If you drop a piece of food on the floor, should you still eat it after three seconds? Unless you are in a public toilet or somewhere the floor is particularly pathogenic, the answer is why not?
The "three second rule" doesn’t actually exist; microbes were on your food within milliseconds, besides, in most cases the exposure is beneficial.
It is our societal obsession with sanitation and safety that is more of a concern; it has, in all likelihood, made Australia one of the most allergic societies in the world.
One in 10 babies, one in 20 children and two in 100 adults in Australia suffer from an allergy.
Increasingly, experts around the world believe the sterility of our environment is contributing to a modern-day phenomenon.
“The asthma/hayfever/eczema epidemic started in the 70s, 80s and 90s and the food allergy started really, we think in the mid 90s,” explains paediatric gastroenterologist, Professor Katie Allen of the Murdoch Children’s Research Institute.
“We think it’s something to do with modern lifestyle and that’s because the developed world has more of it than the developing world. And people who move from the developing world to the developed world have increased rates.”
Allen, who is part of a new PodcastOne original series, Allergies, adds that her own research found that infants of Asian descent born in Australia have higher rates of food allergies, but infants of Asian descent who are born in Asia and then came to Australia are “completely protected”.
What exactly is it about the modern lifestyle that is causing problems in developed countries?
The 'Five D' Hypothesis
Dogs and dribble
The hygiene hypothesis – or the dogs and dribble hypothesis, as Allen affectionately calls it – is the idea that the environment we live in has become overly sterilised.
“We don’t exactly know what aspects are important but we do know, from our own research, that having larger families and having a dog in the house are protective. So it’s something to do with a shared microbiome or shared bugs in families,” Allen says.
In fact, a new study found that babies whose mothers cleaned their dummy by sucking it, instead of following the traditional guideline of boiling it or washing it in hot, soapy water, had fewer allergen antibodies.
A small study, it echoes previous research which found babies who dropped their dummy on the ground, and whose mothers cleaned it with their mouth before giving it back, were less likely to get allergies.
What you can do: "We don’t have any good suggestions at the moment other than get a dog and have a large family, but we can’t make those public health recommendations," Allen laughs.
"But, let babies get dirty, let them play on the grass and, wash their hands before they eat, but let them get out there and play with animals and play in the dirt. It’s not going to harm them."
Dry skin and diet
It’s officially called the dual allergen exposure hypothesis, but to Allen, it’s the dry skin and diet hypothesis.
“We know kids with early onset eczema are much more likely to have food allergies and also, if you don’t introduce the foods like peanut butter and egg and dairy in the first year of life you increase the risk,” she explains, “so not exposing the intestine to food to train the system is a problem.”
Allen does not recommend banning certain foods at schools. "We recommend not sharing food because then everyone can stay safe and knows what they’re eating," she says.
What you can do: "We recommend: don’t soap the baby," Allen says.
"We should have soap-free bathing products or washing with water and that’s to prevent eczema hopefully.
"We should introduce solids around six months but not before four months. And when you do introduce solids make sure you include foods like peanut butter, eggs dairy because you no longer need to be frightened of them or avoid them."
“That’s one we’ve discovered ourselves here in Australia,” Allen says. “We found that the further you live from the equator the more likely you are to have food allergy.”
In fact, Melbourne is the allergy capital of the world which Allen attributes in part to being "the farthest away from the equator" and in part because Australia is the only country in the developed world that does not fortify its dairy with vitamin D.
"We know it keeps your immune system healthy," she explains. "It affects a lot of aspects of the immune system."
Her previous research has found babies with food allergy have much higher rates of vitamin D deficiency. Allen is currently leading a trial with 3000 babies to see whether they can prevent food allergy by giving vitamin D drops.
Allen is hopeful researchers will find a cure for allergies soon: "Food allergy is new and we know it’s something to do with modern lifestyle so if we can turn back the tides, that will be fantastic," she says.
"Food allergy wasn’t around in any great number 20 or 30 years ago, so in my view, it’s not overly ambitious to say it will be eradicated in 20 to 30 years."
In the meantime: "Eat if you’re preventing, avoid if you are allergic. There is a cure on the horizon."
What you can do: Make sure people get healthy amounts of sunshine and eat vitamin D foods like fatty fish, eggs, mushrooms and cheese.