Carnitine

Carnitine is not an amino acid in the strictest sense (it is actually a substance related to the B vitamins). However, because it has a chemical structure similar to that of amino acids, it is usually considered together with them.

Unlike true amino acids, carnitine is not used for protein synthesis or as a neurotransmitter. Its main function in the body is to help transport long-chain fatty acids, which are burned within the cells to provide energy. This is a major source of energy for the muscles. Carnitine thus increases the use of fat as an energy source. This prevents fatty buildup, especially in the heart, liver, and skeletal muscles. Carnitine reduces the health risks posed by poor fat metabolism associated with diabetes; inhibits alcohol-induced fatty liver; and lessens the risk of heart disorders. Studies have shown that damage to the heart from cardiac surgery can be reduced by treatment with carnitine. It has the ability to lower blood triglyceride levels, aid in weight loss, and improve muscle strength in people with neuromuscular disorders. Conversely, it is believed that carnitine deficiency may be a contributor to certain types of muscular dystrophy, and it has been shown that these disorders lead to losses of carnitine in the urine. People with such conditions need greater than normal amounts of carnitine. Carnitine also enhances the effectiveness of the antioxidant vitamins E and C.

Carnitine is helpful in treatment of kidney and liver diseases. Carnitine increases athletes' endurance time. Supports the skeletal muscular system and improves poor muscle tone as well as neuromuscular problems. Carnitine helps alleviate high cholesterol and/or triglycerides. Aids male infertility, caused by weak sperm. Carnitine may be helpful in treating Alzheimer's disease patients, by slowing, preventing or even reversing the disease.

Carnitine can be manufactured by the body if sufficient amounts of iron, vitamin B1 (thiamine), vitamin B6 (pyridoxine), and the amino acids lysine and methionine are available. The synthesis of carnitine also depends on the presence of adequate levels of vitamin C. Inadequate intake of any of these nutrients can result in a carnitine deficiency. Carnitine can also be obtained from food, primarily meats and other foods of animal origin.

Many cases of carnitine deficiency have been identified as partly genetic in origin, resulting from an inherited defect in carnitine synthesis. Possible symptoms of deficiency include confusion, heart pain, muscle weakness, and obesity. Because of their generally greater muscle mass, men need more carnitine than women do. Vegetarians are more likely than no vegetarians to be deficient in carnitine because it is not found in vegetable protein. Moreover, neither methionine nor lysine, two of the key constituents from which the body makes carnitine, are obtainable from vegetable sources in sufficient amounts. To ensure adequate production of carnitine, vegetarians should take supplements or should eat grains, such as cornmeal, that have been fortified with lysine.

Supplemental carnitine is available in different forms, including D-carnitine, L-carnitine, DL-carnitine, and acetyl-L-carnitine. L-carnitine is the preferred form.

Where is it found ?

Dairy and red meat contain the greatest amounts of carnitine. Therefore, people who have limited intake of meat and dairy products tend to have lower carnitine intakes.

Who is likely to be deficient ?

Carnitine deficiencies are rare, even in strict vegetarians, because the body produces carnitine relatively easily.
Rare genetic diseases can cause a carnitine deficiency. Also, deficiencies are occasionally associated with other diseases, such as diabetes and cirrhosis. A carnitine deficiency can also result from oxygen deprivation, which can occur in some heart conditions. In Italy, carnitine is prescribed for heart failure, heart arrhythmias, angina pectoris, and lack of oxygen to the heart.

How much to take

Most people do not need carnitine supplements. For therapeutic use, typical amounts are 1-3 grams per day.
It remains unclear whether the propionyl-L-carnitine form of carnitine used in congestive heart failure research has greater benefits than the L-carnitine form, since limited research in both animals and humans with the more common L-carnitine has also shown very promising effects.

Side effects

L-carnitine has not been consistently linked with any toxicity.
The body needs lysine, methionine, vitamin C, iron, niacin, and vitamin B6 to produce carnitine.

Caution

L-carnitine has no side effects; it is safe. D-carnitine may have toxic side effects. Always consult your health care provider before taking supplements for existing heart conditions. If you take over 1 gram (1000 mg) a day, you may develop a fishy odor. This odor does not occur very often, is not dangerous and quickly disappears as soon as the dose is reduced. Vegetarians may become deficient in carnitine and may consider supplementation, since it is not found in vegetable proteins.

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