Ask A Scientist Molecular Biology Archive

name         Corinne A.
status       educator
age          40s

Question -   Why do certain foods cause the body to release
histamines and how do we ascertain which foods cause this to happen?
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Food allergies are often very specific to individuals. For example,
specific nuts or shell fish can cause the body to over-react and flood the
body with histamines. Histamine release is a body's protective measure;
however, in the case of allergies the body does not know when to stop and
hives, asthma, or life-threatening anaphylactic shock can ensue. Why certain
people are allergic to certain foods, I don't think is known. The way
allergists determine which foods are involved is to make a light scratch on
the arm and/or back with an extract of the test substance and note the
severity of the body's reaction -- redness and/or hive formation. Avoiding
the offending substance and de-sensitization by starting a regimen of
injections of very low levels of the offending substance can help the body's
immune system to not over react to the substance. The success of this
treatment is very individualistic. It is also worth noting that the scratch
testing shows both positive and negative responses, that is, the scratch
test may show the person is allergic to something that has no effect when
the substance is consumed. Likewise, a person may show a negative scratch
test to a substance that has severe reactions when consumed.

Vince Calder
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Allergic reaction...Mast cells bind IgE antibodies that are elicited after
the person is exposed to the allergen (something foreign to the body to
which the body has produced antibodies).  The IgE causes the Mast cells to
release their granules of histamine...causing leakage of fluid into the
spaces between the cells causing tissue swelling.  The only sure way to know
is to test a small amount on the person...usually on their skin.

Peter Faletra Ph.D.
Assistant Director
Science Education
Office of Science
Department of Energy
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The problem with this question is that different people have different
reactions to certain foods. 
Histamines are an immune response and people who are allergic to certain
foods find their bodies attacking the foreign invader even if it is
normally not associated with danger.  Cat and dog dander is no
different.  Antihistamines counter these events, and a doctor should be
consulted in any event.

Steve Sample 
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