Complement plays a role in how inflammatory an IgG antibody is. Complement binds to IgG and creates a synergistic effect in terms of increasing inflammation. The combination of complement and IgG together can increase inflammation 1000 to 10,000-fold.
IgE and IgG should be measured together because they each independently play a role in symptoms to foods. You can either have an allergy/IgE response, or a sensitivity IgG response and both are independent of the other and create inflammation in the body.
Only testing IgG, is a bit like knowing total cholesterol, but not knowing how much HDL/good or LDL/bad cholesterol you have. The reason for this is that different IgG antibodies do different things depending on their subtype. IgG4 decreases IgE or allergic reactions. IgGI-III increase inflammation 3-72 hours after exposure. Also, different subtypes are increased in certain pathologies. For example, while IgG4 is generally good, there are a handful of pathologies where it is of concern, such as auto-immune hypothyroidism and eosinophilic esophagitis.
An allergy is mediated by IgE antibodies and creates an immediate reaction. A sensitivity is created by IgG antibodies and create a delayed response. While these general traits hold true, there are also times when IgG can amplify IgE reactions, and also some examples of if there is a very high level of IgG, it can have more of an immediate reaction too. They create independent reactions but can also influence each other. IgG is most typically a delayed reaction, but if high enough titers are present, it too can react within a few hours. The interplay between parts of the immune system demonstrates why it is best to look at multiple antibodies together.
IgG reactions are both the cause and the result of gut-based permeability. One way we develop IgG reactions is when the gut becomes more compromised or permeable. This allows for larger molecules than normal to “leak” through the gut. These larger molecules look antigenic to the immune system. T cells become sensitized and begin to make an immune response or produce antibodies. However, this is not the only way one can become sensitive to foods. Improper immune queuing in the GI tract, specifically in cells called the Peyer’s patches, can also cause this too.
Once an IgG reaction begins, it increases production of histamine and inflammation. This inflammation continues to damage the gut, thereby contributing to permeability. The best way to reduce gut-based inflammation, is to remove offending foods and work on healing the gut.
Food sensitivities can be related to weight gain in that they will create more inflammation in the body. Inflammation will cause an increase in the hormone leptin, which in turn tells adipose tissue to store more fat. Inflammatory foods create and irritation that leads to weight gain.
Yes! While the beginning of the reaction to foods start in the gut, it does not have to necessarily create gut pain, or be contained in the GI tract. The inflammatory process that starts in the gut can spread and even be more symptomatic in places outside of the gut. Many conditions such as headaches, pain and even depression have a gut-based cause but manifest in other areas of the body.