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Read one chapter at a timeA medium potato with the skin on gives about 2 g of fibre and more potassium than a banana.
How you cook it matters more than the potato itself: boiled and fried are nutritionally different foods.
Cooked and then cooled, potato forms resistant starch, which behaves more like fibre.
Green or sprouted potatoes contain solanine. Throw them out rather than cutting the green off.
The potato reached Iran only about two hundred years ago, which makes it a stranger by the standards of a cuisine that has been arguing about rice for a thousand. It settled in completely. It lines the bottom of the rice pot for a golden tahdig, it's cut into matchsticks and fried over gheymeh, and it's pounded with the meat into the goosht-kubideh of abgoosht. No classical hakim wrote about it, and no modern Iranian kitchen runs without it.
Known to botanists as Solanum tuberosum.
The potato gets blamed for things that are really about oil and portion. Boiled, skin on, cooled and dressed, it's a cheap, filling, potassium-rich staple. Deep-fried into matchsticks, it's a garnish made of fat and starch. Both are Persian, and it's worth knowing which one is on your plate.
Potassium matters for blood pressure, and potatoes deliver more of it per serving than the fruit everyone quotes. They are soft, cheap and familiar, which counts for a lot when appetite and money are both limited. The caution runs the other way in advanced kidney disease, where potassium has to be restricted.
Cooked and cooled, it forms resistant starch that feeds gut bacteria.
Persian temperament: Cool & Moist (1st degree, by later attribution). Read as heavy by later Persian writers, which is why turmeric, cumin and sour flavours accompany it in practice.
The potato is absent from the classical Persian materia medica because it arrived too late for it. Later Persian writers slot it in as cool and moist and heavy, which is a reasonable reading of how a plate of it feels, and they recommend the warm spices Iranian cooks use with it anyway.
It was used: adopted in the nineteenth century as a cheap staple during grain shortages and mashed into abgoosht to stretch a small amount of lamb.
Used as the tahdig layer where bread or rice was scarce.
Potato tahdig is the piece everyone reaches for first, and in most families the argument over who gets it's older than the children having it. Abgoosht without mashed potato in the kubideh isn't abgoosht. For a vegetable with no ancient pedigree, it has bought itself a permanent seat.
Primary compounds
Resistant starch forms when cooked potato cools, and passes to the large intestine undigested.
Solanine is the natural defence compound that makes green potatoes bitter and unsafe.
Vitamin C survives boiling better with the skin on than off.
Potassium is the mineral potatoes carry in genuinely useful amounts.
Vitamins
Vitamin B6, Folate
Other notable constituents
Minerals: Magnesium, Manganese · Fiber: About 2 g per medium potato
Strong evidence
Higher potassium intake is associated with lower blood pressure and stroke risk.Strong evidence
Moderate evidence
Boiled potato ranked highest on the satiety (the feeling of being full) index of common foods.Moderate evidence
Cooking and cooling potato increases resistant starch content and lowers glycaemic response.Moderate evidence
With the main meal. Boiled and cooled if blood sugar is a concern.
Slice 5 mm thick and lay in oiled pot base for tahdig.
Cut into matchsticks and fry until golden for the gheymeh garnish.
Boil whole in the skin, cool, then dress with oil and herbs.
Pound with cooked lamb and chickpeas for goosht-kubideh.
Roast in chunks with turmeric, oil and salt.
Boil and mash for abgoosht.
Turmeric
Rubbed in before roasting, it colours the crust and cuts the flatness.
Split peas
Gheymeh below, fried potato above. Soft and crisp in one mouthful.
Yoghurt
Cool and sour against hot starch, and it slows the blood sugar rise a little.
Dried lime
Sourness is what keeps a potato-heavy stew from tasting dull.
Potassium restriction in advanced kidney disease.
Green skin or sprouts mean solanine. Discard the potato rather than trimming it, because the toxin spreads beyond the visible green.
Frying multiplies the calories several times over. The same potato can be a modest side or a heavy one depending only on the pan.
Potatoes raise blood glucose quickly, more so when mashed or baked. Cooling them after cooking blunts that, and so does eating them with protein or acid.
Green or sprouted tubers.
ACE inhibitors and ARBs — These raise potassium, and potatoes add more. Relevant only in large daily amounts or with kidney disease. (low concern)
Diabetes medicines — Potatoes raise blood glucose quickly. Doses timed to meals may need attention. (moderate concern)
Pregnancy and breastfeeding
Ordinary food in pregnancy, and the vitamin B6 is welcome for early nausea. Avoid green or sprouted tubers with more care than usual, since solanine is one of the few genuine plant toxins in the everyday kitchen.
Children
Almost universally accepted, which is its own kind of nutrition. Boiled and mashed with a little yoghurt beats fried for everyday eating, and the skin is worth keeping once a child can manage it.
Older adults
Soft, cheap and potassium-rich, and it needs no teeth. The exception is advanced kidney disease, where potassium is restricted and potatoes are often the first food a dietitian limits.
Spring
New potatoes, thin-skinned and waxy. Best boiled whole.
Summer
Boiled and cooled into salad, which suits both the heat and the starch.
Autumn
Main-crop potatoes arrive. Store them dark and cool.
Winter
Stews, abgoosht and tahdig. The season it earns its keep.
Is the skin worth eating?
Yes. Most of the fibre and a good share of the minerals sit in and just under it. Scrub rather than peel.
Does cooling really change the starch?
Yes. Some of the starch recrystallises into resistant starch, which is digested less and behaves more like fibre. Reheating keeps part of that effect.
Can I cut the green part off?
No. Solanine spreads through the tuber beyond what you can see. A green potato goes in the bin.
End of the Potato guide