Apart from chicory root, which I never see in the market, and Jerusalem artichokes, the only vegetable with a taste I really dislike, I can eat all of the listed foods with impunity.
This is a list of fructan containing food - it is not only purified inulin/FOS that caused me problems. All of the concentrated prebiotics I tried needed to be treated with great caution.
This is a list of fructan containing food - it is not only purified inulin/FOS that caused me problems. All of the concentrated prebiotics I tried needed to be treated with great caution.
If you take leeks for example, these contain 3 to 10% inulin (ref: here). A couple of large leeks weighs around 400 grams, so if you were to eat two leeks, you would be getting 12 to 40 grams of inulin.
That's quite a bit of inulin, probably more than you would take if you were supplementing with pure inulin power. I take inulin daily, and usually take 2 heaped teaspoons of pure inulin power, which is around 10 grams.
One explanation might be that pure inulin powder is more accessible to the gut bacteria than inulin found in food items. However, this is just guess. The whole thing seems a bit of a mystery.