Hello
I really appreciate your concern for your father in law.
abdominal distension or excess gas in the abdomen might be related to
Aerophagia ( swallowing of air ), us elf carbonated drinks, smoking and ill fitted denture,
indigestion or acid peptic disease
Constipation could be a contributory factor for abdominal distension
Please follow these guidelines
Give him some laxatives or stool softeners like
liquid paraffin or lactulose which is also available over the counter to relieve acute constipation
Give plenty of fresh fruits and vegetables it
dietary fiber supplements
Ask him to take lots of water 3 to 4 liters a day.
Ask him to drink lukewarm water on getting up in the morning and take a small walk
Avoid fatty fried spicy and junk food or carbonated drinks
Hope this answers your question
Best wishes