L-carnitine is a widely available and relatively inexpensive form of the nutrient carnitine, which your body uses to burn fat for energy. You have a natural internal supply of this nutrient, and normally you produce enough carnitine to meet your needs. However, some people either can't make enough of the nutrient or can't transport it properly once it's made. Depending on your circumstances, your daily recommended doses for L-carnitine can vary considerably.
L-Carnitine Basics
In addition to L-carnitine, nonprescription carnitine supplements are available in the U.S. in a form called acetyl-L-carnitine, which combines L-carnitine with building blocks of the neurotransmitter acetylcholine. Another supplement available in Europe, called propionyl-L-carnitine, combines carnitine with a compound called propionate. L-carnitine also comes in oral and injectable prescription forms. Food sources of L-carnitine include beef, avocados, cod, whole milk, whole-wheat bread, ice cream, American cheese, chicken and pork. Your body absorbs roughly 63 to 75 percent of the L-carnitine content in your food, according to Oregon State University's Linus Pauling Institute. Conversely, your body only absorbs about 14 to 20 percent of the L-carnitine contained in oral supplements of the nutrient.
No Supplementation Required
Your natural supply of carnitine originates in your kidneys and liver, and gets stored in your brain, heart and voluntary muscles, as well as in sperm in males. Once carnitine is formed internally or gets consumed in food sources, your body does a highly efficient job of preserving it and keeping it available. Under normal circumstances, your kidneys filter and reabsorb about 95 percent of your supply of the nutrient. Because of this high rate of conservation, you typically have no need to take L-carnitine or any other carnitine supplement if you don't have a problem with carnitine production or transport, the Linus Pauling Institute reports.
Doses for Specific Conditions
If your doctor prescribes L-carnitine for a carnitine deficiency, he will determine both the dosage and the form of the nutrient you receive. Nonprescription dosages in these circumstances can range anywhere from 500 to 2,500 mg per day. Your doctor may also recommend L-carnitine supplements to help treat specific physical ailments, the University of Maryland Medical Center reports. For example, people with heart disease may take anywhere from 600 to 1,200 mg twice a day. People with diabetic nerve damage may take 3,000 mg per day. People with chronic fatigue syndrome may take anywhere from 500 to 1,000 mg of L-carnitine three or four times a day. People with chest pain or heart failure may take anywhere from 1,500 to 2,000 mg a day.
Additional Considerations
Your doctor will tell you if you need L-carnitine supplementation for a specific health problem. Don't use supplements to treat any ailment without your doctor's knowledge and consent. If you take 5,000 mg or more of L-carnitine a day, you may develop diarrhea or more rare side effects, including rash, unusually high appetite or abnormal body odor. Medications that may cause problems in combination with L-carnitine include valproic acid, doxorubicin, isotretinoin and AZT.
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