1. Why is it that some foods cause an allergic reaction and others don't?
Everyone’s immune system is unique and always changing as we contact antigens in the environment. Antigens being anything from microbes to dust to the proteins found in dairy that cause a response from the immune system. When an antigen comes into contact with the immune system different immune responses can occur depending on the type of antigen.
Hypersensitivity reactions are what commonly occur to foods which there are four types. The peanut allergy is caused by a type I reaction mediated by IgE. Peanuts in general are highly allergenic because of their chemical composition, some people’s immune systems will react and others won’t because of the variance in our immune systems. So using the peanut example what commonly happens is the person is exposed to peanuts 1 or 2 times before the reaction becomes anaphylactic. The peanut is ingested for the first few times and the body becomes sensitized to the antigen (peanut) and starts to produce an antibody known as IgE against it. IgE binds to receptors on mast cells which cause them to degranulate releasing histamine causing a variety of reactions ie. Shortness breath. Lots of IgE is formed against the peanuts after 1-2 times of exposure and the next time you consume it will cause a large anaphylactic reaction since it will bind to many mast cells.
With other foods like dairy the body reacts to the protein called casein in it causing IgG to form which is a type 3 immune reaction. IgG is a delayed response so symptoms are more subtle like gas, bloating, skin reactions, mucus formation, etc. (This is not the same as lactose intolerance which is lack of the enzyme lactase causing the inability to break down dairy.)
Some foods are just more commonly recognized by the body as foreign and really it just depends on the person and their immune system.
Hypersensitivity reactions are what commonly occur to foods which there are four types. The peanut allergy is caused by a type I reaction mediated by IgE. Peanuts in general are highly allergenic because of their chemical composition, some people’s immune systems will react and others won’t because of the variance in our immune systems. So using the peanut example what commonly happens is the person is exposed to peanuts 1 or 2 times before the reaction becomes anaphylactic. The peanut is ingested for the first few times and the body becomes sensitized to the antigen (peanut) and starts to produce an antibody known as IgE against it. IgE binds to receptors on mast cells which cause them to degranulate releasing histamine causing a variety of reactions ie. Shortness breath. Lots of IgE is formed against the peanuts after 1-2 times of exposure and the next time you consume it will cause a large anaphylactic reaction since it will bind to many mast cells.
With other foods like dairy the body reacts to the protein called casein in it causing IgG to form which is a type 3 immune reaction. IgG is a delayed response so symptoms are more subtle like gas, bloating, skin reactions, mucus formation, etc. (This is not the same as lactose intolerance which is lack of the enzyme lactase causing the inability to break down dairy.)
Some foods are just more commonly recognized by the body as foreign and really it just depends on the person and their immune system.
2. How is it that we can become allergic to something all of a sudden and, contrarily, how can you just get over an allergy?
So again, the immune system (adaptive immunity) is always changing (ie. You are building up your immunity all the time which is usually why you don’t get the flu twice in one season unless it is a different strain or why you don’t get chicken pox twice since your body has already mounted an immune response to that virus so next time it sees it the body know exactly how to fight it off so you won’t get sick). We can change our immune system by adding different treatments to help modulate the immune response like probiotics, herbs like astragulus, reishi, ginseng, Echinacea etc. In the same way everything we come into contact with will change our adaptive immunity. With IgG food allergies if we avoid the antigen like dairy for a few months the immune system recovers and adapts and when slowly reintroduced it’s possible that there will be no reaction. With IgE reactions it takes a much longer time to change and typically this is why people are allergic to substance all their lives.
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