Download Are we too clean0514 - International Scientific Forum on Home

“Are we too clean” – an outdated concept set to damage our health?
Comment from Professor Sally Bloomfield, Chairman International Scientific
Forum on Home Hygiene (www.ifh-homehygiene.org)
It has now become clear that exposure to microbes, particularly in early life, is essential for correct
functioning of the human immune system. Without this exposure, this system can become over
reactive which is a fundamental cause of allergic diseases such as asthma and hay fever, and other
chronic inflammatory diseases such as Multiple Sclerosis, Type 2 Diabetes and Inflammatory Bowel
Disease.
Equally importantly, we now find that these vital exposures are not infectious diseases, but so-called
“Old Friends” (OF) microbes from our evolutionary past. These microbes still exist, but have become
gradually reduced or eliminated from our bodies and our modern urban living environments through
a host of changes which have protected against infectious disease organisms, but also inadvertently
cut us off from these OFs, which tend to inhabit the same environments
In understanding how to use our growing understanding to tackle this problem, vague concepts such
as whether we are too “clean” in our own homes, or whether we should, or should not, be using
antibacterial products have no useful place in the discussion. The ongoing tendency to link these
concepts is both unsubstantiated and misleading. What we should be focussing on are the lifestyle
changes which science is now showing us can reconnect us with our OFs, the challenge being to
reconnect with these microbes whilst at the same time sustaining protection against exposure to
disease-causing microbes.
Indications are that one of the things we need to do is to encourage and support natural childbirth
and breastfeeding wherever possible to allow early transmission of OFs from mother to baby.
Encouraging physical contact with older siblings from an early age is also indicated. During weaning,
it may be necessary to re-examine the foods which are introduced to ensure they contain beneficial
microbes. The data suggest that children need to be encouraged to play and interact with each other
and their environment, particularly outdoor environments, instead of sitting isolated indoors at
computer screens. All of these measures are important for building a healthy microbiota (microbial
flora) in the gut and on the skin, thereby sustaining vital microbial–human interactions.
There is now evidence that using antibiotics is exacerbating the problem because it alters the
microbial flora of our body and reduces the diversity of species which it contains. It now seems that
finding ways to reduce antibiotic prescribing (particularly in young children) must become a public
health priority, not just to tackle the problem of antibiotic resistance, but also to reduce
susceptibility to chronic inflammatory diseases.
In essence this means that the hygiene measures which protect us from exposure to infectious
diseases are set to become more important, rather than contraindicated, for our health. These
include public health “hygiene” measures such as sanitation, clean food and water, and safe waste
disposal etc. To be effective and sustainable hygiene must be a shared public responsibility, an
accepted part of our normal daily lives. Effective hygiene measures are those we use to prevent
onward transmission of disease-causing microbes from an infected source such as people,
contaminated food, domestic animals and so on. It involves actions such as handwashing after toilet
visits and nappy changing, safe cooking, storage and handling of raw foods and good respiratory
hygiene. It also involves care of those who are infected or are at special risk of infection – both in
hospital and in the community. By targeting hygiene measures in this way, we can optimise
protection against infection whilst at the same time sustaining exposure to Old Friends.
Whether domestic and personal cleanliness play any role in reducing our exposure to OFs is not
known, but if it does, its contribution relative to other factors is likely to be small. Far from
producing a “sterile” environment, even the cleanest of homes abound with microbes.
Unfortunately the terms cleaning and hygiene tend to be used interchangeably. If, as seems likely,
we are stuck with the “too clean” sound bite, it is imperative that we come to understand that, in
this context, it is a “catch all” term for a whole range of lifestyle, medical and other changes which
have altered or reduced our exposure to vital microbes. We must recognise that public and
community measures which protect us from disease-causing organisms (usually termed hygiene) are
something quite different, but equally vital for our health and well-being. Hygiene remains the
cornerstone for protecting us against infectious gastrointestinal, respiratory and other diseases. It is
key to containing new disease threats (pandemic or other) when they arise. It is also vital for
protecting patients in hospital or the community, who are more vulnerable to infection. Hygiene is
also now seen as one of the ways to tackle the problems associated with our reliance on antibiotics
both the problems of tackling antibiotic resistance and of sustaining a diverse healthy human
microbiota.
In tackling our modern obsession with avoiding all types of dirt, germs or microbes, we must avoid
the risk of throwing the baby out with the bathwater by moving too far in the opposite direction and
abandoning “hygiene”