Buckwheat flour

Buckwheat flour is notable for nickel, oxalates, histamine and salicylate. Clear on tyramine, sucrose, FODMAPs, lactose, oligosaccharides, sorbitol, fructose and gluten.

Yes — buckwheat flour is high in nickel. Buckwheat flour keeps the whole seed, hull fragments and all, which is what gives it both its colour and its nickel. The lighter the flour, the less of both.

Yes — buckwheat flour is high in oxalates. Buckwheat flour is milled from the whole groat, hull fragments included, and the hull is where the oxalate concentrates - which is why the flour measures above the cooked groat. It is a staple of gluten-free baking, so the exposure is daily rather than occasional.

Buckwheat flour contains only low levels of histamine. Buckwheat flour is a dry milled product, and dryness is what keeps it low - amine-producing bacteria need moisture. It is what the flour becomes that matters: a long-fermented dough is a different question from the flour it started as.

Buckwheat flour contains only low levels of salicylate. Milled buckwheat, and milling does not concentrate salicylate the way drying a herb does — the flour stays as low as the grain. Amounts vary by brand and recipe, so always check the label of the exact product.