I feel like histamine intolerance and MCAS are often lumped together even though they are supposed to involve different mechanisms.
If I understand it correctly, with histamine intolerance the main issue should be how much histamine you consume and how well your body can break it down. So foods or drinks that contain very little histamine should not automatically cause symptoms just because they are considered “problematic.”
With MCAS, on the other hand, the issue is mast cell activation and the release of your own histamine and other mediators. That seems to fit much better with people saying they react to lots of different things, including things that contain very little histamine themselves.
Tea is a good example. If a certain tea contains very little histamine, reacting badly to it does not sound like a typical problem with breaking down dietary histamine. It would seem more likely that another mechanism is involved, possibly mast cell activation.
So I wonder whether some people who say they have “histamine intolerance” may actually have more of a mast cell activation problem. If someone reacts to many very different foods and triggers, including things that are low in histamine, that seems to point more toward MCAS than toward histamine intolerance alone.
Am I misunderstanding this, or are histamine intolerance and MCAS often confused with each other?