15 Best Acetyl-L-Carnitine Supplements according to doctors reviews

Acetyl-L-Carnitine is an ester form of L-carnitine. Carnitine was discovered in 1905. It is synthesized mainly from the essential amino acid lysine in the liver and kidneys. Acetyl-l-Carnitine plays a critical role in energy production. It transports long-chain fatty acids to the mitochondria so they can be oxidized (“burned”) to produce energy.

There are four common carnitine supplements: L-Carnitine, ALCAR, L-Carnitine L-Tartrate (LCLT), and Propionyl-L-Carnitine (GPLC). L-Carnitine can be synthesized in the human body from two essential dietary amino acids, L-methionine, and lysine. This process involves several vitamin C-dependent enzymes, and vitamin C deficiencies can impair L-carnitine biosynthesis.

What Is Acetyl L-Carnitine?

So what exactly is Acetyl L-Carnitine (ALCAR)? The first ALCAR is converted to L-Carnitine. From here, the acetyl components break off and bind with Coenzyme A to form Acetyl-COA. The substance then combines with the free-floating Choline and is catabolized by another enzymatic process to be converted to Acetylcholine.

It is considered a powerful brain-boosting nootropic and energy supplement as it is able to cross the blood-brain barrier, therefore it enters the central nervous system. From there, the coenzyme L-carnitine acts as a precursor for the neurotransmitter Acetylcholine.

This is a powerful brain chemical noted for its ability to influence a range of cognitive processes, including learning capacity, memory formation, attention, concentration, recall, and focus.

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15 Best Acetyl-L-Carnitine Supplements

ALCAR is the user-friendly name for Acetyl-L-Carnitine, a must-know supplement for its physical and psychological benefits.

It is a compound that provides legitimate benefits and is often overlooked for the more popular carnitine products. This version carries all the benefits in more digestible and far superior support for health and well-being.

If you’re interested in taking a better version of a popular supplement and simultaneously supporting health and performance, read on!

These are some of the most popular and respected products on the market. We cover the ones that get all the attention because of their price, purity, or scientific backing.



Customer reviews

Where to Buy


NaturaLife Labs Acetyl L-Carnitine 



Nutricost Acetyl L-Carnitine 500mg



NOW Supplements, Acetyl-L Carnitine 500 mg



Divine Bounty ALCAR Capsules



Double Wood Supplements Acetyl L Carnitine



Horbäach Acetyl L-Carnitine



We Like Vitamins ALCAR Capsules



Doctors Best Acetyl-L-Carnitine



BulkSupplements Acetyl-L-Carnitine Powder



Nature’s Trove ALCAR Capsules



Jarrow Acetyl-L-Carnitine Capsules



Mental Refreshment Acetyl-L-Carnitine Capsules



Nature's Bounty® L-Carnitine 400 mg



Thorne Research - Carnityl - Acetyl-L-Carnitine



Jacked Factory Acetyl L Carnitine 750mg Supplement


1. NaturaLife Labs Acetyl L-Carnitine 1,500 mg

15 Best Acetyl-L-Carnitine Supplements according to doctors reviews
  • ✔️SUPERIOR POTENCY 1500 MG: Our Acetyl L-Carnitine delivers 1500mg per serving with 100 vegan capsules, making it the most potent formula on the market.
  • ✔️ACETYL L-CARNITINE: Made with 100% pure Acetyl L-Carnitine without the use of fillers or binders.
  • ✔️SUPERIOR QUALITY: We are proud to offer 100% pure Acetyl L-Carnitine, FREE from fillers, magnesium stearate, dioxides, preservatives, gluten, soy, sugar, yeast, starch, GMO.
  • Manufactured in an FDA registered facility in accordance with Good Manufacturing Practices (GMP)
  • Recommendation: As a dietary supplement, take two (2) capsules daily with a meal or as recommended by your healthcare professional. Common side effects are more common if the serving is not taken with a meal and a sufficient amount of water: stomach upset, nausea, dry mouth.

2. Nutricost Acetyl L-Carnitine 500mg

15 Best Acetyl-L-Carnitine Supplements according to doctors reviews
  • Get what you need. Although Acetyl L-Carnitine is found in many foods, getting enough can be difficult. Top up the amount you take with Nutricost Acetyl L-Carnitine!
  • One Capsule, One serving. Get several months’ supply in a single bottle. With Nutricost Acetyl L-Carnitine, you will have everything you need for the coming months.
  • Simplicity in a Bottle. By keeping our recipes simple and specific, you can easily find exactly what you are looking for with Nutricost.

3. NOW Supplements, Acetyl-L Carnitine 500 mg

15 Best Acetyl-L-Carnitine Supplements according to doctors reviews

NOW supplements continue the trend we’ve seen before with a simple and effective product. As with BulkSupplements, it is 100% ALCAR by weight excluding the actual capsule.

1g of supplement is 1g of ALCAR. This is simply dissolved in a high quality stearic acid to harden or stabilize the product. The overall result is a simple yet powerful dose of acetyl-L-carnitine.

However, the cost here is much more than BulkSupplements. When the purity between the two products is equal and one provides a much greater number of servings and a better price, it is clear which would be the best choice.

NOW’s product is effective, but at the same time it won’t give you the full value for money you get with BulkSupplements.

4. Divine Bounty ALCAR Capsules

15 Best Acetyl-L-Carnitine Supplements according to doctors reviews

The purity and potency of these capsules are amazing. They are 600mg each and 20% off some of the other products on this list.

The cost and number of this product are comparable to other products on this list, each count is more effective yet offers better value-per-serving than NOW. A single capsule here is enough to get the 600mg-2,500mg serving you need to maximize the daily benefits.

This product has a subscription and bulk purchase options that allow to maximize its price effectiveness and lead to a competitive price point on a premium product. All you have to do is look at the concentration per serving for this supplement and the cost per gram of the active ingredient.

Overall, if you’re looking for a low dose with a single capsule or a consistently effective product at a reasonable price, it’s worth it.

The main issue we see with this product is actual quality control – with multiple reports of underdosing and undercounting containers! These pose a significant risk, especially since there is no FDA manufacturing practice review to warrant their potency.

5. Double Wood Supplements Acetyl L Carnitine

15 Best Acetyl-L-Carnitine Supplements according to doctors reviews

Double Wood Supplements created Compact by Design to identify products with a more efficient design, even if they don’t always look very different. By removing excess air and water, products require less packaging and their shipping becomes more efficient. At scale, these small differences in product size and weight lead to significant carbon emission reductions.

Acetyl L-Carnitine (ALCAR) is a mitochondrial support supplement that promotes healthy mood, learning and memory. It may also support the mitochondria in your muscles, which supports exercise endurance and gym performance. There is evidence that L-Carnitine may have many other benefits. It can help support circulation and nutrient-rich blood flow after a high-fat meal. Carnitine is also necessary to metabolize fat, and supplementation can support the process of fat metabolism into fatty acids. It can also support muscle recovery so you can hit the gym faster after a tough workout. Double Wood’s Acetyl L Carnitine has been manufactured and tested for safety here in the USA.

6. Horbäach Acetyl L-Carnitine

15 Best Acetyl-L-Carnitine Supplements according to doctors reviews

Safety Information

If you are pregnant, nursing, taking any medications or have any medical condition, consult your doctor before use. Discontinue use and consult your doctor if any adverse reactions occur. Please see product label for full warning.


Acetyl L-Carnitine HCl (Free Form). Other Ingredients: Gelatin Capsule, Rice Powder, Vegetable Magnesium Stearate, Silica, Calcium Silicate.


For adults, take three (3) quick release capsules daily, preferably on an empty stomach.

Legal Disclaimer

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

Statements regarding dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease or health condition.

7. We Like Vitamins ALCAR Capsules

15 Best Acetyl-L-Carnitine Supplement

Another product with 100% purity and the GMP seal, plus the same cost per count we see in Pure’s ALCAR supplements.

Frankly, there is a lot of compression on the market. All of the ALCAR supplements seem to be competing with each other across the board, and there has been little innovation so far. While this is exactly comparable to the previous product, the RRP is much higher.

The selling prices on We Like Vitamins seem consistent – it’s not actually an RRP and hasn’t been in months. Although this may seem like a sales tactic, the result is the same: a product that provides 100% purity with GMP certification.

8. Doctors Best Acetyl-L-Carnitine

15 Best Acetyl-L-Carnitine Supplement

This product comes with the most ridiculous price point on this list so far. It provides exactly the same ingredients as the others, but with a huge premium price tag for no reason.

Efficiency and quality are not the issue here – this product has a GMP certificate as well as regular 3rd party testing. This means you get what it says on the label – only at a cost that makes it untenable compared to previous products.

With such a close field of competition for your money, Doctor’s Best doesn’t seem like your best bet!

9. BulkSupplements Acetyl-L-Carnitine Powder

15 Best Acetyl-L-Carnitine Supplement

BulkSupplements earn points on company values and manufacturing processes. It is a product that is consistently well dosed and affordable.

They start our list with a great, affordable product that offers 100% ALCAR. This is dosed as effectively as any product—contains nothing else, but complicates the foundations!

No shine, no fillers, just 100% ALCAR powder. The powder version provides the best control over your intake and the purest product possible. It does mean, however, that you have to be careful what you buy and how you take it.

You can easily overeat your ALCAR if you’re not careful. Follow service directions and use any scoop provided and you are likely to have a great time with this product.

10. Nature’s Trove ALCAR Capsules

15 Best Acetyl-L-Carnitine Supplement

This is a great middle of the range that comes with a great price point. It lacks the peace of mind benefits like a good production practice.

There is also some concern among customers about the strength of the product – often customers who say it looks weaker than the label says.

Others have mentioned concerns for digestive health with this ALCAR brand; this suggests there are some bigger concerns as the actual compound has not been reliably linked to any digestive problems.

11. Jarrow Acetyl-L-Carnitine Capsules

Jarrow has a mixed reputation in the supplement industry – we’ve covered some of their products before and we’re not completely overwhelmed. They tend to be effective, but they sit in the middle of the pack in most of our supplement guides.

In many ways, their ALCAR is a perfect example of this. It comes at a relatively good price, but with only 60% of the total number of capsules of other products, making the total cost per capsule higher. It’s cheaper than Doctor’s Best, but more expensive than others like Mental Refreshment or We Like Vitamins products.

The actual product is exactly what we saw before: 100% ALCAR by weight, but the serving size is a single capsule and will not work at 500mg each. It is a 60-serving product with 2 capsules per day that matches the effect of other products and is not particularly outstanding.

However, there have been historical issues with quality assurance where different lots are shipped. Some of these included pharmaceutical grade ALCAR, while others did not. This worries us about reliability, especially since different parties have different vegan status.

12. Mental Refreshment Acetyl-L-Carnitine Capsules

While this product comes out with the lowest price per capsule ever, its actual content is similar to the others – 100% pure.

The simplicity of these products means that even small differences come together. While the product itself is virtually indistinguishable from the others on this list, aside from the BulkSupplements prices, the number and cost are comparable, albeit slightly better than others discussed so far.

The only area where Pure’s ALCAR supplement gains is in company standards and values. With FDA “good manufacturing practices” accreditation, this product clearly wins on the basis of consumer peace of mind.

GMP seals are issued for company manufacturing practices that ensure what you see is what you get. This goes a long way toward providing peace of mind, ensuring your supplements don’t spoil, and it shows that a company is proactive when it comes to their products and processes.

13. Nature’s Bounty® L-Carnitine 400 mg

Acetyl L-Carnitine 400 milligrams and ALA 200 milligrams, 30 Capsules

Acetyl L-Carnitine and Alpha Lipoic Acid unite in this healthy aging formula to help your body fight against the cell-damaging effects of free radicals.* These capsules also support energy metabolism.*

  • Exceptional antioxidant support*
  • Contributes to energy metabolism*
  • Supports nervous system health*

14. Thorne Research – Carnityl – Acetyl-L-Carnitine

The potential for adverse effects on neurological health (health of the brain and nerves) is increasing and becoming more common due to increased lifespan, environmental toxicity, and subsequent nutrient deficiencies and malnutrition. Mitochondrial competence appears to be at the core of brain and nerve health. Mitochondria, the energy producing powerhouse of the cell, is an important source of free radical production, even in healthy individuals. The aging process, poor diet, and environmental toxins can stress the body’s built-in antioxidant system, reducing its ability to quench free radicals. Various foods can reduce these activities.* Thorne supplements help maintain neurological health.*

15. Jacked Factory Acetyl L Carnitine 750mg Supplement

  • 1500 Mg per 2 Capsules of Pure Acetyl L Carnitine: Jacked Factory’s Acetyl L-Carnitine is the most potent and pure source of acetyl l carnitine with 1500mg of pure active ingredient in each 2 capsule serving. Don’t settle for underdosed l-carnitine supplements.
  • Energy, Focus & Memory Support: Acetyl L Carnitine is a powerful nootropic brain supplement that helps improve motivation and reduce brain fog.
  • Zero Fillers: Our ALCAR is a truly pure supplement down to the finest details: no magnesium stearate, no food dyes, no fillers at all.

Acetyl-L-Carnitine Benefits and Effects:

  • L-Carnitine in the form of ALCAR is anecdotally reported as a stimulant, but its effects are less than other known stimulants (such as Caffeine). It is currently unknown why these effects occur.
  • There are four common forms of Carnitine supplements: L-Carnitine, Acetyl-L-carnitine (ALCAR), L-Carnitine L-Tartrate (LCLT), and Propionyl-L-Carnitine (usually bound to Glycine and called GPLC)
  • L-Carnitine can be synthesized in the human body from two essential dietary amino acids, L-methionine and lysine. This process involves several vitamin C-dependent enzymes, and vitamin C deficiencies can impair L-carnitine biosynthesis.
  • Acetyl-L-carnitine can directly or indirectly reverse age-related mitochondrial deterioration. It acts as a chaperone to protect macromolecules, including carnitine acetyltransferase, from structural change and/or loss of function. Acetyl-L-carnitine partially reverses age-related loss of mitochondrial membrane potential and decrease in membrane cardiolipin concentration and protects against oxidative damage of mitochondrial DNA. Improves brain function and ambulatory activity in aging rats.
  • Acetyl-L-carnitine as a dietary supplement may improve symptoms of fatigue in humans. Chronic fatigue syndrome (CFS) in humans has been found to be associated with low circulating acetyl-Lcarnitine concentration and reduced accumulation in various brain regions. It has been suggested that acetyl-L-carnitine, through its role as a glutamate precursor in neurons, helps maintain neuronal metabolic activity by promoting glucose and lactate uptake and utilization. In a randomized, open-label study of 30 patients with CFS, acetyl-L-carnitine and propionyl-L-carnitine showed beneficial effects on fatigue and concentration of attention.
  • Acetyl-L-carnitine appears to have specific and perhaps unique roles in brain metabolism. Elderly subjects with mild mental impairment had better scores on cognitive performance tests after such supplementation.[33] A meta-analysis of the efficacy of acetyl-L-carnitine in mild cognitive impairment and mild Alzheimer’s disease included all identified double-blind, placebo-controlled, prospective, parallel group studies using acetyl treatment doses of 1.5-3.0 g=day. -L-carnitine was conducted between 1983 and 2000. This analysis showed a significant advantage for acetyl-L-carnitine over placebo, with L-Carnitine and Acetyl-L-Carnitine 77 observed in both clinical scales and psychometric tests. The benefit was observed with 3 months of supplement use and increased over time. Typical usage recommended by vendors is 1–3 g=day.
  • L-Carnitine infusion improves insulin sensitivity in insulin-resistant diabetic patients. Intravenous administration of acetyl-L-carnitine increases glucose excretion in patients with type 2 diabetes.
  • Clinical note – Acetyl-L-carnitine shows promise as a potent therapeutic agent. Acetyl-L-carnitine, an ester form of L-carnitine, has also been investigated for its use in the treatment of Alzheimer’s disease (Brooks et al. 1998, Pettegrew et al. 1995, Sano et al. 1992, Thal et al. 1996), depression in the elderly (Garzya 1990), diabetic neuropathy (De Grandis & Minardi 2002), peripheral neuropathy (Onofrj et al. 1995), prevention of neuropathy in chemotherapy (Bianchi et al. 2005; Maestri et al. 2005), fatigue in multiple sclerosis (Tomassini et al. 2004), Peyronie’s disease (Biagiotti & Cavallini) 2001), degenerative cerebellar ataxia (Sorbi et al. 2000), and cognitive impairments in chronic alcoholics.

Acetyl-L-Carnitine Side Effects

Acetyl-L-Carnitine, also called ALCAR, has many benefits but also has some side effects. However, it has been determined that these side effects are only seen at high doses.

A small amount of this nutrient produced by the liver and kidneys is already present in our body. ALCAR is considered safe when taken in small amounts and under a doctor’s advice.

Some of the side effects that can be seen are:

  • Nausea;
  • Diarrhea, vomiting, stomach upset;
  • Headache, sleep deprivation;
  • Irritability and fatigue;
  • High blood pressure.

There is also the possibility of other side effects such as increased appetite, sweating, skin rashes, gastrointestinal problems, and fishy odor of urine and sweat, by taking ALCAR more than the recommended dose. Acetyl-L-Carnitine has shown more side effects when combined with other drugs and supplements.

This nutrient can interact with the medications and supplements you take and affect bodily functions. ALCAR is not safe if you have allergies and sensitivities. Also, children, pregnant and breastfeeding women should not take it because the risk involved is not yet known. Therefore, it is always recommended to consult a doctor before taking this supplement.

Acetyl L-Carnitine Dosage, Active Amounts and Forms

Various forms of carnitine supplements are available.

Acetyl-L-Carnitine (ALCAR) is used for cognitive enhancement. 630-2,500mg (ALCAR)
L-Carnitine L-Tartrate (LCLT) is typically used for physical performance and power output. 1,000-4,000 mg (LCLT)
Glycine Propionyl-L-Carnitine (GPLC) is used to relieve intermittent claudication and blood flow issues. 1,000-4,000 mg (GPLC).
L-carnitine is supplemented daily. The standard dose for L-carnitine is between 500-2,000 mg.
Absorption of dietary L-carnitine and L-carnitine supplements appears to occur primarily by passive diffusion. In humans, approximately 54-87% of dietary L-carnitine is absorbed, depending on the amount in the diet.

The bioavailability of dietary supplements (0.6-4 g=day) is 15-20%. Unabsorbed L-carnitine is broken down by microorganisms in the large intestine.

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