The following might well apply to other brands of crisps, and to other foods, as well, and probably does, even though the only things in my possession that are a problem, are Walker’s crisps.
If you have a heart problem and are taking an angiotensin II receptor antagonist drug, like Losartan (Cozaar in the US), you should have been told to not use salt substitutes, as they contain potassium, or take potassium supplements.
The reason for this is that Losartan and its kin cause potassium to be concentrated in the body, and potassium can kill if levels get high enough – simply put, it can stop your heart.
I spotted the potassium chloride in Walker’s Squares (it’s in other flavours, too, but not all of them). I use to love these back when they were called Smith’s Square-shaped Crisps (think that’s right), but the Walker’s version makes me incredibly ill, which is why I was reading the label.
The main undesirable is the preservative, sodium hydrogen sulphite, also known as sodium bisulphite, which, while routinely used as a food additive, has been known t to cause deaths when used in excess, and is banned from use on raw foods in the US after 13 people died. Whether it’s used to excess here I couldn’t say, but it sure as hell did me a power of no good, just one 25g bag causing my stomach to blow up like a balloon, and I’m still gurgling and farting like an explosion in a distillery 24 hours later.
But to return to the potassium chloride, I no longer take Losartan, but those of you who do, or take related drugs, are clearly going to have do an awful lot of label reading if your diet is high in processed foods. It’s there in the crisps, of course, simply to pander to the current anti-salt paranoia, which is frankly bullshit. No normal person would eat enough crisps for salt to ever be a problem.
Likewise a normal person with heart problems wouldn’t eat crisps in bulk either, but if potassium chloride is in other foods, it could build up. This is a particular danger for those taking potassium-sparing diuretics.
I’ve just had a look through my store-cupboard, and it’s in nothing else I’ve got, but it could, possibly, be hidden under the catch-all “Flavourings,” though I suspect it shouldn’t be, legally. Stock cubes are worth checking too – anything, in fact, that’s traditionally high in salt.