A recent headline-grabbing study from the Cleveland Clinic linking L-carnitine with atherosclerosis is a case of shooting the messenger, according a doctor who did much of the early research on the substance.
The Cleveland study found that bacteria living in the human digestive tract metabolize the compound carnitine, turning it into trimethylamine-N-oxide (TMAO), a metabolite the researchers previously linked in a 2011 study to the promotion of atherosclerosis in humans. Further, the research finds that a diet high in carnitine promotes the growth of the bacteria that metabolize carnitine, compounding the problem by producing even more of the artery-clogging TMAO.
The study tested the carnitine and TMAO levels of omnivores, vegans and vegetarians, and examined the clinical data of 2,595 patients undergoing elective cardiac evaluations. They also examined the cardiac effects of a carnitine-enhanced diet in normal mice compared to mice with suppressed levels of gut microbes, and discovered that TMAO alters cholesterol metabolism at multiple levels, explaining how it enhances atherosclerosis.
Indicator, not cause
But high carnitine levels in the blood is an indication of cardiac disease, not it’s cause, said Dr. Stephen DeFelice, founder and chairman of the Foundation for Innovation in Medicine, who has been studying the ingredient for more than 30 years.
“The carnitine literature is vast, and there’s probably nobody who knows it all like I do. Carnitine has broad therapeutic potential. It acts in the mitochondria. High energy tissues use fat as a fuel because fat has more energy per unit than sugar, and you are alive right now because carnitine is in your heart transporting fatty acids to the mitochondria to produce energy.
“When you have a stress to the heart, a lack of oxygen, carnitine leaks out of the heart (rasing blood levels of the substance). The guys at the Cleveland Clinic didn’t know their carnitine literature, They defied logic and say ah the high carninte levels are the cause these events,” DeFelice said.
Mayo Clinic study finds benefit
The Cleveland results are contradicted by a Mayo Clinic study release a few days later in April, DeFelice noted. IN the Mayo study, researchers found carnitine supplementation was associated with a 27% reduction in all-cause mortality, a 65% reduction in ventricular arrhythmias, and a 40% reduction in angina symptoms in patients who had experienced a heart attack.
Carnitine, DeFelice notes, is both a dietary supplement ingredient and an approved pharmaceutical. DeFelice’s early attempts to conduct research with the aim for a drug application were stymied by the lack of a patent on the ingredient itself.
But through the Orphan Drug Act, DeFelice said he did obtain two approvals for use of the substance to treat Primary Carnitine Deficiency, a fatal disease in children and for patients undergoing renal dialysis. There is a record of treatment with carnitine for children who suffer from this malady, DeFelice said. Many of these children have been on very high doses of L-carnitine for long periods of time without any signs of atherosclerosis. It is FDA approved as a drug and also in many other countries where long-term animal safety studies at high doses are required . These studies show no signs of atherosclerosis. The FDA approved package insert lists no serious side effect of L-carnitine, DeFelice noted.
So in cases of high levels of carnitine in the blood, more of the ingredient is called for, not less. It’s a red flag that the heart might be in trouble, DeFelice said.
“Carnitine is nature’s cardioprotective agent against lack of oxygen,” he said.