T Nation

L-Carnitine Differences?

I was wondering if anyone could explain the differences between the effects of acetyl-L-Carnitine and L-Carnitine Tartrate? And which is superior and why? Or do they have different effects?

Carnitine is an amino acid which as a process the body itself does, interconverts between the acetyl ester form and the free amino form, carnitine itself.

Carnitine itself is the active species at least so far as mitochondrial energy production goes. (I have a pretty strong expectation that acetyl-L-carnitine itself has CNS stimulatory properties at higher doses, as this occurs quite rapidly after taking it without time having been available for de-acetylation; and it could be that there are other activities of the acetyl form.)

Acetyl-L-carnitine is better absorbed if I recall correctly (not 100% positive on that, actually the bioavailability is low for any form) and crosses the blood-brain barrier better.

If taking only one form, acetyl-L-carnitine is the better form to take.

Carnitine tartrate is not an ester, but a salt. What this means is that there is no covalent chemical bond between the carnitine and tartrate parts, but only a chemical charge tending to hold them together.

Whether the carnitine and tartrate stay together through the absorption process or its just equivalent to taking carnitine and tartaric acid (which would be a pointless addition) I don’t know.

I would prefer acetyl-L-carnitine over carnitine tartrate, but it’s possible there might be an advantage of carnitine tartrate over carnitine itself. I haven’t looked into it.

Bill,

What about carnitine from fumarate and carnitine from propionate (propionyl-l-carnitine) ?

Good to see you around!

The fumarate is also a salt and likely is very similar or identical in practical properties to the tartrate.

The propionate is another ester, more analogous to the acetyl. There is interesting research on various esters of carnitine. I think it’s unlikely that acetyl-L-carnitine doesn’t cover all the bases but it may be the case that at modest doses, given beneficial effects on for example the brain or the heart may be more efficient with different esters.

Taking plenty of acetyl-L-carnitine ought to do the job completely, though, I expect.

[quote]Bill Roberts wrote:
The fumarate is also a salt and likely is very similar or identical in practical properties to the tartrate.

The propionate is another ester, more analogous to the acetyl. There is interesting research on various esters of carnitine. I think it’s unlikely that acetyl-L-carnitine doesn’t cover all the bases but it may be the case that at modest doses, given beneficial effects on for example the brain or the heart may be more efficient with different esters.

Taking plenty of acetyl-L-carnitine ought to do the job completely, though, I expect.[/quote]

What are your thoughts about injectable L-Carnitine? Is it worth it? Bill or anybody? Sorry if it’s a hijack…

Thanks Bill.

DG

maybe it was discussed in the receptormax thread, but studies show tartrate was what increased androgen receptors. Is it thought that regular L-Carnitine does the same, or has it been proven that it doesn’t?

Only if there’s a study showing the tartrate did and regular carnitine or acetyl-L-carnitine did not could one say there was evidence of that. If the study only looked at tartrate and found it for tartrate then I wouldn’t assume it wasn’t so for other forms.

On injectable, it seems to me a reasonable dosage would require a vast volume. As an IV drop it could be workable, but as for injecting a few mL at a time, I don’t see how the dose could be substantial.

Actually I think Dr Ziegenfuss already stated that he had checked with the researchers of the study in question and their reason for using the tartrate had only to do with shelf-life.

(Carnitine itself does not do so well with time with repeated openings of a container, particularly if humid.)

thanks Bill

Cool thanks Bill.

DG

Sure thing!

[quote]Bill Roberts wrote:
(Carnitine itself does not do so well with time with repeated openings of a container, particularly if humid.)[/quote]

Do you know how long Acetyl-L-Carnitine is good for? Should it be refrigerated?

With reference to bulk powder, the problems seem to be how hygroscopic (water absorbing) it is, and possibly oxidation with repeated exposure to air as well – some of it will turn yellow with time.

If it’s unopened then certainly refrigeration isn’t needed.

If it’s being opened again and again, e.g. to take out a few grams at a time to use, then refrigeration tends not to help problems with absorbing water from the air.

In Florida (where I live) from mid-Spring to early Fall, the conditions are such that buying more than 30 days’ worth of bulk powder is too much. In the winter probably 60 days’ worth is acceptable. That might be true year-round in other parts of the country.

Largely the problem could be solved by, preferably on a dry day, transferring ALC from a bulk container to smaller air-tight containers that were being nearly filled, the smaller containers holding enough for only a few weeks at a time.

So far as a bottle of capsules goes, if the bottle only has enough to last 30 days or whatever there is unlikely to be any problem unless maybe if living in a swamp.

Bill…

And this is really the mad scientist / engineer in me, but what do you think about using those silica gel packs (the ones used to absorb moisture, but I am unsure if they are non-toxic…probably not) or something similar, perhaps taped to the underside of a container’s lid to minimize moisture affecting the powder?

I would do this on Survivor if I ever go on with a tub of BCAAs or Alcar. Watch me get kicked off the show.

Alright, thanks for the explanasion, reason I was asking is because a while ago I found these articles:

http://www.elitefts.com/documents/clt.htm

http://www.elitefts.com/documents/perf_recovery_clt.htm

And in both of these articles the author was specifically pointing to the Tartrate, which as you mentioned is similar to a salt.

So if Acetyl-L-Carnitine and L-Carnitine Tartrate are really the same thing, but the Acetyl is the more “bio-available” or easily absorbed one then it’s all good.

I had just been taking the L-Carnitine Tartrate to aid CNS recovery for a few months, and I saw Receptormax and wondered why Acetyl over tartrate.

But like you said if Acetyl is more “absorbable” then it makes alot of sense why you would choose it over the tartrate.

Thanks Bill!

Glad to be of any help!

[quote]Bill Roberts wrote:
I have a pretty strong expectation that acetyl-L-carnitine itself has CNS stimulatory properties at higher doses, as this occurs quite rapidly after taking it without time having been available for de-acetylation; and it could be that there are other activities of the acetyl form.[/quote]
Can we mix ALC with green tea (or coffee) to enhance its CNS stimulatory properties?