Other names Fibroblast Growth Loop, FGL Peptide, Pentadecapeptide FGL, EVYVVAENQQGKSKA, HA-FGL, Hyaluronate-FGL, FGL(L)
FGL is a research chemical and synthetic peptide that mimics the function of Neural cell adhesion molecule. NCAM is present naturally in the brains of every single living human on this planet and plays a role in neurite outgrowth and synaptogenesis, to neural mechanisms linked to cognitive functioning. Some evidence suggests the use of FGL is effective for improving learning and memory. But how strong is this evidence? And is this drug safe? Read on to find out what the science says about the risks and cognitive benefits of FGL.
Read about the effects of FGL in relation to the amount of evidence we've found
FGL for improved learning and memory
The lack of evidence on the efficacy of FGL entails it is impossible to know what its effects on cognition are.
Because of the lack of research on FGL, we never recommend that people use it.
But we do recommend that people learn about it because it is one of the most special (in mechanisms) but underresearched nootropics out there.
So, for educational purposes, let's dive into the science of the cognitive effects of FGL, as far as they are known.
The only science that exists on the effects of FGL for cognitive enhancement comes from animal studies.
In one study, rats completed two memory and learning tasks, fear conditioning and the water maze learning task.  FGL improved spatial memory and fear learning when administered intracerebroventricularly in rats. It was also found that FGL had no effects on emotional behavior and locomotion, so the learning and memory benefits found could not be due to such effects.
It is far from obvious that such beneficial effects would occur in humans. For one thing, the route of administration included injection into the brains of these rats.  This is not practical in humans, but if oral administration would have similar benefits, it may be best to use FGL just after learning something, since it was found that it enhanced the process of memory consolidation and recall of the learned information 2-4 weeks after training.
The learning and memory benefits were found 24h after the training event and persisted 14 days (spatial learning task) and 28 days (fear conditioning task).
The authors of the study concluded:
"Although a proactive effect on retrieval cannot be excluded, the pattern of effects favors the view that FGL affected memory consolidation processes occurring in the hippocampus." 
However, in one version of the fear conditioning task, FGL only improved memory after 28 days, but not after 24h or 14 days.  It is not known why the peptide had such effects. It could be that the effect that was found was a false positive and that it didn't actually improve this specific aspect of memory after 28 days. But considering its known mechanism of action, it is plausible that long term brain changes are to thank for these potential long term memory benefits. It could also be that the animals in the control group remembered the fear-inducing stimuli well after 24h and 14 days and that this was the reason why a potential memory consolidation enhancement was found between the FGL group and the control group only after 28 days.
The study authors also concluded that the peptide appears to have the ability to facilitate behavioral flexibility and subsequent learning processes.
It was also found in another rat study that FGL improved spatial learning. 
The legality and side effects of FGL
Frequently asked questions about FGL
Studies conducted on the effects of FGL in healthy humans
Last updated Saturday, June 10, 2023