What Is a Food Allergy?
Food allergies occur when the body produces a specific immune response to a certain food. This immune response can be as mild as inflammation or as serious as anaphylactic shock.
Common food allergies include milk, egg, peanut, tree nuts, soy, wheat, fish, and shellfish. Milk, egg, and peanut make up 80 percent of food allergies.
Types of Food Allergies
Food allergies may be IgE, IgG, or non-IgE-mediated (checked with a blood test). When an allergy is IgE-mediated, IgE antibodies are released. These antibodies stimulate proinflammatory cytokines which cause the allergic reaction many consider to be “true” food allergies. This reaction can be life-threatening. This is why many children are prescribed an auto-injector (epiPen) that they carry around in case of food allergy reactions.
A more controversial theory is that IgG may also play a part in food allergies. An IgG-mediated reaction causes a delayed sensitivity to foods, according to some research including this 2007 study.
Other research, however, shows that the presence of IgG may actually signal a greater tolerance of a food later in life. One study published in the journal Pediatric Allergy and Immunologyfound an association between high levels of IgG4 antibodies to foods during infancy and tolerance to the same foods later in life.
Food Allergy vs. Food Intolerance or Sensitivity
Food intolerances and sensitivities don’t involve the immune system. They usually only cause digestive issues, like in the case of lactose (dairy) intolerance. Food intolerances are usually caused by things like:
- enzymatic deficiencies
- nutrient malabsorption
- sensitivity to certain proteins or components of food such as gluten, FODMAPS (a kind of carbohydrate), or histamine
It can be difficult to tell if a food intolerance is also an allergy though. You may not notice mild inflammation or eczema (or recognize the connection). It’s difficult to know if a reaction is an intolerance or a non-IgE mediated food allergy. This is one reason that many people use the terms “allergy” and “intolerance” interchangeably.
You can have an allergy skin test performed to check for an immune response, but keep in mind that they aren’t always accurate. Many families don’t bother with a skin prick test for this reason. They treat their symptoms as if they could be either an allergy or an intolerance. Another test is a food challenge where a child is given small but increasing amounts of a food in a controlled setting. This test is much more accurate and can be done at home.
What Causes Food Allergies?
If you ask around, most people would agree that food allergies are increasing in prevalence. Most of us don’t have a grandparent with any food allergies, but many of us have children with them.
Dr. Katie Marks-Cogan, a board-certified allergist (and mom) explained:
We’re seeing a rise and it’s actually quite drastic. Currently, it’s estimated that about 8% to 10% of children in the United States have a food allergy. So if you break that down, that’s about 1 in 13 children. And if you think about school-aged children, that’s two children per classroom.
She also mentions that the rate of peanut allergy has almost tripled over the last few decades. Cow’s milk and egg are other common offenders.
Food Allergy Theories
Because of this increase in food allergies, you might be wondering what we’re doing differently now that we weren’t doing in the past. Some of the following theories address that question (and some don’t). Here are some of the most common theories on food allergies:
- Food Allergen Avoidance – I don’t think I’ll ever be out of a day job because the science is always changing and evolving. The advice we’ve been getting for a long time is to avoid giving babies the most highly allergenic foods early in life, and delaying past age one or two. Now it’s thought that this avoidance is part of the problem.
- Dual-Allergen Exposure Hypothesis – One theory that has been gaining traction lately is that exposure to food allergens through the skin may be partly to blame for food allergies. This 2012 study found that this may be true while early oral exposure can reduce the risk.
- Nutrient Deficiency – There have been studies suggesting that food allergies may be a reaction to nutrient deficiency such as vitamin D and omega-3s (more on this below).
- The Hygiene Hypothesis – Much research in the past several years has found that being too clean can have a negative effect on the body. The theory states that not being exposed to pathogens early can weaken or skew the immune system so food allergies are more likely. This is one reason I don’t use antibacterial products around the house (even though 6 kids = plenty of dirt and bacteria coming in the house).
- Probiotics – Piggybacking on the hygiene theory, another theory is that lack of healthy gut bacteria plays a part too. For example, a 2009 study performed on infants found that decreased levels of certain probiotics in the first two months of life made infants at higher risk for food allergies later.
- Gut Permeability – Food allergies can be caused by leaky gut syndrome. Normally the gut lining allows only small nutrients through (to be absorbed into the bloodstream) and blocks larger particles like proteins. When the gut is unhealthy (more permeable), these proteins can pass through and trigger an immune response.
- Parasitic Worms – One of the most controversial theories is that food allergies may be an immune response to parasitic worms. This theory came about (and has grown since) when one researcher noticed that rats infected with parasitic worms produced large amounts of IgE antibodies.
It’s frustrating, but at the end of the day, none of these theories fully explains food allergies or why they are on the rise. We just don’t know why food allergies develop. This is one reason that treating and preventing them is so complex.
However, new research has given us a clue on how to prevent food allergies by changing the way we introduce new foods to babies.
Science-Based Ways to Reduce the Risk of Food Allergies
The old wisdom was to avoid giving babies the most highly allergenic foods until after their first birthday. It’s what I did for several of my babies, based on the going advice at the time.
But brace yourself… new research shows that the opposite is true! In fact:
The earlier a child is exposed to allergenic foods, the lower the risk of getting food allergies.
Here’s a rundown of the research behind the change:
- The LEAP study – This UK-based study was the first randomized trial to study preventing food allergies in a large group of high-risk infants. Results reported in 2015 found that peanut allergies were less likely if the child ate peanut protein between 4 and 11 months of age.
- The EAT study – Another study found that introducing allergens between 3 and 6 months significantly reduced allergies later. However, study participants could only achieve 50% compliance with protocol, indicating that early and sustained introduction was difficult to achieve at such a young age. The study also stressed that the recommendation was still to exclusively breastfeed during the first six months of life.
- The PETIT study – In this study, 4 to 5-month-old infants with eczema who were given egg protein were less likely to develop egg allergies later. But it’s important to note that 10 percent of the egg group were admitted to the hospital (presumably from their eczema, but it’s unclear), compared to zero in the control group.
It’s exciting to have some hard data uncovering the causes of food allergies and what to do about it, but how parents can act on these (rather complex) findings is less clear.
So, what’s a parent to do?
A Holistic Approach to Preventing Food Allergies
This new information doesn’t give us all the answers but it is an important piece of the puzzle when it comes to reducing the trend of rising food allergies in kids.
What the studies do tell us with some confidence is that in most cases there is no apparent benefit to delaying in the introduction of allergenic foods, and in fact they should be given to babies:
When Is “Early”?
There is certainly still debate about what this means for the right age to introduce these foods.
I don’t recommend feeding breastfed infants solid or pureed food before at least 6 months of age (and the World Health Organization agrees) for a few reasons.
- Babies don’t lose the tongue thrust reflex until 4-6 months of age. This reflex means if food enters their mouth they automatically push it out with their tongue. This is a protective mechanism.
- Babies who can’t sit up on their own should not have solid food in their mouths (even purees — it’s a choking hazard). Many babies can’t sit up on their own until at least 6 months of age.
- Solid foods displace breastmilk. Meaning baby misses out on some of the nutritional and immune-building benefits of breastmilk.
The new research is compelling, though.
What I Would Do
Of course, as with so many aspects of parenthood, each parent and family should do their own research on this topic and determine what age to start allergen exposure.
If I were introducing solid food, I would wait until 6 months of age but then feed allergenic foods right away (along with nutrient-dense foods like bone broth, liver, etc.). This type of schedule also lines up with the window of allergen exposure in most of the studies and gives baby a longer time of exclusive breastfeeding.
For the first 6 months of life, all baby needs is breastmilk or formula. If baby is formula fed, it is nutritionally all she needs (though you can add probiotics or enzymes or make your own formula to mimic breast milk as much as possible).
Ready, Set, Food!
It’s worth mentioning that there is one company bridging the gap between this research and putting it into practice. Two dads concerned about this issue teamed up with an incredible panel of experts and allergists to develop a simple powdered supplement that can be added to baby’s bottle (either expressed breast milk or formula).
It’s called Ready, Set, Food! and it is organic, non-GMO, and contains small amounts of egg, dairy, and peanut (the 3 top allergens).
(Personally, unless I had to bottle feed I wouldn’t express breast milk in order to do this, as there is some nutrient loss. I would wait until the introduction of solid food and add it at that time, but do your own research about what’s right for your family.)
What’s nice about Ready, Set, Food! is that it makes it very easy on parents (always a fan of that!) to start with very small amounts of allergenic foods without the hazard of intestinal upset or choking by feeding solid food too early. It also makes it easy to be consistent and frequent with exposure in what is often a busy and sleep-deprived stage of life.
Other Things to Try
Early exposure to allergens in carefully calculated doses are one way to help reduce the chance of allergies. There are some other lifestyle factors that can help to optimize as well. While not all of these are definitely going to help, they are generally good for your health anyway, so they can’t hurt.
- Gut healing – Because most of the immune system resides in the gut, it makes sense to make it as healthy as possible. Babies inherit mom’s gut health, so starting with your own gut health is a good first step. Breastfeeding, if possible, is a good way to get baby off to a good gut-health start.
- Eat allergenic foods while pregnant and breastfeeding – It would make sense that this could be helpful since we know that babies get their first taste of foods from amniotic fluid and breast milk. At this point, researchers aren’t convinced that a mom’s diet during pregnancy and breastfeeding affects the baby’s allergy development. However, one study in mice shows that this prenatal and breast milk exposure can reduce food allergies.
- Immune support – Allergies are sometimes thought of as a misfiring or overreaction of the immune system. Making sure the immune system is properly developed may help. Since we know baby inherits some of his immune system from mom, it’s not a bad idea to make sure your immune system is at its best. The tips in this post can help support your immune system. However, there is no research to support this idea.
- Vitamin D – Studies suggest that infants with low vitamin D levels are at higher risk for food allergies. Boosting your own vitamin D during pregnancy and breastfeeding can help. Vitamin D drops after birth are also a good choice but always talk to a doctor before giving a baby any supplement.
- Omega-3 fatty acids – In one study, women who took fish oil supplements during pregnancy had a 30 percent lower risk of their child developing egg allergies. Again, check with a doctor and make sure to choose a high quality omega-3.
As mentioned, there isn’t much evidence that the above advice will help avoid food allergies. But at the same time, most of this advice has no drawbacks and is good general health advice, so it can’t hurt to try.
How to Introduce Allergens Early
Always consult your child’s healthcare provider before making any decisions to introduce food. If you’re planning on introducing allergenic foods at 6 months of age here are some tips for doing it:
- Start with milk, egg, and peanut as these are the most likely allergens.
- Offer very small amounts of one food at a time. Then and work your way up to larger amounts.
- Offer them often. Once is not enough. Baby needs time to “learn” about these foods.
- Consider using Ready, Set, Food!’s system which gives baby a very small amount of the highest allergenic foods (one at a time). It makes giving baby these foods (in small amounts and on a regular basis) easy for you.
While you begin feeding baby these foods, always be aware of any allergic reactions that pop up.
Allergy Signs to Look For
Even though you’ll be feeding very small amounts of these foods, baby may still have a reaction. Here are some allergy symptoms to look for:
- Digestive issues like vomiting or diarrhea
- Hives, welts, or other skin rashes
- Face, tongue, or lip swelling
- Coughing or wheezing
- Trouble breathing
- Loss of consciousness
Severe reactions require medical care. If you feel your child is having a severe allergic reaction, call your child’s doctor or 911.
Food Allergies in Children: Bottom Line
Food allergies, especially in children, are on the rise. We don’t know yet what is causing it. But the most recent research shows us that early introduction to allergenic foods is the best way to prevent food allergies.
Have you tried feeding allergenic foods early? What was your experience?