Jennifer Shaffer first noticed her son Jonathan had a problem with milk after feeding him rice cereal mixed with a milk-based formula. “As I was feeding it to him, his face started to turn red and get bumpy,” she recalls. She quickly realized her six-month-old had hives. A positive skin test by an allergist confirmed that he had a milk protein allergy — one the now six-year-old didn’t outgrow until he was almost four.

Food allergies typically develop in the first year of life. The most common in babies are milk, eggs and soy, however, children may also develop allergies to peanuts, tree nuts, sesame seeds, seafood (crustaceans and shellfish) and wheat. But not all food allergies are easy to recognize, and may be diagnosed as less severe food intolerances. Knowing the difference can save your child’s life.

is it allergy or intolerance?

When the body’s immune system reacts to specific proteins in a food, mistaking them for harmful invaders, this is known as a food allergy. The immune system attacks the protein by pumping out immunoglobulin E (IgE) antibodies and histamine, a chemical that produces inflammation in tissues (skin or airways), resulting in a potentially life-threatening anaphylactic reaction that may include hives, swelling, vomiting, diarrhea and difficulty breathing.

Conversely, food intolerances do not generally involve the immune system and usually produce symptoms that are confined to the gastrointestinal (GI) tract, such as cramping, bloating, gas and diarrhea because the digestive system can’t properly break down or absorb nutrients from the food (eg. lactose intolerance). Complicating the issue in very young children are food allergies that still involve the immune system but usually produce only gut-related symptoms that resemble food intolerances, says Dr. Wade Watson, a pediatric allergist at the IWK Health Centre in Halifax. But unlike food intolerance, “these allergic symptoms tend to be much more severe, and include profound vomiting, failure to thrive, blood or mucus in stools and diarrhea,” says Dr. Watson.

food challenges

Be prepared to educate your child’s caregivers, advises Shaffer. “Most people thought that Jonathan was lactose intolerant, so we had to clarify that, no, this was a milk protein allergy. His stomach doesn’t just get upset — he could die from this.” Also, when it comes to food allergies, even trace amounts (in a few cases, skin contact) must be avoided, whereas food intolerances generally seem to be more dose-related, says Wendy Busse, a dietitian in Red Deer, Alta., specializing in food hypersensitivity.

And while kids can sometimes outgrow allergies — some will grow out of milk and egg allergies by the time they are school age — intolerances tend to be life-long, says Dr. Watson.

cooking up clues

So how do you find out what’s affecting your child? If there is a history of a possible allergic reaction to a food and a skin test is positive, it confirms the diagnosis of an IgE-mediated allergy, says Dr. Watson. Skin tests performed as a screen for allergies may not give an accurate diagnosis and are not recommended. For non-IgE reactions, there’s no standard test, just a process of elimination — but do this with expert guidance, cautions Dr. Watson.

Once you’ve determined the culprit, you also need to know what you’re looking for. For example, milk can show up in foods as milk-proteins such as whey and casein, and in items you wouldn’t even suspect like crackers or french fries. ”We learned how to read labels,” explains Shaffer. Keeping a food and symptom diary can help piece things together. Report any reaction soon after you notice it, says Dr. Watson. “Any blood or mucus in stools should be taken very seriously at this age, and not growing well should trigger parents to see a doctor.”

Angela Pirisi is a Hamilton, Ont.-based health writer who is relieved that her family can stomach any food — knock on wood.

which one is which?

It may be a food allergy if: There’s a family history of allergies; Symptoms aren’t
GI-related (IgE type); GI-related symptoms are severe (non-IgE type); Eczema develops (an early warning
sign of a possible allergy)

It may be a food intolerance if: There’s a family history of intolerances; No hives, rash, swelling, or breathing trouble; GI symptoms are present but not severe; Symptoms are restricted to GI system