https://healthydebate.ca/2017/01/topic/igg-tests-science/
That’s a problem for IgG tests, because IgG is an immune response. And in studies on lessening allergic reactions to things like milk or peanuts,
researchers have found that IgG levels go up as the severity of an
allergic reaction goes down. It’s thought that we produce the most IgG
antibodies to foods that we eat regularly—“like getting a constant
booster shot,” says allergist Stuart Carr. That’s why common foods, like
dairy, wheat and egg, will often show up positive on an IgG test.
Kirste says
that message resonates with her clients. “I’ll tell them that IgG may
simply indicate that the food is in the diet. And we know that in
children who are outgrowing an allergic condition, IgG goes up, and IgE
goes down,” she says. “Then the light bulb goes on—they get it.”
Across the country, Carr is having
similar conversations. He says he often has people who have had IgG
tests get referred to him – and he has to explain to them that they’ve
paid big bucks for something that offers no useful information.
“When I see a patient come into my clinic, and they say we had this
[IgG] test done, they will reach in their bag and try to hand me this
booklet of results,” he says. “I’ll say, I don’t need to see that, and
explain why we can ignore it.”
And a more recent review
on allergy management and diagnosis published this fall in the CMAJ
also expressed concerns about them. “Food-specific immunoglobulin G
(IgG) testing is being increasingly used to identify food
‘sensitivities,’” it reads. “… In fact, food specific IgG is to be
expected, marking the presence of exposure and tolerance to a food.”
