Food allergies in babies are a little more complicated than you might expect. And typically, they’re the second step of the atopic march - which involves atopic eczema, food allergies, and asthma.
If you notice signs of food allergy in your baby, you might wonder what the trigger food could be.
Cow milk? Eggs? These are common allergens.
But did you know that there are four different types of food allergies that show up in babies? And sometimes, what looks like a food allergy is actually a food intolerance.
Immune-mediated food reactions, also called allergies, include:
- IgE mediated. For example, hives.
- Non-IgE mediated. This includes a vomiting disorder known as EoE (eosinophilic esophagitis) and celiac disease, an autoimmune condition triggered by gluten.
- Mixed IgE and non-IgE mediated. For example, a type of eczema often seen in babies known as atopic dermatitis.
- Cell mediated. Like a contact rash.
Non-immune mediated food reactions - which can be mistaken for food allergy - include food intolerances. A common food intolerance is lactose intolerance.
Can babies have allergies?
It was recently estimated that food allergies affect 3% of babies under one year old, up to 8% of children, and 3% of adults in industrialized countries , . And in 2018, 4.8 million children in the US were reported to have food allergies. Peanut allergy was the most common .
The top eight food allergens are:
- Tree nuts, such as walnuts or almonds
- Cow’s milk
What’s worth pointing out here is that food allergies in babies often follow eczema and this is part of something known as the atopic march. In fact, when babies are diagnosed with eczema within their first year, they’re also 11 times more likely to develop peanut allergy during that same year .
There’s a good chance that the appearance of food allergies in babies involve genetics, diet, and baby gut health.
For example, changes in the baby gut microbiome - or the bacteria that live in the gut - have been found in those with different types of food allergies. Such as egg, peanut, soy, wheat, or cow milk allergy.
This is one reason why the Tiny Health baby gut test looks for biomarkers linked to food allergy development.
What are the signs of food allergy?
Food allergies are an immune system reaction that shows up soon after eating an allergen, or trigger food. Sometimes, even a small amount of food can be responsible for a major reaction.
Signs of food allergy in a baby can range from:
- Digestive troubles
- Hives or itchiness
- Swollen airways
- Anaphylaxis, a severe allergic reaction that’s life-threatening
Typically, when you notice signs of food allergies in babies, the immune system mistakes an allergen as a real threat and releases something called IgE, or immunoglobulin E. IgE then signals other immune cells, causing symptoms of food allergy.
Cow milk protein allergy in babies
Cow milk protein allergy is one of the earliest and most common food allergies in babies. It affects 3-7% of babies and usually shows up within a baby’s first year. Fortunately, 75% of kids outgrow cow milk allergy by the time they are three years old .
While there is no diagnostic test for cow milk protein allergy, like a blood or skin prick test, you may notice signs of cow milk protein allergy within the first week of your baby’s exposure to cow’s milk. This can include:
- Digestive troubles, like gas or diarrhea
- Rash or eczema that does not improve
- Hay fever-like symptoms
- Blood or mucus in the stool
Some babies are more sensitive to milk protein than others. And have more severe symptoms.
Even though breastfeeding seems to protect babies against the development of cow milk protein allergy, exposure to cow milk protein can occur through breastmilk alone. In this case, it’s still ideal for a mother to continue breastfeeding. However, it may help to try a dairy-free diet or work with a practitioner to avoid both obvious and hidden sources of cow milk protein. It can take up to 72 hours for a mother's breastmilk to become free of milk protein.
It’s worth pointing out that cow milk protein allergy is not the same as lactose intolerance, which does not involve an immune response and is very rare in kids under the age of 5 years old.
This means that probiotics and supplements with lactose, a milk sugar, will not trigger cow milk protein allergy. And if breastfeeding, it’s not necessary to seek out lactose-free dairy products.
When using formula, cow milk protein allergy can be especially tricky since many formulas are made with cow’s milk. With the support of your health care provider, you may want to consider:
- Starting with a formula made from broken-down proteins, also called hydrolyzed formulas, because these eliminate symptoms in 90% of children.
- An amino acid formula if signs of allergy do not improve.
- Steering clear of soy-based formulas, since many babies - roughly 30% - can have a similar reaction; goat or sheep’s milk milk formula tend to have the same reaction.
Cow milk protein allergy is especially noteworthy within a baby’s first year because it does increase the risk of other atopic conditions, like eczema, and other chronic immune-mediated disorders such as inflammatory bowel disease .
Milk allergy in babies may have a microbiome connection
As it turns out, there seems to be a relationship between milk allergy in babies and baby gut health.
For example, we know that high levels of certain friendly bacteria - like some Clostridia and Firmicutes - at the age of 3 to 6 months is associated with the resolution of milk allergy by the time a child is 8 years old .
Likewise, interesting research has been done with germ-free mice, which are mice that have no bacteria living in or on them. When the gut bacteria from babies with cow milk protein allergy are placed in germ-free mice, these mice seem more vulnerable to a strong, anaphylactic response to a cow's milk protein . Whereas germ-free mice with bacteria from healthy babies are protected from cow milk allergy.
We also see a connection between interventions that impact the microbiome and food allergy.
Research suggests that babies born by C-section delivery have more than double the risk of developing food allergies and asthma later in life . What’s more, antibiotic use early in life - specifically penicillin - also appears to increase the risk of developing milk and non-milk (such as nuts and seafood) allergy .
This implies that while food allergy is probably driven by factors like genetics and diet, there are also some notable differences in the gut microbiome of folks with different types of food allergy. Such as egg, peanut, soy, wheat, or milk allergy.
That said, research currently lacks consistency. So it’s tough to interpret what these differences really mean. But it suggests that baby gut health and the baby microbiome are potentially important in regulating a baby’s response to food allergens.
Non-IgE-mediated food allergies in babies
Non-IgE food allergy is an umbrella term for several conditions. The one thing that unites them all is inflammation of the gut.
On the whole, these conditions are rare. But when they do occur, the most common non-IgE food allergies are:
- Eosinophilic esophagitis (EoE)
- Food protein-induced enteropathy (FPE)
- Food protein-induced enterocolitis syndrome (FPIES)
- Food protein-induced allergic proctocolitis (FPIAP)
When it comes to non-IgE food allergies, we see a relationship with baby gut health there too.
For example, we know that FPIES is more common in babies who have been exposed to antibiotics during pregnancy and infancy, increasing their levels of unfriendly bacteria .
Cow milk FPIES is more likely to show up in babies born by C-section delivery section than those born by vaginal delivery.
FPIAP is rare and defined by bloody stool. The response is often triggered by cow’s milk protein and it tends to show up in babies under 12 months old.
When addressing FPIAP, probiotic formulas that include Lactobacillus rhamnosus GG may be useful . And if fecal microbiota transplantation is an option that’s available, research has found that this type of therapy can relieve symptoms of FPIAP within days with no relapse over the following 15 months .
Food intolerance is not an allergy
Food intolerance is not an allergy because it does not involve a response from your baby’s immune system. That said, the signs of food intolerance are very similar to food allergy. They include:
Food intolerance can show up if your baby doesn’t have the enzymes needed to digest a particular food. For example, lactose intolerance shows up when there isn’t enough lactase enzyme in the small intestine to digest the milk sugar, lactose. While many adults are lactose intolerant, babies make plenty of lactase in order to digest breastmilk.
Other causes of food intolerance include:
- Sensitivity to food additives
- Food poisoning
- Histamine toxicity caused by some kinds of fish, including tuna, mackerel, anchovy, and herring
Common food allergies and food sensitivities in babies
Baby gut microbiome testing shows what’s really going on
Hopefully at this point it’s clear that signs of food allergy in a baby can show up at any time. And while a baby’s immune system is still developing, food allergy in babies has a strong relationship to baby gut health.
Which means that we have a small window of time when we can make a difference. And even change the trajectory of a baby’s immune development.
If you suspect lactose intolerance is an issue for your baby, it’s worth pointing out that this is very rare in children under the age of 5 years old. You’re more likely to see an immune mediated reaction in a baby than a food intolerance.
This is why we take a close look at the bacteria in a baby’s gut.
Gut microbiome testing cannot diagnose a food allergy or lactose intolerance. But it can give you a clear snapshot of the environment that’s impacting your baby’s immune development.
We want to see a lot more good bacteria than unfriendly bacteria. This is because typically these good bacteria create helpful compounds that are soothing and supportive to your baby’s immune system.