In the U.S., 33 million Americans are living with food allergies – including 1 in 13 children. In the last couple of decades, food allergies in children have doubled and nut allergies have tripled. Many experts believe old feeding recommendations to avoid peanuts and other common food allergens in infancy may have unintentionally contributed to the increase. The good news: now we know better, so we can do better.

The LEAP Study: U-Turn in Guidelines

In the year 2000, the American Academy of Pediatrics recommended that babies avoid allergens like peanuts and egg in infancy. This guidance was not based on solid data, and was rescinded 8 years later, however avoidance became the norm (and food allergy rates began to climb rapidly). Fast forward two decades, and the guidance to avoid common allergens in infancy has been reversed by groundbreaking research. The LEAP Study, led by Dr. Lack, found that when babies regularly eat peanut-containing foods starting early in the first year of life through toddlerhood, it can reduce their risk of developing peanut allergies by 86%. 

As a direct result of Dr. Lack’s seminal research, today, leading organizations recommend introducing peanuts and other common food allergens early and often, once a baby starts solid foods. There’s more: the recent publication of the follow-up 2024 LEAP-Trio Study, also led by Dr. Lack, tracked babies from the original study into adolescence, and found that the tolerance developed from starting peanut foods in infancy endured through the teenage years - proving that early peanut consumption has a lasting protective effect.

Brush up on the latest clinical guidelines – from the USDA to AAP – here.

Hygiene Hypothesis: Too Clean for Our Own Good?

So, the evidence is clear that early introduction of peanut in infancy can lead to long term tolerance and protect children from food allergies well into adolescence. A simple intervention – introducing baby-safe peanut-containing foods early to infants, in the right amount, at the right time – can have a huge impact on future generations in reducing the rate of peanut allergies, a lifelong burden that greatly affects quality of life.

But there may be something else at play with rising rates when it comes to the role eczema and overall hygiene plays in food allergies. The hygiene hypothesis, first proposed in 1989 by epidemiologist Dr. Strachan, is a theory that suggests exposure to certain microorganisms at a young age in early childhood may help to develop a healthy immune system and protect against allergies. There are even some studies that suggest that having a dog can lower the risk of developing food allergies. 

Simply put, the fear around germs and a growing obsession with cleanliness might actually be doing more harm than good. Indeed, fear may be one of the big causes of food allergies – fear of food and fear of dirt and germs that results in an over-sanitization that can be detrimental to a little one’s skin. As Dr. Lack explains, excessive cleanliness or bathing at a young age, using stronger soaps on our bodies and detergents on our clothes, etc. may actually break down the skin barrier and make it easier for allergens to penetrate the skin (keep reading for more on why that matters). 

As general guidance, try to keep the 5 “Ds” of food allergy prevention top of mind: Dry skin, Dogs, Diet, Dirt, and Vitamin D – all simple ways to help build up your little one’s immune system at a young age. Early and often exposure to common allergens falls into the “diet” D. At the end of the day, letting your kids “get their hands dirty” isn’t always the worst thing. [Learn more here.]

When we talk about the hygiene hypothesis, we also have to talk about the related, dual-allergen exposure hypothesis – so let’s explore the connection between eczema and food allergies.

The Connection: Eczema and Food Allergies

Did you know that eczema impacts 20% of children, and young children with eczema are 6 times more likely to develop a food allergy than their peers without eczema? The Dual-Allergen Exposure Hypothesis is a theory, first proposed by Dr. Lack, that may help explain how exposure to food allergens can lead to either tolerance or allergy, depending on the route of exposure (simplistically put, oral exposure = tolerance, while exposure via a broken skin barrier = allergy).

When something foreign enters the skin, the body's response is to make IgE molecules, which are allergic antibodies that mount an attack on these allergens. So if a baby has dry skin – perhaps due to eczema in the first year of life – the skin barrier is already broken down. Food proteins are prevalent in our environment. If that baby’s mom or dad is making scrambled eggs and eating them for breakfast in the same room, or snacking on peanuts, it may lead to baby’s first exposure to that food occurring through the skin, rather than orally, which increases the likelihood of an allergic response when the baby tries eggs or nuts for the first time, several months later.

Eczema can change the skin microbiome and different types of bacteria found on the skin and in the gut, while also breaking down the skin and stripping it of its natural oils and lipids – essentially eradicating a dead skin barrier that forms a protective outer coating.

To read more in-depth about the connection between eczema and food allergies, check out our blog here.