Busting the Hygiene Hypothesis Myth

Is the rise of allergies in developed societies correlated to hygiene? That was the idea behind the now famous hygiene hypothesis posited by epidemiologist David Strachan in 1989.

Strachan had noticed that in a survey of 17,000 British children, those with many siblings were less susceptible to eczema and hay fever. He concluded that more siblings meant more exposure to germs, which in turn trained the immune system to be more robust. With five times the prevalence of allergies in Western society compared to the developing world, the hypothesis struck a chord with media and the medical community.

People mistakenly inferred that cleanliness needed to be reduced in order to live healthier lives. They implicitly understood from Strachan’s hypothesis that decreased infections from modern hygiene practices came at the cost of overall human health and resilience.

Since then multiple studies have shown that positive germ exposure for children and good hygiene are not mutually exclusive, and that both play a vital role in human health.

The Science

A 2016 review on the hypothesis concluded that ”the public idea that obsessive hygiene is the root cause of the rise in allergies is no longer supported.” ¹

The study instead lends support to Graham Rook’s “old friends” hypothesis. This 2003 theory outlines the concept that exposure to friendly microbes in our early childhood trains our immune system and positively integrates with our microbiome. It is these microbes that we want to increase exposure to, while continuing to avoid detrimental pathogens. Due to changes in our lifestyles – such as our shift from rural to urban societies – our exposure to old friends has been decreased, independent of hygiene behaviour. Antibiotic overuse and altered diet were found to be the main actors in destroying the relationship between friendly microbes and our microbiome. ¹

Unlike antibiotics and diet, better overall hygiene was shown to be “almost entirely unrelated” to deterioration of the microbiome. ¹ This is largely attributed to sufficient microbial interactions occuring through the airways.

In contrast to the notion that decreased exposure to infections leads to more immune disorders, a 2004 study also showed that a number of respiratory diseases, including measles, occurring in children, were linked to an increased risk of allergic disease after infection.²

What Causes Allergies?

Understanding allergies is still a work in progress, but a number of factors have been identified that support a healthy microbiome. As previously mentioned, avoiding antibiotics is a critical step to ensuring gut health, which has been shown to reduce the likelihood of allergies. Additionally, maintaining a balanced diet, and consuming foods that promote gut health, also have a positive impact on your microbiome.¹

Increasing early childhood interactions with other children is seen as vital for the exchange of friendly microbes. Swapping indoor for outdoor play is also strongly encouraged. The review also highlights a great deal of scientific research advocating for natural childbirth, a critical step in shaping a healthy microbiome.¹

Beyond those factors, further research is needed on the impact of frequent allergen exposure, genetics and pollution.¹

Targeting Pathogens

By 2050 it is estimated that antimicrobial resistance (AMR) will become the leading cause of death, with more than 10 million deaths per year. Fighting AMR is something we can actively combat by preventing infections before they must be treated with antibiotics. The best way to prevent infections is through good hand hygiene.

Studies have also shown that an improvement in hand hygiene alone can reduce gastrointestinal illnesses by 31 percent and respiratory illness by 21 percent.¹  We also know that up to 80% of acquired infections have been transmitted by hands.

The International Scientific Forum on Home Hygiene promotes “Targeted Hygiene” as the best method to assess when hygiene is needed. The approach looks at sources of pathogens, routes of transmission, critical control points, and appropriate interventions to determine what course of action is best. Targeted hygiene subscribes to the concept of chains of infection, that need to be interrupted. It identifies the hands, hand contact surfaces, food contact surfaces, and cleaning utensils as presenting the highest risk of transmission. Since the presence of potentially harmful microbes in the home is inevitable, this means that the way to protect ourselves from infection is by stopping these critical moments as shown in Fig. 1.³

At OPHARDT hygiene Breaking the Chain of Infection is our mission. We offer a variety of dispensing solutions, IOT solutions and accessories to help you prevent infections in healthcare, public spaces and in your home. Visit our website to find out what products can help you live a healthier life.