[CliffordK]

Prunes are ripening in my orchard.
And I just love prunes & plums.

But, I'm sitting here (alone) wondering why the prunes cause so much gas.

One note on the web suggested it was fructose, but the body can break down and digest fructose relatively easily, and prunes are worse than other types of fruit so I find that explanation doubtful.

[chris]

Prunes are rich in soluble fibre; this ends up in the large bowel where it is responsible for the motility benefit associated with said foodstuff. But while there it is also fodder for the large bowel microflora, which have the enzymic knives and forks we lack to degrade the fibre, producing in the process the gas you complain of...

[CliffordK]

Thanks,
That makes a lot of sense.
Just like wheat bran isn't digested, and can both add to bulk, as well as causing gas.

[chris]

That's right; it soluble because it binds water, acting as a bulk-forming laxative. But unlike us, the microbes can break it down, producing gaseous products in the process...