No, ketchup is not low histamine. Even banana ketchup isn’t low histamine, as both bananas and tomatoes should be avoided in the initial stages of an elimination diet for histamine intolerance. But beyond the tomatoes, ketchup can be problematic due to it’s high sugar content and abundance of preservatives. The highly-concentrated vinegar, umami, and, sweet flavors of ketchup are very alluring because they’re a glutamate bomb.
That means that it’s chock-full of excitatory glutamate, the same amino acid believed to be responsible for histamine activity when we consume caffeine. A sensitivity to glutamate is also thought to be the reason behind the migraines and headaches suffered by a small portion of the population after consuming monosodium glutamate (MSG). This means that ketchup and most other bottled condiments should be avoided in the first few months of a low histamine diet, and reintroduced alongside other high histamine foods.