For most people, when they think of their gut, the first thing that comes to mind is the area around the stomach – which is half true.
When doctors or health professionals talk about the gut, they refer to the billions of microbiomes and other microorganisms that exist in the intestinal tract. As one of the most important organs in your body, the gut is responsible for the digestion, absorption and utilisation of nutrients. It also makes up 70 per cent of a person’s immune system.
So, it’s safe to say that poor gut health can lead to a string of negative effects on the body – including the increased risk of a food hypersensitivity to certain proteins - and it could mean the body lacks the types of colonies in the microbiome that are crucial for a healthy digestive system.
Those microbiomes are especially important when it comes to allergies. But what does gut health have to do with allergies?
Food and health expert, Associate Professor Alice Lee from UNSW School of Chemical Engineering, has devoted her career to researching this area.
“Generally, if you have good gut health, then typically your chances of developing allergies are lower compared to someone with poor gut health,” says A/Prof. Lee.
“We now know that the epithelial cell, the single cell layer that forms the lining of both the small and large intestine of our gut, looks very different in people with food allergies compared to those without and this can be attributed to the microbiome and how those cells process food proteins.”
Food allergies are hypersensitive reactions to a specific food antigen with most people developing them from a very young age. In Australia, almost every two in 100 people live with a nut allergy and approximately three per cent of infants have a peanut allergy. It’s becoming so common that many schools and early learning centres have banned peanuts from school lunches altogether.
A/Prof. Lee says while genetics do play a role in the development of allergies, epigenetics, such as the environment factors, also dictate how the infant immune system develops.
“The gut microbiomes found in people with allergies is less diverse than people without allergies,” she says.
“The maternal diet can influence the immune system of the infant. During pregnancy, avoiding allergens altogether is no longer recommended, and it’s important for the mother to have a balanced diet to ensure their baby gets a good share of the nutrients needed to support healthy gut bacteria.
“Whether it’s through breastmilk, or infant formula, the protein in the milk is the first thing babies are exposed to and this can influence their child’s hypersensitivity towards that protein as their immune system develops.
“We also see the development of allergies through other epithelial cells such as the skin.
“Kids can present with a weak skin barrier or some kind of skin microbiome deficiency. And at a young age, they can be exposed to allergens through things such as almond oils which are found in baby creams, lotions, or body wash or traces of wheat protein in oatmeal baby bath soak – so it’s not always through the consumption of these proteins.”
Living with a food allergy
There is still some hope for young kids living with an allergy. About 80 per cent of babies allergic to egg and milk grow out of it by the age of four. This is a stark contrast to children with nut allergies where only 20 per cent grow out of it and the remaining 80 per cent of people carry it into adulthood. For these people, absolute avoidance of their allergens is very important.
Recently, the Food and Agriculture Organisation of the United Nations and the World Health Organisation recommended setting the regulatory levels for each allergen to standardise the allergen regulation policy worldwide. This work is crucial in supporting the development of international food safety standards and guidelines relevant to the management of food allergens.
Is there a way to outgrow allergies quicker?
“Science hasn’t yet taught us how to speed up the process of growing out of an allergy. The best treatment option we currently have is allergen-specific immunotherapy which has shown promising results,” says A/Prof. Lee.
“Currently, at least 60 per cent of patients who have gone through immunotherapy successfully develop desensitisation and can consume their allergens in much higher doses after the therapy. However, we’re continually striving to improve the efficacy and safety of the treatment.”
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Since the increase in production of plant-based protein alternatives, such as pea and other legume proteins, as well as novel substitutes such as insect proteins, new food allergies have also been on the rise.
A/Prof. Lee says people might be sensitised to certain foods but don’t know it. She theorises that people can still consume foods they are sensitised to because it’s at levels lower than their tolerance level.
“For example, you can be sensitised or even allergic to soy protein, but you can still have a small amount of soy protein in foods without any reaction,” she says.
“On the flip side, even trace amounts of the allergenic food protein can trigger a life-threatening reaction.”
While probiotic supplements are touted to help maintain digestive health, it doesn’t mean they are the magic pill to end allergies altogether.
“These days, there are supplements or health-conscious drinks such as probiotic or kombucha promising to correct problems in our gut. This is only one small piece of a large pie,” says A/Prof. Lee.
“We know that your gut microbiome changes when you have an allergy and restoring the gut microbiome could help the body respond better to the therapy, but there are other parts to this puzzle.
“There is current research looking at the efficacy of combining immunotherapy with both probiotic and prebiotic supplements and initial analysis of the data has shown positive results.
“However, there’s still a way to go before we know the exact dosage of those supplements and in which combinations are needed to have that impact and how they work in the body.
“In the allergy prevention and treatment space, it’s the billion dollar question.”