Nut allergies are one of the most common types of food allergy seen in children and adults. In this post, I look at the causes and consequences of nut allergies and then profile the emerging treatment of oral immunotherapy.
A nut or peanut allergy is one of the most common food allergies seen in infants and children. Just for peanuts alone, about 3 in every 100 infants will have an allergy to them. And while some children will naturally outgrow their allergy, most will still have the allergy in adulthood.
A nut allergy happens when the body’s immune system becomes over-sensitive to a protein in a nut. And that sensitivity can mean that people can react even if exposed to tiny traces of nuts in food. Even simply breathing in or touching a nut can be enough to trigger a reaction. People with a nut allergy need to avoid the nut that triggers their allergy entirely.
Types of nut allergies
When you think of a nut allergy, it is peanuts that usually come to mind. But people can be allergic to all types of nuts. The proteins in peanuts that can trigger an allergic reaction are very different to those in tree nuts. That means that that someone who is allergic to peanuts is not automatically going to be allergic to tree nuts.
And just to confuse things, peanuts are not a nut, but a legume. Legumes include foods like chickpeas, lentils and soybeans. That’s why it is correct to talk about peanut and tree nut allergies as different things. A wide range of tree nuts can cause allergic reactions. These include:
- Brazil nuts
- macadamia nuts
- pecan nuts
- pine nuts
What causes a nut allergy?
All allergies have a common base. It is when the immune system reacts to a specific allergy trigger called an antigen. The immune system produces antibodies against the allergen which causes inflammatory reactions and the release of a chemical called histamine. Histamine causes hives, hay fever and other allergic symptoms.
Food allergies are very common. Food allergy is found in around 10 percent of infants, 4-8 percent of children, and about 2 percent of adults in Australia. The most common types of food allergies seen in children and adults are to:
- cow’s milk
- tree nuts (almonds, walnuts and pecans).
A food allergy needs to be diagnosed. This can be done by a doctor or an allergy specialist. A combination of questions to help narrow down the likely list of suspected allergy triggers combined with skin or blood tests is normally done. While the results of allergy tests are a useful guide in determining whether a person is allergic, they are not a reliable guide to how severe a reaction will be.
Symptoms of an allergy
Signs and symptoms of peanut, tree nut or seed allergies can vary. They range from mild reactions right through to severe anaphylaxis. Some factors can make allergic reactions to foods worse. These include the amount of food eaten, exercising around the time of exposure to the allergen, alcohol, asthma and being unwell.
Signs and symptoms of a milder to moderate allergic reaction to food include:
- raised red bumps of skin (hives)
- swelling of the face, lips and eyes
- runny nose
- nausea or vomiting.
Peanuts and tree nuts are among the most common foods to cause severe allergic reactions. This is called an anaphylactic reaction and it is life-threatening. Signs and symptoms of a severe reaction include:
- difficult or noisy breathing
- swelling of the tongue
- swelling or tightness of the throat
- difficulty talking
- wheezing or a persistent cough
- dizziness or collapse
- paleness and floppiness in young children.
If you or a person you care for experiences a severe allergic reaction, this is a medical emergency. An ambulance should be called immediately. If available and you have been trained, the use of an EpiPen® autoinjector to administer adrenaline (epinephrine) can be life-saving.
Emerging treatments: oral immunotherapy
There is no cure for nut allergy. The only way to manage it is to completely avoid exposure to the nuts a person is allergic to. That means being an avid label reader because nuts can be hidden in all sorts of foods – even in trace amounts.
But science is not standing still, and new treatments are now being explored. People with a nut allergy need to avoid the nut that triggers their allergy entirely. Called oral immunotherapy, it is emerging as a possible way to desensitise people to nuts and allow small amounts to be eaten safely. The benefits (in those that respond to it) can build a safety margin against inadvertent life-threatening exposure to peanuts.
In one early clinical trial of peanut oral immunotherapy, 40 children aged between 9 months and 36 months old were given either high- or low-dose peanut exposure daily for around 29 months. After the end of the treatment and allowing for a month of following a peanut-free diet, peanut protein was added back into the children’s diet. The results were impressive. Around 80 percent of children given either treatment dose of peanuts were able to eat peanut-containing foods without having an allergic reaction.
To put the newly developed tolerance to peanuts into context, the children in the clinical trial were 19-times more likely to be able to eat peanuts without a problem compared to a similar group of children with the allergy, but who didn’t have the treatment.
And published in only January of 2022, a clinical trial in 150 highly peanut-allergic children aged 1 to 3 years found that peanut oral immunotherapy safely desensitised 71 percent of them to peanuts. It also induced remission of peanut allergy in one-fifth of the children as well. Compare that to the placebo group where just 2 percent of children experience remission from their peanut allergy. Remission was defined as being able to eat 5 grams of peanut protein (equivalent to 1.5 tablespoons of peanut butter) without having an allergic reaction six months after completing immunotherapy. And I’ll link to this study in the show notes.
What was used for the immunotherapy in this recent trial was peanut flour. The amount of flour eaten was increased to finally provide 2 grams of peanut protein. That’s the equivalent of about 8 peanuts. And the benefit of the treatment grew the earlier in life it was given with 1-year-olds showing the highest rates of remission.
There have even been oral immunotherapy clinical trials using a special drug called AR101 which is derived from peanuts. AR101 gives a dose equal to 300 milligrams of peanut protein. In one study, a total of 551 people (most aged 4 to 17 years) with severe peanut allergy were enrolled in the trial and randomised to receive either AR101 or a placebo for 24 weeks.
At the end of the trial, each person received a peanut food challenge. For those in the AR101 group, 67 percent were able to tolerate the comparable of at least 2 whole peanut kernels without symptoms. This was in stark contrast to the placebo group where only 4 percent passed through the peanut challenge without reaction. And I’ll link to this study in the show notes.
No matter how impressive the results of oral immunotherapy are, it is not implying that the allergy has been cured and peanut butter is back on the menu for kids with a peanut allergy. Only that children can now live a life with a much greater safety margin against accidental exposure.
Because of the serious dangers of intentionally exposing children to peanuts, any form of oral food immunotherapy should only ever be considered under direct medical supervision by healthcare professionals.
Advice during pregnancy
With nut allergies so common in infants and children, for many years conventional wisdom was that women should avoid peanuts during pregnancy. In utero exposure to nuts was at one time thought to be a trigger for raising the risk of allergy risk in children. But this idea has fallen out of favour due to the findings of recent research.
Simply, there is little evidence to support the claim that eating peanuts during pregnancy will make a child more likely to develop a peanut allergy.
There is even some research to show that women who eat peanuts or tree nuts during pregnancy pass on a lower risk of developing a nut allergy in their infant. So, it seems that the early introduction of food allergens leads to the development of tolerance to these food allergens, reducing the risk of developing food allergies. Unless a woman who is pregnant has a nut allergy herself, nuts are definitely okay to consume during pregnancy.
What it all means
So, let’s wrap all this up. A nut allergy has many serious health consequences. While avoiding nuts that a person is allergic to will stop an allergic trigger, it can be hard to maintain this throughout life if the nut allergy doesn’t naturally subside. Oral immunotherapy is now emerging as a potential way to treat food allergies to desensitise people to nuts and allow small amounts to be eaten safely.