Food Allergy Vs. Food Intolerance

South Carolina Gov. Mark Sanford wipes his tears as he admitted to having an affair during a news conference in Columbia, S.C Wednesday, June 24, 2009, and said he is resigning as chairman of the Republican Governors Association. "I spent the last five days crying in Argentina," Sanford said. (AP Photo/Mary Ann Chastain)
AP Photo/Mary Ann Chastain
Many Americans think they have food allergies. But in reality, only about one percent actually have them.

Saturday Early Show Medical Correspondent Dr. Mallika Marshall explained the difference between food allergies and the more common food intolerances, and also offered advice on how to manage them.

A food allergy occurs when your body's immune system mistakenly thinks that a harmless substance (meaning whatever food you happen to be eating) is harmful. In response, the body creates antibodies to that food. The next time you eat that food, the body releases massive amounts of chemicals and histamines to protect you. These chemicals trigger allergic reactions, typically in the respiratory system or gastrointestinal tract.

An intolerance is typically when your digestive system has trouble processing foods that you've ingested. Other parts of your body (such as the respiratory system) may not be affected.

Someone who is allergic to a substance, such as food, will typically react to it in a very short time, whereas someone with an intolerance can react hours later. This is an important thing to keep in mind, because symptoms of allergies and intolerances can be very similar. They include trouble breathing, hives, vomiting, diarrhea and cramping.

There is evidence to suggest that if a parent or a sibling has an allergy, you are more likely to have one. There is also evidence to suggest if that one of these close relatives has a condition such as asthma or eczema, you are more likely to have a food allergy.

Common Food Allergies:

  • Dairy
  • Eggs
  • Wheat
  • Soy
  • Peanuts
  • Tree Nuts
  • Fish
These are the most common foods to cause allergic reactions. That said, people can be allergic to almost anything. There are certain allergies (such as milk) that often start and finish in childhood. The nut and fish allergies are more likely to extend into adulthood.

Common Food Intolerances:

  • Dairy
  • Wheat
  • Peanuts
  • Tree Nuts
Again, you can have an intolerance to almost any food (just like you could have an allergy to any food), but these are the most common.

For certain foods, there are ways to manage intolerances. It's estimated that 50 million Americans are lactose intolerant, meaning they have a hard time digesting any dairy products such as cheese or ice cream. But there are now products such as Lactaid available, which you take before consuming a dairy product, that help the body digest the lactose without bloating, gas or diarrhea.

If you think you have a food allergy or intolerance, Marshall suggests you begin keeping a very accurate food diary. Make sure you include what you ate, when you ate it and how long after you ate it that you got a negative reaction. However, if you experience very severe reactions after eating a food, forget the diary and go to a doctor who can begin testing immediately. If the allergic reaction is severe, it may require emergency treatment.

The most common way doctors test for allergies is the skin prick test. The doctor puts a small amount of the protein from the suspect food under the skin. If you develop a reaction such as a red dot at the site of the injection, then you may have an allergy. However, this test doesn't always detect allergies, so the doctor may also give you a blood test.

If it's determined that you do have a food allergy, there are no known cures, so the only thing you can do is manage the condition. The best way to do that is to avoid the foods to which you are allergic. This may not be as easy as it sounds, because sometimes things you are allergic to are ingredients in other products.

For instance, manufacturers sometimes add peanuts to their products to boost the protein content. So it's very important to check labels. The good news is that the Food and Drug Administration requires that food labels list all the ingredients.

In some cases, people with very severe allergies will get sick and have to give themselves prescribed shots of epinephrine. These people should also wear medical alert bracelets so that bystanders know what to do in the case of an emergency.