In recent decades, disinfectants and hand sanitizer sales have rocketed. Homes in developed and developing countries are more sterile than ever. So why are allergies more rampant?
The American Centers for Disease Control and Prevention report a 50% increase of food allergies in children between 1997 and 2011. Peanut or tree nut allergies have tripled. We aren’t talking about a little more congestion: medical procedures to treat allergy-based anaphylaxis have increased by 380% in a similar timeframe.
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What exactly is going on?
In the late 1980s, epidemiologist Dr David Strachan presented the hygiene hypothesis which, in a pathogen-free nutshell, posed that a lack of early childhood exposure to bacteria and parasites could prevent proper development of the immune system.
In the late 1990s, Dr Erika von Mutius compared the prevalence of allergies and asthma in East and West Germany. This was before unification. She expected East German children, who grew up in less hygienic conditions, to have a higher percentage of allergies and asthma than the more privileged West German children. Remarkably, her findings were the exact opposite: children in East Germany had lower rates of allergies and asthma than those in the more hygienic West Germany!
In their book Let Them Eat Dirt, Drs Finlay and Arrieta explore how, for millions of years, our immune systems have matured by exposure to innumerable microbes from the environment:
Our natural behaviour in the early years of life definitely tries to maximize our exposure to microbes: babies are in direct contact with maternal skin while breastfeeding, they are constantly putting their hands, feet, and every imaginable object in their mouths. Crawlers and early walkers have their hands all over the floor, and then in their mouths… Perhaps this is actually natural behaviour designed to populate kids with even more microbes.
Interestingly, it is the friendly bacteria which colonises our gut which controls allergic responses. In the absence of appropriate bacteria, the allergic immune response becomes unregulated and allergies proliferate. Recent studies have shown a correlation between amount of detergent used in a household and extent of allergies. Not only do the volatile organic comnpounds contribute to allergen load, but detergent use kills the allergy suppressing bugs which we so need.
The discovery of antibiotics was a medical breakthrough that saved lives. However, recent research shows that some of the greatest damage to the human microbiome (the complex ecosystem of microorganisms living in the gut and other body sites) is through the misuse of antibiotics. This includes using antibiotics for viral infections (they kill bacteria, not viruses) and, particularly, the indiscriminate use of antibiotics in babies and young children.
Dr Finlay says a person’s microbial makeup is mostly set in the first 100 days of life, before eating solids. Here are some of his guidelines for gut health:
Children who take antibiotics in the first year of their life are more prone to developing allergies;
Children born by caesarean section are more prone to developing allergies;
Living on a farm gives you a stronger immune system and decreases your risk of developing allergies; and
If you were breast-fed instead of bottle-fed, you have a decreased chance of developing allergies.
Perhaps we need to rethink our war on bugs! We might start by calling them immune stimulants since the microbiome can literally train the immune system and prevent allergies!