Latest on preventing and managing childhood food allergies

…does peanut allergy in particular get so much attention?

Helen Brough: Food allergy affects around six to eight percent of children globally, with the highest prevalence in countries that are urbanised and more westernised, and it has doubled or tripled over the last few decades in high income countries, and peanut allergy has gained particular attention because it is one of the most common and persistent food allergies, and the reactions can be severe or life-threatening. And until recently, there was no approved treatment for peanut allergy, and it also typically emerges early in life, so within the first year or the first eighteen months of life. So it’s a lifelong condition.

Gina Furnival: So why is this happening to so many children?

Helen Brough: Food allergy is actually quite a recent development in terms of its exponential rise. So although we think that there are some genetic factors that come into play, there are certainly a lot of environmental factors that are driving this.

And so it is a complex interplay between genetic, environmental, and immunological factors, and there’s various different reasons. For example, with genetics, we now understand that there is a particular gene that can increase the risk for developing eczema. It’s called the filaggrin gene. And then we know that actually having eczema is the strongest risk factor for developing peanut allergy, particularly early-onset severe eczema. And there are lots of things that increase the risk of developing eczema, which are environmental, such as detergents and antibiotic exposure in early life.

The old advice with regards to peanut introduction in infants was that children should delay introducing peanuts until they were three years of age. We now know that advice was incorrect based on the LEAP study and EAT study and other studies that have shown that early peanut introduction is actually what’s beneficial for the prevention of peanut allergy and that in particularly high risk children that have severe eczema, these children had peanut introduced from four months of age into the family diet and into the child’s diet on a regular basis, three times a week, a teaspoon of peanut butter every week until they were five years of age, and that showed an eighty-one percent reduction in peanut allergy.

And then there are other things like microbial exposure and gut health. So C-sections increase the risk of developing eczema, antibiotic use, and then other dietary factors like dietary diversity and ultra-processed foods.

Gina Furnival: So how is it possible for a child to react the first time they eat a peanut?

Helen Brough: Most children who are exposed to egg or peanut and react, will react the very first time they eat egg or peanut. And the reason is that they are being exposed to it, but not through the gut. They’re being exposed to it through the skin, particularly if they have eczema. So we now know from an increasing body of evidence that having eczema is the strongest risk factor for developing peanut allergy, particularly early onset severe eczema, and a longer duration of eczema also increases the risk.

There was some landmark work done by Prof. Adam Fox looking at household peanut consumption around a child that’s not eating peanut, and they found that this significantly increased the risk of peanut allergy. And then in my PhD, I was able to validate a method to quantify peanut protein in dust, and I was able to show that in children that have eczema or this filaggrin gene that I mentioned before, that if they’re exposed to peanut in their environment before they’ve introduced peanut into their own diet, that substantially increases their risk of developing peanut allergy. This is a hypothesis called the dual allergen exposure hypothesis.

It essentially postulates that there’s a window of opportunity in the first year of life where if you’re exposed to a food through the skin, through an inflamed disrupted skin barrier, then you’re more likely to become allergic to that food. But if you’re exposed to that food through the gut, which is a tolerant organ, then you are more likely to become tolerant to that food.

Gina Furnival: One of the biggest shifts has been the introduction of peanuts early into infants’ diets. What research drove that early introduction? How did it shape the national and international guidelines?

Helen Brough: It has certainly shaped national and international guidelines. So now in countries where peanuts are consumed, it is recommended in multiple international guidelines to introduce peanut and egg into the infant’s diet within the first year of life. And in certain international guidelines, they recommend in high risk children introducing it between four to six months of life and certainly not to delay the introduction of peanut and egg into the diet. But what’s really important and what I do see in my clinic is that people often think they just need to introduce peanut once, and that is not the case. It’s really important that they need to introduce peanut and then give that regularly, because that keeps reminding the child’s gut immune system that this is a safe food and that this is good for the baby to eat.

So just giving peanut once and then not giving it to the baby again could actually increase the risk of peanut allergy because then there’s peanut butter in the home and other family members might start eating peanut around the baby whereas the baby’s not eating peanut.

Gina Furnival: I see. And so you mentioned there, you mentioned eggs as well as peanut. What about fish and dairy?

Helen Brough: The evidence for fish and dairy is less strong, but there’s a lot of data that suggests that we use peanut and egg as a model food for other food allergens. And so introducing other food allergens is also recommended, particularly if it’s part of the family diet. I see all kinds of food allergies, and often when I ask the family, is this something that you eat at home? Then they will say, yes.

I had one child whose parents ate kiwi every morning for breakfast, but unfortunately, the child was not eating kiwi, and then that child developed kiwi anaphylaxis. I know another family where the father was having flaxseed flour and the child developed flaxseed anaphylaxis. So it’s very much about what the baby is exposed to at home and what the family is eating at home is what the baby should be eating at home as well, of course, with the usual provisos with no extra salt or sugar and no honey before one year of age.

Gina Furnival: We talked earlier about risk factors, and being eczema being one of them.  Can early treatment of eczema help?

Helen Brough: This is something that we’re actually investigating right now in the SEAL study called the Stopping Eczema and Allergy study. This is a study that is being sponsored by Harvard University and is funded by the NIH, and we are recruiting children with the earliest signs of eczema, including dry skin up until twelve weeks of age at Guy’s and St Thomas’ Hospital in King’s College London, and we are seeing whether early proactive skincare with good quality moisturisers and good topical anti-inflammatories will be able to prevent the development of food allergy and sensitisation to food.

Gina Furnival: And how far are we along with that study?

Helen Brough: We have just finished recruitment, and we are now going to follow up these babies for two years. We’re going to do blood tests at the two-year mark to look for sensitisation and some food challenges, which is the gold standard way to diagnose food allergy, to assess whether these children are allergic or just sensitized to the food.

Gina Furnival: Now sticking with some of the risk factors, a lot of your recent research has been around maternal risk factors. Can the maternal diet or exposures during pregnancy and breastfeeding impact a child’s food allergy risk?

Helen Brough: Absolutely. There’s lots of things that parents can do in advance of planning to have a baby, during pregnancy and during breastfeeding, that can help protect the child. So the first thing will be things that we all know about, which is not smoking, eating a healthy varied diet, a diet that’s not full of ultra-processed foods. So for example, one of the things that was recently published was evidence looking at dietary diversity both in the infant and in the mother, and they found that having a high diet diversity (lots of different foods in the family diet) was actually protective against all forms of allergy. And then particularly in pregnant mothers, a diet rich in vegetables, which contains prebiotics, which is good food for good bacteria, and also yoghurt, which has got fermentation and therefore has good bacteria, were protective against all forms of allergies in the baby.

And this then was also corresponding in the baby with a high dietary diversity. There was an interesting study done in a UK population that showed that in children that introduced any type of food before six months of age, even in tiny tastes, that for each food that was introduced, there was an eleven percent reduction in the risk of food allergy over ten years.

They also looked at each introduction of a food allergen before twelve months of age and found that there was a thirty-three percent reduction in the risk of food allergy over ten years. What I recommend for families that have a baby with eczema is that they get really good control of the eczema because the eczema is the route through which the child might become allergic through the skin, and then that they introduce the main food allergens early, from six months of age in egg and peanut in the general population. But if they do have eczema, that they introduce egg and peanut around four months of age, not before seventeen weeks of age.

Gina Furnival:
And vitamin D — can that help?

Helen Brough:
Yes. That’s really important with regards to vitamin D during pregnancy and also during the baby’s first year of life.

Many mothers are vitamin D deficient in pregnancy, and they don’t know. It’s really important that mothers make sure that they not vitamin D deficient during pregnancy and then that will be very important for their babies — especially with breastfeeding — because they will be giving their vitamin D and their iron to their baby.Also, babies that are breastfed should receive vitamin D from birth, and that’s recommended by many different governments, including the UK. That will prevent vitamin D deficiency, and we know that vitamin D deficiency in itself can actually cause eczema.

Gina Furnival:
We’ve touched on the microbiome previously. When it comes to antibiotic use in pregnancy, can that impact our chance of a child developing a food allergy?

Helen Brough:
Yes. There’s evidence that shows that antibiotic exposure during pregnancy, and antibiotic exposure in the first few days of life — as well as in the first year of life — can increase the risk of developing eczema.
A lot of the time I think of eczema as a reflection of the gut microbiome being reflected on the skin. If you’re going to help with the gut to become more happy and have better homeostasis, then you’re going to see a better improvement in the skin as well.

Gina Furnival:
When it comes to developing an allergy prevention is absolute key, but say you have an allergy, what’s on the horizon then to help manage that?

Helen Brough:
The first thing when it comes to having a food allergy is to get the basics right. It’s really important to know what your child is allergic to, to be able to recognise an allergic reaction, and to know how to manage an allergic reaction well,  and to have a written allergy action plan with the right medication.

It’s also really important that you’ve been given advice on what foods to avoid — for example, cashew is often hidden in pesto sauce — and that you’re also given alternatives.
For example, if your child is allergic to egg or milk, you’re given alternatives so that your child is able to thrive and grow. So that’s the basics of food allergy.

And then, in terms of managing the food allergy:
The Pronuts study was a study conducted at St Thomas’ Hospital and King’s College London, which I was the principal investigator for.
In the study we took children with one nut allergy (confirmed on food challenge) and challenged them to all the different nuts and sesame seed to see if they were allergic to all the nuts or just to a few.Many of these families had been advised to avoid all nuts and sesame seed because they had just the one nut allergy.

What we were able to show is that by introducing these other nuts into the child’s diet using oral food challenges — a process where the child comes into the clinic or the hospital and is given very small amounts of the food, building up to a larger dose — we can confirm if the child is allergic or not to that food. Then we were able to get that food into the diet. What we found was that it improved the quality of life for the children who participated in the study and also for the families. They were able to include several different nuts in the diet after that — and it was mostly just two nuts that they had to avoid, not all nuts. Many children were also able to introduce sesame seed.

Gina Furnival:
I suppose for these individual that were allergic to peanuts [by understanding which nuts] it gives you more liberty and less anxiety about where you go out to and what you can and cannot eat.

Helen Brough:
Yes. What we found often was that children were often just allergic to peanut. And even though they had positive allergy tests to other nuts, when we introduced those in a clinical setting with everything available to manage an allergic reaction, some of them did react — but many did not. They were then able to introduce those into their diet.

In terms of other treatments, we now actually have treatment for established food allergies — oral food immunotherapy.

Gina Furnival:
Oh yes. What role can immunotherapy play in the future management of food food allergies?

Helen Brough:
This is a really exciting area. This is something I absolutely love about allergy: that it’s moving forward so quickly and that we’re able to implement things from research straight into the families I see in the clinic to improve their lives.

Oral food immunotherapy is now becoming quite well established. In the US, it’s been happening for many years, as well as in many parts of Europe. In the UK, we are now starting to implement peanut oral immunotherapy.

There is a licensed product called PALFORZIA, which is licensed from four to seventeen years of age. At the Evelina Children’s Hospital we have the largest PALFORZIA service. But because there are very few services that offer this, it is very difficult to get this treatment on the NHS. We now have over a hundred children doing this at St Thomas’ Hospital, and it’s going really well.

Peanut immunotherapy works by introducing very small amounts of peanut, starting at milligram doses and building up to 300 mg (approximately one and a half peanuts) over around fifteen visits.

These up-dosing appointments always occur in hospital, never at home. The child is seen every two to four weeks and the dose is increased under supervision. They are observed for one to two hours and then allowed to go home to continue eating that dose.

This treatment has been shown to prevent the risk of accidental exposures to peanut in the environment.

When a child can tolerate the 300 mg dose, they no longer have to avoid “may contain traces” labels, for example, because they’re already having 1.5 peanuts daily. It also reduces the risk of severe reactions.

Helen Brough:
There is also a study currently being conducted by the Natasha Allergy Research Foundation in multiple UK hospitals, using real food, cow’s milk, egg, and peanut, for immunotherapy

We expect publication soon and hope to have strong evidence using real foods.

In the US and Europe, many hospitals already use real foods, because PALFORZIA is the only currently licensed product — and it’s only for peanut.

Gina Furnival:
I see. And when it comes to the peanut patch, can you tell us a bit about that?

Helen Brough:
Yes, exciting developments. Also, sublingual immunotherapy, where drops or a tablet go under the tongue, is another exciting field.

The peanut patch has also been shown to protect against accidental exposure to peanut and reduce the risk of severe reactions.

Helen Brough:
The peanut patch contains even smaller doses — 250 micrograms of peanut — applied on the back. That means over the full three-year duration, you’re only getting one to two peanuts in total.
Despite that, it’s still been shown to provide substantial protection and reduce reaction severity.

In terms of administration, oral immunotherapy has a higher risk of anaphylaxis than the peanut patch. There are golden rules with oral immunotherapy: no doses when the child is unwell, and no vigorous exercise for two hours after dosing. These restrictions don’t apply to the patch, which carries far fewer risks because it’s applied topically and doesn’t go systemically.

Gina Furnival:
Clearly the field is evolving — and exciting research, a lot of which you’re involved in — into prevention and management.
But as we try to translate these findings into clinical practice, what are your key takeaways for clinicians, caregivers, or parents when it comes to preventing food allergies?

Helen Brough:
I’ve got a leaflet on this, which is patient-facing and also for healthcare providers, that puts forward some really simple steps to take.
The main thing that is really important is to make sure that the eczema is well controlled, and that parents are not inadvertently making the eczema worse by doing certain things — such as putting their hands into the pots of ointments or creams and then putting that onto their child’s skin.
What will happen is that the bacteria on their hands will go into the pot, and because the cream or the ointment is like agar, the bacteria just grow in that pot. So every time they’re putting their hand in the pot and then onto their child’s skin, the child has more bacteria on the skin — and that’s been shown to make the eczema more severe.

Helen Brough:
In fact, we know that there’s a certain bacteria called Staphylococcus aureus that is usually found on the skin of children with infected eczema. This has been shown to increase the risk of developing food allergies, lead to more persistent food allergies — such as persistent egg allergy — and prevent the effectiveness of early peanut introduction into the diet. Making sure that you’re not inadvertently causing an infection on your child’s skin. The way to do it differently is just to use a clean spoon every time you take the cream or ointment out of the pot. Or you could use gloves so that you’re not just putting your hand inside the pot or use a tube or a pump. But for ointments, it’s hard to use a pump, so you may have to use a tube or a pot. That’s a really, really important tip.
I don’t think that’s out there enough, and I think it’s a really simple thing that people can do. It really breaks my heart when I see parents in the clinic who come to me thinking that their child’s eczema is driven by food allergy — but their child’s eczema is being driven by infection. And having hands inside the pots is one of the things that’s contributing to that.

So that was my number one takeaway for families. It’s such a simple thing to do. It doesn’t cost anything, and it’s a really important way to protect your child.

The second thing would be that you consider introducing solids into the baby’s diet earlier than six months of age if the child has eczema — when the child is ready to do so.

They need to be able to sit with support they don’t have to sit unsupported.
They should have reasonably good head control, and they should be able to accept a spoon into the mouth (so not pushing it out again). At that age, it will need to be spoon-feeding rather than baby-led weaning, because they won’t be able to manage that at that stage. And it needs to be thin purées, mixed with breast milk, or with water that’s been boiled and cooled to make it sterile or mixed with vegetables. Try to get lots of different fruits and vegetables into the child’s diet as early as possible, especially if the child has eczema. That will improve their gut microbiome. And just small tastes, it doesn’t have to be huge amounts.
Try to use home-cooked food where possible, because that has all the healthy microbiome in it, better nutrition, and more fibre for the baby to grow.

Gina Furnival:
If your child doesn’t have eczema and is under six months old, would you still recommend earlier weaning?

Helen Brough:
That’s not necessary. If the child doesn’t have dry skin and doesn’t have eczema, you can introduce solids from around six months of age, which is the Department of Health guidance, and the WHO guidance, and promote exclusive breastfeeding for six months.

Gina Furnival:
Looking ahead to the next five or ten years, what advances do you anticipate in childhood food allergy care, and are you generally optimistic?

Helen Brough:
I think the first thing will be implementing all these great research findings into the community.
I’m part of a study happening in the UK funded by the NIHR called the Parent and Baby Feeding Project. We’re going to be looking at getting the introduction of peanut and egg early into the diet of at-risk children, or at least at six months of age in the general population,  across all communities in the UK and getting that message out there.
I think there’s still some historical memory from before 2009, when people were told to avoid food allergens during the first year of life and that needs to be reversed.
This is very much a grassroots movement where we are trying to reach lots of different communities to implement that change.

There’s also lots of research happening internationally in the same way.
For example, the iREACH study in the US is looking at electronic health prompts that appear for primary care practitioners and paediatricians, so they can encourage the early introduction of peanut, particularly in children with eczema, to help prevent peanut allergy.

And then there’s quite a lot of exciting data emerging around the microbiome and how we can target it early to improve allergic outcomes.

Gina Furnival:
Indeed — exciting times. Well, that’s it for today. Helen, thank you so much for joining me. It’s been a pleasure and a real privilege having you here with us today.

Helen Brough:
Thanks so much, Gina. I’ve really enjoyed being here

Gina Furnival: If you’d like to access Helen’s patient leaflet, click the link in the bio accompanying this podcast. And before you go, please subscribe to Visionary Voices. You can now find us on Spotify, Amazon Music, and Apple Podcasts.