L-Carnitine Still Good in My Book

By Stephen T. Sinatra, M.D., F.A.C.C., F.A.C.N., C.N.S., C.B.T.

For many years I have touted the benefits of regular carnitine supplementation to patients, readers of newsletters and blogs, and medical colleagues. This amino acid, one of my top five supplements, produces a jackpot of cardiac, muscle, energy, and anti-aging gains. I was already so impressed in 1999 that I wrote a book on it: L-Carnitine and the Heart (Keats).

I’ve never lost my enthusiasm for carnitine. Just the opposite. The research on carnitine over the years has made my enthusiasm even more steadfast.

As an avid consumer of medical research, I long ago got used to seeing medication and supplements, and even food, taking a beating one day in some new study and then getting high marks in another new study the next day. It always reminded me of the ups and downs of the stock market. I simply learned to weigh the evidence against my own clinical experience and logic.

A prime example occurred in April 2013 involving carnitine. The amino acid soared to headline status after researchers from the Cleveland Clinic and University of Pennsylvania published a report suggesting a hitherto unknown link between carnitine and atherosclerosis (Koeth, et al.). The link, they said, involved large amounts of trimethylamine N-oxide (TMAO), a waste product produced by certain intestinal bacteria as a result of exposure to carnitine and a long-term diet high in red meat. Vegetarians and vegans have much lower levels of TMAO and the carnitine-converting class of bacteria.

My response: don’t be influenced by this one piece of research. Wait for more evidence to either confirm or replicate the findings.

Is there any reason to stop taking a carnitine supplement? Absolutely not. I have seen carnitine help too many patients over the years.

A week after the study, another carnitine study appeared. It was a review of data from thirteen different controlled trials and made the conclusion that carnitine supplementation reduces all causes of mortality, angina symptoms, and ventricular arrhythmias following a heart attack. The article, published in the journal Mayo Clinic Proceedings, attributed survival benefits to the ability of carnitine to limit infarct-size, stabilize heart cell membranes, and improve compromised cellular energy metabolism.

Carnitine and 100-year-old hearts

Some of the data reviewed in this newer study included the use of carnitine supplementation for up to a year, suggesting a protective role both for acute therapy and secondary prevention.

The new study made much more sense to me than the earlier one. It confirmed my own clinical findings, of carnitine as a heart and energy booster, and reminded me of a fascinating piece of Italian research I reported on in 2007.

In that trial, researchers took a group of sixty-six men and women over the age of 100 and randomly divided them in half. One group took a carnitine supplement for six months. The other group took a harmless placebo pill. At the end of the experiment, the individuals in the carnitine group reported significant improvements in energy, muscle mass, and mental function along with less fatigue and fat mass. The placebo takers had no such benefits.

Keep in mind these were centenarians!  If there was ever a great display of supplementation effectiveness, this was right at the top.

To me, carnitine is a winner. I don’t see how a substance like carnitine, that is also produced in the body, can be toxic. But I’m keeping an open mind about that first negative study. If it turns out to be confirmed, I believe the findings will show that any potential harm via the gut bacteria comes more from overeating what I regard “junk” red meat, that is, meat packed with unnatural hormones, insecticides, pesticides, and other unhealthy substances along for the ride, and not the carnitine itself in the meat. There’s nothing wrong with eating red meat in moderation, as I have said many times. Two or three times a week is fine, but make it organic free-range lamb, beef, or bison.

And don’t stop taking your carnitine supplement. And while you are at it, routinely take a good probiotic supplement as well. Probiotics include familiar beneficial bacteria, such as acidophilus and bifida, strains that populate your intestines and help support a beneficial bacterial balance.

The Sinatra Solution

Carnitine is best absorbed on an empty stomach and in small doses, such as 500 mg at a time. I recommend about 500 mg a day for a healthy person and 1-3 g for someone with cardiovascular disease.

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