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Food Allergies or Food Intolerance?

A small minority of adults – less than five percent – have true allergies to foods. Common food allergens include milk, eggs, peanuts, tree nuts, shellfish, soy and wheat. When true food allergies occur, the immune system reacts to a benign substance as if it were a harmful one, and produces antibodies against it, releasing histamines and other compounds in the process. This causes symptoms such as a tingling mouth, hives, swollen tongue and throat, drop in blood pressure, or even anaphylactic shock.

Food intolerance
- which is much more common - may produce less serious but still uncomfortable symptoms (diarrhea, gas, headaches or flushing). Food intolerance may be due in part to a lack of enzymes needed to break down food.

If you feel you have a true food allergy, or have been bothered by symptoms of food intolerance, talk with your physician about your concerns; he or she can arrange tests to determine what, if anything, is causing allergies or intolerance.

My thoughts on allergy testing: blood vs. skin tests

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Reader Comments (6)

A good way to find out is by the elimination method. The elimination diet involves removing specific foods or ingredients from your diet and gradually reintroducing the foods one at a time. This process helps link allergy symptoms to specific foods. Don't forget to consider a gluten intolerance.

September 8, 2010 | Unregistered CommenterLynn Lotto

To continue the Elimination Diet discussion, a great way to give you some perspective on whether you have a food intolerance, is to omit wheat, dairy, and sugar from your diet for 7 days. On the 8th day, add back one of these foods (sugar) and notice your symptoms and how you feel. On the 9th day, add back one of the other foods (dairy) and again notice your symptoms and how you feel. Again, on the 10th day, add the last food category (wheat) and notice your symptoms and how you feel.

September 9, 2010 | Unregistered CommenterMelanie Albert

Food allergies often cause a massive histamine response in the body almost creating anenvironment where our body is fighting against us which can have serious consequences. On the other hand food intolerances often hit our GI tract and although uncomfortable they subside without intervention. As a nutritionist I often recommend an elimination diet to help determine intolerance so that individuals can avoid foods that cause disruption.

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September 9, 2010 | Unregistered CommenterJim Scheibel

I think you have to be careful with this definition of "intolerance". In some cases, such as Hereditary Fructose Intolerance (HFI), a child ingesting fructose or sucrose can do more than make him/her uncomfortable. It can be fatal simply because parents are trying to feed the child "healthy" fruits and vegetables.

My son has HFI and as an infant (before he was diagnosed through DNA testing at age 3) his spasms and projectile vomiting were alarming to us and his doctors. He was "normal" and healthy until I transitioned him off breast milk around 9 months to solid foods. His 9 month weight dropped to below his 6 month weight, but we had no idea what was causing it (HFI babies have a natural protection mechanism that makes sweet food taste bitter so they won't eat it). The next two years were tortuous as we watched our healthy baby violently spasm and vomit. Though, we were lucky -- he ended up surviving on grits and cheese until we met a doctor who knew about HFI. After he was diagnosed we learned that HFI infants are often identified as Failure To Thrive and they end of up starving themselves to death. Some of the stories are horrific.

Happily, my son is now 17 and has survived because we've eliminated all fructose and sucrose from his diet. At his age, now, we are most concerned with cirrhosis of the liver, as the fructose molecules "attack" his liver because he lacks the enzyme to properly digest it. We have his liver and kidney tests done every year to make sure all is healthy.

Hereditary Fructose Intolerance is not a condition that simply makes a person "uncomfortable". It is a metabolic condition that can frequently be fatal to babies and children, simply because the parents are trying to introduce a nutritionally sound diet.

September 9, 2010 | Unregistered CommenterRebecca Adams

Onions. I have never been able to eat them, or even smell them. Just the smell gives me a migraine and nausea. If I should happen to eat a bite hidden in food by accident, or even eat something that has sat next to them my whole body becomes severely nauseated along with migraines. I am certain that if I was forced to eat onions it would most definatley kill me! To me it is more then :intestinal distress, for I never get any reaction like that. To me it feels very systemic, like my whole body is reacting. I once had a bout of diary intollerance and it felt completley different then my onion issue. Onions to me are poisonous, and that is how I feel about them in my body, I really beleive they would kill me if I ate a large quantity.

Any ideas? I feel I am allergic to them.

September 9, 2010 | Unregistered CommenterElizabeth

When I ingest caffeine I get mild to medium flu symptoms that last several days (they are very disruptive). Since these are the same symptoms that ones get when a virus invades the body, I guess I can conclude I have a caffeine allergy?

It took many years to figure this out and it then was challenging to find all the places caffeine (esp. green tea) was lurking in my toiletries and food products to eliminate them all. But once I eliminated them all I felt fully healthy again.

I have searched the internet and haven't found any mention to this kind of a response to caffeine. Dr. Weil, do you have any insight onto this? I am glad I figured out what the cause of my symptoms is, but I feel very weird about my unusual symptoms.

September 11, 2010 | Unregistered CommenterBecca
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