Do you have a dumb question that you're kind of embarrassed to ask in the main thread? Is there something you're just not sure about?
This is your opportunity to ask questions. No question too simple or too silly.
Culture war topics are accepted, and proposals for a better intro post are appreciated.
Jump in the discussion.
No email address required.
Notes -
No, the original thought on how tryptophan crosses BBB was extremely murky, because it a lesser competitor to other LNAAs. So we knew that we could toggle greater crossing by reducing the competitors (see wurtman lab) by flushing LNAA to to muscle via pure carbohydrate insulin spike (tryptophan stays bound to albumin). We also knew exercise increases serotonin synthesis, and tryptophan depletion decreases this. What was relatively new, I believe from 2015-2018, was that tryptophan selectively unbinds with albumin at the BBB, so the albumin-bound tryptophan will release uniquely there. It’s an example of how we know little about the mechanisms of serotonin. There’s also controversy about whether how important T:LNAA ratio is to sum total T, the mice studies are not clear. Maybe I’ll dig up the metastudy I read a bit ago
Re: serotonin, I don’t actually disagree, but the consensus I read was that “more serotonin” does not decrease depression.
https://www.nature.com/articles/s41380-022-01661-0
The distinction I would make is that these studies are flawed and there is actually very limited ways to organically increase serotonin production in the brain: increasing dietary T:LNAA ratio (also found to be widely healthful per a large Japanese population cohort study, on things like sleep); using fruit to flush LNAA muscle tissue; or exercise (somehow; possibly by using up LNAAs).
There are some other interesting things about this: certain human domesticated crops have higher tryptophan than wild-type; there’s a possibility fruit consumption in humans is kind of evolved to increase serotonin, and certain fruit actually have serotonin itself, like kiwi and strawberry, which is fascinating
Thanks Cafe, that is a great comment, exactly the kind of informatively rich comments the motte desperately lacks.
I will give you a proper answer tomorrow but when I said that tryptophan cross the BBB, I actually meant about 5 hydroxy tryptophan (5htp), which has good bioavailability, cross the BBB and bypass the rate limiting enzyme conversion of L-tryptophan to 5htp (which itself downstream will again be converted to serotonin in a rate limited manner)
1998:
https://pubmed.ncbi.nlm.nih.gov/9727088/
More options
Context Copy link
More options
Context Copy link