Peanuts contain more than 10 different allergic proteins. A “positive” skin or (traditional) blood test does not differentiate between those proteins more closely associated with a risk of anaphylaxis and those associated with a birch pollen allergy (which has a much lower risk, if any, of anaphylaxis). A component test (ImmunoCAP) can determine which proteins someone is actually allergic to. These results may factor into a decision about whether or not to conduct a food challenge. Those with a birch pollen allergy may be needlessly restricting their diets. And the incidence of a misdiagnosed peanut “allergy” may be incredibly high. One study found that out of 100 children who tested positive (aka were sensitized) for a peanut allergy, only 22% showed a clinical reaction (aka had an allergy).
This article discusses the advantages and limitations of blood, skin, and component testing.
We had our daughter, Bubba, component tested for peanut because she has never actually been exposed to them. We were hoping she was one of the ‘lucky’ ones who are unlikely to experience anaphylaxis. Unfortunately, Bubba tested positive for ara h 1, ara h 2, and ara h 3. These are the proteins associated with risk of anaphylaxis.
Only 20-25% of children will outgrow a peanut allergy spontaneously. The chance of spontaneous resolution decreases dramatically after age 8 (other studies say age 6 or 10). Factors associated with outgrowing a peanut allergy are:
- Low initial peanut specific IgE at diagnosis – lower than <0.7ku/L
- Being allergic to only one food
- Being white (versus black)
- Being male
- Not allergic to multiple foods
- Strict avoidance of traces of peanut is associated with spontaneous resolution
- Strict avoidance may prevent “natural immunotherapy” (also see this article)
For those that do not outgrow their peanut allergy, the teen years can be more dangerous. This study found a greater sensitivity to peanut to be associated with increasing age, higher specific IgE level and the absence of atopic dermatitis (eczema). However, outside of the lab, one expert explains that the teen years can be riskier because of developmental and social factors.
Bubba has never had a contact reaction to peanuts, but here is a helpful article about how best to clean peanut residue.
Bubba’s younger brother has been tested for food allergies and came up negative for everything. Phew. Studies show that 7% of children with a peanut-allergic sibling will have the allergy too (this is about seven times higher than expected).
We are done having kids in our house, but for those who are pregnant or nursing and you want to know whether or not to consume peanuts, be aware that current research shows that children whose nonallergic (obviously) mothers had the highest consumption of peanuts or tree nuts while pregnant has the lowest risk of developing a nut allergy. So take that off your list of things to be paranoid about. Additionally, the AAP has revised recommendations that pregnant and nursing mothers avoid potential allergens.
Tree nuts – Bubba is also allergic to all tree nuts except almonds. 25-40% of people with a peanut allergy also have a tree nut allergy. This article states 28-50% of peanut allergic folks are allergic to at least one tree nut.
Legumes – Bubba has officially outgrown allergies to soy, lentils, a variety of beans, chick peas, and green peas. Yee haw! She had previously tested positive for soy, had a few reactions, and then showed a decreasing sensitivity. We conducted a food challenge, she passed, and then she had a few small reactions to soy (‘spicy’ mouth and nothing else). We avoided for awhile and upon reintroduction she had no reactions. Peas are another story. Bubba had two anaphylactic reactions to pea protein and unfortunately this is a common ingredient is what would otherwise be safe vegan products. After two negative skin prick tests we went ahead with a food challenge and she passed. We couldn’t be more excited to incorporate Daiya, Hampton Creek Mayo, Ben and Jerry’s Dairy-Free Ice Cream, and a variety of other vegan products containing pea protein.