The Case:  Julie has digestive issues, headaches, lots of skin rashes and irritation, brain fog, and fatigue She is also very sensitive to environmental triggers like fragrances, smoke, and chemicals.   She eats and lives as clean as possible but nothing seems to help.  She’s seen a dozen doctors who have prescribed a variety of medications but nothing helped.  It’s so common for conventional doctors to focus on treating the symptoms as if they are unrelated instead of considering what the collection of symptoms might mean. Julie knew that her symptoms had to be connected which is when she reached out to me. My feeling was that this was a systemic issue and we got to work investigating the root cause of her problems.  The Investigation With my suspicions of a systemic issue, I knew that Beth O’Hara would be a great source of information. She’s been on Health Mysteries Solved before to speak about Oxalates (episode 67) and Histamines (episode 81). This time, I wanted to dive into the topic of Mast Cells and Mast Cell Activation Syndrome which is Beth’s expertise. What are Mast Cells? Mast cells are one of the most important types of immune cells in our bodies. They're present at every interface between our bodies and the outside world, and they're also found in every single tissue except for the retina. So, if we think about that, they're in the skin, in the lining of the sinus passages, in the digestive tract from the mouth to the stomach, and they're also found in muscles and bones. They migrate to very important areas like nerve endings and the brain's limbic system. Mast cells are responsible for a number of functions ranging from the sleep-wake cycle to pregnancy and wound healing. They also help the body monitor for whether or not we're safe from things like toxins, mold, candida, pathogens, parasites, viruses and bacteria. They even monitor for co-infections (like lyme disease). Mast cells are also looking for all types of stressors including psychological stress, physical stress and stress caused by outside factors like electromagnetic fields (EMF) in the environment. How do Mast Cells Work? Mast cells use what are called receptors - you can think of them like little antennae on the outside of the cell. There are over 200 of these receptors sending out signals using mediators. There are over 1000 different mediators. All of these allow the cells to connect with and monitor the different functions of the body.  When a mast cell detects an issue it will respond, often causing inflammation. It is not the only immune response but it is one of the primary cells responsible for answering a threat to the immune system.  The problem is that our modern world has more threats to the immune system that can cause mast cells to react. These include things like mold, high levels of EMF (wifi, smart homes, etc add to these high levels), environmental chemicals and other toxins. The challenge is that the mast cells are constantly triggered (or in activation) by these things and they don’t have time to rest and reset. This can overwhelm the mast cells and create a chronic issue.  The Link Between Autoimmunity and Mast Cell Activation Mast cells are heavily involved in the development of various autoimmune diseases. The mast cells are involved in both innate and adaptive immunity. Mast cells respond to the initial threat from a pathogen but when that fails, they shift their response and this can be what causes chronic inflammation. This continues as long as there are unresolved root triggers over an extended period of time. Over time, this opens the door for the development of autoimmunity in people who are predisposed for it.  So, if we want to avoid autoimmunity, we need to respond faster to the root trigger so that the mast cell response can be regulated. Regulating the mast cells can also reverse autoimmunity, in some cases, if you identify which mast cells have been activated.  Different mast cells can be triggered (and often trig