Soy protein

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

Yes — Soy protein is high in nickel. Soy protein isolate concentrates the bean's protein, and the nickel comes with it. It hides in bars, shakes and meat substitutes where nobody reads the portion as a serving of soy.

Soy protein contains only low levels of FODMAPs. Soy protein comes from a plant that carries the raffinose family, which is why the ingredient alarms people - but the washing and precipitation that isolate the protein are exactly what strips the galacto-oligosaccharides out. They leave with the water. The isolate is low where the whole soybean is high. A protein isolate is not its source plant on this axis. The galacto-oligosaccharides sit in the whole bean or pea, and isolating the protein is precisely the step that leaves them behind - which is why this reads low where the plant it came from does not.

Soy protein contains only low levels of histamine. Soy protein isolate is washed and dried from the bean with no fermentation step, and the washing removes the free amino acids amines would have been built from.

Soy protein contains only low levels of oligosaccharides. Soy protein isolate is the protein separated from everything else in the bean, and the GOS are part of the everything else - they leave in the water. Protein extraction is one of the most effective ways to strip a legume of its chains. Amounts vary by brand and recipe, so always check the label of the exact product.