What is carnitine?

(Extraído de medicalnewstoday.com)

Carnitine is a substance found in almost every cell in the body, it is biosynthesized from the amino acids lysine and methionine. The compound plays a crucial role in energy production, as it is responsible for transporting fatty acids to the mitochondria.

Mitochondria exist inside every cell in our bodies. They are responsible for producing the energy that cells need to function. Mitochondria are like tiny power stations.

According to the Office of Dietary Supplements, part of the National Institutes of Health (NIH), carnitine transports long-chain fatty acids into mitochondria where they are burned (oxidized) to produce energy.

Carnitine also transports waste and toxic compounds out of the mitochondria, preventing their buildup. Given these key functions, skeletal and cardiac muscle that use fatty acids as a dietary fuel have high concentrations of carnitine.

The body normally produces enough carnitine. However, some people cannot produce enough of the compound due to genetic or medical reasons.

The following diseases, conditions or situations can result in carnitine deficiency:

• angina
• severe liver disease
• major burns
• severe diarrhea
• sepsis
• intermittent claudication
• malnutrition
• major surgery of the gastrointestinal tract
• hemodialysis
• some anticonvulsant medications (valproate)
• zidovudine (HIV medication)

Carnitine has also been proposed as a possible treatment for a number of health conditions including heart failure, angina, heart attack, and diabetic neuropathy.

There are three different forms of carnitine:

• L-carnitine
• acetyl-L-carnitine
• propionyl-L-carnitine

How much carnitine should you consume?

It is not necessary for healthy adults and children to take supplements containing carnitine as the liver and kidneys usually produce enough of it.

In 1989, The Food and Nutrition Board (FNB) of the National Academies (formerly National Academy of Sciences) concluded that carnitine is not an essential nutrient.

However, people who lack this compound may need to take supplements or eat carnitine-enriched foods.

Foods that provide carnitine are mainly animal products, with red meat having one of highest concentrations.

Foods high in carnitine include:

• Beef steak, cooked, 4 ounces: 56-162 mg
• Milk, 1 cup: 8 mg
• Chicken breast, cooked, 4 ounces: 3-5 mg
• Cheese, cheddar, 2 ounces: 2mg

Adults who eat diets are rich in red meat consume on average around 60-180 mg of carnitine per day, compared to only 10-12 mg per day among vegans.

 

Carnitine for treating health conditions

Carnitine is said to have many therapeutic properties that may be useful in treating a range of conditions and illnesses. As an antioxidant, carnitine fights off harmful free radicals, which cause severe damage to cells.

Health conditions that carnitine may be used to treat include:

• Angina - there is substantial evidence to indicate that along with conventional treatment, L-carnitine and propionyl-L-carnitine can reduce the symptoms of angina.
• Treating fatigue in chronic diseases - in almost every chronic disease, loss of good mitochondrial function leads to excess fatigue, as well as some other symtpoms.

  In a study published in Alternative Therapies In Health And Medicine, researchers wanted to determine what effect natural supplements, such as L-carnitine, alpha-lipoic acid (α-lipoic acid [1,2-dithiolane-3-pentanoic acid]), and coenzyme Q10 (CoQ10 [ubiquinone]) might have on improving mitochondrial function, and consequently symptoms of fatigue in patients with chronic diseases.
  The researchers concluded "Combinations of these supplements can reduce significantly the fatigue and other symptoms associated with chronic disease and can naturally restore mitochondrial function, even in long-term patients with intractable fatigue."

• Intermittent claudication - a study published in the journal Thrombosis research looked at the efficacy, safety and tolerability of propionyl-L-carnitine (PLC) given to patients with intermittent claudication.
  Intermittent claudication is caused by poor blood supply during exercise. It typically affects the blood vessels in the legs, but in some cases the arms may be affected. The patient experiences pain when walking or running. The pain is usually felt in the feet, calves, thighs, hips or buttocks - depending where the artery damage or narrowing occurs.
  The authors concluded in an abstract in the same journal "The study showed PLC significantly prolonged the maximum walking time and walking distance of Chinese patients with peripheral arterial disease with well-tolerated performance."
• Heart attack - a study published in Mayo Clinic Proceedings, found that L-carnitine significantly improves cardiovascular health in patients after a heart attack.
• Heart defects - carnitine may normalize blood vessel dysfunction that accompanies congenital heart defects, according to Dr. Stephen M. Black, cell and molecular physiologist at the Vascular Biology Center at the Medical College of Georgia at Georgia Regents University.
• Alzheimer's disease - a study published in the journal Neurobiology of Aging found that patients on acetyl-L-carnitine experienced much less deterioration in their Mini-Mental Status and Alzheimer's Disease Assessment Scale test scores, compared to those on placebo.
• Sexual dysfunction - propionyl-L-carnitine and acetyl-L-carnitine improved the effectiveness of sildenafil (Viagra) in restoring sexual potency among 32 patients who had undergone bilateral nerve-sparing radical retropubic prostatectomy.

 

Does carnitine improve athletic performance in healthy people?

Go to any sports supplement or health shop and you will see carnitine for sale on the shelves. Thousands of athletes and gym enthusiasts swear by it.

The hypothesis is that carnitine supplementation improves exercise performance in healthy athletes through various mechanisms. It is said to improve muscle fatty acid oxidation, alters glucose homeostasis, enhances acylcarnitine production, modifies the way the body responds to training, and alters muscle fatigue resistance.

Eric A. Brass, at Harbor-UCLA Medical Center, Torrance, California, carried out a study which was published in The American Journal of Clinical Nutrition. He gathered and analyzed data from several studies and found that it was not possible to draw any definitive conclusion.

Brass wrote that the studies suggest that carnitine supplementation for healthy athletes does not improve maximal oxygen uptake or metabolic status during exercise. Although taking supplementation was found to increase blood levels of carnitine, it did not result in increased muscle carnitine content.

Brass concluded "Additional clinical trials integrating physiologic, biochemical, and pharmacologic assessments are needed to definitively clarify any effects of carnitine on exercise performance in healthy persons."

 

Side effects and precautions

Taking carnitine supplements should be supervised by a doctor, especially if you suffer from the following conditions:

• Diabetes
• Kidney disease
• High blood pressure
• Cirrhosis

Side effects may include:

• Diarrhea
• Increased appetite
• Rash
• Body odor

Written by Joseph Nordqvist