Since diagnosis, I was including bran (not bran cereal) with my breakfast and all went well. Ahem.
Whilst away for a protracted period, I couldn't source bran for weeks, but, as a revelation to me, I found my issues were completely resolved by upping my fluids further. I would have bet my pocket money I was drinking enough, because I consciously drink water, but clearly not.
Since then, I've been better than ever and haven't bought any bran. Just a thought.