Every day people ask me the question about whether we are too clean. My first answer is that if we were too clean, then so many people would not fall ill from a food related disease, or for that matter flu and colds.

These diseases are preventable – through basic hygiene measures, so that’s why I don’t think we are too clean. There is still plenty of room for improvement! Simple hygiene measures need to be followed by food businesses to make sure we are safe when we eat out or buy food from the shops. However, many illnesses occur because WE are not very clean – nothing to do with businesses – they are caused by poor personal and home hygiene!

Think about where your hands have been before you eat. Recently I was at a lovely awards dinner and as we sat down (after lots of networking) I used some hand gel before eating lunch (and before picking up a bread roll). I offered the gel to the guest sitting next to me and he said “I don’t want to be too clean, I like my microbiome” so I pointed out that he had probably shaken hands with about 20 people, 10 of whom may not have washed their hands after going to the toilet, and all of whom had no doubt shaken hands with lots of other people. The mind boggles about how many shared bugs could have been on his hands. He took the gel.

So why do people think we are “too clean?” A scientific paper in the 1980s[1] blamed hygiene for an increase in allergies and the rot started there; suddenly the “hygiene hypothesis” was born, and with it an excuse to be less than clean. The main problem with this is that by being unhygienic we may expose ourselves not only to the good bacteria but also the pathogens - those that cause illness. The theory has now been discredited, but the myth lives on. However, something called the microbiome is very pertinent to this story. This is the natural flora that we have on our bodies, in our respiratory tract and in our gut, and it needs to be cherished as it is critical to our health, and can even be influential in our mental state, weight gain or loss as well as physical well-being. A very interesting book by Michael Mosley elaborates more. [2]

Loss of diversity of the microbiota is thought to be an issue, rather than too much hygiene in itself. According to scientists such as Dr Graham Rook[3], we need as many of the “old friends” as possible to give us the protective, diverse microbiota that we used to have in our guts and on our skin. These “old friends” microbiota include bacteria and even some parasitic worms which inhabit indoor and outdoor environments, together with the largely non-harmful commensal microbes acquired from the skin, gut and respiratory tract of other humans. These organisms enter the body not only via ingestion but also via the airways where some stay in the respiratory tract and some are subsequently ingested.

The current thinking is that the microbial exposures we need to boost our immune system are therefore not colds and other childhood infections but are the microbes present when the human immune system was evolving in hunter gatherer times[4],[5].

These old friends may have been depleted not because of us cleaning up, but because of factors such as:

  • caesarian birth
  • lack of breast feeding
  • use of antibiotics (they wipe out the good and the bad bacteria)
  • less outdoor play and living
  • a beige diet

So, what should be done about this? It is not being less hygienic, because failing to wash your hands or clean and disinfect at the right time could make you sick, and then ironically you may need antibiotics which is not a good thing for your microbiome; furthermore, antibiotics are increasingly not particularly effective if you have become ill with an antibiotic resistant organism.

The important thing is to clean hygienically at the right place and the right time. Understanding the way infections are caused and when to break the chain of infection is critical and makes it all much easier to understand and keep safer. This is all about targeted hygiene.

Two simple tips are:

  • Make sure that your hands are fit for purpose - are they clean enough for eating finger food, preparing food for others or even rubbing your eyes (a route of respiratory infection). Wash your hands thoroughly using soap and warm water, rubbing fingers, thumbs and cleaning nails in the palm of your hand in the lather to make sure you wash the germs away.
  • Make sure if you have handled raw meat, poultry, fish or vegetables (which may contain germs such as Campylobacter or coli) that all utensils are cleaned thoroughly, if possible in the heat of the dishwasher.

Mainly infections are caused by mistakes – so knowing how to prevent the chain of infection can help us to help ourselves. The International Scientific Forum on Home Hygiene has created a free e-learning resource which gives useful information on this subject– take a look![6]

For other cleaning tips please visit:

[1]Strachan DP. Hay fever, hygiene, and household size. BMJ 1989;299:1259–1260



[4] Bloomfield, SF, Rook, GAW, Scott, EA, Shanahan, F, Stanwell-Smith, R, Turner, P. Time to Abandon the Hygiene Hypothesis: new perspectives on allergic disease, the human microbiome, infectious disease prevention and the role of targeted hygiene. July 2016 Vol 136 No 4 l Perspectives in Public Health 213

[5] Rook G.A.W. regulation of the immune system by biodiversity from the natural environment: An ecosystem service essential to health. Proceedings of the National Academy of Science U S A 2013; 110: 18360–7. 



Chartered Environmental Health Practitioner, RSPH Professorial Fellow, and Winston Churchill Fellow Dr Lisa Ackerley is an independent food safety consultant providing advice and support to most food industry sectors and to the mass media on food safety issues. She is passionate about making it easy for everyone to understand how simple changes to behaviour can really make a difference to reducing the risk of infection – in particular hand washing. Also known as “The Hygiene Doctor” she has a web site all about hygiene in the home and everyday life.

Currently she is Food Safety Adviser to UKHospitality where she represents the organisation at the Food Standards Agency Expert Advisory Group on Regulating our Future. A regular speaker on food safety issues, she is Visiting Professor of Environmental Health, University of Salford and Chair of the RSPH Special Interest Food Group. And Professorial Fellow of the RSPH. She represents UKH on the SALSA board. Lisa is also a member of the Editorial Board of the RSPH publication Perspectives in Public Health. In 2011, she received “The most Significant Contribution to Food Safety Award” from the Society of Food Hygiene Technology.

Lisa’s PhD from the University of Birmingham explored public perceptions of food safety and how to change behaviour, and this has been an important part of her life in the mass media, where appears regularly as a food safety expert on TV and Radio in shows including BBC Watchdog, BBC Panorama, BBC 1 Rip off Britain, ITV “Tonight”, BBC 1 Rogue Restaurants. She was the hotel inspector in The Secret Tourist and Holiday Hit Squad. She is also Trustee and Vice Chair of the International Scientific Forum on Home Hygiene

Lisa is also a Trustee and Vice Chair of the charity IFH, which provides scientific advice on home and everyday life


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