Spinach

Spinach is the one leafy green consistently high in nickel: it takes up metals from the soil readily, which is also why it is discussed for cadmium and oxalates. Cooking does not remove it. The nickel here follows a survey of heavy metals in VEGETABLES. A vegetable takes up what its soil holds, so a figure of this kind describes the growing region as much as the plant.

Spinach is the highest-oxalate leaf in ordinary use, and it has been measured directly against kale for exactly this reason: kale's iron is absorbed and spinach's is not, because spinach's own oxalate locks it up. The same binding works for you at the table - spinach with cheese or yoghurt is a different exposure from spinach alone. Boiling and draining removes a real share; wilting in the pan removes none. Jaeger is the mechanism behind that: only the SOLUBLE form of oxalate can be absorbed, and how much is soluble depends on pH and on the calcium and magnesium present — which is why calcium eaten in the same meal lowers what reaches the blood. It is a review and a model, publishing no oxalate figure for any food, and it says nothing about the oxalate the body makes itself. How much of this reaches the urine was measured rather than assumed: on controlled diets, dietary oxalate accounted for 24 to 42 per cent of urinary oxalate — well above the 10 to 20 per cent believed before — and cutting the calcium of a 250 mg oxalate diet from 1,002 to 391 mg raised urinary oxalate by 28 per cent, taking the dietary share to 53. The calcium eaten alongside is most of the answer.

Spinach is one of the few vegetables that genuinely carries histamine, and it climbs quickly once picked or left cooked in the fridge. Buy it fresh, cook it the same day, and do not reheat leftovers — that is where most reactions come from.

Spinach is sold pre-washed and bagged more often than any other leaf, and it wilts faster than most - a bag that has gone slimy at the bottom is bacterial growth you can see, and those bacteria are what build tyramine. Fresh loose spinach cooked the day it is bought is a different entry from the bag at the back of the fridge.

Low in salicylate, which is worth stating plainly because spinach is high on several others — oxalate especially. One low rating is not a general clearance.

Spinach is genuinely low: a leaf eaten in quantity but low. Vegetables split on this axis by which organ you eat - storage organs like onion and garlic hoard fructans, while leaves, stems and young shoots do not. Knowing which part of the plant is on the plate answers most of the question.