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What Is L-Carnitine: Benefits, Dosage, And Side Effects

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Is L-carnitine Good Or Bad For You?

On today’s episode of Live Lean TV, I’m diving into the research to uncover what is L-carnitine, including the health benefits, dosage, and side effects.

Is L-carnitine a good supplement for your specific needs, or is it just a waste of money?

Let’s find out.

Welcome back to the second episode in our new supplements series, where I’m giving you a quick science backed and evidence based overview of popular supplements.

The goal of this supplement series is to cut through all the marketing BS, to help you make healthier decisions, while saving you time and money.

Science Backed Research Studies

To do this, I’ll quickly answer the most frequently asked questions, by diving into the research, then articulating the findings in an easy to understand format.

I’ll do my best to focus on scientific research from high quality studies conducted on humans, preferably randomized controlled trials with placebo controls.

For the most part, these studies tend to provide the most reliable evidence to assess the effectiveness of a supplement.

To date, over 50,000 people viewed the first episode on taurine, so let’s keep this momentum going.

L-carnitine: Frequently Asked Questions

The most frequently asked questions about L-carnitine include:

  • What Is L-carnitine?
  • Foods High in L-carnitine
  • What is the difference between L-carnitine tartrate and Acetyl L-carnitine?
  • L-carnitine Tartrate Health Benefits
  • L-carnitine For Weight Loss
  • Acetyl L-carnitine Health Benefits
  • L-carnitine Heart Health Benefits (Blood Pressure, Cholesterol)
  • Does L-Carnitine Help Reduce Type 2 Diabetes?
  • Does L-Carnitine Help Reduce Depression?
  • How Do You Know If You Have A L-carnitine Deficiency?
  • What Is A Safe And Effective Dosage Of L-carnitine?
  • What Are The Side Effects Of L-carnitine?
  • Which Is More Effective: L-carnitine Injections Or Oral Supplementation?
  • Is L-Carnitine With Fucoxanthin Effective?

Before we jump in, let me know in the comments below if you have ever supplemented with L-carnitine.

With that said, let’s jump right into it.

What Is L-carnitine?

L-carnitine is an amino acid that is naturally produced by your body, but it can also be consumed from food or supplements.

L-carnitine helps transport fatty acids into your cell’s mitochondria, to be metabolized, and converted into energy.

In other words, think of your cell’s mitochondria as a furnace.

When fatty acids are transported into your mitochondria, they are burned for energy.

Foods High In L-carnitine

L-carnitine is found primarily in animal protein foods including:

You can also supplement with L-carnitine, however according to this study:

  • Bioavailability of dietary L-carnitine is 54-87%.
  • Absorption of L-carnitine dietary supplements is primarily passive; bioavailability is 14-18% of dose.

What Is The Difference Between L-carnitine Tartrate And Acetyl L-carnitine?

The two most popular types of L-carnitine are:

  • L-carnitine tartrate (LCLT)
  • Acetyl L-carnitine (ALCAR)

These two popular types of L-carnitine appear to provide different health benefits, therefore you should choose based on your desired goals.

L-carnitine Tartrate Health Benefits

L-carnitine tartrate is primarily used in exercise performance supplements with the goal to:

  • improve exercise performance
  • increase power
  • reduce muscle soreness
  • improve muscle recovery
  • increase weight loss

According to this randomized, double-blind, placebo-controlled trial study on the National Library Of Medicine, supplementing with L-carnitine tartrate over a 5 week period helped improve exercise recovery in men and women.

However, there is a lack of research on the longer-term effects in the general population.

In addition to this, although some studies have reported positive effects, the results have been mixed, and the overall evidence is not entirely consistent or conclusive.

L-carnitine For Weight Loss

As mentioned, since L-carnitine helps shuttle fatty acids to the mitochondira to be burned for energy, many supplement companies market it as a weight loss supplement.

According to this review of 37 studies on the National Library Of Medicine:

  • L-carnitine supplementation provides a modest reducing effect on body weight, BMI and fat mass, especially among adults with overweight/obesity.”
  • “No significant effect was seen for waist circumference (WC) and body fat percent.”

According to this randomized control trial with humans:

  • “Subjects who received carnitine lost significantly more weight and showed a decrease in body mass index compared with the control group.”
  • “The magnitude of weight loss resulted by carnitine supplementation significantly decreased over time.”

While there have been studies conducted, including randomized controlled trials (RCTs) with placebo controls, the results have been inconsistent, and the overall impact of L-carnitine on weight loss appears to be modest at best.

Acetyl L-carnitine Health Benefits

According to this National Library Of Medicine study, Acetyl L-carnitine is better known for it’s effectiveness on brain function.

Acetyl L-carnitine is believed to have a better ability to cross the blood-brain barrier and potentially impact cognitive function.

Although the results are not always consistent across studies, some studies have suggested the following potential cognitive benefits from supplementing with acetyl L-carnitine:

  1. Reduce Cognitive Decline, Dementia, and Age-Related Disorders
  2. Improve Memory and Learning In Older Adults
  3. Decrease Depression And Improve Mood
    • This study concluded: “ALC supplementation significantly decreases depressive symptoms compared with placebo/no intervention, while offering a comparable effect with that of established antidepressant agents with fewer adverse effects. Future large scale trials are required to confirm/refute these findings.”

Even though the research looks promising, the study concludes:

“Based on the currently available evidences, the role of ALC in Alzheimer’s disease and other cognitive disorders is still under debate.”

L-carnitine Heart Health Benefits

When it comes to heart health, L-carnitine has been studied to see if it helps:

  • Improve blood pressure in obese and overweight individuals:
    • This study found: “L-carnitine supplementation decreased diastolic blood pressure without affecting systolic blood pressure levels. Research is required to determine the molecular mechanism underlying the relationship between of L-carnitine on blood pressure.”
  • Decrease risk of heart failure
    • This study found: “L-carnitine treatment in chronic heart failure patients may improve clinical symptoms and cardiac function.”
  • Improving cholesterol levels by reducing total and LDL levels, while improving HDL levels in people with a risk of heart disease:
    • This study found: “L-carnitine supplementation could improve lipid profile levels, particularly in doses more than 1500 mg/day. More RCTs with large sample sizes, focusing on gut microbiome profiles and dietary patterns are needed to better understand the effect of L-carnitine on patients with cardiovascular risk factors.”

L-carnitine Type 2 diabetes

L-carnitine may also be helpful with type 2 diabetes as it may help overweight and obese individuals:

This study showed:

L-carnitine supplementation had a significant effect on fasting blood glucose, hemoglobin A1c, and homeostasis model assessment-estimate insulin resistance in the intervention compared to the control group.

How Do You Know If You Have A L-Carnitine Deficiency?

The levels of L-carnitine in your body are impacted by your dietary intake and your body’s natural production.

Based on this, the three main groups of people who may be deficient in L-carnitine include:

If you fall into any of these groups, you may want to have your L-carnitine levels checked.

What Is A Safe And Effective Dosage Of L-carnitine?

Although supplement dosages vary based on the study, here are the common dosage ranges:

What Are The Side Effects Of L-carnitine?

When consumed in regular dosages, L-carnitine does not seem to have any major side effects.

However, L-carnitine administered orally may occasionally cause heartburn or indigestion in some people.

Lastly, supplementing with L-carnitine may cause a fishy smell in your urine, breath, and sweat.

Which Is More Effective: L-carnitine Injections Or Oral Supplementation?

L-carnitine can be supplemented orally via:

  • Powder
  • Capsules
  • Tablets
  • Liquid

These are convenient and easy to consume options.

However, when taken orally, L-carnitine is absorbed through the digestive system, thus the absorption rate and bioavailablity varies based on your gut health and stomach acid levels.

You can also get L-carnitine injections which administers the supplement directly into the bloodstream, rather than the digestive system, thus rapidly increasing the absorption and bioavailability.

However, L-carnitine injections are not as convenient as they are typically given by a health care professional.

Is L-Carnitine With Fucoxanthin Effective?

Lastly, there are a few supplement companies that have paired L-carnitine tartrate with fucoxanthin.

Fucoxanthin is an antioxidant carotenoid found in brown seaweed.

Recent studies have reported that fucoxanthin may help reduce the risk of obesity, however:

“The results of animal studies showed that fucoxanthin had potential value in preventing and treating lifestyle-related diseases, as obesity, diabetes, cancer, cardiovascular disease, and other chronic diseases. Though there are a few studies in human subjects, more clinical trials should be conducted.”


Based on the research, it appears:

  • L-carnitine tartrate may help increase weight loss and fat burning
  • Acetyl L-carnitine may help improve brain function

However, to get better conclusive findings, more scientific research from high quality studies conducted on humans, preferably randomized controlled trials with placebo controls, needs to occur.

With that said, since L-carnitine supplements are fairly affordable, if you are looking to improve in any of these areas, you can always test it on yourself, with the appropriate dosages, since there does not appear to be any serious side effects, besides a little fishy smell.

Here are Amazon links to:

As always, when it comes to your specific needs, always speak with your healthcare provider to find out if supplementing with L-carnitine is good for you.

That’s all for today’s quick overview on L-carnitine.

In the comment section below, tell me which supplement you would like me to do a deep dive on next.

Do you want to see a video on glutamine, BCAAs, leucine, creatine, or something else?

Thanks for watching and keep Living Lean.


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Question Of The Day:

  • Have you ever supplemented with L-carnitine?
  • Which supplement would you like me to do a deep dive on next: glutamine, BCAAs, leucine, creatine, or something else?

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