Early Allergen Introduction: A Conversation with Professor Gideon Lack

Interview by Dr. Sakina Bajowala, Pediatric Allergist & Immunologist (MD, FAAAAI)

Professor Gideon Lack of the Lack Allergy Clinic is one of the world’s leading pediatric allergists and a pioneering researcher in food allergy prevention. His landmark studies — LEAP, LEAP-On, LEAP Trio, and EAT — have reshaped global feeding recommendations and helped reverse decades of guidance to avoid allergenic foods in infancy. Today, early introduction and routine inclusion of common allergens is recognized as one of the most powerful tools we have to reduce food allergy risk.

In addition to his academic work, Professor Lack is also a co-founder of Mission MightyMe, a line of healthy, science-backed snacks for infants and kids that make it easy for parents to follow pediatric recommendations to introduce nuts early, and keep them in the diet consistently, to help prevent allergies from developing in the future. His work bridges the gap between research and real life: from randomized controlled trials to the everyday challenges parents face at the table.

We sat down with Professor Lack to discuss what sparked his interest in this field, what the science shows today, how his research connects to practical solutions like Mission MightyMe, and where allergy prevention research is headed.

How did you first become interested in the link between infant feeding and food allergy prevention?

When I trained as a pediatric allergist, we routinely advised parents to avoid allergenic foods in infancy. The belief was that early exposure caused allergies — advice I followed in my own family.

A turning point came in the early 2000s when I lectured in Tel Aviv and asked a room of 200 pediatricians and allergists how many had seen a case of peanut allergy in the past year. Only a few hands went up. In the UK, almost everyone would have raised their hand.

Initially I wondered if it was genetic. But in London, where I worked with many Jewish families, peanut allergy rates were the same as the general population. When I talked to Israeli colleagues, I learned that infants there were routinely eating peanut snacks as early as four months — the opposite of what we advised in the UK.

This led us to compare Jewish children in the UK and Israel, and we found a ten-fold higher rate of peanut allergy in the UK. Israeli babies were consuming significant amounts of peanut protein well before six months of age. That observation ultimately led to the design of the LEAP study.

Can you explain the LEAP study and how it changed our understanding of peanut allergy?

LEAP enrolled 640 high-risk infants — babies with severe eczema, egg allergy, or both — between 4 and 11 months of age. These children were randomly assigned to either consume peanut regularly or avoid it completely until age five.

Infants in the introduction group consumed about six grams of peanut protein per week (roughly three servings). Allergy outcomes were assessed using double-blind, placebo-controlled food challenges.

The results were striking:

LEAP demonstrated that early, sustained introduction of peanut prevents peanut allergy, especially in the highest-risk infants.

What did the follow-up studies — LEAP-On and LEAP Trio — show about the long-term durability of this protection?

This was a crucial question. Were we simply suppressing symptoms by feeding peanut regularly, only for allergy to appear later?

In LEAP-On, after the initial LEAP trial ended at age five, we asked both groups to avoid all peanut for a full year. Remarkably, families adhered to this. At age six, protection persisted — the children who had consumed peanut early remained tolerant, even after a year of complete avoidance.

In LEAP Trio, we followed the same cohort into adolescence — ages 6 through 13. During those years, some children ate peanut regularly, others sporadically, and others not at all. Yet the protective effect persisted. Early introduction created long-lasting tolerance despite real-world eating patterns.

This shows that early introduction doesn’t just delay allergy — it fundamentally alters the immune trajectory.

The EAT study looked beyond peanut. What were the key findings?

EAT enrolled infants from the general population, not just high-risk groups. Babies were exclusively breastfed until 12 weeks, then randomized to either:

Overall, we saw about a 20% reduction in food allergy in the early-introduction group. But only about 40% of families were able to adhere to the full protocol — giving multiple allergens several times a week to a very young baby is challenging.

Among those who did adhere, we saw a 66–70% reduction in food allergy, particularly for peanut and egg. This showed that early introduction of multiple allergens is effective, but families need practical, sustainable ways to do it.

Parents often worry that they can’t meet the amounts used in studies. Are lower doses still protective?

This is one of the most common concerns I hear.

Our analyses across LEAP and EAT suggest that around two grams of protein per week (for each allergen) provides strong protection for most babies. One gram still offers some protection, but below that, the effect diminishes significantly.

This is why practical strategies matter. Nut butters, soups, ground nuts, commercial puffs — all can be tools. What matters is:

Just like training a muscle, the immune system learns through repeated practice.

How can parents maintain exposure when babies refuse certain textures or only take a few bites?

Feeding should never become a battle of wills. If a baby isn’t hungry or refuses a certain texture, don’t push. Take a break for a few days or change the format:

Culinary flexibility helps. Food is both a science and an art — texture, format, and taste can all be adjusted.

Let’s talk about egg. What forms count, and how early should egg be introduced?

Egg allergy develops even earlier than peanut allergy, sometimes as early as 3 months.

In EAT, early introduction of egg was protective when infants consumed at least two grams of egg white protein per week.

Forms that are appropriate include:

Most babies will eventually accept egg in one form or another. I often recommend introducing egg around 3–4 months, especially for infants with eczema.

Importantly, this is not about replacing breast milk — breastfeeding continues alongside early allergen introduction.

What is the ideal timing for allergen introduction? Should recommendations differ for high-risk babies?

This is a complex question with a nuanced answer.

My current view:

We may eventually adopt a single unified recommendation for the whole population, but for now, risk-based nuance is useful.

I also believe — although more evidence is needed — that breastfeeding alongside allergen introduction may enhance tolerance.

What major research questions remain?

Several areas need further study:

1. Milk allergy

We need stronger evidence on whether early introduction prevents milk allergy the way it does for peanut and egg.

2. Wheat and celiac disease

In the EAT study, we saw zero cases of celiac in the early-wheat-introduction group, compared to seven cases in the avoidance group. These numbers are small, but the signal is intriguing and warrants further research.

3. Rising rates of eczema

Eczema has tripled or quadrupled since WWII. Because impaired skin barrier allows allergens to enter through the skin, understanding why eczema is so common — and how to prevent it — may be the key to stopping allergic disease at its source.

4. Practicality

How can families realistically introduce multiple allergens early? How do we support parents with simple, safe, sustainable tools? This question has influenced ongoing work, including the development of convenient foods designed to help families follow the science.

Thank you to Dr. Lack for spending time with us and discussing his ground breaking research!