Recap: Simple steps to prevent allergies | Prof. Gideon Lack

0:00Hello, and welcome to Zoe Recap, where each week we find the best bits from one of our podcast episodes to help you improve your health. Today, we're turning our attention to allergies. For decades, conflicting advice on how to prevent allergies from developing has left parents unsure about the best ways to protect our children. Should you introduce peanut products to your newborn or avoid them entirely? Many are still unclear. What is clear, however, is that allergies are on the rise. I'm joined by groundbreaking researcher Dr. Gideon Lack to help bring clarity to this conversation about allergies.

0:37His pioneering work has challenged long-held beliefs and offers potentially life-saving advice. He begins by sharing his first light bulb moment.

0:50Well, there were a few light bulb moments. Unfortunately, the light wasn't quite as bright, or perhaps I was too dim. And it took a while for the penny to drop. But there were a series of observations that puzzled me. One goes back very early to when I was training and doing research, and I noticed that the way you made little mice pups allergic to foods such as peanut or egg was by rubbing it very gently in low doses on abraded skin, suggesting that they became allergic through inflamed skin. In contrast, if you gave peanuts or egg or milk to a young mouse pup, you could never induce allergies in that.

1:33And that first exposure protected it long term. And I remember asking my professors at the time, well, why are we telling babies not to eat the foods if these foods are protecting mice? Why are we thinking differently about human babies? When guidelines started changing, parents, mothers were coming to me and saying, look, I don't understand what's going on. I took all the advice from my doctors. I avoided peanuts during pregnancy, during breastfeeding. I didn't give it to my little boy or girl. And at three years of age, they ate peanut butter, developed a severe allergy with the first known exposure.

2:11And I started to realize with these very digital and parents that avoidance was not the way forward. I suppose the key turning point was when I gave a lecture in Israel, I was invited to speak about peanut allergy. And my first question, as I often ask, this was an audience of about 200 pediatricians and allergists, asked, how many of you seen a case of peanut allergy in the last year? Less than a handful put out their hand. and in the UK, even, you know, pediatricians, allergists, GP, virtually everyone would have put up their hand. So it was like completely, incredibly rare there, and here you would have said every single doctor would have seen it.

2:56So there were two explanations. One is they really don't see peanut allergy, or they weren't diagnosing it correctly. The latter was very unlikely. Actually, many of them were colleagues who'd been trained like me in the US, not wishing to belittle my specialty, it is not that difficult to diagnose peanut allergy when the parent comes and tells you. Sometimes it is, but very often, in most cases, the history is very obvious. So I started to think, is this a real difference? Could this be genetic? And then it dawned on me, gosh, well, the Israeli population, Jewish population, largely Ashkenazi of Eastern European origin, North African and Spanish origin.

3:41And I see a lot of that same population in London, and they have food allergies. So it didn't seem to be the case. A key observation, which the Israeli doctors and parents of children were telling me, was that the first snack in the Israeli diet was, or the first food was peanut. For babies. For babies. And it's funny, but there's a joke in Israel that the first three words that a baby learns to say are mother, father, bamba, bamba being the name of this peanut snack. And it's so much part of the culture. Babies are eating this from four months of age. So we decided to formally test this in this observational collaboration where we took 5 ,000 Jewish children from Jewish day schools in the UK and compared them with 5 ,000 Israeli school children who shared a common, not identical genetically, but shared a common ancestral genetic background and looked at the rate of peanut allergy.

4:44And indeed, it was tenfold higher in the UK children and almost non-existent in the Israeli children. And we again, we quantified the amounts of peanuts the babies were eating in Israel, which was extremely high. In the UK, it was zero. So we confirmed it through an observational study. That's still not evidence. Okay. There could be other factors. There could be differences in sunlight, lifestyle. Vitamin D is thought to influence allergies. More sunlight might influence the rate. So you sort of had a hypothesis now. We had a hypothesis, exactly. But you hadn't proven that it was the peanuts because maybe it was some other thing they were preteen or whatever else that was different at this point.

5:25Correct. And how long did it take you from the point that you'd sort of had this light bulb moment in Tel Aviv to actually getting the first child to participate in this RCT, this randomized control trial? The light bulb moment was in about 2002, 2003. But it took a long time to execute the study, of course, because we took these 640 babies, high risk of developing food allergy. Why? Because they had eczema. And I alluded to earlier that allergies, we believe, develop through the skin in babies with eczema or dry skin. So we chose a group of high risk babies where you would actually see peanut allergy.

6:11And we randomly allocated these 640 babies to either complete avoidance of peanut for the first five years of life, similar to previous guidelines in the US and UK. And the other half actively ate this Israeli snack or peanut butter, in some cases, peanut soup. What happened? So we followed this group of 640 babies all the way through to five years of age. And it's a remarkable testimony to these families and to the whole research team that we were able to evaluate peanut allergy in 98 % of these babies who turned five years of age. So virtually everyone stuck with the study. Dropout rates are usually much higher, but these families were so committed that that gave us a lot of statistical power to analyze virtually the whole population.

7:09And sure enough, we found that the rate of peanut allergy in the avoiding group was close to 20%, on average 17%. So it was 20 % in the avoidant group, but it was less than 3 % in the consuming group. And there was about an 85 % reduction in the rate of peanut allergy. There was an 85 % reduction in the level of peanut allergy in the group that you were giving peanuts to, despite the fact that all the advice had been like, make sure that whatever you do, you don't give your children any peanuts. Absolutely. And we were not expecting this degree of efficacy. We were expecting a 30, 40, 50 % reduction, but we got a substantial reduction that really is comparable to the efficacy of a vaccine.

8:00Vaccination rates very often will usually give 80, 90 % protection. And so were you shocked by this? Because I mean, that is amazing, right? Normally, we talked to a lot of scientists about their studies. It's extremely rare when you have a randomized control trial to have that like 85 % lower. As you said, it's like some magic drug. Yeah, we were thrilled, but pleasantly surprised. We hadn't anticipated that degree of an effect. Moreover, because this was a very high-risk group, close to 40 % of these babies in the entire group were already making low levels of allergic antibodies to peanut because they were being exposed to peanuts that their parents ate through the skin.

8:44and we only knew about these blood levels later but what I'm saying I suppose is the immunological process of becoming allergic had already started the ball had started rolling when we intervened in many of these babies and despite having these low-level allergic antibodies we were able to halt the peanut allergy or to stop it in its tracks. So that was what really surprised me. I had expected that once you've got allergic antibodies to peanut in the bloodstream, the dyes cost. There's no going backwards. Peanut allergy is going to develop. That was not the case. And it would be a bit like saying, well, to give a drug in the early stages of a disease, take COVID and reverse it.

9:40So we were able to do what we call primary prevention before there were any signs of the disease and secondary prevention once the disease had started to develop. That's amazing. And that to me was really striking. And the irony is we're not talking here about fancy vaccines or immunotherapy. We're just talking about a very simple, cheap, effective, and safe strategy, eating the food. So how has that led to change in guidelines in the US, in the UK, in other countries? So I was really gratified to see very rapid response in the guidelines. The first big set of guidelines came actually from the NIH, who funded the study in the United States.

10:27It's a government agency, and they thought it was important to get the message out saying that babies as early as four to six months of age should eat peanuts. The Australians were the next to take it on, and then American professional bodies, others. We eventually took on these guidelines in the UK. I still think they've been watered down a bit and are not specific enough. There's a difference about the UK guideline versus the US guideline you described? Well, they came later, and the emphasis more is that delaying introduction of these foods beyond six months of age could increase the risk of these allergies.

11:12That's a sort of, I would say, that's the half-full or negative way of saying it, rather than actively give peanuts to babies. It's softer, and the message hasn't gone out. And, you know, we learn, we all learn as we go along. and I was involved in consulting to the first US guidelines, my views on how the guidelines should be formulated have changed. And it's an evolving process. Initially, the guidelines said, apply this mainly to children with eczema. It then became apparent that it's not only children with eczema who develop peanut allergies, but children with dry skin who develop peanut allergies, and even some children without any skin problems.

11:55And for this policy to be effective, it has to be applied to the whole population. And one of the things we also learned during the LEAP study, there were 76 babies who we evaluated at the beginning of the LEAP study who could not be enrolled. Why? Because they already had peanut allergy. So they were excluded from the study because this was a study about preventing peanut allergy. Now, you can't prevent something that is already there. So one of the things we've learned is the intervention has to be very early, ideally by six months of age, and in babies with eczema, by four months of age, the peanut has to be introduced.

12:38So timing is critical, and quantity is critical. In the LEAP study, we gave these babies six grams of peanut protein a week, which is about the equivalent of 25 grams of peanut butter, which is close to two heap tablespoons of peanut butter a week. That's a lot. If we say, give your babies peanuts, most parents interpret it as a tip of a teaspoon once every few weeks, and that does nothing. It would be a bit like taking the results of COVID vaccines and the high success rates and saying, well, we don't have enough vaccine. Let's give it to more people. let's dilute it tenfold and give tiny amounts of vaccine.

13:18That's not going to work. So you need to make sure there's enough exposure. And your other one, I think what you're saying is that you feel the guidelines in some countries, and I think the UK is an example here, are not strong enough about saying you really should be introducing your babies to peanut and doing it sort of regularly and in enough quantity to make sure that they understand that this is a safe food rather than their immune system saying this is something really dangerous. So the problems in the guidelines, and that's normal, guidelines take time to fully fledge out the detail. But there's also other problems.

13:55For years, we've been making parents fearful of peanuts, but not only peanuts, other foods as well, egg and milk, and talking about delaying all these foods. So there's a culture of food phobia, food fear, and food avoidance. And for parents, especially first-time parents, it's a big deal giving a food very early on in life.