Another ''power'' article to feast your eyes upon from Trevor Macca!
It seems that L-carnitine L-tartrate, a form of carnitine widely present in well known carnitine supplements is more bioavailable and fast absorbed than most of the other carnitine forms.
What are these other forms?
They are... Free form L-carnitine, L-carnitine esters (acetyl-L-carnitine and lauroyl-L-carnitine) and Carnitine salts (L-carnitine L-tartrate, L-carnitine fumarate, L-carnitine magnesium citrate). In a study, six groups of piglets were administered 40 mg/kg BW of each of these carnitine forms. The results were... For Bioavailability: Free and total plasma carnitine concentrations were similar for free form L-carnitine and carnitine salts while those of the carnitine esters were lower. For Rate of absorption: Administration of L-carnitine L-tartrate yielded a higher plasma free carnitine in the initial hours post administration suggesting that L-carnitine L-tartrate is absorbed faster than the other L-carnitine compounds.
And this probably is the reason why L-carnitine L-tartrate (carnitine salt) is the form used by best brands like Scitec Nutrition and ON