Miracon Science

L-carnitine

Synonym(s): carnitine
Nutrient group: Amino acids

Sources and physiological effects

Dietary Sources

L-carnitine is a vitamin-like compound synthesized from the two amino acids L-lysine and L-methionine in the liver, kidneys and brain. Iron, vitamin B6 and vitamin C are required as co-factors. Certain circumstances such as liver disease, dialysis or chemotherapy can disrupt the self-synthesis of L-carnitine and make a supplementary supply necessary. At the beginning of the 20th century, L-carnitine was first isolated from meat extract and named after its source („carnis“ Latin („flesh“). Accordingly, high amounts of L-carnitine are also found in red meat such as beef, lamb or game. Fruit, vegetables and cereals, on the other hand, contain barely measurable amounts of L-carnitine. Depending on the diet, exogenous intake also fluctuates. Vegans do not take in significant L-carnitine through their diet, omnivores, on the other hand, receive about 20 - 300 mg of L-carnitine per day through their diet.
Physiological effects
Energy metabolism
  • Supply of fatty acids. Fatty acid transport takes place at L-carnitine bound by the mitochondrial membrane
  • Regulation of the citrate cycle
  • Stimulation of glucose utilization via pyruvate dehydrogenase
Membranes
  • Stabilization of the membranes of erythrocytes, immune cells and cell organelles
Nervous system
  • Promotion of nerve cell regeneration
  • Increase of the neurotransmitter metabolism (acetylcholine)
Immune system
  • Increase in lymphocyte proliferation
  • Increase of phagocytosis activity of granulocytes and monocytes
Cardiovascular
  • Energy source of the heart muscle 
Antioxidant
  • Inhibition of lipid peroxidation 

Recommended intake

Requirements
Group with increased demand Premature babies, pregnancy, immunodeficiency, competitive sports, alcohol abuse, diets, renal insufficiency, diabetes mellitus, gestational diabetes, liver disease, NNR insufficiency,  
Special groups at risk of deficiency Diabetes mellitus, pregnant women, athletes
Nutrient safety  
GRAS status in USA.
EFSA rates Carnipure™ tartrate as safe for daily consumption. 

http://www.lonza.com/products-services/nutrition/human-nutrition/health-ingredients/carnipure.aspx 

Detailed information

Physiological function of L-carnitine
L-carnitine, a vitamin-like compound, is a water-soluble hydroxycarboxylic acid which is synthesized endogenously in a five-step reaction sequence from the essential amino acid lysine. This process can only take place in the brain, kidney and liver. L-carnitine is required primarily in the skeletal muscles and in the heart muscle, where it is involved in the oxidative degradation of long-chain fatty acids and the resulting release of energy. L-carnitine functions as a transport molecule that channels the activated fatty acids into the mitochondria where beta-oxidation takes place. It is therefore a decisive factor for energy supply and physical performance (1). This also explains the increased demand in competitive athletes, which difficult to cover with regular dietary intake alone.
Causes of L-carnitine deficiency
Carnitine deficiencies are often the result of diseases. A limited self-synthesis, as can be found in liver cirrhosis and renal insufficiency, can be one reason for this. Increased renal excretion caused by diabetes mellitus, metabolic stress, as is typical in post-aggression metabolism, and the use of certain drugs can also lead to carnitine depletion (2). The first non-specific signs of a carnitine deficiency include reduced performance, rapid fatigue, fat deposits in the tissue and increased blood fat values.
L-carnitine and cardiovascular diseases
L-carnitine is used therapeutically and complementary therapy in cardiological diseases. Coronary sclerotic changes such as angina pectoris or heart failure respond well to adjuvant carnitine therapy (2). Since the heart covers about 80% of its energy requirements through the breakdown of fatty acids, a correspondingly high carnitine concentration in the tissue of the heart muscle is necessary. A latent carnitine deficiency can therefore also be responsible for heart muscle weakness and cardiac arrhythmia (3).
L-carnitine in diabetes therapy
In diabetes mellitus, therapeutic doses of L-carnitine can compensate for increased excretion, which contributes to a reduction in blood lipids, which are often elevated in diabetes. Carnitine prevents the accumulation in serum of triglycerides which appear to play a role in the development of insulin resistance (4). In addition, L-carnitine can significantly improve the regeneration of nerves and nerve sensations in diabetic neuropathic disorders (5)(6).
Supplementation with L-carnitine during pregnancy
L-carnitine is also particularly important during pregnancy and lactation. Pregnant women have a lowered plasma level (7), while significantly higher L-carnitine concentrations can be detected in fetal blood and in the umbilical cord. Breastmilk also contains high amounts of L-carnitine, as the ability for self-synthesis is not yet fully developed in infants (1).
L-carnitine for sufficient energy in old age
Due to its antioxidant properties (8) supplementation of L-carnitine, substitution with L-carnitine can also positively influence aging processes. As we age, the ability of self-synthesis decreases continuously, which also leads to reduced energy production at the mitochondrial level. Studies have shown that supplementation with L-carnitine in combination with alpha-lipoic acid can bring energy production back to normal levels (9).

Deficiency symptoms

Impact on Symptoms
General health Reduced performance, rapid fatigue
Immune system Increased susceptibility to infections 
Carbohydrate metabolism

 

 Hyperinsulinemia, Hypoglycemia, Insulin Resistance
Fat metabolism Fat deposits in tissue and increased blood lipids
Increase in lipid peroxidation
Cardiovascular Arrhythmias, Cardiomyopathies, Heart Failure
Development Growth disorders in infants

Administration

General mode of administration
 When L-carnitine should be taken throughout the day before or at mealtimes.
Side effects
In rare cases high doses can lead to gastrointestinal complaints (nausea, vomiting, diarrhea).
Contraindications
No contraindications are known to date.

Interactions

Drug interactions
Cardiaca
(Nitrates)		 Carnitine can reduce the need for cardiac drugs, increases the stress tolerance of the heart.
Acne therapeutics
(Vitamin A – Analogues)		 Carnitine counteracts the side effects of vitamin A analogues, especially on the liver.
Thyroid drugs
(L-thyroxine)		 Carnitine partly blocks the activity of thyroid hormones.
Cholesterol-lowering medication
(statins)		 Combination with carnitine shows an improvement in lipoprotein(a) levels.
Nutrient interactions
Trace elements Iron deficiency leads to reduced self-synthesis.
Magnesium and carnitine support each other in their cardiovascular effects.
Food substances Coenzyme Q10 improves the effect of L-carnitine.
Amino acids Sufficient lysine and methionine levels are essential for the biosynthesis of carnitine.
Vitamins Vitamin C, vitamin B6 and niacin are important for carnitine production.
Fatty acids Alpha-lipoic acid and carnitine show synergistic effects regarding performance and reduction of oxidative stress. 

Description and related substances

Description
Natural ammonium compound synthesized from the amino acids L-lysine and L-methionine.
Related substances 
L-carnitine tartrate is a non-hygroscopic salt form of carnitine and provides 68 % carnitine.

References

References

1) Gröber, U. 2002. Orthomolekulare Medizin. Ein Leitfaden für Apotheker und Ärzte.
2) Hahn, A. et al. 2005. Ernährung. Physiologische Grundlagen, Prävention, Therapie.
3) Burgerstei, L. 2002. Handbuch Nährstoffe.
4) Mingrone, G. Carnitin in type 2 diabetes. Ann N Y Acad Sci 2004;1033:99-107.
5) Sima, A. A: et al. 2005. Acetyl-L-carnitine improves pain, nerve regeneration and vibratory perception in patients with chronic diabetic neuropathy. Diabetes Care. 28(1):89-94.
6) Rui, Z. et al. 2012. Neuroprotective Effects of Pre-Treatment with L-Carnitine and Acetyl-L-Carnitine on Ischemic Injury In Vivo and In Vitro. Int. J. Mol. Sci. 13:2078–2090.
7) Cho, S. W., Cha, Y. S. 2005. Pregnancy increases urinary loss of carnitine and reduces plasma carnitine in Korean women. 93(5):685-91.
8) Çekın, A. H. et al. 2013. The protective effect of L-carnitine on hepatic ischemia-reperfusion injury in rats. Turk J Gastroenterol. 24(1):51-6.
9) Savitha, S. et al. 2005. Efficacy of levo Carnitin and lipoic acid in ameliorating the decline in mitochondrial enzymes during aging. Clinical Nutrition. 

References Interactions
Stargrove, M. B. et al. Herb, Nutrient and Drug Interactions: Clinical Implications and Therapeutic Strategies, 1. Auflage. St. Louis, Missouri: Elsevier Health Sciences, 2008.
Gröber, U. Mikronährstoffe: Metabolic Tuning –Prävention –Therapie, 3. Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2011.
Gröber, U. Arzneimittel und Mikronährstoffe: Medikationsorientierte Supplementierung, 3. aktualisierte und erweiterte Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2014.
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