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L-Carnitine vs Acetyl-L-Carnitine: Which Form Did the Nerve Studies Use?
The nerve studies used acetyl-L-carnitine, at 500 to 2,000 mg a day, and pain fell about 20% more than with placebo in small, short trials. Plain L-carnitine is a different form, usually studied at 1 to 2 g a day. Neuralisse lists plain L-carnitine, at most 143 mg by label math.
Written by the Neuralisse editorial teamUpdated · 8 min read
Basics
What is carnitine, and do you need to take it?
Carnitine is a nutrient that helps carry fat into your cells' power plants, where it is burned for energy. Most healthy people make all the carnitine they need, the NIH Office of Dietary Supplements says (ODS, Carnitine).
Your liver and kidneys build it from two amino acids. You also get it from food, mostly red meat, fish and dairy. Vegetarians eat less of it, but their bodies usually make up the difference (ODS, Carnitine (HP)).
So for a healthy adult, carnitine is not a nutrient you are likely to be short on. The question is whether extra carnitine does anything useful. For nerves, the answer depends on the form.
The two forms
What is the difference between L-carnitine and acetyl-L-carnitine?
Acetyl-L-carnitine is L-carnitine with an acetyl group attached. The NIH names these two as the main supplement forms (ODS, Carnitine). They are related, but they are not swapped freely in research, and results for one do not carry over to the other.
| Point | L-carnitine | Acetyl-L-carnitine |
|---|---|---|
| What it is | The basic form | L-carnitine plus an acetyl group |
| Common trial doses | 1-2 g a day | 500-2,000 mg a day in nerve trials |
| Used in nerve pain trials | No | Yes, in people with diabetes |
| On the Neuralisse label | Yes, at most 143 mg | No |
The research
Which form of carnitine was used in the nerve studies?
Acetyl-L-carnitine. A 2019 systematic review found four trials in people with diabetes, using 500 to 2,000 mg a day. Pain scores fell about 20% more than with placebo (Di Stefano et al., 2019).
That sounds useful, and it may be. But the authors called the trials small and short. A separate review of acetyl-L-carnitine, later corrected, still showed lower pain scores, again for the acetyl form only (Li et al., 2015 (correction)).
We found no nerve trials in our sources that used plain L-carnitine. If a product lists L-carnitine, the nerve research does not directly apply to it.
Remember too that tingling, burning or numbness needs a doctor's visit. Diabetes is the leading cause of peripheral neuropathy, and treatment depends on the cause (NINDS, Peripheral neuropathy).
Dose
How much carnitine do studies use?
Studies of plain L-carnitine usually used 1 to 2 grams a day (ODS, Carnitine (HP)). The acetyl-L-carnitine nerve trials used 500 to 2,000 mg a day (Di Stefano et al., 2019). Both ranges sit far above what a small blend ingredient can hold.
L-carnitine trials
The daily range the NIH describes for most research on the plain form.
Acetyl form, nerve trials
The low end of the dose range in the diabetes nerve studies.
Neuralisse ceiling
The most plain L-carnitine the capsule could hold, by label weight order.
Safety
What are the side effects of L-carnitine?
At about 3 grams a day, carnitine can cause nausea, stomach cramps, diarrhea and a fishy body odor, the NIH says (ODS, Carnitine (HP)). At lower doses, side effects are uncommon.
- Stomach upset: the most common complaint at high doses.
- Fishy odor: from breath, sweat or urine, also tied to high doses.
- Seizure medicines: some of them lower the body's carnitine. Do not change those drugs on your own.
If you take seizure medicine, ask your neurologist before adding any carnitine product. Your doctor may already be watching your levels.
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Does L-carnitine raise TMAO and heart risk?
Gut bacteria turn carnitine into a compound called TMAO, the NIH notes (ODS, Carnitine (HP)). Some research links higher TMAO levels to heart disease, which is why the question comes up.
The science is still open. The NIH flags TMAO as an area that needs more study, not as a proven danger. If you have heart disease, or a high risk of it, it is a fair topic to raise with your doctor before taking carnitine regularly.
At small amounts, such as a blend ingredient, the effect is likely smaller than in high-dose studies. But no one has measured it for a product like this.
Neuralisse
What form of carnitine is in Neuralisse?
Neuralisse lists plain L-carnitine, not acetyl-L-carnitine. It is the fourth of six ingredients in a 575 mg blend, and no amount is printed.
FDA rules list blend ingredients from most to least by weight (FDA, Labeling guide). So the fourth ingredient can be at most 575 divided by 4, or about 143 mg. The real amount is probably lower. Read our guide to reading a proprietary blend for the full method.
In its favor
- L-carnitine is a familiar nutrient with known safety data.
- The amount is far below the 3 g level tied to stomach upset.
- The full ingredient list is printed.
Weak spots
- The nerve studies used the acetyl form, not this one.
- At most 143 mg, well under 1-2 g trial doses.
- No amount printed on the label.
More on the L-carnitine ingredient page, and every blend ingredient side by side below.
| Ingredient | Label order | Per capsule | Amount used in research | Evidence |
|---|---|---|---|---|
| Magnesium Glycinate | 1 of 6 | 80 mg of magnesium (19% DV), printed on the label | RDA 310-420 mg a day from all sources; supplement upper limit 350 mg (ODS, Magnesium) (ODS, Magnesium (HP)) (FDA, Daily Values) | Essential nutrient |
| Alpha Lipoic Acid | 2 of 6 | Not disclosed; at most 287 mg by label math | 600 mg a day; the clearest results used IV infusions for 3 weeks (MSKCC, Alpha-lipoic acid) (LiverTox, Alpha lipoic acid) (Mijnhout et al., 2012) (NCCIH, Diabetes and supplements) | Mixed |
| Butcher's Broom (Ruscus aculeatus) Root Extract | 3 of 6 | Not disclosed; at most 191 mg by label math | Studied in a combination product for leg vein symptoms; no nerve trials (MSKCC, Butcher's broom) | Some (leg veins only) |
| L-Carnitine | 4 of 6 | Not disclosed; at most 143 mg by label math | 1-2 g a day in trials; nerve studies used acetyl-L-carnitine at 500-2,000 mg (ODS, Carnitine (HP)) (ODS, Carnitine) (Di Stefano et al., 2019) | Limited (nerve research used another form) |
| Turmeric (Curcuma longa) Rhizome Extract 95% Curcuminoids | 5 of 6 | Not disclosed; at most 115 mg by label math | Products range from 100 to over 1,000 mg a day (NCCIH, Turmeric) (LiverTox, Turmeric) (MSKCC, Turmeric) | Not enough to conclude |
| Coenzyme Q 10 (as Ubiquinone) | 6 of 6 | Not disclosed; at most 95 mg by label math | Typical doses 300-1,200 mg a day (NCCIH, CoQ10) (MSKCC, CoQ10) (LiverTox, CoQ10) | Not confirmed in larger trials |
Bottom line
Which carnitine should you look for?
If nerve research is your reason, the form studied was acetyl-L-carnitine at 500 to 2,000 mg a day. Plain L-carnitine has not been tested for nerves in our sources. Neuralisse lists plain L-carnitine at no more than 143 mg, so judge it as part of a general blend, and talk to your doctor about any nerve symptoms.
FAQ
L-carnitine and acetyl-L-carnitine questions
Is acetyl-L-carnitine better than L-carnitine for nerves?
For nerves, acetyl-L-carnitine is the form that was studied. Four small trials in people with diabetes used 500 to 2,000 mg a day, and pain fell about 20% more than with placebo. Plain L-carnitine was not tested in those nerve trials.
What is the difference between L-carnitine and acetyl-L-carnitine?
Acetyl-L-carnitine is L-carnitine with an acetyl group attached. The NIH names them as the two main supplement forms. They are related, but research on one form does not automatically apply to the other.
How much acetyl-L-carnitine was used for neuropathy studies?
The trials in a 2019 systematic review used 500 to 2,000 mg a day in people with diabetes. The trials were small and short, so the results are promising but not firm. Ask your doctor before trying it.
What are the side effects of L-carnitine?
At about 3 grams a day, L-carnitine can cause nausea, stomach cramps, diarrhea and a fishy body odor, according to the NIH. Some seizure medicines lower the body's carnitine, so people taking them should talk to their neurologist.
Does L-carnitine cause heart problems through TMAO?
It is an open question. Gut bacteria turn carnitine into TMAO, and some research links high TMAO to heart disease. The NIH says more study is needed. If you have heart disease, ask your doctor before taking carnitine regularly.
Does Neuralisse contain acetyl-L-carnitine?
No. The Neuralisse label lists L-Carnitine, the plain form. It is fourth in a 575 mg blend, so it can be at most about 143 mg. The amount is not printed, and the nerve studies used acetyl-L-carnitine instead.
Do I need a carnitine supplement?
Most healthy people do not. The NIH says the body makes all the carnitine it needs from two amino acids, and food such as meat, fish and dairy adds more. Some medical conditions change that, so ask your doctor.
Who wrote this
Written and reviewed by
Plain-language pages built from the bottle label, the order page and linked public health sources such as NIH, FDA and CDC.
Last updated . Read our editorial standards and how we check reviews. This website is run by an American stocking outlet for Neuralisse, not by the manufacturer. We earn money when you buy through our order links.
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