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
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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
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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.
.jpg) |
| 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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