, a higher sodium concentration can help drive more carnitine into the cell. Additionally, insulin increases the availability of OCTN2, further supporting carnitine uptake.
Stephens et al. conducted multiple experiments to determine the most effective way to utilize this physiological mechanism. Their research demonstrated that a combination of carnitine infusion and insulin could significantly enhance cellular carnitine levels. The results showed a 15% increase in muscle carnitine, a 30% reduction in pyruvate dehydrogenase activity, and a 40% decrease in muscle lactate, while acetyl-CoA levels rose by 30% and muscle glycogen increased by 40%.
Clinical trials aimed to identify the optimal insulin levels required for efficient carnitine transport, revealing that approximately 70–90 mIU/L of insulin is necessary.
In another study, Stephens et al. found that consuming 2 grams of oral carnitine along with 80 grams of carbohydrates twice daily for 24 weeks led to a 21% increase in carnitine levels. This rise was accompanied by a 50% reduction in glucose utilization during low-intensity exercise and a 44% decrease in muscle lactate accumulation.
Carnitine Protocol
- We will use injectable L-carnitine, which can be administered either intramuscularly (IM) or subcutaneously (SubQ). The minimum recommended dose is 400 mg per day, while the maximum dose has not been firmly established; however, I personally use 800 mg.
- For optimal effectiveness, L-carnitine administration should be accompanied by a state of hyperinsulinemia. This can be achieved by consuming a high amount of simple carbohydrates, with a minimum intake of 60 g and an ideal intake of 90 g, as used in studies.
- Alternatively, hyperinsulinemia can be induced by injecting insulin. A subcutaneous injection of approximately 10 IU of ultra-rapid insulin (e.g., insulin as a part) can raise blood insulin levels by about 33 pmol/L. Given that 6.94 pmol/L corresponds to 1 mIU/L, and baseline insulin levels typically range from 10–20 mIU/L, if all insulin elevation comes from an exogenous source, a slightly lower dose (~8 IU) may suffice.
Once carnitine saturation is reached in the mitochondria, elimination slows significantly (~190 mg in 24 hours), allowing for a reduction in dosage.
Timing is not crucial, as its effect is dependent on intracellular concentration rather than immediate ingestion.