L-Carnitine: Everything You Need To Know

man drinking l-carnitine supplement in liquid form

If you’re familiar with pre workouts and amino acid supplements, you may have come across L-Carnitine before.

These days you can find it in a range of different products, from pre-workouts to fat-burners to post-workout recovery supplements.

Supplement makers just keep coming up with new ways of marketing L-Carnitine, but the reality is most of the claims made about L-Carnitine are based either on preliminary research that isn’t concrete, or just completely made up.

The reality of it is, L-Carnitine is an effective supplement for some purposes, and entirely ineffective for others.

And that’s exactly what this article is all about!  By the time you’re done reading, you’ll know:

  • What L-Carnitine Is
  • The Proven Benefits
  • The Not-So-Proven Benefits
  • How To Dose L-Carnitine Properly
  • Side Effects And Safety

So, if you’re ready to look past the hype and take a look at the actual research behind L-Carnitine, let’s get right to it…

What Is L-Carnitine?

Carnitine molecule

For the sake of simplicity, L-Carnitine is often referred to as an amino acid but it’s actually a dipeptide (two amino acids combined).  It’s formed through a combination of Methionine and Lysine.

You can get L-Carnitine through your diet, assuming you eat a lot of meat and/or dairy products.

The average diet may yield enough Carnitine to fulfill it’s primary roles throughout the body, but if you want to obtain all the benefits L-Carnitine has to offer–especially with regards to exercise–you need to supplement with additional L-Carnitine.

There just isn’t a sufficient amount of L-Carnitine in most meats and dairy products to actually supply you with a true clinical dose each day.

You’ll find supplements with various forms of Carnitine, the most common of which are:

  • L-Carnitine
  • L-Carnitine L-Tartrate
  • Acetyl-L-Carnitine (ALCAR)
  • Glycine Propionyl L-Carnitine (GPLC)

For the most part, all of these are effective, but there are some differences between them with regards to absorption and bioavailability.

For instance, L-Carnitine L-Tartrate (LCLT) is very quickly absorbed and has good oral bioavailability so that is often the form used in studies–especially those regarding exercise.

You don’t need to pay much attention to small difference like that though.  Just know that when we talk about “L-Carnitine”, we’re really referring to any of the above forms (unless otherwise noted).

All of them are effective at their respective clinical doses (which we’ll talk about later on).

Now, let’s talk proven benefits and not-so-proven benefits.

What Are The Benefits Of L-Carnitine Supplementation?

Scoop of L-Carnitine next to a dumbbell and shaker

L-Carnitine is unique in that it possesses antioxidant properties.

While research is ongoing, it looks like these antioxidant properties underlie a fair amount of the exercise-related benefits.

L-Carnitine And Exercise Recovery

L-Carnitine, in various forms, has been used clinically in conjunction with exercise, specifically to test how it affects exercise recovery.

All the research indicates that it is indeed effective for enhancing exercise recovery.

Specifically, it has been shown to reduce markers of oxidative damage in muscle tissue as well as decrease muscle soreness post-workout.

The exact mechanism by which L-Carnitine accomplishes this remains unknown, but researchers have hypothesized that an increase in muscle oxygenation is responsible.

More research is certainly warranted in this area, but the research that has been conducted is pretty unanimous.  L-Carnitine is a worthwhile supplement for enhancing exercise recovery.

L-Carnitine And Performance Enhancement

Some of the exercise-related studies on L-Carnitine have measured not only exercise-recovery, but physical performance as well.

There is some preliminary evidence to suggest that L-Carnitine can enhance physical performance.  Some studies have shown some modest performance enhancement, but the magnitude is pretty small.

What’s more, L-Carnitine has also failed to impact performance, so it can’t be considered entirely reliable as a performance enhancing supplement.

Overall, there’s no overwhelming evidence that L-Carnitine, or any other form of Carnitine, can significantly enhance exercise performance.

That said, it makes sense to supplement with L-Carnitine prior to or during exercise for the recovery benefits anyway.  A slight performance boost would just an additional benefit.

L-Carnitine And Fat-Loss

Perhaps the most common misconception about L-Carnitine is that “it’s an effective fat-loss supplement”.

It’s not.

Don’t get me wrong…

Within the human body, Carnitine is absolutely essential because it plays a vital role in the transport of fatty acids into the Mitochondria (where they are burned for energy).

But just because a particular substance plays an important role in the human body doesn’t mean that supplementing with additional amounts of that substance make it work better.

The truth is, while some studies have noted a slight increase in fat-oxidation rates with L-Carnitine supplementation, longer-term studies measuring actual body weight have failed to show any significant benefit.

Unless you’re deficient in Carnitine (which may actually be the case if you’re vegan), L-Carnitine supplements aren’t going to help you burn fat.

L-Carnitine And Cognitive Function

You’ll find L-Carnitine (usually as ALCAR) in all kinds of cognitive enhancement and nootropic supplements.

While it has been shown to reduce mental fatigue in elderly people suffering from chronic fatigue, there isn’t a whole lot in the way of research in healthy people.

There is preliminary evidence which indicates ALCAR may be useful for treating aspects of ADHD and anecdotal evidence suggests that normal people may derive some cognitive benefit from supplementing with it, but nothing concrete.

All in all, I wouldn’t bet on Carnitine or ALCAR as a cognitive enhancer.

Like most cognitive enhancement supplements, it’ll probably only make a noticeable difference if you have some sort of cognitive impairment initially.

L-Carnitine And Insulin Sensitivity

Some studies have started to look at how various forms of L-Carnitine can potentially impact glucose metabolism and insulin sensitivity.

In people with impaired glucose metabolism (Type 2 Diabetes), L-Carnitine has been shown to improve Insulin Sensitivity.  ALCAR has proven effective as well in this regard.

However, there’s no evidence to suggest that it can further enhance Insulin Sensitivity in people with initially healthy Insulin Sensitivity.

If you have Type 2 Diabetes, you may want to talk to your doctor about supplementing with L-Carnitine or ALCAR.  If you’re not Diabetic, it probably won’t do much in the way of improving Insulin Sensitivity.

L-Carnitine Dosing

Scoop of L-Carnitine powder in glass of water

The clinical range for L-Carnitine is 1-3 grams, depending on the form.

  • L-Carnitine – 500-2000mg
  • L-Carnitine L-Tartrate – 1000-2000mg
  • ALCAR – 500-2000mg
  • GPLC – 2000-3000mg

To enhance exercise recovery and reduce muscle soreness, go with 2 grams of L-Carnitine L-Tartrate.

This has been the preferred form and dosage in many of the studies pertaining to exercise recovery.

That’s why I included 2 grams of L-Carnitine L-Tartrate in each serving of Amino Beyond, the ultimate intra-workout performance/recovery powerhouse.

A lot of supplement makers tend to under-dose Carnitine in the hopes you, the consumer, won’t notice.  That’s why it’s so important to keep in mind that a clinical dose of most forms of Carnitine is 1-2 grams and you should accept nothing less when buying supplements.

Remember, as a consumer, you vote with your dollars.  If we all stop buying under-dosed supplements, they’ll cease to exist!

What Kind Of Results Can I Expect?

bodybuilder experiencing muscle soreness

The most noticeable impact of supplementing with a clinical dose of L-Carnitine is going to be in the area of exercise recovery.

Decreased soreness and less tissue damage results in a faster recovery so you can get back to crushing the weights.  Over time, this should translate into greater muscle gains.

If you’re expecting Carnitine to pack on muscle like Creatine does though, you may be disappointed.  It’s not a “muscle-builder” in the direct sense, but the recovery benefits should indirectly help you gain muscle in the long-term.

Recovery is often the most over-looked aspect of training, perhaps because it’s basically the opposite of training.

But make no mistake…

Your ability to recover from your workouts in a timely, efficient manner is going to dictate how much muscle you’re able to gain in a given amount of time.

Most people sabotage their recovery from the gym by:

  • Not Sleeping
  • Not Eating Right
  • Drinking A Lot

While there’s certainly no supplement that will make up for not sleeping, not eating right, or drinking way too much, you can think of Carnitine as a useful tool to aid in your exercise-recovery.

Are There Side Effects Associated With L-Carnitine?

Doctor giving a thumbs up

Carnitine is entirely safe when used at dosages like we discussed above.  Absolutely no studies have observed any kind of adverse impact of Carnitine supplementation in the 1-3g/day range.

That makes sense when you consider that Carnitine is also present in many of the foods you may already eat on a regular basis, especially meat and dairy, and your body makes it on it’s own from two amino acids.

If you’re a vegetarian or vegan, who refrains from all meat and dairy products, you may actually be Carnitine deficient.  In such circumstances, Carnitine supplementation would not only be safe, but would be downright healthy for you.

If you really are deficient, you may actually benefit in a lot of ways from Carnitine supplementation.  That’s actually the only circumstance under which you might see some fat-loss.

As with any supplement, it comes down to a matter of quality.  If you’re buying a single-ingredient Carnitine supplement, just make sure you get it from a brand you can trust.  Hopefully they Third Party Test their products and remove the need for you to “take their word for it”.

Carnitine itself is perfectly safe, but let’s face it…

The supplement industry is shady!

Third Party Testing is the only way to be absolute sure that a supplement contains what it’s supposed to and nothing else, but most brands don’t do it.

That’s why I just stick with my own supplements mostly.

The Best L-Carnitine Supplement

There are an unlimited umber of Carnitine supplements out there with all sorts of claims attached to them.

You can purchase it as a stand-alone supplement or find it in the formula of multi-ingredient supplements.

If you’re interested in the exercise benefits (recovery and possibly performance) that L-Carnitine has to offer, consider my personal intra-workout creation, Amino Beyond.

Momentum Nutrition Amino Beyond

Amino Beyond enhances endurance, preserves lean muscle, reduces muscle soreness, and speeds up recovery.

It really is the ultimate intra-workout performance/recovery supplement and is especially useful if you engage in any kind of fasted cardio/training.

Each serving contains:

As with all Momentum Nutrition supplements, Amino Beyond is also free of artificial dyes and useless fillers, not to mention it tastes great!

I personally don’t workout without it.

The Bottom Line On L-Carnitine

A women with her arms folded in gym attire

Some of the benefits of L-Carnitine supplementation have certainly been exaggerated by mainstream supplement companies, but it is useful as an exercise supplement.

While research indicates that it’s not a particularly reliable performance enhancer, the recovery benefits are quite clear.

Multiple studies have proven that L-Carnitine can reduce muscle soreness and speed up recovery from exercise.

That makes it worthwhile for anyone who workouts out frequently and is looking for a slight edge.

If you were hoping L-Carnitine would make you smarter or help you burn fat, you may be disappointed, but the recovery benefits make it a useful addition to the stack of any serious weight-lifter.

I’m Matt Theis, founder of SuppWithThat, Momentum Nutrition, and Singular Sport. I created SWT to separate the science from the hype and publish accurate, research-based information on supplements. If you like what I have to say here, feel free to check out my supplements at and

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