AMINO ACID SUPPLEMENT ARTICLE SERIES
Carnitine: an analysis of its fat burning and performance enhancing effects
Exclusive for Bodybuilding Mauritius
Welcome back to the article series on amino acids. In the first instalment we provided an overview of the basic science of amino acids. If you haven't read it, we strongly suggest that you do. In this article we will discuss a popular amino acid supplement: L-Carnitine. Carnitine supplements have been around for a long time. From personal observation, it was very popular in the 90s as a fat burning supplement before the widespread use of Ephedra based fat burner supplements. Carnitine, especially in its common supplemental form L-Carnitine, enjoyed massive popularity at that time. Carnitine is marketed mainly for its alleged fat burning benefits although it is sometimes pushed for other benefits, e.g. performance, the evidence for which will be reviewed in this article.
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An L-Carnitine supplement from the 90s |
Sources of L-Carnitine
L-Carnitine can be made by the body from the amino acids Lysine and Methionine. It is made by the liver and kidneys. Under certain conditions, it becomes necessary to obtain L-Carnitine from the diet. Good sources include beef steak, ground beef, chicken, pork and pork products. L-Carnitine is stored in muscles and it is estimated that about 75% of L-Carnitine in the body comes from the diet.
Carnitine supplements and formulations
L-Carnitine is the most basic form of supplemental carnitine used in most carnitine supplements. You may sometimes (although rarely) see Carnitine labelled as “D-Carnitine” which is not good in quality as it may produce effects that are opposite to that of L-carnitine. The “D and L” designations are due to structural differences. Newer forms of supplemental forms of carnitine have also made it to the shelves. Some of these newer forms are listed below:
- Acetyl-L-Carnitine (ALCAR): consists of a carnitine molecule bound to a molecule of Acetyl-Coenzyme A. It is one of the two forms of Carnitine existing in the body, notably in nervous tissues. Supplemental ALCAR may help in reducing fatigue.
- Glycine Propionyl L-Carnitine (GPLC): is a new form of Carnitine consisting of the amino acid glycine and a short chain fatty acid. GPLC looks quite promising at it has been shown to increase the production of the vasodilator Nitric oxide in several populations, including athletes. Health-wise, GPLC may play a role in blood flow and its regulation. An advantage of GPLC over L-Carnitine is that, unlike the latter, it does not require carbs and insulin for uptake. A 2007 study (Bloomer et al, 2008) found increases in NO levels. The research was funded by Sigma-Tau which manufactures GPLC under the trademark Glycocarn.
Glycine Propionyl L-Carnitine (GPLC) marketed under the trademark GlycoCarn.
- Carnitine-L-Tartrate: a carnitine molecule bound to a molecule of Tartaric acid. This form of carnitine probably has a faster absorption rate but is not superior in terms of overall bioavailability.
Assessing L-Carnitine as a fat burner
L-Carnitine is essential for burning fat
The idea that L-Carnitine supplements can help burn fat comes from the discovery that L-Carnitine is very important for the transport of fats for burning inside cells. Cells contain structures called mitochondria which are the 'powerhouses' of the cells, meaning they are the sites where energy is produced. Fats are burned in the mitochondria by the process called Beta-Oxidation. However, for the fats to reach there they must pass through special transporters found on the surface of the mitochondria. An important transporter is called the Carnitine palmitoyl transferase I (CPT-I). CPT-I is so important that the rate of fat oxidation depends on its activity. Carnitine works by binding fatty acids and then shuttling them through CPT-I.
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Mitochondria are structures inside cells where energy is produced. L-Carnitine is essential for transporting fats into these structures for burning Taking extra L-Carnitine supplements may help under some circumstances |
Does taking extra L-Carnitine mean greater fat burning?
There are some reports that taking L-Carnitine supplements can increase the activity of the CPT-1 transporter and thus increase the process of fat beta-oxidation. Conversely, other studies have shown that L-Carnitine supplementation does not positively influence fat oxidation unless the subject was previously deficient in L-Carnitine, in which case supplementation brought a rescue effect. One may be deficient in L-Carnitine as a result of age, poor utilisation, low intake of meat and vegetarianism or veganism. In these cases, L-Carnitine supplementation seem to help. Anecdotally, L-Carnitine users that I have known personally report good results in terms of weight loss but it must be noted that they were also on thermogenic fat burner supplements. However, they do note an increase in exercise performance and a reduction of muscle soreness following intense workouts compared to when they were not taking L-Carnitine. This point will be discussed in the coming section.
The take-home lesson with regard to L-Carnitine and fat loss
Well, L-Carnitine will help you burn fat if you are deficient in the amino acid. It does not mean that taking more L-Carnitine will help you burn more fat. Burning fat depends largely on your diet and exercise program. It does not mean that taking L-Carnitine in the absence of these two important elements will make you lose fat. Serious bodybuilders already understand this important point. The same applies to other types of fat burners.
L-Carnitine as an exercise performance enhancer
Based on the finding that L-Carnitine is important for fat breakdown for energy, scientists performed experiments on endurance sports persons (who use fat preferably as fuel) to see whether Carnitine can improve their performance by using more fat for energy. The findings from these studies were not consistent as some studies showed a positive effect while others showed no effect. Well, what can I tell you? If you are an endurance sports person and if you think that taking L-Carnitine gives you a solid boost (in spite of what research says) then go for it.
L-Carnitine improves blood flow and muscle soreness
Scientific research on L-Carnitine shifted from fat burning effect and performance enhancement to a different avenue: the improvement of muscle soreness induced by exercise. As you know, when you train harder or do unaccustomed exercise, muscle pain or soreness sometimes occurs a day or two later. This is called delayed onset muscle soreness (DOMS) and this is what makes you want a wheelchair the day or two following a hardcore squat session. The good news is that L-Carnitine can protect muscle from exercise-induced damage. L-Carnitine does so by improving blood flow (through vasodilation) to working muscles for better oxygenation and waste removal. Muscle cell oxygenation is very important during exercise because lack of oxygen (hypoxia) can lead to muscle damage. In one research study (Giamberardino et al., 1996), 3-g of L-carnitine was given to research participants who were doing muscle damaging exercise that produce DOMS. The subjects reported less soreness when they were taking L-Carnitine. This indicates that L-carnitine can protect against pain and exercise-induced muscle damage and may therefore be a recovery aid.
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| 3g of L-Carnitine has been found to reduce muscle soreness |
Research that found positive effects of L-Carnitine used dosages from 2-3 g (2000-3000mg) per day. Do not let anyone sell you products that contain 200-300mg L-Carnitine and tell you that you will experience positive effects while citing these papers. This is an old trick now. Dosage is very important. Furthermore, the safety of these recommended intakes of L-Carnitine has been evaluated. No negative effects were seen on most safety parameters (e.g liver and kidney function etc). There have also been recent concerns about L-Carnitine as a possible causative agent of heart problems. L-Carnitine coming from meat is purported to be broken down by gut bacteria to a compound called TMAO which causes atherosclerosis (narrowing of blood vessels). However, current evidence shows that L-Carnitine is more protective to the heart than destructive (Mayo Clinic Proceedings, 2013) and that the Carnitine-TMAO-Atherosclerosis link is too early to tell and has been been inflated by media.
In the light of current evidence, I give L-Carnitine a decent 3 out of 5 star rating. If I had money I'd buy L-Carnitine for sure.
References:
Bloomer RJ, Tschume LC and Smith WA. Glycine propionyl-L-carnitine modulates lipid peroxidation and nitric oxide in human subjects. Int J Vitam Nutr Res 79: 131-141, 2009.
Giamberardino MA, Dragani L, Valente R, Di LF, Saggini R and Vecchiet L. Effects of prolonged L-carnitine administration on delayed muscle pain and CK release after eccentric effort. Int J Sports Med 17: 320-324, 1996.
Huang A and Owen K, Role of supplemental L-Carnitine in exercise and exercise recovery. Lamprecht M (ed): Acute topics in sports nutrition. Med Sport Sci. Basel, Karger, 2013, vol 59, pp 135-142
L-Carnitine in the Secondary Prevention of Cardiovascular Disease: Systematic Review and Meta-analysis,” by James J. DiNicolantonio, PharmD; Carl J. Lavie, MD; Hassan Fares, MD; Arthur R. Menezes, MD; and James H. O’Keefe, MD, Mayo Clinic Proceedings, Volume 88, Issue 6 (June 2013), DOI: http://dx.doi.org/10.1016/j.mayocp.2013.02.007, published by Elsevier.
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