Researchers study links between hygiene, processing and food allergies


Dear readers,

Food allergies are on the increase in the United States, and it is estimated that up to 8 percent of children have at least one food allergy. A food allergy occurs when your body’s immune system reacts to a particular food as being harmful and reacts. These reactions can range from itchy skin, vomiting, diarrhea, difficulty breathing, wheezing, or life-threatening anaphylaxis.

While it is uncertain why food allergies have increased, one theory is the hygiene hypothesis. The job of our immune system is to fight germs and prevent infections. However, our homes have been disinfected with bleach and antibacterial soap. In our efforts to provide clean homes for our families, our immune systems may have encountered an identity crisis, so they are looking for a new job. In this scenario, the body reacts to a particular food as being harmful and takes steps to protect itself.

Another contributor to food allergies can be food processing. For example, peanut allergies in China are much less common than in the United States. While peanuts are roasted in the United States, they are boiled in China. Boiling does not affect the protein in peanuts the way roasting does, and it is usually the protein in foods that acts as allergens.

There are eight foods that account for 90 percent of all food allergies. They are:

  • Peanuts
  • Cow milk
  • Eggs
  • Fish
  • Corn
  • Sea food
  • Nuts
  • Soy

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

In the past, doctors have advised parents not to introduce potentially allergic foods to children before the age of 3. However, recent studies have shown that introducing these foods earlier in infancy can help prevent the development of allergies. The LEAP (Learning Early About Peanuts) study was the first randomized trial to study the early introduction of allergens as a preventive strategy. It found that introducing foods that are safe for infants containing peanuts between 4 and 11 months of age significantly reduced the risk of developing a peanut allergy in high-risk infants (1).

High-risk infants were defined as those with severe eczema or an egg allergy, or both. The results of the LEAP study were published in the New England Journal of Medicine.

Similar studies have been done on the early introduction of eggs to prevent allergies, but the results have been mixed or inconclusive. More research needs to be done on food allergies to provide safe recommendations.

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

Until next time, be healthy!

Dear dietician

The references

1. Du Toit G, Roberts G, Sayre PH, Bahnson HT, Radulovic S, Santos AF, et al. Randomized trial of peanut consumption in infants at risk of peanut allergy. N Engl J Med 2015; 372 (9): 803-813. 02/26; 08/2015.

DOI: 10.1056 / NEJMoa1414850

Leanne McCrate, RD, LD, CNSC, aka Dear Dietitian, is an award-winning dietitian based in Missouri. Its mission is to educate consumers about healthy, evidence-based diets. Do you have a nutritional question? Email him at [email protected] Dear Dietitian, does not endorse any product, health program or diet.

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