Guinness

As a dark, nitrogen-conditioned stout, Guinness brings together several histamine-relevant factors that tend to make dark beers more commonly reported as problematic than lighter styles.

• Fermentation histamine and DAO blocking — Like all beers, Guinness accumulates histamine through fermentation, and the alcohol temporarily impairs DAO, meaning that histamine lingers rather than clearing normally

• Gluten overlap — The barley in Guinness means it contains gluten, and many people with histamine intolerance also report difficulty with gluten, which may add a further layer of sensitivity

Lighter, lower-fermentation drinks are generally reported as easier starting points if beer comparison is useful.