L-carnitine is a compound that the human body produces in small quantities from the amino acids lysine and methionine to facilitate the transfer of long-chain fatty acids to the 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 big dose you’ll need to supplement. And that’s what most people mean when they talk about L-carnitine: the supplement.
As a supplement, L-carnitine offers a number of benefits across a wide variety of physiological systems:
- Weightloss
- Body recomposition
- Energy production
- Hormonal optimization
- endothelial function
- Heart health
- Liver health
- Antioxidant status and oxidative stress.
- Cognitive function
Let’s explore these in more detail.
Loss of fat
L-carnitine increases fat utilization at the mitochondrial level, thereby reducing fat reserves and increasing fat loss. Could everything be so simple? Yes, it really works. It is not a wonderful supplement. It will not result in rapid fat loss and it is not surprising that it is a weight loss medication. But it helps:
- A meta-analysis of human studies found that L-carnitine supplementation has a modest effect on fat loss.
- Another meta-analysis found similar results.
Body recomposition
Body recomposition means improving the distribution of body tissues: reducing body fat and increasing lean mass, which includes muscle, bone and connective tissue. In reality, body recomposition is even more important than “weight loss,” since we all want to lose body fat and build muscle, not just “lose weight.” It turns out that L-carnitine helps tremendously with this.
- Dialysis patients taking L-carnitine retain more lean muscle mass while improving their ability to function in the world.
- Children with muscle wasting disease had much lower levels of carnitine in their blood.
- Carnitine increases fat burning in overweight subjects while maintaining lean mass and blocking protein catabolism that normally accompanies fat loss.
- In pancreatic cancer patients, those who took carnitine lived longer and gained weight, while those who did not take L-carnitine died earlier and lost weight.
- In elderly patients with rapid muscle fatigue, L-carnitine helps reduce fat mass, increase strength, and increase lean muscle mass.
- Recent guidelines even highlight the role of carnitine in red meat’s ability to counteract sarcopenia, or muscle atrophy.
Energy production
The basic physiological function 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 living humans? Do they really get more energy and reduce fatigue?
- In patients with hypothyroidism, L-carnitine has been shown to relieve fatigue.
- L-carnitine may reduce the neuromuscular fatigue that often occurs with blood flow restriction training.
- It helps older adults suffering from rapid muscle fatigue follow a training plan and become stronger, fitter and leaner in the process.
Male hormonal optimization
One of the most popular reasons men take L-carnitine is to improve their hormonal environment. Works?
- L-carnitine increases androgen receptor activity. Without active androgen receptors, any testosterone you have has nowhere to go and no way to interact with cells.
- In infertile men, L-carnitine improves sperm motility and concentration, as well as testosterone and luteinizing hormone levels.
endothelial function
Endothelial dysfunction, characterized by poor blood flow, increased blood pressure, and low nitric oxide levels, is almost always accompanied by carnitine deficiencies, prompting researchers to explore whether carnitine supplementation could
- Both animal models and human studies show that carnitine supplementation reduces blood pressure.
- Carnitine supplementation has also been advocated to prevent endothelial dysfunction.
- L-carnitine directly increases nitric oxide levels.
Heart health
By any marker of heart health, L-carnitine improves it.
- Reduces LDL and triglycerides while increasing HDL.
- When given to patients with heart failure, it improves function and outcomes.
- It even improves blood pressure (itself a great predictor of heart problems).
Liver health
A recent meta-analysis found that L-carnitine consistently and reliably reduces liver enzyme levels, which is a strong indicator that it is making the liver healthier. Once again, this comes down to the compound’s ability to enhance mitochondrial energy production and respiration: when the 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 reduces inflammation in the face of stress, especially in people who face a lot of oxidative stress.
- L-carnitine supplementation reduces CRP levels in patients with heart disease, indicating less initial inflammation.
- In critically ill patients, L-carnitine reduces inflammatory markers.
Cognitive function
A recent large review concluded that L-carnitine and other carnitine supplements are effective in improving cognitive function in a wide range of dementias and cognitive degeneration diseases, primarily by improving mitochondrial respiration and ATP production. It appears to reduce age-related mitochondrial decline, reduce brain cell death, and decrease brain cell stress.
Overall, L-carnitine is a good and safe option for anyone with cognitive impairment.
Who should take L-carnitine?
- Vegans and vegetarians. Since red meat is the most abundant source of L-carnitine in the human diet, those who refuse to eat meat tend to have low levels of this nutrient. 1-2 grams per day is a smart allowance for anyone on a plant-based diet. Studies show that it is much more bioavailable in vegans/vegetarians than in omnivores, suggesting that ought eating it: the body wants it very much. There isn’t much research on vegetarians taking the supplement, but those I’ve talked to about taking it report having much more energy than before.
- Hypothyroid patients: As it has been shown to relieve fatigue in this population, L-carnitine is a no-brainer.
- Older people who don’t eat a lot of meat: The frailer an older person is, the lower their blood carnitine levels tend to be. Taking supplemental L-carnitine is an easy win.
- Anyone who is under a lot of stress.: Stress is stress is stress, and L-carnitine has been shown to help you be more resilient when faced with it.
How much L-carnitine should you take?
Typical doses are 1 to 2 grams per day divided in two, but doses as high as 5 to 6 grams per day have been taken and appear to be safe.
If you prefer to stick to food, 100 grams of lean beef contains around 150 mg of carnitine.
Should you be worried about TMAO?
L-carnitine supplementation (or consumption through meat) increases a compound called TMAO, which is a metabolite that gut bacteria produce after coming into contact with L-carnitine and other nutrients such as choline. TMAO has been linked to atherosclerosis, sending the masses into a frenzy about meat consumption and L-carnitine supplements. Is this a legitimate concern? Can L-carnitine increase heart disease?
All the evidence we have suggests that L-carnitine reduces heart disease – simply refer to the benefits sections above. Improves the lipid profile, reducing LDL and triglycerides and increasing HDL. Improves mortality from all causes. It even reduces body weight and improves body composition. All signs point to L-carnitine improving heart health, not worsening it. The fact that TMAO also increases suggests that people should stop worrying about TMAO as well.
However, if you are concerned about TMAO levels, eat raw garlic every day. The allicin in garlic can reduce TMAO levels. Crush or chop it and let it sit for ten minutes before consuming to allow the allicin to proliferate.
Is all for today. If you have any other questions about L-carnitine, let me know below!
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