I am trying to determine if one needs to use PS supplements. These are
expenisve and I would rather avoid it if possible. It is medical dogma
that PS helps maintain or improve cogntive functions, at least among
senior citizens. All reserach into the subject matter seems to have
dealt with elderly people.  I'm middle age but might as well start
sooner than later.

After Googling "phosphatidylserine dietary source",
"phosphatidylserine dietary intake", "phosphatidylserine quantity
food", "phosphatidylserine food source", "phosphatidylserine natural
source amount", etc. etc.,  only one of website provided any
quantitative values:

http://www.degussa-bioactives.com/bioactives/html/e/products/brands/lecips/phosp
hat_dietary.htm

Credibility-wise, it is a commerical website and like other commerical
sites, they do try to convince you to buy PS supplements (look at
their Nutritional Undersupply of PS link for example). But it does
have a link to the source of that information on the table ("62"
beside  where it says PS content in different foods). It  leads to a
book, S.W. Souci, E. Fachmann, H. Kraut. Food Composition and
Nutrition Tables 2000. I have not seen this book but at first seems
like a credible source that physicians and scientitsts would rely on.
Presumeably the authors of this reference book had compiled the lists
according to credible sources.

Now, if indeed PS daily requirement is around 300 mg/day according to
may sources (no RDA established since PS is not considered essential),
then eating 200 g of mackeral (less than 1/2 pound, I think that is
about half the fish) will supply over 900 mg or 3 days worth by itself
according to that table! Not only that, it's an animal source like the
bovine brain derived PS used in medical research but which not
available commerically due to (mad cow disease concerns. Commerical
sources supply  soy dervied PS which apparantely may not be as
effecitve (eg. http://www.raysahelian.com/ps.html Phosphatidylserine
by Ray Sahelian, MD : PS or BS??). I suppose you can't eat mackeral,
pickled herring, those eel sushi, organ meats all the time but it does
seem to me that getting a few hundred mg of PS a day through regular
food, albeit certain kinds, is achievable without the need to buy
supplements.

Any thoughts?