Spices and oxalates: 69 foods rated

Green cardamom is the highest-oxalate spice of the ten measured, and not by a little: 4,014 mg per 100 g of total oxalate, of which 3,977 is soluble - almost all of it in the absorbable form. What keeps the eaten dose small is the pod: three or four in a rice dish, usually lifted out before serving, so most of that 100 g figure never reaches the plate. Ground cardamom in a spice mix is the form where the number starts to count.

• Ghosh Das S & Savage GP, Plant Foods Hum Nutr 67 (2012), total and soluble oxalate of ten Indian spices
• Noonan SC & Savage GP, Asia Pac J Clin Nutr 8 (1999)

Licorice root is high in oxalate, which is easy to miss because it arrives as a sweet rather than a vegetable. Roots concentrate more than the parts above ground, and this one is chewed slowly and in quantity.

• Noonan S.C. & Savage G.P., Asia Pac J Clin Nutr 8:1 (1999) 64-74, oxalate content of foods and its effect on humans

Turmeric is not the highest-oxalate spice - cardamom is, by a wide margin - but it carries the form that matters: 91 per cent of its oxalate is SOLUBLE, against 6 per cent in cinnamon, and soluble is the fraction that gets absorbed. A teaspoon in a curry is still a teaspoon. What changed the exposure is the supplement aisle: turmeric is now taken in gram doses, daily, which is a different food from a seasoning.

• Ghosh Das S & Savage GP, Plant Foods Hum Nutr 67 (2012), total and soluble oxalate of ten Indian spices
• Noonan SC & Savage GP, Asia Pac J Clin Nutr 8 (1999)

Capers are flower buds preserved in brine or salt, and both cures draw water out of the bud - taking soluble oxalate with it. Rinsing salted capers before use, which the recipe asks for anyway, takes a little more.

• Chai W & Liebman M, J Agric Food Chem 53 (2005), 3027-3030, which measured 30-87 % loss of soluble oxalate on boiling against 5-53 % on steaming
• Noonan SC & Savage GP, Asia Pac J Clin Nutr 8 (1999)

Curry powder is a blend, and its oxalate comes mostly from the turmeric that gives it the colour - the more yellow the powder, the more turmeric, and the more oxalate. It is used by the tablespoon rather than the pinch, which is what separates it from a single spice.

• Ghosh Das S et al., Plant Foods Hum Nutr 67 (2012), total and soluble oxalate of Indian spices
• Ramasastri B et al., Qual Plant Plant Foods Hum Nutr 33 (1983)

White pepper is the same berry as black with the outer layer removed, and removing that layer takes some of the oxalate with it - so white measures below black. Both are used in quantities too small to matter unless the diet is otherwise very restricted.

• Ghosh Das S et al., Plant Foods Hum Nutr 67 (2012), total and soluble oxalate of Indian spices
• Ramasastri B et al., Qual Plant Plant Foods Hum Nutr 33 (1983)

Allspice is a dried berry ground whole, so a spoonful of it is the entire fruit and not a leaf or a seed coat. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Cinnamon carries oxalate, which the sweetness and the small spoon both disguise. It is one of the ten spices Ghosh Das measured, and what makes it gentler than the amount suggests is the FORM — only 6 per cent of its oxalate is soluble, against 91 per cent in turmeric, and soluble is the fraction the body takes up. No total figure for cinnamon is published, only that proportion.

• Ghosh Das S & Savage GP, J Food Compos Anal 25 (2012), total and soluble oxalate content of Indian spices

Coriander seed goes into a curry paste by the teaspoon and into a dry rub by the tablespoon, and that difference decides this axis more than the seed does. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Elderflower is steeped and never eaten, and an infusion transfers only the soluble oxalate of what it holds. Its usual form is cordial rather than tea, though: the flowers steep for a day or two and the liquid is what is kept, so whatever dissolved goes into the bottle instead of the bin.

Garam masala is a blend, and no blend was assayed: what is established is the range its possible parts cover, not a figure for the jar. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Garlic powder is dehydrated garlic, so whatever the clove carries is concentrated by the water it lost - and it is still used by the half-teaspoon. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Garlic salt is garlic powder cut with salt, so the garlic fraction is smaller again than in the powder before the portion divides it a second time. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Ginger powder is the dried rhizome, more concentrated by weight than the fresh root and used in proportionately smaller amounts. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Herbes de Provence is a European leaf blend - thyme, rosemary, savory, oregano - and the oxalate assay behind this axis covered Indian spices, none of them a leaf blend. Nobody eats a hundred grams of a spice. The level here reflects the portion, and both facts are true at once: concentrated in the jar, negligible on the plate.

Hibiscus flowers are steeped and never eaten, and an infusion transfers only the soluble oxalate of what they hold. What sets hibiscus apart is the volume: karkadé is drunk cold by the jug rather than by the cup, and the dose follows the litre.

Italian seasoning is dried leaf herbs rather than seeds, barks or rhizomes, which is a different part of a different set of plants from anything that was assayed. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Mustard as a condiment is seed, vinegar and water, so the seed's own content is diluted before the portion divides it again. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Nutmeg is the lowest of the ten Indian spices Ghosh Das measured — and lowest still meant 194 mg per 100 g of total oxalate, with 41 of that in the soluble form the body can absorb. Against green cardamom's 4,014 that is genuinely small. The figure is for the ground spice as sold; a béchamel takes a grating.

• Ghosh Das S & Savage GP, J Food Compos Anal 25 (2012), total and soluble oxalate content of Indian spices

Onion powder is dehydrated onion, and the onion is not a notable oxalate food to begin with - drying concentrates what little there is. Nobody eats a hundred grams of a spice. The level here reflects the portion, and both facts are true at once: concentrated in the jar, negligible on the plate.

Ras el hanout can hold a dozen spices or more and no two makers agree on which, so there is no single composition for it to have. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Rose petals are steeped and never eaten, and an infusion transfers only the soluble oxalate of what they hold. Rose water goes a step further: it is distilled, and oxalate does not travel with the steam, so that water carries none of it at all.

Smoked paprika is dried, smoked capsicum, and its distinguishing feature here is the portion: a teaspoon colours a whole pan. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Star anise is usually infused whole and lifted out, so most of what the pod contains never reaches the plate at all. Nobody eats a hundred grams of a spice. The level here reflects the portion: the oxalate is concentrated in the jar and negligible on the plate, and both are true at once.

Sumac is the dried, ground drupe of Rhus coriaria, a Levantine spice that appears in no published oxalate assay. Nobody eats a hundred grams of a spice. The level here reflects the portion, and both facts are true at once: concentrated in the jar, negligible on the plate.

Verbena is a LEAF and not a flower — lemon verbena is picked for its leaves — and it is steeped rather than eaten, so an infusion transfers only the soluble oxalate of what it holds. One cup at the end of a meal is the usual form, and the leaves stay in the pot.