Olives may be low histamine. The disagreement here comes thanks to the many different formats in which olives are sold around the world. Fresh olives technically qualify as low histamine, but almost all the olives sold internationally are fermented or otherwise cured, increasing the histamine content beyond tolerable levels. This makes things confusing, because olive oil is widely considered to be low histamine, and can even help with DAO production. But unless you have access to fresh-off-the-tree olives, you probably want to steer clear of olives until you’re no longer dealing with histamine issues.