Q: What are the symptoms of someone either having an allergy or a sensitivity to a certain type of food?  I’ve noticed that when I eat onions, I really get bad indigestion.  Can that be an allergy? ~ Alex

A: Hi Alex! A food sensitivity is an adverse reaction to a food. Food allergies, sensitivities and intolerances fall under this umbrella term. Allergies are sensitivities caused when your body's immune system reacts to specific protein's in a food. It can affect the respiratory system, gastrointestinal tract, skin or cardiovascular system. In some cases, it can be fatal, such as with extreme nut allergies. According to Health Canada, allergies affect only 3 - 4% of adults.

A food intolerance on the other hand, is a food sensitivity that does not involve the immune system. It generally takes a larger portion to have an effect, compared to a an allergic reaction. Symptoms of an intolerance can be mistaken for a food allergy, but food intolerances are more likely to originate in the gastrointestinal system, and are usually a result of difficulty absorbing or digesting foods. A common intolerance is lactose intolerance (ie. dairy), and symptoms may include abdominal pain, bloating, diarrhea and flatulence.

So Alex, with regards to onions, it's difficult to say what is happening to your body, if it is an allergy or an intolerance without more information. Do you experience the symptoms when you have even a tiny bit of onion? Or does it take a larger portion to cause you to feel uncomfortable? If a small amount triggers a reaction, it is possible it is an allergy, but if it is a larger portion, is may be an intolerance. Your best bet is to check with your doctor, especially if it is serious.

Yours in Health,

Maria Thomas, RD
Registered Dietitian/Nutritionist

Nutrition Expert for The Last 10 Pounds Bootcamp

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