Carnitine is a non-essential amino acid that the body uses in energy metabolism to produce fuel for the body cells from dietary intake of fatty acids. It is considered non-essential because the body can synthesize the nutrient from dietary sources of two other amino acids, lysine and methionine.
Carnitine has been studied as a nutritional supplement product, particularly in the areas of exercise enhancement, weight loss, cardiac health and Alzheimer's disease. But, since the average American gets adequate amounts of carnitine through the daily diet, are supplemental products necessary?
A deficiency in carnitine is rare, but can occur as a result of a genetic mutation or another disorder that interrupts the ability of the body to use the carnitine ingested from food. Some of the best studied side effects of carnitine deficiency are cardiomyopathy (enlarged heart) and certain arrhythmias.
Carnitine has been used in addition to medication as a treatment for angina, or chest pain. Some clinical trials have found that L-carnitine and propionyl-L-carnitine can help reduce symptoms of angina and improve the ability of those afflicted to participate in physical activity. Other studies have not found conclusive evidence to recommend carnitine for the prevention of heart attack or the treatment for those after having a cardiac event.
Conditions Affecting the Extremities
Peripheral vascular disease (PVD) and diabetic neuropathy can both cause pain and damage to the arms, legs and feet. PVD is caused by plaque buildup in the blood vessels that leads to decreased blood flow and aching, causing a cramping pain in the legs while walking or exercising. Diabetic neuropathy occurs when high blood sugar levels are left untreated, leading to nerve damage in the legs and feet. Some small studies have found that carnitine supplements may be beneficial in the treatment of these two conditions. In diabetics, for example, L-carnitine may help with improved glucose uptake and storage, leading to decreased blood sugar levels.
Because the body's storage of carnitine diminishes with age, carnitine has been studied as a treatment for slowing the progression of certain dementias, including Alzheimers disease. Some small studies have shown some benefit, but larger and better designed studies have not found a link between supplementation and improving memory.
Chronic Fatigue Syndrome
Chronic Fatigue Syndrome (CFS) is still a largely misunderstood condition. Some researchers have speculated that the condition is related to nutritional deficiencies, including that of carnitine because one of the symptoms of carnitine deficiency is muscle fatigue and weakness. Again, small studies have shown a benefit, but more research is needed with larger and more varied populations.
Supplemental Products Available
Carnitine supplements are available in three forms. L-carnitine is the most widely available and least expensive, so it is the primary source of carnitine in nutritional supplements. Acetyl-L-carnitine is the form most studied in Alzheimers and dementia patients. Propionyl-L-carnitine is the form found most beneficial for heart disease and PVD, but is not available in the United States.
Adult doses vary depending upon the specific health condition being treated. The usual dose of most supplements is 500-1000 milligrams taken three times a day.
Carnitine supplements are not as well absorbed and used by the body as natural carnitine sources found in the diet. One study found that bioavailability of oral supplements is only 14 to 18%, while absorption from dietary sources is much higher.
All nutritional supplements, including carnitine, should be evaluated by your personal physician to ensure that it is an appropriate treatment and that it does not interfere with other medications you are taking.