Food Allergies Guide

Development of allergies appears to be a combination of the environment and genetic make-up. Many studies have demonstrated that the greater the incidence of allergy in both your immediate and extended family, the greater the likelihood that your children will also have allergies.

However, the environment in which live will also plays a role. For example, the allergens in Alaska will be different than those in Florida. Therefore, if you lived in Florida for many years and then moved to Alaska, chances are you would not respond to many of the allergens in Alaska that someone else, who has lived in Alaska their entire life, might respond to and vice versa.

Food allergy is not an instant reaction. The food causing the hypersensitivity can remain in the stomach or the intestine for up to 3-5 days before causing a reaction. An allergic reaction to food is difficult to distinguish from food intolerance unless the reaction results in hives, itching, or severe difficulty breathing. Only about 10% of food allergy reactions can be diagnosed by laboratory tests.

This means that 90% of reactions are difficult to distinguish from food intolerance. Recall that an allergic reaction is immune mediated - some allergic reactions are immediate - these are the ones we currently have diagnostic tests for - others are delayed and occur via a different immune response pathway than the immediate reactions. Because they have a different set of mediators, delayed reactions are more difficult to diagnose.

A baby growing in its mother's womb is capable of mounting an immune-mediated allergic response by 11 weeks of gestation. This can occur when allergens from the environment enter the mom's circulation and cross the placenta. The baby's immune system sees these allergens as "foreign" and develops antibodies to recognize and mount a defense against the allergen.

Later, after the baby is born, when it encounters the same allergen, it's immune system "remembers" the molecule and an allergic reaction occurs.
It is estimated that about 8% of children are affected by food allergies. Children can have a wide variety of allergies to food - many of which they will out grow by the time they are two years old. The most frequent food allergy encountered in children is cow's milk allergy.

This allergy however, may substantially diminish with a few milk-free months and either be totally gone or very minimal in 1-3 years. Other common food allergies among infants and children are eggs and wheat.

Interestingly, peanut allergies may be life-threatening, and once they develop, they are usually permanent. People who are allergic to peanuts often are allergic to tree nuts as well. About 100 deaths per year are caused by peanut allergy, usually by accidental exposure to peanuts or peanut products in other foods. Unlike milk, eggs or wheat where diets free of these items for periods of time can reduce or eliminate the allergic reaction, the peanut allergy is life-long for most individuals. However, recent research suggests that up to 20% of children may outgrow their peanut allergy.

Not all reactions to food are true allergies. For instance, food toxicity is when a food contains a substance that would be toxic to anyone who ate it. A food idiosyncrasy is when the food item only causes symptoms in some people who are either unable to break down the food because their body doesn't make the right enzyme or they have an abnormal sensitivity to some part of the food. A true food allergy is an immune-mediated reaction that occurs every time you eat a particular food. It is estimated that only 2% of adults in the US are affected by a food allergy.

Adults may develop allergic sensitivities to almost any food including, but not limited to, milk, eggs, fish, wheat, rye, oat, corn, soybeans, and potatoes. Interestingly, a peanut allergy generally will not initially manifest in adults unless they never had peanuts as children.

Ways to prevent Infant Food Allergies
There are few recommendations of ways to avoid sensitizing your unborn child.

1. Avoid foods that could possibly cause sensitivities during the third trimester and while breastfeeding.

2. Breast-feeding has the benefit of removing some of the potential allergens and at the same time provides the baby with added immune defenses.

3. Use of medications when there is a food allergy.

Treatment

In general, avoidance (don't eat it) is the only treatment available and is also the safest route. Often food allergies are diagnosed by eliminating one item after another from your diet and watching for resolution of symptoms.