There is often
confusion between food allergies and food intolerances/sensitivities. In this article I will explain what
they each mean and help you decide if you should get tested for them.
Our bodies make
several different immunoglobulins (Ig), also known as antibodies, which bind to
microbes in order to neutralize them or tag them for other immune cells to deal
with.
A food allergy is
when the body has an immune response to a food protein. This reaction is due to the
immunoglobulin IgE. A food intolerance can be the immune response of the
immunoglobulin IgG or sometimes a lack of certain enzymes needed to properly
digest food. An IgG reaction is
also an immune response to a food protein, but the term ‘food allergy’ is
reserved for IgE reactions.
Food Allergies
IgE attacks
parasitic worms when they are present in our bodies and also binds to allergens
to produce histamine. IgE causes
an immediate reaction in the body (usually in less than 2 hours) and can be in
the form of asthma, hives, skin rash, headache or anaphylaxis.[i] The most commonly talked about IgE reactions are those to
peanuts and bees, but people can have reactions to all sorts of substances including medications, dust mites, seafood, grass and pollen. The most common test for this is a skin prick test where small scratches are made on the skin and small amounts of different allergens are applied. This gives results in 10-20 minutes so they can be discussed immediately. People are often able to self-diagnose food allergies due to the immediacy of the reaction. One theory explaining the rise in food allergies is that we are not often exposed to worms leaving IgE with nothing to do.
Food Intolerance
IgG is the main immunoglobulin
in the body and protects the body against viruses, bacteria and fungi. IgG is the only immunoglobulin that
passes the placental barrier providing protection to the fetus and also passes
into breast milk along with IgA.
Measurement of IgG is used to check for immunity to some viruses such as
measles, mumps and chicken pox.
Unfortunately IgG
can also react to foods if there is inflammation in the bowel allowing small
particles of undigested food to pass through. This can present as a variety of symptoms including
headaches, fatigue, irritable bowel syndrome, depression, arthritis, chronic
respiratory problems, weight problems, anxiety, insomnia and migraines.i [ii]
IgG reactions are often delayed and can last for weeks or months after ingestion
of the problem food. i Given this and the large variety of
symptoms it can cause, it can be difficult to diagnose this reaction. Common IgG reactions are to wheat,
gluten, dairy and soy. The common
test for IgG reactions is an easy finger prick blood test.
If you think you
may have food allergies or intolerances it is important to see your naturopath
or other health care provider to ascertain the problem foods or substances so
they can be avoided and you can begin the journey to better health.
