Distracted wrote:As I said, true anaphylactic type allergic reactions are not hereditary, but what you're describing, especially the diarrhea, doesn't sound allergic. It sounds like a food intolerance. What the mechanism could be I have no idea. I know of no inherited diseases which might give a person diarrhea from eating onions. Milk products, sure. There's even a disease that gives you diarrhea if you eat wheat products because of the gluten. There are hereditary malabsorption syndromes where people can't digest fat and it goes right through them. But I have no clue why the onions are your Achilles heel.
Now, fruit like cantaloupe causes food allergies all the time. And the tendency to GET allergies does run in families. Exactly what you end up allergic to, though, depends on exposure. Melon allergy is so common that I can see several members of the same family all becoming allergic to cantaloupe.
I'm no allergist, though...and probably neither was the dietician, so I'd talk to a specialist before blaming diarrhea on a food allergy.
Aquarius, the whole principle of allergy shots is that gradually increasing doses of allergens cause tolerance. I have also seen tolerance develop to one particular allergen over time with continued exposure even without shots, even though a doctor probably wouldn't treat respiratory allergies that way because it's likely to take months and nobody wants to be miserable that long. You don't want to do that with food allergies, though. Too dangerous, since minute amounts of the offending food can cause a fatal reaction in someone who's highly allergic.
I'm late, sorry, but simply I would want to confirm what Distracted said.
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