L-Carnitine Benefits

October 18, 2023

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L-carnitine is a compound the human body produces in small amounts out of the amino acids lysine and methionine to facilitate the transfer of long chain fatty acids into mitochondria for energy production. But most of the carnitine we use comes from the animal products we eat, particularly red meat, and if you really want a large dose you’ll need to supplement. And that’s what most people are referring to when they talk about L-carnitine: the supplement.

As a supplement, L-carnitine offers a host of benefits across a wide variety of physiological systems:

Weight loss
Body recomposition
Energy production
Hormone optimization
Endothelial function
Heart health
Liver health
Antioxidant status and oxidative stress
Cognitive function

Let’s explore these in more detail.

Fat loss

L-carnitine increases fat utilization at the mitochondrial level, thereby reducing fat stores and increasing fat loss. Could it all be so simple? Yes, it actually works. It’s not a wonder supplement. It’s not going to result in rapid fat loss and it’s no wonder weight loss drug. But it helps:

A meta-analysis of human studies found that L-carnitine supplementation has a modest effect on fat loss.¹
Another meta-analysis found similar results.²

Body recomposition

Body recomposition means improving the tissue distribution of your body—reducing body fat and increasing lean mass, which includes muscle, bone, and connective tissue. Body recomposition is actually even more important than “weight loss,” since we all want to lose body fat and build muscle, not just “lose weight.” Turns out that L-carnitine helps immensely with this.

Dialysis patients who take L-carnitine retain more lean muscle mass while improving their ability to function in the world.³
Children with a muscle wasting disease had much lower levels of carnitine in their blood.⁴
Carnitine increases fat burning in overweight subjects while maintaining lean mass and blocking the protein catabolism that normally accompanies fat loss.⁵
In pancreatic cancer patients, those taking carnitine lived longer and gained weight, while those not taking L-carnitine died earlier and lost weight.⁶
In elderly patients with rapid muscle fatigue, L-carnitine helps lower fat mass, increase strength, and increase lean muscle mass.⁷
Recent guidelines even stress the role of carnitine in red meat’s ability to counter sarcopenia, or muscle wasting.⁸

Energy production

The basic physiological role of carnitine is to facilitate the production of ATP—the body’s energy currency—in the mitochondria. If you supplement with L-carnitine, it stands to reason that you will increase energy production. Does this happen in live humans? Do they actually get more energy and reduce fatigue?

In hypothyroid patients, L-carnitine has been shown to alleviate fatigue.⁹
L-carnitine may reduce the neuromuscular fatigue that usually occurs with blood flow restriction training.¹⁰
It helps older adults who suffer from rapid muscular fatigue stick to a workout plan and get stronger, fitter, and leaner in the process.

Male hormone optimization

One of the most popular reasons men take L-carnitine is to improve their hormonal milieu. Does it work?

L-carnitine increases androgen receptor activity. Without active androgen receptors, any testosterone you have has no where to go, no way to interact with the cells.¹¹
In infertile men, L-carnitine improves sperm motility and concentration as well as testosterone and luteinizing hormone levels.¹²

Endothelial function

Endothelial dysfunction—characterized by poor blood flow, increased blood pressure, and low nitric oxide levels—is almost always accompanied by carnitine deficiencies, leading researchess to explore if carnitine supplementatio could

Both animal models and human studies show that carnitine supplementation lowers blood pressure.¹³
Carnitine supplementation has also been sown to prevent endothelial dysfunction.¹⁴
L-carnitine directly increases nitric oxide levels.¹⁵

Heart health

By any marker of heart health, L-carnitine improves it.

It reduces LDL and triglycerides while increasing HDL.
When given to heart failure patients, it improves function and outcomes.¹⁶
It even improves blood pressure (itself a huge predictor of heart trouble).

Liver health

A recent meta-analysis found that L-carnitine consistently and reliably lowers liver enzyme levels, which is a strong indicator that it’s’ making the liver healthier.¹⁷ Once again, this comes down to the compound’s ability to improve mitochondrial energy production and respiration—when your power plants are running smoothly, everything else falls into place.

Oxidative stress

By increasing energy production at the mitochondrial level, L-carnitine improves resilience and lowers inflammation in the face of stress, especially in people facing a lot of oxidative stress.

L-carnitine supplementation lowers CRP levels in heart disease patients, which indicates lower baseline inflammation.¹⁸
In critically ill patients, L-carnitine lowers inflammatory markers.¹⁹

Cognitive function

A large recent review concluded that L-carnitine and other carnitine supplements are effective at improving cognitive function across a broad range of dementias and cognitive degeneration diseases, primarily by improving mitochondrial respiration and ATP production. It appears to reduce age-related mitochondrial decay, reduce brain cell death, and lower brain cell stress.²⁰

Overall, L-carnitine is a good and safe option for anyone with cognitive decline..²¹

Who should take L-carnitine?

Vegans and vegetarians. As red meat is the most abundant source of L-carnitine in the human diet, those who refuse to eat any meat at all tend to be low in the nutrient. 1-2 grams per day is a smart concession for any plant-based dieter. Studies show that it’s far more bioavailable in vegans/vegetarians than omnivores, which suggests they should be eating it—the body greatly desires it.²² There isn’t a ton of research on vegetarians taking the supplement, but those I’ve talked into taking it report having far more energy than before.
Hypothyroid patients: As it’s been shown to alleviate fatigue in this population, L-carnitine is a no-brainer.
Seniors who don’t eat much meat: The more frail an older person is, the lower their blood carnitine levels tend to be.²³ Taking supplemental L-carnitine is an easy win.
Anyone under a lot of stress: Stress is stress is stress, and L-carnitine has been shown to help you become more resilient when faced with it.

How much L-carnitine should you take?

Doses of 1-2 grams per day split into two are typical, but doses of up to 5-6 grams per day have been taken and appear to be safe.

If you want to stick to food, 100 grams of lean beef contains around 150 mg of carnitine.

Should you worry about TMAO?

L-carnitine supplementation (or consumption via meat) increases a compound called TMAO, which is a metabolite gut bacteria produce after they come into contact with L-carnitine and other nutrients like choline. TMAO has been linked to atherosclerosis, which has led the frantic masses to worry about meat consumption and L-carnitine supplementation. Is this a legitimate worry? Can L-carnitine increase heart disease?

All the evidence we have suggests that L-carnitine reduces heart disease—just refer back to the benefits sections above. It improves the lipid profile, reducing LDL and triglycerides while increasing HDL. It improves all-cause mortality. It even lowers body weight and improves body composition. All signs point to L-carnitine improving heart health, not worsening it. That it also increases TMAO suggests that people should stop worrying about TMAO, too.

However, if you are worried about TMAO levels, eat raw garlic every day. The allicin in garlic can reduce TMAO levels.²⁴ Crush or chop it and let it sit for ten minutes before consuming it to allow the allicin to proliferate.

That’s it for today. If you have any other questions about L-carnitine, let me know down below!