OAS is similar to a typical food allergy except in most cases it's not as dangerous or life-threatening as a peanut or bee-sting allergy.
The medical literature states that the reaction only affects the lips, mouth, and throat. OAS being only recently classified, it's difficult to find thorough information, or complete consensus.
Typical OAS timeline (increasing severity, decreasing likelihood):
Why, Why, Why?
- ingest: one sprig of parsley garnish
- instantly: hives or sores on the lips, tongue, and throat
- three to ten minutes: itching and swelling of the pharynx and esophagus
- 30 minutes to 2 hours: severe indigestion, diarrhea, abdominal cramping, and later, gas
- one to 4 hours: atopic dermatitis: hives, or blotchy red itchy areas (armpits, groin and neck; rarely palms of hands and soles of feet
- 30 minutes onward: feeling of impending death
According to Health On The Net the oral-allergic response is
"believed to be due to pollen protein cross-reactions (responses to fruits and vegetables frequently occurring as clusters of hypersensitivity to members of the same botanical family, for which the immunologic basis lies in a number of common allergens)"
-- Health On the Net Foundation. (Last modified: Tue Jun 20 2000) "HON Allergy Glossary Oral Allergy Syndrome."
www.hon.ch/Library/Theme/Allergy/Glossary/oas.html. Accessed May 3, 2001.
Nice. I've always had trouble with hayfever, now I can't eat carrots. My hyperactive immune system is confusing its food proteins with its pollen proteins. The ironic thing is: since I moved away from the grassy plains of my home state, I have no problem with pollens. One thing leads to another...
Nobody can explain why my Immunoglobulin E (IgE) antibodies suddenly decided to treat nectarine proteins as dread antigens, and ignore all the birch pollen that (seven years ago) would have had me sneezing for 45 minutes.
Medical conspiracy theory: this all started after some coke fiend cardiologist prescribed Beta Blockers for a bout of panic anxiety disorder back when I was 22.
As a child, I was known to have allergic reactions to:
Thanks to my confused IgE I've traded sneezing at all those things, into not being able to eat most of these things:
apples, almonds, celery, cherries, hazel nuts, parsley, peaches and pears.
almonds, apples, apricots, carrots, celery, cherries, coriander, fennel, hazel nuts, kiwis, nectarines, parsley, parsnips, pears, peppers, plums, potatoes, prunes and walnuts.
melons, oranges and tomatoes.
banana, cantaloupe, chamomile, cucumber, dandelion, honey dew, watermelon and zucchini.
Sensitivity to these foods is usually mitigated if they are well cooked. Tabouli leaves me itching and heaving for hours; carrot juice or V-8 could very well kill me; but french fries are fine. I'm happy broccoli and green beans aren't on the list, or I might starve.
The literature states that usually OAS does not require medical treatment. They say it's just best to avoid the offending foods. And I say, in a wry aside, "Yeah, and what kind of malnourished, pasty blob will that turn me into???"
So I don't even try to keep track of all the cross-reactivity stuff. I just carry antihistamines everywhere; prefer a diet of tortilla chips, pastry, and beer; and avoid potlucks. It's not that bad: I just don't eat most fruits, vegetables, or nuts. Vegan I'm not.
But what really frightens me is this:
One article suggests that certain of these cross-reactions could turn into a latex allergy. It seems some patients who report allergic sensitivity to latex sometimes experience symptoms after eating avocado, banana, chestnuts, or kiwi. Hmmmm. Nice. First my diet is shot to hell, next thing you know my favorite fetish object sends me into anaphylactic shock.
Now I'm hungry...