Benefits of L-carnitine

Carnitine heartthrob

You know that old cliché: The left hand doesn’t know what the right hand is doing?

Well, the latest research on L-carnitine–a compound that’s abundant in red meat and dairy products, and which helps your body convert fat into energy–illustrates this particular turn of phrase pretty perfectly.

Why? Because one set of study authors is actually claiming that carnitine could contribute to cardiovascular risk.

I’ll explain to you why this is so ridiculous in a minute. First, let me give you a few details.

A group of Cleveland Clinic researchers recently discovered that a specific form of bacteria in the gut can metabolize L-carnitine into a substance called trimethylamine-N-oxide (TMAO).

It seems that high-carnitine diets promote the growth of this TMAO-generating bacteria. And research has linked TMAO to hardened arteries.

Of the roughly 2,500 heart patients that these researchers examined, those with high carnitine levels suffered a greater risk of heart disease, heart attack, and stroke. But only if their TMAO levels were high, as well.

According to the researchers, these results could point to a new way to minimize heart disease risk. Namely, by taking a closer look at the bacterial environment of the gut.

Amen to that.

That’s the reason this study caught my attention in the first place. As you know, the link between gut bacteria and total body health is one of my favorite topics.

So it’s too bad these researchers had to go and get all crazy on us.

Straight from the study authors’ mouths: “Carnitine is not an essential nutrient; our body naturally produces all we need. We need to examine the safety of chronically consuming carnitine supplements as we’ve shown that, under some conditions, it can foster the growth of bacteria that produce TMAO and potentially clog arteries.”

That’s a giant leap–and a gross oversimplification–if ever I heard one.

What about all of the studies on L-carnitine that don’t show any adverse health effects at a variety of doses? Or the studies that show it can actually improve heart health (and a whole lot more)?

Allow me to provide you with a comprehensive list of all the conditions that published research shows carnitine can help to combat:

  • Angina
  • Heart attack
  • Heart failure
  • Peripheral vascular disease (and intermittent claudication, in particular)
  • Diabetic neuropathy
  • Overweight and obesity
  • Alzheimer’s disease
  • Depression
  • Memory loss
  • Male infertility
  • Erectile dysfuntion

One study does not negate all of this research. It’s simple as that.

And not to put too fine a point on this carnitine-causes-heart-disease business, but there’s another new study out that directly contradicts this outlandish claim anyway.

This recent meta-analysis looked at 13 controlled trials of L-carnitine therapy in more than 3,500 heart attack patients.

And wouldn’t you know? Results showed that, in this kind of acute setting, L-carnitine can reduce all-cause mortality, angina symptoms, and ventricular arrhythmias.

So, let’s see here. One study shows that L-carnitine might promote plaque under certain circumstances. (And I should add that this conclusion is at least partially based on data from mice.)

Meanwhile, this second study shows with a fair amount of certainty that, for as long as one year post-heart attack, L-carnitine supplementation is harmless. And it could even reduce mortality by a significant margin.

I don’t know about you. But I’m not going to stop taking my carnitine because of a mouse. And needless to say, I agree with the authors of the second study.

They believe that L-carnitine therapy is a safe and cost-effective alternative for heart attack patients who can’t use ACE inhibitors or beta-blockers. (Two drugs that I have serious issues with, anyway.)

And why not use it for prevention, too? This study certainly indicated that in patients with angina, carnitine is an obvious choice to help alleviate the symptoms.

In other words, don’t let one questionable conclusion fool you. Carnitine is a keeper for any patient with heart disease or with a strong family history of heart disease.

“L-carnitine in the secondary prevention of cardiovascular disease: Systematic review and meta-analysis.” Mayo Clin Proc 2013; DOI: 10.1016/j.mayocp.2013.02.007.
“Intestinal microbiota metabolism of l-carnitine, a nutrient in red meat, promotes atherosclerosis.” Nat Med. 2013 May;19(5):576-85.