Vegetables and nickel: 61 foods rated

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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

Black beans take nickel up through urease like every legume. Canned and rinsed they measure lower than dried and boiled at home, because some of the metal leaves with the cooking liquid.

• Flyvholm M-A et al., Z Lebensm Unters Forsch 179 (1984) 427-431, nickel content of food and estimates of dietary intake

Dulse is a red seaweed eaten as a snack and a seasoning, which means it is eaten dry. Everything the plant took from the water is still in it, minus the water. Seaweed is the reason nickel is asked about here at all: it concentrates trace elements from seawater, and the review behind this level is about exactly that load in seaweed and in the ingredients made from it.

• Bouga M. & Combet E., Foods 4 (2015) 240-253, trace elements and contaminants in seaweed and seaweed-containing foods

Edamame is the soybean harvested green, before it has finished loading. It carries less nickel than the mature bean and rather more than a green vegetable - which is what it is usually mistaken for.

• Noel L et al., Food Chemistry 132 (2012) 1502-1513, second French Total Diet Study, nickel among nine trace elements

Kimchi is cabbage, garlic, ginger and chilli - a stack of vegetables and ground spices, each contributing a little. Fermentation concentrates nothing here; the metal was in the plants before the jar was sealed. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

Pinto beans carry the legume nickel load. They are usually cooked long and slow, and long acidic cooking in a stainless pot adds a little more from the pan than the bean brought.

• Flyvholm M-A et al., Z Lebensm Unters Forsch 179 (1984) 427-431, nickel content of food and estimates of dietary intake

Rocket takes up metals from the soil the way most fast-growing leaves do, and it is eaten raw and by the handful. Washing removes soil, not what the plant absorbed. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

Seaweed concentrates whatever the seawater carries - that is the same property that makes it rich in iodine. Dried sheets and flakes are the concentrated form, and a few grams go a long way in both directions. Seaweed is the reason nickel is asked about here at all: it concentrates trace elements from seawater, and the review behind this level is about exactly that load in seaweed and in the ingredients made from it.

• Bouga M. & Combet E., Foods 4 (2015) 240-253, trace elements and contaminants in seaweed and seaweed-containing foods

Artichoke is low in nickel despite being a thistle grown in heavy soil. Most of the plant is discarded - it is the heart and the leaf bases that are eaten. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

Artichoke hearts are the tenderest part of the plant, and they are usually sold in jars or cans. The brine is the thing to watch here - acid in contact with metal for months pulls a little out of the container. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

Cassava is a root that stays in the ground for a year or more, but the processing it must have - peeling, soaking, cooking - to remove its cyanogenic compounds takes soluble minerals out with them. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

Fennel is low in nickel. The bulb grows above the soil line rather than in it, which limits what it can take up compared with a true root. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

Parsnip is a true root and sits in the soil all season, which is why it carries more than the leaves above it. It is still low, because the metal concentrates in the skin that gets peeled away. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

Sauerkraut is cabbage and salt, and cabbage is a low-nickel vegetable. Fermentation produces acid, and acid in a metal vessel would matter - which is why traditional kraut is made in stone or glass. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

Shallots grow as bulbs just under the surface. Like onions and garlic they take up little nickel, and the papery outer layers that hold the most are the ones thrown away. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

Taro is a tuber, and tubers take up more than leaves - but taro is always cooked in plenty of water, and part of what it held leaves with the water. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables

White asparagus is grown covered so it never greens, which means it develops entirely underground. That is more soil contact than green asparagus gets, and it is usually sold canned besides. 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.

• Guerra F. et al., Scientia Agricola 69:1 (2012) 54-60, heavy metals in vegetables