Manufactured from the amino acids lysine and methionine, L-carnitine helps transport long-chain fatty acids across the mitochondrial membrane of cells, where they're metabolized as fuel. Because it's the only substance that can perform this vital task, we all need plenty of carnitine, which is available in meat and in supplements. While outright deficiency is uncommon in well-nourished populations, vegetarians, older individuals, and those who have kidney and liver disease or who take anticonvulsant medications may need more of this vitamin-like nutrient than their diets provide.
Cardiovascular Health
The heart gets 60 percent of its fuel from fat, making L-carnitine important for cardiovascular health. By enhancing fatty acid metabolism, carnitine prevents the buildup of toxic fat metabolites.
Numerous double-blind, placebo-controlled studies find this substance effective in treating angina, a crushing sensation in the chest caused by inadequate blood flow to the heart muscle. "Having enough carnitine in the tissue to metabolize fatty acids efficiently lets the heart do more with less oxygen," explains cardiologist Stephen T. Sinatra, MD.
Since physical exertion tends to trigger angina, exercise studies are a useful way to explore L-carnitine's effects. Among 200 angina patients 40 to 65 years old, those taking L-carnitine showed better cardiac performance, as well as improved quality of life. Surprisingly, those with the most compromised heart function experienced the greatest improvement with L-carnitine, which also improves exercise duration and oxygen consumption in research with heart failure patients.
In peripheral vascular disease (painful leg cramping in patients with arteriosclerosis), "no pharmaceutical drug has been observed to convey significant benefit," says cardiologist Seth J. Baum, MD. "What does work quite well, however, is the supplement L-carnitine."
Among obese individuals with insulin resistance, L-carnitine appears to improve vascular function, as reported in investigations of leg blood flow. In a study at Indiana University School of Medicine, researchers found that increasing L-carnitine levels may delay cardiovascular disease progression in obese subjects.
Ongoing European investigations suggest that carnitine, administered early in a heart attack, can slow the advancement of heart disease. L-carnitine also showed protective effects in a double-blind study of arrhythmia patients.
"Perhaps the most outstanding aspect of the use of L-carnitine supplementation in cardiovascular conditions has been its ability to assist coenzyme Q10 and D-ribose in reducing the mortality from end-stage congestive heart failure," adds Dr. Sinatra. Compared to healthy individuals, heart failure patients have significantly lower carnitine concentrations in their heart muscle. The good news is that recent research suggests that carnitine supplementation can reverse this dangerous trend.
Using L-carnitine
Red meat is the richest food source of L-carnitine, and Dr. Baum recommends that omnivores choose organic sources. "I am convinced that the less opportunity man has to impose his artificial imprint [antibiotics and hormones] the better off food is," he adds.
L-carnitine is also a safe supplement; just don't take it with the medication pentylenetetrazol. For aging and overall heart protection, Dr. Sinatra recommends 250 to 750 mg of L-carnitine, along with CoQ10, D-ribose, magnesium, and fish oil daily. Angina and arrhythmia patients can take 1,000 to 2,000 mg of L-carnitine daily. For congestive heart failure, Dr. Sinatra suggests 2,000 to 3,500 mg daily, depending on that condition's severity.
Selected Sources Age Strong, Live Long by Seth J. Baum, MD ($12.95, Desert Spring, 2005) "Cardiac Carnitine Leakage Is Promoted by Cardiomyopathy" by H. Baker et al., Nutrition, 3/05 "L-Carnitine May Attenuate Free Fatty Acid-Induced Endothelial Dysfunction" by S. S. Shankar et al., Ann N Y Acad Sci, 11/04 The Sinatra Solution by Stephen T. Sinatra, MD, FACC ($24.95, Basic Health, 2005) "Therapeutic Effects of L-Carnitine . . . on Cardiovascular Diseases: A Review" by R. Ferrari et al., Ann N Y Acad Sci, 11/04
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