I just found annother tryptophan article, which covers my
old tryptophan/serotonin topic in an easy to understand way:
http://smart-drugs.net/ias-tryptophan-article.htm

There's also described the reason why high protein diets
- which are very high in TRP- are unsuited to provide TRP for the brain,
where it is needed to counterbalance "over-arousal, fear, anger, tension,
aggression, violence, obsessive-compulsive actions, over-eating (especially
carbohydrates), anxiety and sleep disturbances."

Interesting for low-carb eaters may be that stress hormones
increase the breakdown of TRP, hence even more decrease the availability of
TRP to the brain.
("Cortisol, produced by the
adrenal glands, is the "state of siege" stress hormone. It is released
in response to unremitting chronic stress, which we can neither fight
against, nor flee from." )
Stress hormones are elevated in low-carbing to produce enough
gluconeogenesis (glucose from protein).
The above may be an explanation for the "flight or fight" feeling
some low-carbers have reported.

A countermeasure may be to eat TRP at a time when no protein was eaten (for
1 or 2 hours). Pure TRP is banned in the US as far as I know.

But there are food items which are *relative* high in TRP.
I once made a list of items, relative high in TRP:
http://www.geocities.com/paleolix/TRY_PROTEIN_RATIO.html

Here's a paleolithic diet point of view:
Wild protein sources appear to be higher in TRP as the usual "farmed beef
muscle". Some organs as well (pig pancreas, whoever finds this appealing).

I vote for tahin (sesame) or pumpkin seeds.

regards

Amadeus S.