Hi Mike in Havana,
The answer to your question about bran and gas is no, it is not known to
cause gas. (Cconstipation, yes, but gas, no).
But large amounts of cruciferous vegtables, such as broccoli or cabbage,
can cause gas. Sometimes it's just a matter of the body needing time to
adjust, but if it persists, it probably means you need something like
"Beano" to neutralize the gas-forming enzymes that your body is unable to
handle very well.
But, if you can't get something as basic as whole wheat flour in Havana,
you probably can't get Beano, which is available in just about any drug or
discount store in the U.S..
Harry