Are childhood allergies on the rise?

Many parents wonder if allergies are simply “in the genes” and the answer, it turns out, is partly yes. “Allergies are a result of an overactive immune response, and genetic factors play a major role in priming the immune system for this,” explains Dr Maxine van Greenen, a paediatrician at Netcare Garden City Hospital.

If one parent has an allergic condition, their child’s risk of developing a food allergy roughly doubles. “If both parents have allergies, that risk can rise even higher, sometimes exceeding 60–80%, depending on the type of allergy,” she says.

Interestingly, it doesn’t need to be a specific food allergy in the family. “The presence of any familial allergic disease suggests a genetic predisposition toward an overreactive immune response to an allergen,” adds Dr Van Greenen. Scientists have even identified specific genes involved in immune system regulation and skin barrier function that increases this susceptibility.

But here’s the thing: our genes haven’t changed, yet allergy rates are soaring. “Genetics alone cannot explain why so many children have allergies today. This is where the environment comes in,” she says. Factors like diet, pollution, and reduced exposure to microbes are interacting with our genes in new and powerful ways.

Food for thought: the diet connection

It’s not just what children eat, but how and when they eat it that could be affecting their risk of allergies. “Over the past few decades, children’s diets have changed dramatically,” says Dr Van Greenen. “Western-style diets tend to be higher in processed foods and lower in fresh fruits, vegetables, and fibre. This can negatively affect the gut microbiome – the millions of bacteria in our gut that help train the immune system.”

A healthy gut microbiome acts like an immune system tutor, teaching it to tolerate harmless foods. But with fewer gut-friendly microbes (thanks to poor diet, antibiotics, and even birth by C-section), some children’s immune systems start treating foods like peanuts or eggs as enemies.

The way we introduce solid foods matters, too. “For many years, parents were told to avoid giving babies foods like peanuts or eggs until after infancy,” Dr Van Greenen explains. “However, research such as the LEAP study has shown that delaying these foods may actually increase the risk of allergy.” Early introduction (between four to six months), especially while breastfeeding, seems to help the immune system build tolerance.

Modern living, modern problems

Beyond the dinner table, modern lifestyles have changed the way our children interact with the world, and their immune systems are noticing.

“Urbanisation, industrialisation, and reduced outdoor time have transformed the environments children grow up in,” says Dr Van Greenen.

One major culprit? Air pollution.

“Exposure to pollutants such as diesel exhaust particles can inflame the airways and disrupt the immune system, making it more reactive to allergens.”

Even climate change gets a mention, as longer pollen seasons can increase allergy severity. And inside our homes? We’re often too clean for our own good. “Children now spend more time indoors and have less exposure to diverse microbes found in soil, plants, and animals. This may make the immune system less skilled at distinguishing harmful from harmless triggers.”

Add to this the overuse of antibiotics and cleaning products, reduced contact with animals, and more time in sealed, microbe-poor indoor environments, and you’ve got the perfect storm for allergies.

The hygiene hypothesis revisited

This brings us to a long-standing idea in allergy science: the hygiene hypothesis. “It suggests that children in ultra-clean, industrialised societies may have higher allergy risks due to insufficient microbial exposure,” says Dr Van Greenen.

Basically, the immune system needs practice, and dirt helps.

“Children raised with farm animals or who attend daycare early tend to have lower allergy risks,” she explains. “This may be due to greater exposure to a variety of microbes that help train the immune system.”

The hygiene hypothesis has since evolved into the “old friends’ hypothesis”, which stresses the importance of contact with specific beneficial microbes, the ones humans co-evolved with for millennia.

Dr Van Greenen notes, “Reduced contact with these microbes, due to cleaner environments, less time in nature, and frequent antibiotic use, may leave children more vulnerable to allergies.”

Can we prevent allergies?

Parents can take steps to reduce allergy risk, even if not all can be prevented. “Recent research has shown that early introduction of allergenic foods, especially between four and six months, can help prevent food allergies,” says Dr Van Greenen. “Study results showed that in high-risk babies, introducing peanut containing products in infancy reduced peanut allergy by up to 80%.”

Breastfeeding supports gut and immune health, though it’s not a cure-all.

Dr Van Greenen adds, “Maintaining a healthy gut microbiome through a varied, fibre-rich maternal diet and avoiding unnecessary antibiotics can further support immune tolerance.”

She also recommends encouraging outdoor play, exposure to pets, and avoiding excessive antibacterial cleaning. “On the flip side, it’s important to reduce harmful exposures like tobacco smoke and air pollution,” she says.

Want to raise allergy-smart kids?

Here’s Dr Maxine van Greenen’s top advice:

1. Introduce allergenic foods early – between four and six months.
2. Support gut health with a fibre-rich diet.
3. Don’t over-sanitise – let kids play outdoors and get a bit grubby
4. Avoid unnecessary antibiotics in infancy.
5. Keep homes smoke-free and ventilated.
6. Educate schools and caregivers about allergy risks and emergency plans.

Because sometimes, a bit of mud really is the best medicine.