Carbohydrate rich foods are often the worst offenders.
Most gas results from sugars and starches. Colonies
of harmless bacteria in the colon eat the carbohydrates,
giving off the by-products hydrogen, carbon dioxide
and methane in some people. A special type
of sugar called raffinose is found in beans and
in smaller amounts in some vegetables and grains.
The human body lacks the enzyme called alpha-galactosidase
to digest this sugar and so bacteria in the colon
have a feast.
Avoid the gas forming foods and then add back those
that are tolerated well. People vary in their reactions
to foods, so don't assume that what is "gassy" for
someone else will be "gassy" for you.