Potato

Potato sits high here largely because of the skin: the oxalate is concentrated in it and just under it, so a jacket potato eaten whole and a peeled boiled one are not the same food on this axis. Boiling and pouring the water away is the lever that works, since the soluble fraction leaves with it, and peeling first removes most of what would have leached anyway. Cultivar does change the content, but no published measurement ranks red potatoes against white, and skin colour is not a reliable guide to cultivar.

Peeled white potato is reported at zero salicylate — one of the few foods that reaches nothing at all. The skin is where it is, so peeling is not optional here. How it is cooked moves the phenolic content, and this vegetable is one of the four that were measured. Deep frying and sautéing RAISED total phenols; both kinds of boiling lowered them. Frying in extra virgin olive oil also transfers the oil's own phenols into the food - oleuropein, hydroxytyrosol, tyrosol, pinoresinol - so the dish is not simply the vegetable. All the methods preserved or raised antioxidant capacity. These are PHENOLS in general, though: the study measured eighteen of them and salicylic acid is not the subject.

Potatoes are eaten cooked and fresh, and a fresh tuber has had no fermentation step — which is what this axis counts. The processed forms are where a question enters: crisps, dehydrated flakes and ready-made purées may carry sulfites, a separate sensitivity that travels with this one.

The potato sits at the bottom of the measured range rather than by assumption: Biesiekierski quantified fructans per portion as eaten across fifty-five grains, breads, cereals and pulses, and potato chips came out at 0.05 grams a portion — against couscous at 1.12, the highest of the fifty-five. Rice was the only thing lower, at zero. The potato is not where a FODMAP load comes from; what is done to it can be, and the note on any dressed or creamed version is the one to read.