Is Your Diarrhea a Sign of a Food Allergy?

If you experience occasional diarrhea, it could be caused by a food allergy or food intolerance. Most people connect food poisoning with diarrhea, but that is not always the case.

A true food allergy is an abnormal response to a food triggered by the immune system.  Research shows that around 3 to 4 percent of people have food allergies. The first symptoms may be within minutes of coming into contact with the problem food – meaning you may have simply touched it, not consumed it - or several hours later. 

If you have a true food allergy,  you will have a reaction every time the food is consumed. The diagnosis may require a combination of lab tests, physical exam, thorough diet history and a controlled food challenge. 

These eight foods account for 90 per cent of all food allergic reactions.

1. Milk – not the same as lactose intolerance, includes milk casein and whey
2. Eggs – includes both the white and yolk
3. Peanut – is a legume, not a true nut
4. Tree nuts – includes but not limited to walnut, almond, hazelnut, coconut, cashew, pistachio, Brazil nuts
5. Finfish – such as salmon, tuna, halibut
6. Shellfish – such as shrimp, crabs, lobster
7. Soy –includes soy milk, flour, oil, and soybeans
8. Wheat – not the same as gluten, which is a protein found in wheat, rye, barley

The most common symptoms of a food allergy are:

• Gastrointestinal: Nausea, vomiting, diarrhea
• Skin: Rash, itchiness, swelling
• Respiratory: Congestion, runny nose, sneezing, coughing, wheezing
• Other: Anaphylaxis, a swelling of the throat and difficulty breathing that can be fatal 

Food intolerances can also result in diarrhea. A food inolerance is the inability to completely break down or digest a food. Small amounts of a suspect food may be tolerated without difficulty, while larger amounts will bring on symptoms.  It may take some trial and error testing to determine if you have a food intolerance. 

Common food intolerances:

• Sugars: lactose in milk, fructose in fruit, honey and high fructose corn syrup
• Gluten: protein found in wheat, rye, barley and some other grains
• Preservatives: sulfites commonly used in wine and dried fruit, monosodium glutamate (MSG) a flavor enhancer 

The same types of symptoms can occur with a food intolerance as those experienced with a food allergy. The key is to figure out which food(s) are responsible for your symptoms and how much, if any, you can tolerate if you're unwilling to give up the food.

You can find more information from The Food Allergy & Anaphylaxis Network (FAAN)