I have read that exposure to hydrochloric acid in the stomach can make some
fats into trans-fats.

Any fats subjected to abuse such as heat or pressure can break down
into trans fats. It is probable that trace amounts of trans fats exist
in any food containing fat.

The major problem is that hydrogenation produces large quantities of
trans fats. It is possible that pasteurization and homogenization also
affect trans-fat levels.

Keep using butter. Avoid anything hydrogenated, and prefer oils that
are explicitly labeled "cold pressed".

Regards,
Len.

Naturally occuring fats have some of every type of fatty acid.  It's
a matter of amounts.  Look hard enough for anything and you'll find
a trace.

No need to go crazy avoiding every possible microgram of whatever in
naturally occuring foods.  Avoid the stuff that has it bt the gram
not by the microgram.