Like all peptides, it's vulnerable to enzymatic degradation when exposed to the gastrointestinal (GI) tract
On the contrary, alterations in the C-terminal seemed less critical for activity and for instance a deletion of the C-terminal phenylalanine residue of 1 had only a minor impact and the binding affinity was essentially maintained (Sardinia et al., 1993
Nikkhah Bodagh, M., Maleki, I., & Hekmatdoost, A
When using a high-bioavailability format like Liposomal Glutathione, some people notice improvements in energy and skin clarity within 4 to 8 weeks of consistent use
The effects of carnitine on bone health in humans are unknown
Kinetic analysis of L-carnitine uptake by the choroid plexus [PMID: 1933300] Laboratory literature summary: Kinetic analysis of L-carnitine uptake by the choroid plexus