Elvis Bueller

Potato skin carries up to 10 times the poison of the flesh, and the advice for forty years has been to leave it on for the goodness. The poison is solanine, with its twin chaconine. The potato makes both to stop being eaten, and it puts them where the attack comes from: the peel, the eyes, the sprouts, and anywhere the tuber has gone green. Light makes more of it. Storage makes more of it. Boiling does not touch it. In 1979, 78 boys at a London school ate a lunch of potatoes that had sat in a sack over the summer holiday. Seventeen went to hospital, 3 of them seriously ill, and the report in the medical journal traced it to the glycoalkaloids in the skin. Germany's food safety institute is blunter than any British packet. Small children should not eat potatoes with the skin on. Green or sprouting potatoes go in the bin. The cooking water is discarded, because the poison the boil pulls out is in the pan, not in the drain. The legal limit is 200 milligrams a kilo, and the institute wants it halved. Then the fads that put the peel back on. The jacket potato, skin and all, for the fibre. The roasted skin-on wedges. The cook-and-cool trick for resistant starch, done with the skins left on because the recipe said so. Every one of them concentrates the one part of the plant it built to hurt you. A grandmother peeled every potato in this country until about 1985, cut out the eyes and threw the green ones away, and was told by a generation of food writers that she had been wasting the goodness. The nightshade the potato belongs to is the same family as deadly nightshade. The tuber has never forgotten it. The packet says leave the skin on.