Troublesome Foods: Distinguishing Allergy vs. Intolerance

Food allergies affect about 2 to 4% of adults and 6 to 8% of children. Food intolerances, often confused with allergies, are much more common. In fact, nearly everyone at one time has had an unpleasant reaction to something they ate.  It's important to distinguish food intolerance from food allergy.

Food allergies can be triggered by even a small amount of the food and occur every time the food is consumed. People with food allergies are generally advised to avoid the offending foods completely. On the other hand, food intolerances often are dose related.

People with food intolerance may not have symptoms unless they eat a large portion of the food or eat the food frequently.

What Is a Food Allergy?

A food allergy occurs when the body mistakes an ingredient in food as something that is harmful.  The body then creates a defense system (antibodies) to fight it. Allergy symptoms develop when the antibodies are battling the "invading" food.  This is an immune system response.  Lactose intolerance, the most common food intolerance, affects about 10% of Americans.

The most common foods that people are allergic to are peanuts, tree nuts (such as walnuts, pecans and almonds), fish, and shellfish, milk, eggs, soy products, and wheat. 

There are no medications that can cure food allergies. Avoiding the food is the only sure way to prevent a reaction. Food allergies often run in families, suggesting that the condition can be inherited.

What Are the Symptoms of a Food Allergy?

Symptoms of a food allergy can range from mild to severe, and the amount of food necessary to trigger a reaction varies from person to person.

Symptoms of food allergy may include:

• Rash or hives
• Nausea
• Stomach pain
• Diarrhea
• Itchy skin
• Shortness of breath
• Chest pain
• Swelling of the airways to the lungs
• Anaphylaxis – a severe, whole-body allergic reaction

What Is Food Intolerance?

A food intolerance is a digestive system response rather than an immune system response. It takes place when something in a food irritates a person's digestive system or when a person is unable to properly digest or breakdown, the food.  The most common food intolerance is to lactose, which is found in milk and other dairy products. There are many factors that may contribute to food intolerance. In some cases, as with lactose intolerance, the person lacks the enzymes necessary to properly digest the food. Also common are intolerances to some chemical ingredients added to food to provide color, enhance taste and protect against the growth of bacteria.

What Are the Symptoms of Food Intolerance?

• Nausea
• Stomach pain
• Gas, cramps or bloating
• Vomiting
• Heartburn
• Diarrhea
• Headaches
• Irritability or nervousness

What Should You Do If You Think You Have An Allergy or Intolerance?

If you believe you have either a food allergy or food intolerance, keep a diary of the foods you eat and any symptoms you experience, and then review this with your healthcare professional to look for common factors. Your doctor can also order simple skin tests or blood tests to determine if you are allergic to specific foods.  Once your food allergy or intolerance is confirmed, you can consult with a registered dietitian to develop a meal plan that will ensure you are meeting all of your nutrient needs.