Koji

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

Koji contains only low levels of histamine. Koji is the exception in this whole group: it is not a purified compound but a living mould culture, and it is the starter that makes miso, soy sauce and sake. The koji itself is low; what it is used to make is not. Low in histamine, that is: it is the months of fermentation that follow, not the starter itself, that build the amines in miso and soy sauce.

Koji contains only low levels of gluten. Koji is a mould grown on a grain, and which grain decides the answer: rice koji is gluten-free, barley koji is not. The same word covers both across miso, soy sauce and sake. What a label may promise is set by regulation and not by a recipe: 828/2014 allows "gluten-free" at or below 20 mg/kg, sets the conditions oats must meet, and admits wheat-derived ingredients in a gluten-free food provided the finished product stays under that ceiling. It measures nothing — it says what a food must meet to carry the claim, which is exactly what a food name cannot tell you.

Koji contains only low levels of tyramine. Koji is a living mould culture, and it is the starter behind miso, soy sauce and sake - the soy ferments at the top of this axis. The koji itself is low; it is what it is used to make, over months, that is not. Fermented soy is where this axis is decided, and it was measured as such: the level follows a survey of biologically active amines in FERMENTED SOY PRODUCTS. The fermentation is the variable - the same bean unfermented is a different food here. Amounts vary by brand and recipe, so always check the label of the exact product.