The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 42

51. What is the difference between mast cell activation syndrome and histamine intolerance?

Histamine intolerance is not widely accepted by the mainstream medical establishment. I haven’t been able to find much about it in the way of peer reviewed literature. That said, it doesn’t seem ridiculous to me. It feels plausible, I just haven’t seen convincing evidence of that yet.

Histamine intolerance is when a patient has symptoms from ingesting something that has a lot of histamine in it, that causes the body to release histamine, or that interferes with the body’s ability to break down histamine. In histamine intolerance, the problem is what is being put into your body rather your body itself. The problem is external, not internal.

Mast cell activation syndrome is when a patient’s mast cells are fundamentally dysfunctional. The problem is internal, not external. There is no evidence at this point that patients with MCAS can’t break down histamine normally with enough time, there’s just so much of it that it takes longer.

Many patients with MCAS (and other mast cell diseases) often have symptoms when they ingest something that has a lot of histamine in it or that causes the body to release histamine. There are two theoretical ways in which ingestion of histamine can cause symptoms: either the histamine released/ingested makes it way to other parts of the body and causes symptoms there directly; or, the histamine released/ingested makes mast cells release more histamine.

Regardless of exactly what is happening, patients with MCAS and histamine intolerance can have identical symptoms to ingesting a trigger. Importantly, MCAS patients may have histamine symptoms from lots of other things, not just ingesting something.

Histamine intolerance is much more commonly discussed in holistic and alternative medicine groups, which is definitely not where my expertise is. If you are aware of some recent data on histamine intolerance, or if I have made a mistake in this post, please let me know so that I can correct it.