Blood sausage

Blood sausage combines blood, organ meats, and processing — all factors that push histamine levels up.

• Organ content — organ meats tend to accumulate biogenic amines more rapidly than muscle meat, especially once processed; blood adds further complexity, though how quickly it accumulates histamine compared to muscle meat is less clearly characterized

• Processing and storage — like most sausages, it's cured, cooked in casings, and stored for extended periods, all of which allow histamine to build further

This one tends to sit near the top of the processed meat concern list.