IgG antibodies to foods (270)

IgG antibodies against foods show that the immune system has had contact with proteins from these foods. In studies, higher values have been observed, among other things, with a more permeable gut lining. How the classes are to be read is set out in your findings report.

What IgG antibodies against foods show

With every meal, small amounts of undigested food proteins reach the gut lining and partly pass through it. The immune system in the gut constantly checks these proteins; B cells can respond by producing IgG antibodies, mainly of the subclasses IgG1 and IgG4. Such antibodies show that the immune system has had contact with the food in question. They are also found in many people without symptoms, and their amount depends strongly on how often and how much of a food is eaten. In research, IgG4 tends to be associated with habituation (tolerance). The mechanism differs from classic food allergy, in which IgE antibodies cause mast cells to release histamine within minutes.

IgG against a food not detected – what does it mean?

The immune system has not formed any measurable IgG antibodies against this food. Often the food is eaten rarely or not at all, so there has been little contact. The absence of IgG says nothing about other reaction pathways – for example IgE-mediated allergies or intolerances without involvement of the immune system, as in lactose or fructose intolerance.

IgG against a food detected – what does it mean?

A positive result shows that B cells have responded to proteins from this food and formed IgG. The more food protein reaches the immune system in the gut, the more IgG can be formed – with frequent consumption and, in studies, also when the gut lining is more permeable, for example with inflammation of the gut. IgG antibodies can form immune complexes with the food protein, which are normally cleared by phagocytes. Whether and how strongly raised IgG levels are connected with symptoms is assessed differently in studies; a positive result on its own is not proof of an allergy or intolerance.