Grapefruit

Like all citrus, grapefruit prompts your body to release stored histamine rather than delivering large amounts directly.

• Citrus as a liberator — citrus is consistently flagged across histamine intolerance resources as prompting the body to release its own stored histamine; the precise mechanism behind this effect is not fully established, but the observation is widely reported across major sensitivity lists

• Compared to other citrus — grapefruit sits in the high category alongside most other citrus; its well-known enzyme interactions relate to drug metabolism pathways that are distinct from histamine breakdown, so it is not clearly a step above other citrus specifically for histamine-sensitive people

Among citrus, lime tends to be reported as easier to tolerate in small amounts, though it's still worth caution.