MTHFR is one of those topics that can send parents down a rabbit hole very quickly. A child has anxiety, allergies, ADHD symptoms, food sensitivities, a tongue-tie, a sacral dimple, or a “sugar bug” vein between the eyes, and suddenly the internet says: “It’s MTHFR.” While it may be MTHFR, the truth is far more nuanced and definitely less scary.

In clinical practice, however, patterns often emerge before the research fully catches up. One such pattern I observe is a striking overlap between individuals with MTHFR gene variants and symptoms of ADHD or ADD. To be clear: this is not yet a fully established causal relationship. But there is enough emerging evidence—and strong biochemical plausibility—to warrant a closer look.

Histamine and MTHFR are bound together for so many reasons. Histamine levels are affected by methylation, and histamine breakdown is methylation-dependent. Another big reason is that just like MTHFR, histamine has its fingers in so much more than just allergies.