One thing to remember as you get older - never trust a fart.

I found, a few years ago, that carbohydrates such as potatoes, rice and cereals give me the runs. Avoiding them solves the problem. I think that you just have to pay more attention to the signals your body gives out as you get older.

Mind you, that was useful to know after my recent hernia op - I avoided the constipation that seems to be a natural follow on from any op. for me by eating Kendall's chicken soup, which contained potatoes. Worked like a charm.