Rye

Rye as a plain cooked grain isn't a significant histamine source, but rye is rarely eaten that way — it's most commonly found in fermented or long-leavened bread products.

• Fermentation process — rye is often used in long fermentation and sourdough baking, which are the processes associated with greater histamine accumulation in bread; the histamine level in any rye product is largely a function of how long and how extensively it was fermented.

• Crispbreads and crackers — plain rye crispbreads made without sourdough are a lower-fermentation option than rye sourdough bread, offering a more predictable middle ground.

If you're eating rye regularly, the form it comes in — crispbread versus sourdough loaf — makes a meaningful difference.