Supplement Label Index

L-Carnitine L-Tartrate vs. Acetyl-L-Carnitine (ALC)

Among 2,330 on-market l-carnitine products with an identifiable primary form, 36.9% use L-Carnitine L-Tartrate (859 products) and 27.6% use Acetyl-L-Carnitine (ALC) (644).

L-Carnitine L-TartrateAcetyl-L-Carnitine (ALC)
Quality tierUnratedUnrated
L-Carnitine by weight68.2%79.3%
Share of market36.9%27.6%
On-market products859644
Median declared dose404.6 mg
middle half: 150–682
396.5 mg
middle half: 158.6–500
Most common brandsGNC Pro Performance AMP, AdvoCare, CellucorWonder Laboratories, Source Naturals, XYMOGEN

Doses are declared per serving in mg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).

Why L-Carnitine L-Tartrate is unrated

The form used in several RCTs (2g/day carnitine as LCLT in Volek 2008, 2g LCLT twice daily with carbohydrate in Wall 2011, which raised muscle carnitine 21%), but no human study comparing tartrate directly with free L-carnitine or other salts was located.

Source: Volek JS et al. 2008, Am J Cardiol 102(10):1413-7, PMID 18993165; Wall BT et al. 2011, J Physiol 589(4):963-73, PMID 21224234

Why Acetyl-L-Carnitine (ALC) is unrated

A different molecule from L-carnitine with its own evidence base (diabetic neuropathy, mood); no human study comparing ALC with L-carnitine on carnitine delivery or the same outcomes was located, so no tier is assigned.

Source: Sima AA et al. 2005, Diabetes Care 28(1):89-94, PMID 15616239

Tiers summarize published comparative bioavailability or outcome evidence for each form (see methodology). This page describes the market; it is not a recommendation to take either form. Talk to a clinician about what's right for you.

Other l-carnitine comparisons