The rate of food allergies in children has increased over the years. According to this article by the Centre for Disease Control in the USA, food allergies increased from 2.4% in 1997 to 3.4% in 2011. One interesting correlation in this article notes that the rate of food allergies increased with higher incomes! The richer you are, the more likely your child is to develop a food allergy!
Considering a food allergy could be potentially fatal if a child accidentally ingests the food allergen, prevention is certainly something to aim for. Unfortunately, scientists have yet to isolate the exact mechanism that causes a person to develop a food allergy.
what is a food allergy?
Compared to a food intolerance, a food allergy always involved the immune system. A classical allergy is when a protein found in food (the allergen) causes the immune system to release IgE antibodies. These antibodies are responsible for the allergic symptoms: hives, swelling of the mouth, tongue, and airways, vomiting, and fatigue. If not treated immediately, the reaction can be fatal. It is called an abnormal response to a normal, harmless protein. Our bodies use the IgE response to attack foreign bodies such as bacteria and viruses that could cause harm. When a person has a food allergy, this person’s body has mistaken a harmless protein for a vicious invader.
which foods can cause an allergy?
While any food count potentially cause an allergy, 90% of food allergies are attributed to:
- fish and shellfish
- sesame seeds
the developing child’s intestine
Our intestines are lined with cells that are held together by tight junctions. These junctions hold the cells close together so as to prevent proteins from passing through into the blood. A baby is born with more loosely connected cells. As the baby matures, the tight junctions bring the cells closer together. The newborn baby’s liquid diet creates an additional barrier as it coats (or paints) the intestine. With this knowledge of the developing child’s intestine, recommendations were made around the year 2000 to delay the introduction of the top 9 food allergens until the space between the baby’s intestinal cells closed up around 12 months.
Parents followed these recommendations but the rate of food allergies still continued to climb. Clearly, delaying the introduction of these foods was not the solution. Scientists went back to the drawing board. It’s now shown that these foods should be introduced once solids are initiated: around 4-6 months. In the Learning Early About Peanut (LEAP) study children at high risk of developing a peanut allergy were placed in one of two groups: Group A was told to avoid feeding peanuts to the children until they turned 5. Group B was told to feed a peanut snack 3x/week starting between 4-11 months old. At age five 17% of the children in the avoidance group (A) had developed an allergy to peanuts while only 3% of the children in group B did.
There’s a theory behind this observed effect. The body has an amazing barrier to the outside world but if something gets past the barrier, the body instantly analyzes the material to determine whether or not it is a threat to the health of the body. When it comes to food, the normal way our bodies determine that the food is not a threat is by ingesting the food, digesting it, and absorbing the nutrients. When this happens, the body understands that you have fed it food and accepts the material as non-threatening. But if you don’t eat a particular food and instead, this food finds its way inside you via another mechanism (for example, low-dose exposure through air particles on the skin, especially if eczema is present), the body has not established that this is non-threatening. Alarm bells go off and IgE antibodies are called upon to deal with the offender.
is my child at risk?
Babies who have either a parent or a sibling with ANY type of allergy are considered more at risk. The relative doesn’t have to have a food allergy. It could also be a seasonal allergy, environmental, asthma, or eczema.
When babies have a first degree relative (parent or sibling) with an allergy, this baby then has a 20-30% chance of developing an allergy. The risk drops to 10% when there’s no family history.
what you can do
- If you’re still pregnant while reading this (or maybe you’re pregnant with the next baby!) don’t avoid any foods unless you personally have an allergy or intolerance. It is now known that avoiding food allergens while pregnant or nursing do not help to prevent food allergies from developing in your children.
- Breastfeed for as long as possible. Exclusive breastfeeding until you start solids is important but so is the total duration of breastfeeding! Some evidence points to a protective effect of breastfeeding while introducing new foods!
- Introduce highly allergenic food early and feed it often. There is no research to show a benefit of delaying these foods beyond 4-6 months. Some studies show that babies and children need repeat exposure to foods to develop tolerance. So you can’t just feed your baby a food once and then call it a day! Then should receive it on a regular basis. The LEAP study gave the children peanuts 3x/week. While this may be ideal I don’t know whether it is practical advice to offer all 9 foods at the same frequency!
- Support your child’s immune defence. Recent studies conducted in Korea and Australia showed that children with food allergies or eczema were more likely to be Vitamin D insufficient than children who were allergy-free. While this study doesn’t show that a lack of Vitamin D causes food allergies, it adds weight to the necessity of having adequate Vitamin D levels. See the section on Vitamin D for more on the importance of this amazing vitamin!
- Support your child’s gut health. I highly recommend discussing this point with your child’s pediatrician. There are some studies that show giving a daily probiotic supplement with the strain Lactobacillus Rhamnosus may help to prevent the development of eczema and allergies. Then there are studies that show no effect. In addition, there are some children for whom a probiotic may be more harmful than beneficial. That’s why I don’t give a blanket recommendation for everyone to supplement their child with a probiotic.