Food allergy or food intolerance?
A food allergy and a food intolerance are two different things. In a true food allergy, the body misidentifies food as a foreign substance; in a food intolerance, a person lacks the enzymes needed to break down a particular food. Since histamine isn’t involved in a food intolerance, reactions are less severe than in a food allergy and usually involve stomach cramping, gas or diarrhea. One way to control a food intolerance is to consume the offending food in small amounts.
For example, many of the 30 to 50 million Americans who are lactose intolerant can avoid symptoms by sticking to small servings, such as 4 ounces of milk. Hard cheeses and yogurt usually have less lactose than other dairy products and might be easier for some people to digest.
Other common sources of food intolerance include:
- monosodium glutamate, or MSG; common in Chinese food and processed foods
- sulfites; common in dried fruits, dried potatoes, shrimp and wine
- benzoates; common in bread, milk powder, potato powder, fat, oil, chocolate, mayonnaise, margarine and soft drinks
- FD&C yellow dye #5, or tartrazine; used in various items that may or may not be yellow—read product labels
- phenolphthalein; used to make candy pink—read product labels
To hear most people tell it, food allergies have reached epidemic proportions. In fact, true food allergies affect about 2 percent of American adults and 8 percent of children, according to the American Academy of Allergy, Asthma and Immunology. Still, that’s nothing to sneeze at: Depending on a person’s degree of sensitivity, food allergies can be quite serious—in some cases, even life threatening.
Common allergy-causing foods include milk, peanuts, eggs (especially egg whites), wheat, soy, tree nuts (such as almonds, walnuts, cashews and pecans), fish and shellfish. These eight foods cause 90 percent of all allergic reactions. Other culprits are legumes, citrus fruits and berries.
The reactions start when the body doesn’t recognize a food as a nutritious substance. Instead, the food is seen as a foreign object. This prompts certain cells in the immune system to release histamine, which in turn triggers symptoms such as:
Reactions may occur immediately after eating or up to 72 hours later. Because some allergic reactions may become more severe with each subsequent attack, you should talk to your healthcare provider as soon as a food allergy is suspected.
- sneezing, runny nose or nasal congestion
- difficulty breathing
- stomach cramps
- swelling and tenderness of the mouth
- flushing of skin or rash
- nausea and vomiting
Because some food allergies don’t cause an immediate reaction, it is sometimes difficult to find the trigger. A food diary can make this easier. By writing down everything you eat for a few weeks and keeping track of symptoms, you and your healthcare provider will be better able to pinpoint the problem foods.
To find out if you have an allergy, your healthcare provider may perform one of two tests. In a skin prick test, a doctor places a drop of the substance being tested on your forearm or back and pricks the skin with a needle, allowing a tiny bit to enter the skin. If you are allergic, a small bump will form within 15 minutes.
The other method is a blood test called RAST, or the radioallergosorbent test.
For people with allergies, eating out can be frustrating. Just a trace of the offending item in your meal can cause a full-blown reaction. For those allergic to peanuts, even 1/500th of a teaspoon of peanut butter can create a problem. These hints can make dining out an enjoyable experience:
- Call the restaurant before you arrive and have a chef handle your concerns. If that’s not possible, eat a small meal at home before you go out—that way, a side dish or an appetizer will satisfy you in the absence of a safe entree.
- If your meal arrives with the allergy-causing substance on the plate, don’t try to remove the ingredient—traces are likely to remain even if you can’t see them. Reorder the dish without the ingredient or order something else.
- Avoid alcoholic beverages. Alcohol speeds the absorption of food from the intestine and can prompt a reaction in cases where a small amount of the offending food is normally well tolerated.