Histamine Intolerance & Mast Cell Activation Glutathione Reductase from bakers yeast (S. cerevisiae) Mast cell activation syndrome (MCAS) is one of the most misunderstood conditions I see in my telehealth functional medicine clinic. and it's often the missing piece for people who feel like they're Mast cells are hypersensitive immune cells that release histamine and other inflammatory mediatorsoften in response to oxidative stress, environmental toxins, and immune imbalance. Many patients with MCAS have low levels of glutathione. Role of glutathione in oxidative stress. During oxidative stress there Download Scientific Diagram