It sometimes seems that in any group of three people, one will be “allergic” to some food, and another will be “sensitive” to at least one food. Clearly, there are lots of myths and misunderstandings about food allergies and other reactions.
A food allergy occurs when an allergen in food provokes an immune response. It’s hard to know exactly how many people have food allergies, but most estimates range from one to four percent of adults and five to eight percent of young children. About 90 percent of these allergies are caused by proteins found in just eight foods: cow’s milk, eggs, peanuts, tree nuts, soy, wheat, fish and shellfish.
Typical symptoms are hives, rash, abdominal pain, nausea, diarrhea, itchy and teary eyes and swelling of skin, as well as tightness in the throat and chest and shortness of breath, leading in severe cases to anaphylaxis.
Food allergies are diagnosed along the same lines as other allergies. You’ll be asked about your diet, your symptoms and the timing of your reaction. Skin testing can help identify potential food allergens; the results should be confirmed by challenge tests done in a medical setting.
If you have a food allergy, you must guard carefully against ever eating the food that provokes the reaction. In rare cases, even a tiny amount of the food—such as that left on cooking utensils or somehow made airborne—can cause a lifethreatening reaction. Reading food labels is a necessity, as is asking about the ingredients in foods served in restaurants or prepared by family or friends. In the U.S., the presence of any major food allergen must be clearly mentioned on labels, or even the fact that the food was made in a facility where such allergens were present.
Most children outgrow their allergies to cow’s milk, eggs, soy and wheat, typically by age five, even if they have a history of severe reactions. However, allergies to peanuts, tree nuts and seafood are seldom outgrown. Repeat allergy testing can help determine if food allergies have resolved over time.
Food intolerances, which do not involve the immune system reacting to allergens, are far more common than food allergies and less severe (an exception: sensitivity to sulfites, the preservatives in dried fruit, wine and many other foods, can cause dangerous reactions, similar to true food allergies, especially in people with asthma). The reaction usually involves a food component that can’t be properly digested or that irritates the gastrointestinal tract. The symptoms are similar to some of those caused by food allergies, but usually milder, including abdominal pain, nausea, vomiting, gas and diarrhea. Other foods, such as wine, cheese and chocolate, can trigger headaches in some people.
If a food seems to make you ill, the simple solution is to avoid it and see if that helps. The trouble is that many people with symptoms such as indigestion or headaches incorrectly diagnose themselves as having food allergies or intolerances and put themselves on restrictive diets. Since such symptoms tend to be transient, people may think it’s the new diet that’s helping, but this may not be true. Thus they may explain away gastrointestinal or other symptoms caused by some treatable condition.
If you believe you are allergic or sensitive to certain foods, talk to your doctor. If food does turn out to be the culprit, a special diet can be devised that still allows you to eat healthfully.
The most common food intolerance by far, lactose intolerance is the reduced ability to digest milk sugar. It is very different from a milk allergy, which is much more dangerous and requires avoidance of all milk proteins.
Lactose can be digested only with the aid of lactase, an intestinal enzyme that virtually all infants produce. Many people, usually those whose ancestors came from northern Europe or around the Mediterranean, manufacture sufficient lactase all their lives. But most other people gradually lose the ability to make lactase starting at about age two. This leads to lactose intolerance, characterized by gas, cramps, bloating and diarrhea after consuming dairy products. It’s estimated that 15 percent of white Americans, 50 percent of Hispanics, 70 percent of black Americans and 90 percent of Asian Americans have some degree of lactose intolerance.
Studies have found that most people with lactose intolerance can drink up to a cup (or even two) of milk daily without symptoms, particularly if they drink a small amount at a time and drink it with meals. Yogurt usually causes no symptoms. You can also try lactose-reduced dairy products, add lactase drops to milk yourself or take lactase pills just before eating dairy.
Severe lactose intolerance is rare, but people with severe symptoms may need to watch for even small amounts of lactose hidden in many processed or prepared foods.
Persistent digestive symptoms may indicate something more serious than lactose intolerance, so check with your doctor. There are breath or blood tests for lactose intolerance.
Should You Go Gluten-Free?
Gluten-free diets are pitched as a healthy way to eat and as a way to lose weight. But there’s only one very good reason to avoid gluten: if you have a gluten-related disorder, notably celiac disease or gluten sensitivity.