Gelatin

Gelatin is produced by the partial breakdown of collagen from animal connective tissues, bones, and skin through a combination of acid or alkaline pre-treatment and prolonged heating, and it appears on several histamine intolerance lists as a moderate concern.

• Reported sensitivity — many people with histamine intolerance report reacting to gelatin; bacterial activity during the extended processing of animal connective tissue (before sterilization) is the most commonly cited candidate for histamine and biogenic amine accumulation in the final product, though whether this or something inherent in the protein itself drives reactions isn't definitively established

• Freshness matters less here — unlike fresh meat or fish, gelatin is a shelf-stable processed product, so the usual freshness rules for animal proteins don't apply in the same way

Using agar-agar or pectin as a setting agent is a common swap for those watching histamine.