Break it Down: L-Carnitine Types and Benefits

I’ve had a lot of people requesting information about a really simple amino acid that has gotten very complicated over the years due to different types provided to …

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Acetyl L Carnitine Benefits

Acetyl L Carnitine BenefitsI’ve had a lot of people requesting information about a really simple amino acid that has gotten very complicated over the years due to different types provided to the consumer. If you’re confused about what L-Carnitine does, how to optimize its benefits and what each type does specifically, read on and I’ll do my best to break it down for you.

First, let’s start with L-Carnitine. It’s a conditionally essential amino acid, and in fact isn’t necessarily an amino acid, as much as it is a dipeptide, or two amino acids joined together. Lysine and Methionine can be bound together to provide L-Carnitine, so it is considered “conditionally essential”. My take is that if you are pushing your body hard and you have limited your intake of any aminos, then supplementing with L-Carnitine could be of benefit. L-Carnitine is responsible for the delivery of fatty acids to the mitochondria, or more specifically – it esterifies the fatty acids, making it transport into the powerhouse of the cells. L-Carnitine can be broken back down into Lysine and Methionine in the blood, in a reaction known as hydrolysis. The bonds are broken and we are left with the two former amino acids.

One of the drawbacks to L-Carnitine supplementation, in terms of astounding, mind-blowing results are concerned, has to do with saturation of the mitochondria. Only so much L-Carnitine can be stored up, so taking tons of it will only help if you are deficient in this amino, and then at some point, once saturation is reached, there isn’t going to be any net gain. There is hope however. By increasing insulin, through diet manipulation or using exogenous insulin, L-Carnitine transport can be increased beyond what is normally held in the mitochondria. There has been a lot of discussion as to whether or not this works, and there is definitely a cautionary tale or two to be found when messing around with insulin. The drawback to increasing Insulin by means of dietary manipulation, i.e. consuming sugars, is just that: You have now increased calorie consumption, and have spiked insulin levels in the presence of carbs. This method may offset the benefits of increased Carnitine supplementation, although it’s important to point out that adequate L-Carnitine levels, specifically Acetyl-L-Carnitine levels, can shift the mitochondrial preference of fuel over to fatty acids instead of carbohydrate. But I am not going to suggest anyone start using insulin, nor am I going to speculate on whether the added carbohydrate intake necessary to induce an insulin spike sufficient to drive up and super-saturate cells with L-Carnitine is going to be a positive net gain.

Overall, L-Carnitine is conditionally essential, but I will add that I can definitely tell a difference in my body when I am taking Acetyl-L-Carnitine. That may be more for the other reasons I am about to expand upon, but there is definitely something very noticeable about it. My muscles feel fuller, my workouts tend to be less exhausting (which makes sense because L-Carnitine helps remove excess ammonia from cells) and I have noticed a much more stable blood sugar level using a glucometer.

So here is a quick run-down of the benefits of L-Carnitine

  • Increased Fat Loss
  • Increased Muscle Mass
  • Decreased Bone Loss
  • Heart Health
  • Male Infertility
  • Type 2 Diabetes Symptom Improvement
  • Brain Function

I think it’s important to point out here. Most of these benefits are really the outcome of correcting a deficiency. In other words, if you are deficient in L-Carnitine, then you will most likely achieve some success using this. If you are topped off, it’s still a good idea to supplement, but this isn’t a drug that will go above and beyond what you would expect from anything that was once deficient and is now restored.

Different Types, Different Benefits

So what is the big deal about the different types of L-Carnitine? Well it basically comes down to what that specific extra “stuff” is that is attached to the L-Carnitine. In some instances, the type can help increase absorption, but for the most part, the benefits come down to the extra components of that L-Carnitine formula. For instance….


Acetyl L-Carnitine

Acetyl L-Carnitine is probably one of the most popular forms of L-Carnitine available today. What makes it unique is that it is acetylated. The acetyl group bound to L-Carnitine is useful for a number of reasons. One, it enhances transport across the blood-brain barrier. This will boost L-Carnitine levels in the brain, which can lead to better functioning mitochondria there. Two, the acetyl group is also used in the break-down of fatty acids in what is known as the Acetyl-Coa cycle. Acetyl L-Carnitine has been studied for its effects on everything from heart health, glucose metabolism, all the way to nerve growth factors and depression.

Glycine Propionyl L-Carnitine

Most of GPLC’s (Glycine Propionyl L-Carnitine) benefits, in my opinion, come down to its effect on nitrate levels. GPLC has a unique ability to increase nitrate levels, which elevates nitric oxide levels, leading to a greater degree of muscle pump, and relaxed arterial constriction. Several studies have been done, studying its effect on sprinters and those engaged in moderate exercise. Another benefit of GPLC comes from the increased Glycine consumption, since this formula contains glycine, a useful anti-oxidant in its own right.


The basic advantage of L-Carnitine-L-Tartrate is that its salt form seems to absorb quicker, although there really aren’t any major differences in bioavailability. In other words, it gets into the bloodstream quicker, but not necessarily better.


So what kind should I take?

That’s a good question. Should you take it? Even better.

I think many people who love to take supplements and workout hard are going to find a great deal of benefit from Acetyl L-Carnitine and/or GPLC. It really depends on your budget and how your body responds to it. I’m not going to advise on using these with insulin, but know that there is a lot of discussion out there about an injectable form that used along with insulin, can lead to noticeable fat loss and energy results.

I would also add one thing to my recommendation. Should you feel the desire to experiment with this amino acid, I also suggest taking R-Alpha Lipoic Acid. Preferably a stable form, such as the Potassium salt, otherwise known as K-R-Ala, or the sodium salt, Na-R-Ala. Together with Acetyl L-Carnitine, or any type of Carnitine, you are getting a great deal of anti-oxidant protection, along with glucose control that will rival even some pharmaceutical preparations such as metformin. This has been my experience.

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  1.    Reply

    Obviously the Conwict question is rhetorical. Dat would share if it was appropriate. I did not make that clear and I apologize.

    1. Profile photo of Metabolic Alchemy Staff


      No apologies necessary to me, and I doubt DAT stops by here all that often 😉

      I’m not sure what happened there, and I really don’t visit the forums as much as I used to, so I’m clueless when it comes to these types of things.

  2.    Reply

    People using 94 grams of carbs 2x daily with injectable Carnitine did not put on fat, even without adjusting for 188 grams of extra (and in most cases higher glycemic) Carbohydrates. That is 752 extra sugary calories……dieting by the numbers, a good pound of fat every five days. Granted, a lot of people were on hypo caloric diets to start with, but the carbs used to shuttle the Carnitine made no difference to their rate of loss. That was one of the main reasons people decided to give it a go. And 1iu of insulin is like ten grams of carbs so the exogenous route made no sense. This is why Conwict stopped recommending doing it post workout on CPWO. He was so excited about these findings. What happened with him, do you know? Not for Gossip’s sake but because I really thought he was a contribution.

    1. Profile photo of Metabolic Alchemy Staff


      That sounds pretty epic! I don’t remember reading about this switch in protocol. Very impressive numbers. I don’t know Conwict personally but I definitely remember him being at the forefront of these experiments, along with DAT. Have you experimented with this protocol yourself? What has been your experience thus far? I used a bottle or two some time ago but it’s been so long ago, and I was already using several other powerful nutrient partitioners at the time so it was hard to gauge specific benefits.

  3.    Reply


    This is great info. Thanks.

    Let me ask this; can ALA be used POST workout? (Especially on a keto diet)

    So I use a postworkout shake of Hydrosolates + Leucine + Creatine.

    I follow up with a protein/fat meal an hour later. Will ALA be useable here?

    Also, should you take carnitine before every meal?

  4.    Reply

    I’m a big fan of taking ALCAR pre-workout, but I would hold off on the ALA. It’s such a strong antioxidant with capabilities to recycle other antioxidants, that you’re likely looking at calling upon the same negative effects as you would see from taking a pre-workout dose of Vitamin C or Vitamin E themselves.

    Even though ALA has a short half life, it is quite likely that the metabolites are providing the effect you’re looking for when combining it with ALCAR, which relieves the burden of acute timing.

    Ultimately, when you take ALA depends on your diet, and your current status of insulin and blood glucose signaling. If you’re on a low carb diet, take it 15 minutes before any meal, away from your workout. If you’re on a moderate or high carb diet, take it 15 minutes before one or two of your highest carb meals of the day, but still away from your workout.

    I use about 300mg/day on a ketogenic diet, and just take it before either of my meals away from the workout.

    1. Profile photo of Metabolic Alchemy Staff


      Thanks Marc! Can you briefly expand upon the reasoning behind not taking them preworkout? I know it has to do with ROS (Reactive Oxygen Species) but if you could give us a simple explanation of why it’s not good, that would be awesome.

  5.    Reply

    What about plcar?

    Also, I take alcar + ala before my workouts in the AM (fasted). Is this ok, or a poor strategy due to antioxidant timing around workouts? Should ala not be used then?

    If so, what’s the best timing for ala?

    1. Profile photo of Metabolic Alchemy Staff


      I’m not sure this is the best time to take ALCAR/ALA. I will refer this to a friend of mine who is very knowledgeable in antioxidant timing…

  6.    Reply

    Also, followup on the injectable form—in your experience or research, how effective is it at assisting with weight loss? What is required to make it effective besides the insulin coadministration (or sugar)…how rapid is the fat loss and does cardio or weightlifting trigger the effect better? Simply cannot lose this last 15 lbs regardless of diet or exercise! Even CKD for 8 weeks only generated 10 lbs loss and i’m stalled!

    1. Profile photo of Metabolic Alchemy Staff


      That is all you need (an insulin spike via exogenous insulin or endogenous release due to simple sugar). I am not sure how rapid the fat loss is, and I wouldn’t rely on it alone to get the results you’re looking for. It’s really an add-on that will help if one is employing other methods.

  7.    Reply

    Great post. I’ve always wondered though if it is worth taking a combination if one is looking to get both the brain benefits and the body/muscle benefits. i.e. if I just took GPLC, would it also provide the brain benefits that alcar does? Partially? None at all? Wondering if you know much about effective dosing for GPLC, or what overconsumption of carnitine might cause.

    I’m curious about the injectible form also–would I expect that to help brain function, or just body. If I understand you correctly only the acetlyated version can get into the brain effectively.

    You also didn’t mention some of the patentend formulations– Alcar-arginate. formate, taurinate…can you speak about those?

    1. Profile photo of Metabolic Alchemy Staff


      The brain benefits of alcar come mostly from its ability to cross the blood brain barrier more effectively AND due to it’s acetyl group, which can be used to produce acetylcholine. So using a little bit of both isn’t a bad idea. I don’t think overconsumption of Carnitine would be much of a problem. It’s not gluconeogenic (doesn’t convert to glucose). I wouldn’t take any more than a few grams of both ALCAR and GPLC daily. Aim for 2 grams of each daily…

      The Alcar Arginate and Taurinate are supposed to be pretty revolutionary, but the patent holders seem to be the only ones raving about it. Alcar Arginate is supposed to act like nerve growth factor in the brain. While studies done in vitro show a lot of promise, the human in-vivo trials have yet to be performed.

      I wouldn’t waste any money on those forms. Stick with ALCAR and GPLC…