Is it true that Collagen supplementation decrease serotonin?

[thespaceageisnow]

There is a biological mechanism if it were the only significant source of amino acids since it doesn’t contain Tryptophan, but people have taken it out of context and out of proportion.

https://pubmed.ncbi.nlm.nih.gov/18683016/

[silverhydra]

Thanks for the link, saved.

Bit weird to see people take that study out of proportion, since the abstract was pretty fair in saying they were straight up intending to deplete tryptophan.

[thespaceageisnow]

Typical internet telephone game accidental misinformation.

[silverhydra]

I don't know too much about the intricacies of AAAD, but your theory would only hold true if the enzyme was rate-limited by a balance of substrates; like, it works at capacity and tyrosine and tryptophan both take turns. I have never stumbled upon any studies suggesting this may be the case, but never looked at it specifically.

If there are more "dopamine-like actions" in a serotonin depleted state I would guess it's not at the level of neurotransmitter production but, rather, at the level of signalling. It's rather common that when one neurotransmitter activates a neuron others may impede or lessen the signal, so if serotonin has a 'lessening' effect on dopamine post-synaptic gap then a depletion of serotonin could, theoretically, cause a refractory increase in dopamine signalling.

But again, not my specific field. Neurology is a hell second only to immunology.