Carnitine - my fat-burning favourite!!
Well.. let me tell you what I know about this amazing little compound!
So what is it??
Carnitine is found in nearly all cells of the body and its name is derived from the Latin carnus or flesh, as the compound was first isolated from meat.
Animal products like meat, fish, poultry, and milk are the best sources of carnitine and we absorb around 50-75% of the carnitine we ingest. In general - the redder the meat, the higher its carnitine content; 3 ounces of beef provides approx. 81mg of carnitine. Dairy products contain carnitine primarily in the whey fraction.
Carnitine can also be manufactured in the body (primarily in the liver, but also in the kidneys ) from the amino acids lysine and methioine. Sometimes the body’s demand for carnitine may exceed the rate at which the body can manufacture it and in this way it may become a conditionally essential nutrient (meaning supplementation is needed).
I should also point out that carnitine is the generic term for a number of compounds that include L-carnitine, acetyl-L-carnitine, and propionyl-L-carnitine.
Ok.. So what does it do..?
Carnitine is essential for energy production and fat burning. It transports long-chain fatty acids into the mitochondria so they can be oxidised ("burned") to produce energy. It also transports the toxic compounds generated out of the cell to prevent their accumulation. Given these key functions, carnitine is concentrated in tissues like skeletal and cardiac muscle that utilise fatty acids as a dietary fuel.
And why should I consider taking it??
Carnitine has been shown to support many different aspects of improving body composition (fat-to-muscle ratio).
In one particular study of overweight subjects, carnitine greatly increased weight loss.
The subjects were split into two groups and for 12 weeks both groups ate a healthy diet and performed moderate exercise. One group was given 2000mg of carnitine, and the other a placebo. In the placebo group, the average weight loss after 12 weeks was one pound (just under half a kilogram). In the carnitine group, weight loss averaged 11 pounds (almost 5 kilograms).
That’s an eleven-fold increase in weight loss, simply by increasing carnitine levels. Body fat levels also decreased markedly in the carnitine group.
Other research has shown carnitine may help us build muscle mass as well. Given that our metabolic rate is heavily influenced by the amount of muscle mass we have, and our muscle tissue is where we store our carbohydrates, this is very helpful!
Interestingly carnitine can also boost muscle recovery after exercise!
A double-blind, placebo-controlled, crossover study found 2000mg a day reduced muscle soreness after exercise as well as having a positive effect on a range of biochemical markers like free radicals. Its protective effects were seen immediately after exercise as well as 24 and 48 hours afterwards. This makes sense as carnitine provides antioxidant activity in cell walls.
For the athletes - carnitine has been shown to increase sports endurance. It enhances aerobic performance and allows athletes to exercise longer without fatigue4,5. It also helps to prevent muscle damage during vigorous exercise and delays the onset of that lactic acid burn6,7.
In another study carnitine improved how the body handled glucose and prevented spikes in blood sugar levels which, of course, has implications for diabetics. In terms of weight-loss, however, this further supports fat-burning by reducing insulin spiking8.
Clients report having more energy both during their workout, and generally through-out the day, which makes sense when you think about what the carnitine is doing. It is optimising access to our fuel reserves (our fat stores) and facilitating their use for energy production. This effect has also been demonstrated scientifically9.
Acetyl-l-carnitine is a slightly different version of L-carnitine. It offers all the same benefits but with added advantages. It is better absorbed from the small intestine than L-carnitine and is able to cross the blood-brain barrier (i.e., gets into brain tissue) and thus boosts energy production (and memory performance) there also!
So.. how much should I take??
For the most part, the weight-loss benefits of carnitine are attributed to around 2000mg a day. It has been shown that administration of 2000mg of acetyl-L-carnitine per day for 50 days increased plasma acetyl-L-carnitine levels by 43%.
Ideally you would take this in divided doses i.e. 1000mg morning and afternoon, and.... if you can manage it - take that first dose on waking (empty stomach), exercise 30 minutes later, and then have a healthy breakfast. Using it this way you'll optimise your results.
So - if you want to get more bang for your buck (read burn more fat for the effort you put in to your exercise) then consider trying carnitine!
1 Rebouche CJ, Paulson DJ. Carnitine Metabolism and Function in Humans. Ann Rev Nutr 1986; 6:41-66
2 Owen, K. et.al. (1996) Swine Day Rep. I
3 Owen, K, et. Al. (1994). Swine Day. 161
4 Swart, I. et al (1997). Nut. Res. 17:405.
5 Siliprandi, N. et al (1990). Biochim. Biophys. Acta. 1034:17
6 Sacks, T. et al (1978). J Clin Invest 61:1661
7 Soop, M. et al (1998). J. Appl. Physiol. 64:2394
8 Amino Acids. Volume 41, Number 2, 507-515, doi: 10.1007/s00726-010-0770-5 “Effects of oral l-carnitine supplementation on insulin sensitivity indices in response to glucose feeding in lean and overweight/obese males”
9 Kaats, G.R. (1992). Cur. Ther. Res. 51:261