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Dear Dietitian – facts about food allergies

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PICT Leanne McCrate Dear Dietitian
Leanne McCrate, RD, LD, CNSC

Dear Readers,

Food allergies are on the rise in the United States, and it is estimated that as many as 8% of children suffer from at least one food allergy.   A food allergy is when your body’s immune system responds to a certain food as harmful and has a reaction.  These reactions can range from itchy skin, vomiting, or diarrhea to trouble breathing, wheezing, or anaphylaxis, which is life-threatening.

Although it is uncertain why food allergies have increased, one theory is the hygiene hypothesis.  Our immune system’s job is to fight germs and stave off infections. However, our homes have been sanitized with bleach and antibacterial soap.  In our efforts to provide clean homes for our families, our immune systems have lost their job, so they are looking for something to do. It may sense a certain food as harmful, and take measures to protect the body.

Another theory is the way foods are processed.  For instance, in China, peanut allergies are far less common than in the United States. While peanuts are roasted in the US, they are boiled in China. Boiling does not alter the protein in peanuts as does roasting and typically, it is the protein in foods that acts as the allergen.

There are eight foods that account for 90% of food allergies:

  • Peanuts
  • Cow’s milk
  • Eggs
  • Fish
  • Wheat
  • Shellfish
  • Tree Nuts
  • Soy

Peanuts, milk, and eggs are the most common food allergies in children.  While many children outgrow these allergies, some will have them their entire lives.

In the past, physicians have advised parents not to introduce potential allergy foods to children until age 3. However, recent studies have shown that introducing these foods early may help prevent the allergy from developing. The LEAP study (Learning Early About Peanuts), which was the first randomized trial to study early allergen introduction as a preventive strategy, found that the introduction of infant-safe peanut-containing foods at 4–11 months of age significantly reduced the risk of developing peanut allergy in high-risk infants.  High-risk infants were defined as those who had severe eczema and/or egg allergy. The LEAP study was led by Professor Gideon Lack, and the results were published in the New England Journal of Medicine.

Similar studies have been conducted on early introduction of eggs to prevent allergies, but the results have been mixed or inconclusive. More research needs to be performed in the area of food allergies to better guide the path.

If you are concerned about food allergies for your child, talk to your pediatrician.  Refrain from providing any of the above-mentioned foods to your child until approved by your doctor.


Dear Dietitian

Leanne McCrate, RD, LD, CNSC is an award-winning dietitian based in Missouri. Her mission is to educate the public on sound, evidence-based nutrition.  Do you have a nutrition question?  Email her at