Tag Archives: AOBiome

How To Make Yourself Less Attractive to Mosquitoes

Last updated 6/17/2014.

Are you one of those people who attract every mosquito in the neighborhood while others around you don’t get a single bite?





Mosquitoes have been around for about 170 million years – considerably longer than modern man. Archeological and fossil evidence says Homo Sapiens evolved around 276,000 years ago. So it seems modern humans have been dealing with mosquito bites from the very beginning.


A mosquito and a fly in this Baltic amber necklace are between 40 and 60 million years old
A mosquito and a fly in this Baltic amber necklace are between 40 and 60 million years old
There are about 2,500 to 3,000 different species of mosquitoes found around the world. (Mosquito Magnet, 2014) More than 175 species have been  identified in the US alone. (Heubeck, 2005-2014)
Makes you itch just to think about all those mosquitoes, doesn’t it?





The most common – and most dangerous – are the various species in the Culex, Anopheles, and Aedes genera. Culex pipiens, known as the northern house mosquito, is the principal  carrier of West Nile virus. Anopheles  carries the parasite that causes malaria. The parasite gets transmitted through the mosquitoes’ saliva when they bite us. Anopheles‘ bites are responsible for over one million deaths per year. Two species of Aedes are carriers of other dangerous diseases: Aedes albopictus, the Asian tiger mosquito, transmits dengue fever and eastern equine encephalitis while Aedes aegypti, the yellow fever mosquito, transmits dengue and yellow fever. (Mosquito World, undated)



Mosquitoes cause more human suffering worldwide than any other organism – killing over one million people every year. They also transmit serious diseases and parasites to dogs and horses.


Malaria kills children


The National Center for Infectious Diseases (NCID), a division of the Centers for Disease Control and Prevention (CDC), publishes a list of some of the diseases transmitted by mosquitoes. (NCID, 2007)  The American Mosquito Control Association (AMCA) also publishes information on mosquito-borne diseases affecting humans, horses and dogs. (AMCA, 2013) Below is a combination of both lists:
  • Malaria
  • Dengue Fever
  • Yellow Fever
  • Rift Valley Fever
  • Japanese encephalitis
  • La Crosse encephalitis
  • St Louis encephalitis
  • Chikungunya – rarely fatal but causing excruciating joint pain that is debilitating and may persist for several weeks
  • Dog Heartworm (Dirofilaria immitis)
  • Eastern equine encephalitis – affects both horses and humans
  • Western equine encephalitis




Mosquitoes’ sensory organs seek sources of carbon dioxide and lactic acid – because these substances lead them to humans and other warm blooded animals. Chemical repellents like OFF! work because the DEET in them is highly effective at masking the smell of both carbon dioxide and lactic acid, not because mosquitoes don’t like the smell of the repellents themselves. (Reinagel, 2010)
A common misconception is that mosquitoes are attracted to humans and some other warm blooded animals who have sweet or pleasant tasting blood. Mosquitoes aren’t particularly interested in our blood – although people who have Type O blood are known to get more bites than people with other blood types.  What they ARE very attracted to is the scents emitted by various bacteria and other micro-organisms living on our skin. These can differ from person to person and on us at different times.




Mosquitoes can detect plumes of carbon dioxide in our exhaled breath at a distance of several hundred feet.  At under 100 feet they smell the odors of the bacteria and micro-organisms living in our skin microbiota. (Mosquito World, undated)




It’s only the female mosquito that bites – and what she does isn’t actually a bite. She lands on your skin and uses heat sensors on her antennae and around her mouth to detect a capillary near the surface of the skin. When she finds one, she inserts her proboscis (a long, needle-like mouth part containing two tubes) into the vessel and draws some blood out through one tube. Through the proboscis’ second tube, she inserts a little of her saliva, which contains enzymes that keep the blood from coagulating so she can feed freely. These enzymes also act as a mild painkiller so we don’t notice that our skin has been punctured. The female mosquito needs a protein in human blood to make her eggs fertile. (Ferris, 2013)



The mosquito's proboscis piercing the skin
The mosquito’s proboscis piercing the skin


Our body’s immune system recognizes these enzymes as foreign. Antibodies prompt our mast cells to release histamines, which arrive at the scene and start to do their work of healing the breach and neutralizing the foreign enzymes by binding to receptors, causing the blood vessels there to dilate. The increased blood flow attracts more white blood cells to help vanquish the invading antigens. The histamines cause the spot to swell and become itchy. (Mosquito World, undated)


Mast cells containing histamines
Mast cells containing histamines
Mast cells are a clever and  important part of our immune systems and pretty interesting in their own right. To read more about how they work, see The Role of Mast Cells and My Own Struggle with Mast Cells Gone Wild.





High magnification reveals a host of bacteria underneath a human toenail. A new analysis has shown that the billions of bacteria that inhabit human skin are not only highly diverse but also change their composition over time.  (Image Credit: Darlyne A. Murawski/NGS) (Text Credit: resident-alien.blogspot.com)
High magnification reveals a host of bacteria underneath a human toenail. A new analysis has shown that the billions of bacteria that inhabit human skin are not only highly diverse but also change their composition over time.
(Image Credit: Darlyne A. Murawski/NGS) (Text Credit: resident-alien.blogspot.com)


A 100 trillion or so micro-organisms live on and inside our bodies. One percent of these, about a trillion, live in and on our skin and determine our unique body odor. Without these bacteria, human sweat would be odorless. And these microbes, our skin’s microbiome, produce a variety of chemicals – some of which smell more attractive to mosquitoes and some of which don’t interest them at all. The composition of these trillion microbes varies greatly from person to person: We share 99.9% of our DNA with other humans but share only about 10% of our microbes. (Loria, 2014)
Interesting tidbit: It’s not the smell of our blood but the unique odors given off by our skin microbiota that  so-called blood hounds can pick up. We’re constantly shedding a cloud of minute skin flakes. Bloodhounds are particularly adept at following a trail of these flakes, sniffing their odors.  (Black, 2012)




Dutch researchers demonstrated that it is certain types of micro-organisms living on our skin that attract mosquitoes. For the study, they asked 48 adult male volunteers to avoid consuming alcohol, garlic, onions, and spicy foods, and not to shower or wear scented cosmetics for two days prior to the sampling event. The men were also instructed not to use soap the last time they showered before the experiment.  All 48 volunteers were free from chronic illnesses and not taking any medications on a regular basis. (Verhulst, 2011) (Loria, 2014)
The men were given nylon socks to wear for 24 hours to build up a collection of their unique skin microbes.  For the testing, researchers rubbed glass beads against the soles of the men’s feet to collect their scent as mosquito bait.


Our feet have approximately 250,000 sweat glands each and can excrete as much as a pint of moisture every day.  (Source: Young Living Essential Oils)
Our feet have approximately 250,000 sweat glands each and can excrete as much as a pint of moisture every day. (Source: Young Living Essential Oils)


The sweat from 9 of the 48 men in the sample proved to be especially attractive to mosquitoes. Mosquitoes largely ignored the odors of  the sweat from 7 of the men. The ‘highly attractive’ group’s sweat contained a 2.62 times higher concentration of one common skin microbe (Staphylococcus spp.) and 3.11 times higher concentration of another common microbe (Pseudomonas spp.) compared to the 7 in the ‘poorly attractive’ group. There was no significant difference between the amounts of Brevibacterium spp. and Cornynebacterium spp. in the ‘highly attractive’ and ‘poorly attractive’ groups. The ‘poorly attractive’ group also had a significantly more diverse bacterial colony living on their skins. (Loria, 2014) (Verhulst, 2011)
The microbial ecology of human skin is highly complex but science is still in the early stages of studying it.  At this point, little is known about its species composition and only a small fraction of the micro-organisms living on – and in – us is culturable now – many species have not even been identified yet. The same is true for the microbes living in our gut microbiomes.
Nonetheless, the findings from this study are leading to the development of new mosquito attractants and repellents.






Mosquitoes are attracted to beer drinkers
Mosquitoes are attracted to beer drinkers – the reason why isn’t yet known


Another study, this one conducted by the National Center for Biotechnology Information, found that mosquitoes and biting insects are also attracted to beer drinkers. Even one beer was found to increase the number of times  subjects were bitten.
The researchers hypothesized that the attraction was due to increases in the amount of ethanol in sweat or because alcohol raises body temperature, but neither was found to correlate with mosquito landings.
This study also found that exercise, metabolism, clothing color, and pregnancy affected vulnerability to mosquitoes. (Salaky, 2013)








(Reinagel, 2010), (Thompson, 2014), (Joseph, 2010), (Stromberg, 2013) and (Hadley, 2014)




Standing water can become a breeding ground for mosquitoes
Standing water can become a breeding ground for mosquitoes. Covering it with a screen is a deterrent.


  • Wearing solid, dark clothing and dark, flowery prints
  • Using beauty products and lotions such as hair spray, perfume, and suntan lotion
  • Having standing water around – such as in backyard pools and in undisturbed  pails or buckets
  • Working up a sweat. When you exercise, you give off more lactic acid and more carbon dioxide.
  • Being outside early in the day or at twilight, when mosquitoes bite the most
  • Eating sweet, sugary foods
  • Eating salty foods or ones high in potassium: Salt and potassium increase the amount of lactic acid you off-gas. Unfortunately, fruits and vegetables are the foods richest in potassium. Cabbage, green peppers, cucumbers, blueberries, apples, and watermelon are relatively low in potassium. Potatoes, lima beans, acorn squash, spinach, prunes, raisins, bananas are high in potassium.
  • Eating limburger cheese: It’s made with the same bacteria that cause our feet to smell.
  • Drinking beer: Consuming even one bottle of beer makes you bait for mosquitoes. I’ve been unable to find what it is about beer that is so attractive to them but only learned that it’s not due to an increased amount of ethanol excreted in sweat or because alcohol increases body temperature. If you find out what the connection is between beer consumption and attraction to mosquitoes, please let me know.
  • Being pregnant: Pregnant women attract roughly twice as many mosquitoes as non-pregnant people. Pregnant women exhale about 21% more carbon dioxide and run about 1.26 degrees Fahrenheit warmer. Mosquitoes are attracted to both the carbon dioxide breathed out and the heat given off by warm blooded animals.
  • Using alpha hydroxy products on your skin: Many skin care lotions and creams contain lactic acid, which is highly attractive to mosquitoes.





Some herbs mosquitoes don't like
Some herbs mosquitoes don’t like


  • Wearing plain, light-colored clothing
  • Spraying your skin with a diluted mixture of essential oils that are known to repel mosquitoes – such as tea tree oil, geranium oil, oil of cedar, peppermint oil,  lemon grass oil, and citronella
  • Dabbing small amounts of the above essential oils on your skin is also effective against mosquitoes. A good choice is TerraShield, made by doTerra – a blend of 15 essential oils, it repels mosquitoes and ticks for up to six hours. It has a pleasant citrus smell and can be dabbed directly on your skin.
  • Diffusing one of these essential oils or oil blends (such as TerraShield) into the air
  • Placing a few drops of these essential oils or oil blends on ribbons and strings and hanging them near air vents, windows or openings where bugs might come in
  • Applying crushed herbs directly on your skin. Crushed catnip, citronella, vanilla leaf, tea tree, lemon balm, clove, lavender, eucalyptus, sagebrush and pineapple weed are safe to use in this way.
  • Spraying your skin with an infusion of herbs and plants that mosquitoes don’t like – such as calendula, catnip, lavender, pennyroyal, rosemary, basil, lime basil, peppermint, horsemint, lemon balm, lemon thyme, lemon grass, chamomile and goldenseal
  • Planting fragrant herbs from the list above, plus aromatic plants – such as ageratum, citronella grass, citrosa, marigolds*, common lantana, fever tea,  myrrh, stone root and pennyroyal – in your garden or in pots outside. They’re all natural mosquito repellents.
  • Using a garlic spray in your garden or a garlic-scented lotion on your skin
  • Eating garlic provides mild protection – both from the scent of your breath and the sulfurous compounds you’ll emit through your skin. Of course, eating garlic or smearing its scent on your skin will probably keep away more than mosquitoes!
  • Eating foods high in vitamin B – such as fish, brown rice, molasses, brewers yeast and wheat germ. Mosquitoes don’t like vitamin B.
TerraShield (by doTerra) - a blend of 15 essential oils that repel mosquitoes and ticks
TerraShield, made by doTerra  is a blend of 15 essential oils that repels mosquitoes and ticks for up to 6 hours
See here for a list of pest-repelling plants and here for another useful list with details on which plants to use and where to plant them, plus more on applying crushed herbs to your skin as a mosquito deterrent.
Here’s a good article containing recipes for making your own natural mosquito repellent using essential oils. Non-chemical mosquito repellents contain a diluted mixture of essential oils that mosquitoes find distasteful or which confuse their ability to detect your own odors so they can’t find you and therefore won’t bite you.



A recipe for a homemade, chemical free mosquito repellent
A recipe for a homemade, chemical-free mosquito repellent



* WARNING:   Never keep marigolds in areas close to windows, patio tables and other outdoor areas where you spend time as the flowers’ bright colors often attract wasps. (wikiHow, undated)


I would have included Avon’s Skin So Soft in the list of mosquito repellents except that they contain some not so nice chemicals – including methylparaben and proplyparaben.
Parabens are used as preservatives to increase shelf life in many cosmetic products (lotions, underarm deodorants and antiperspirants, hair care products, moisturizers, shaving products and make up), medicines and foods. Some of the major parabens we absorb or ingest in these products are benzylparaben, butylparaben, ethylparaben, isobutylparaben, methylparaben and propylparaben.
The US Environmental Protection Agency (EPA) reports that parabens have hormone-disrupting qualities that mimick estrogen interfering with the body’s endocrine system. The EPA has linked methylparabens in particular to metabolic, developmental, hormonal and neurological disorders, as well as to various cancers.
Companies like Burt’s Bees, Botanical Skin Works and Barefoot Botanicals do not use parabens in their products. For more information on products containing parabens visit www.thinkbeforeyoupink.org
For more information on the parabens-breast cancer link and some paraben-free alternatives, see here (Johnson, 2011) and here (Mercola, 2012).












Artist Sonja Bäumel explores the skin microbiome in her project Cartography of the Human Body
Artist Sonja Bäumel explores the skin microbiome in her Cartography of the Human Body project


In doing the research for the post just before this one, Living Bacterial Skin Tonic – Instead of Soap?!, I came across this about a living bacteria skin tonic being developed by a Massachusetts start up called AOBiome – I’ve highlighted the last two sentences:

The company’s scientists think that this product will be good for us because it could refill our bodies with microflora that do us good. In this way, it could actually be better for us than the antibacterial hygiene products that we are accustomed to using. Although these kill off bacteria, they can harm us due to the chemicals they contain (such as triclosan) which have been linked to various health problems.

If you’re still not convinced that you would want bacteria on your skin, consider this: bacteria can assist in treating various skin conditions, such as eczema and acne. It helps to heal wounds that are resistant to antibiotics. It can also change body odour so that it keeps mosquitos at bay.  This is especially good if one considers illnesses like malaria that can run rampant and affect many people. (Simolo, 2014)
Our usual approach to the bacteria and other micro-organisms living on our skins – and everywhere else we can get to them – is to KILL THEM DEAD. We generally regard bacteria and their relatives as dangerous and just plain nasty. So this is an entirely new approach – a U turn in how to think about the bacteria living in and on our skin: This new spray contains billions of cultivated Nitrosomonas eutropha, an ammonia-oxidizing bacteria (AOB)
It’s to be used in lieu of – or as an adjunct to – taking showers. Bathing with most soaps and shampoos KILLS ALL THE HEALTHY ELEMENTS OF OUR SKIN MICROBIOME.  This new living bacterial skin tonic REPLENISHES the biome of microscopic organisms living on our skin.
If you recall the Dutch experiment described above, in the OUR SKIN MICROBIOME section, one of the findings was that the group of men who were the least attractive to mosquitoes had a significantly more diverse bacterial colony living on their skins.
So it makes sense to me that we would want to reverse our ill-considered search and destroy approach to bacteria and begin valuing and supporting our skin microbiomes, the trillion  bacteria and other micro-organisms that dwell in and on our skin – for many reasons, not making ourselves so attractive to disease and parasite spreading mosquitoes being only one.






American Mosquito Control Association (AMCA). 2013. Mosquito-Borne Diseases. See:  http://www.mosquito.org/mosquito-borne-diseases

Black, J.G. (2012) Microbiology: Principles and Explorations, 8th edition. Wiley, p. 403.  See: http://books.google.com/books?id=pnVMAgAAQBAJ&pg=PA403&lpg=PA403&dq=odors+skin+microorganisms+blood+hound&source=bl&ots=rjhDyvguWv&sig=qVThuBz4sVzeq-Mi4q2Rdr5ij9E&hl=en&sa=X&ei=BaaXU-7hNcvesASCl4CgBg&ved=0CDgQ6AEwBA#v=onepage&q=odors%20skin%20microorganisms%20blood%20hound&f=false

Davis, L. (2014). Parabens Linked to Breast Cancer? Beauty News NYC – Skin Care. See:  http://www.beautynewsnyc.com/skin-care/parabens-linked-to-breast-cancer/

Ferris, R. (2013). How to Deal With and Prevent Mosquito Bites. Business Insider – Science. See:  http://www.businessinsider.com/a-few-tips-on-mosquito-bites-2013-7

Hadley, D. (2014). 10 Ways to Guarantee You’ll Get Mosquito Bites. About.com – Insects. See:  http://insects.about.com/od/flies/a/how-to-get-mosquito-bites.htm

Hardin, J.R. (2014). Living Bacterial Skin Tonic – Instead of Soap?!  AllergiesAndYourGut.com. See:  http://allergiesandyourgut.com/2014/06/07/living-bacterial-skin-tonic-instead-bathing/

Hardin, J.R. (2014). My Own Struggle with Mast Cells Gone Wild. AllergiesAndYourGut.com. See:  http://allergiesandyourgut.com/about-me/my-own-struggle-with-mast-cells-gone-wild/

Hardin, J.R. (2014). The Role of Mast Cells. AllergiesAndYourGut.com. See:  http://allergiesandyourgut.com/symbiosis-versus-dysbiosis/the-role-of-mast-cells/

Helmenstine, A.M. (20). Natural Mosquito Repellent Recipe. About.com – Chemistry. See:  http://chemistry.about.com/od/healthbeautyprojects/a/naturalmosquitorepellent.htm

Heubeck, E. (2005-2014). Are You a Mosquito Magnet? WebMD – Allergies Health Center. See:  http://www.webmd.com/allergies/features/are-you-mosquito-magnet

Johnson, C. (2011). Are Parabens Really Harmful? Are There Alternatives? HappyMothering.com. See:   http://www.happy-mothering.com/06/beauty/skincare-cosmetics/are-parabens-really-harmful-are-there-alternatives/

Joseph, S. (2010). Naturally Repel Mosquitoes and Ticks: doTerra Essential Oils. Dr. Mom Essentials. See:  http://drmomessentials.com/naturally-repel-mosquitoes-and-ticks-doterra-essential-oils/

Loria, K. (2014).  Some People Don’t Get Bitten By Mosquitoes — Why That’s True Will Surprise You. Business Insider- Science. See:  http://www.businessinsider.com/skin-bacteria-attracts-mosquito-bites-2014-3

Mercola, R. (2012). 40 Women With Breast Cancer Had This “Cosmetic Ingredient” in Their Tissues. The Mercola Newsletter, Mercola.com. See:  http://articles.mercola.com/sites/articles/archive/2012/04/02/toxic-parabens-on-breast-cancer-patients.aspx

Mosquito Magnet. (2014). FAQs – Mosquitoes. See:  http://www.mosquitomagnet.com/resources/faqs

Mosquito World. (undated). Mosquito Bites. Mosquito World: Your guide to effective mosquito control.  See:  http://www.mosquitoworld.net/mosquitobites.php and http://www.mosquitoworld.net/mosquitospecies.php

National Center for Infectious Diseases (NCID). 2007. Infectious Disease Information – Mosquito-Borne Diseases. Centers for Disease Control and Prevention (CDC). See:  http://www.cdc.gov/ncidod/diseases/list_mosquitoborne.htm

Reinagel, M. (2010). What to Eat to Avoid Mosquito Bites. QuickAndDirtyTips.com.  See: http://www.quickanddirtytips.com/health-fitness/trends-fads/what-to-eat-to-avoid-mosquito-bites

Salaky, K. (2013). Beer Drinkers Attract More Mosquitoes, Study Finds. The Daily Meal. See:  http://www.thedailymeal.com/beer-drinkers-attract-more-mosquitos-study-finds

Simolo, G. (2014). How a Company is Using Bacteria to Replace Soap. Wind.org. See: http://www.wind.org/view-post/How-A-Company-is-Using-Bacteria-to-Replace-Soap

Stromberg, J. (2013). Why Do Mosquitoes Bite Some People More Than Others? Smithsonian.com. See:  http://www.smithsonianmag.com/science-nature/why-do-mosquitoes-bite-some-people-more-than-others-10255934/?no-ist

Thinkbeforeyoupink. Think Before You Pink – A Project of Breast Cancer Action. See: http://thinkbeforeyoupink.org/

Thompson, K. (2014). How to Control Mosquitoes. Pest Control – About.com. See:  http://www.answers.com/guides/how-to-control-mosquitoes

Verhulst, V. O. et al. (2011). Composition of Human Skin Microbiota Affects Attractiveness to Malaria Mosquitoes. PLoS One, 6:12. See:  http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028991

wikiHow. (undated). How to Use Plants to Keep Mosquitoes Away. See: http://www.wikihow.com/Use-Plants-to-Keep-Mosquitoes-Away

Wikipedia. (May 29 2014).  List of Pest-repelling Plants. See:  http://en.wikipedia.org/wiki/List_of_pest-repelling_plants



© Copyright 2014 Joan Rothchild Hardin. All Rights Reserved.


DISCLAIMER:  Nothing on this site or blog is intended to provide medical advice, diagnosis or treatment.

Living Bacterial Skin Tonic – Instead of Soap?!

Last update 8/22/2015.

AOBiome linked to this post on their Facebook page: https://www.facebook.com/AOBiome




Information on a new product called AO+ Refreshing Cosmetic Mist caught my eye recently. (Scott, 2014)
It’s a liquid developed by a biotech start up company in Cambridge MA to spray on our bodies in lieu of – or as an adjunct to – taking showers. Showering with most soaps and shampoos kills all the healthy elements of our skin microbiome. The company, AOBiome, says its new living bacterial skin tonic, made of safe live-cultured Nitrosomonas bacteria, replenishes the biome of microscopic organisms that live on our skin.
This does indeed sound novel, interesting – and important!




I started this site to write about how the micro-organisms living in our guts – the gut microbiome – affect the entire body and how to restore your gut – and the rest of you – to good health. See The Gut Microbiome – Our Second Genome.  Reading about AOBiome’s brilliant work on restoring our skin’s microbiome, produced a moment of clarity in me – one of those true light bulb moment: It’s not just our gut’s we’re destroying but our other microbiomes as well.





Our usual approach to the bacteria and other micro-organisms living on our skins – and everywhere else we can get to them – is to KILL THEM DEAD. We regard bacteria and their relatives as dangerous and just plain nasty. So this is an entirely new approach – a U turn in how to think about bacteria: The new spray contains billions of cultivated Nitrosomonas eutropha, an ammonia-oxidizing bacteria (AOB) most commonly found in dirt and untreated water in rivers, lakes, and the sea.  (Martinko, 2014)








Skin Microbiome
Artist’s Rendition of the Skin Microbiome – Our Second Genome. (Credit: genome.duke.edu)



The aggregates of micro-organisms living inside and on our bodies, collectively referred to as the human microbiome or microbiota, make their homes in many places:
  • In our GI tracts
  • On the surface of and in deep layers of our skin
  • On our hair
  • In the saliva and mucosa in our mouths
  • In our noses and sinuses
  • In our urogenital tracts
  • In the conjunctiva (the lining inside the eyelids and covering the white part of the eye)



Some of the Microbiomes of the Human Body. (Credit: National Human Genome Research Institute
Some of the Microbiomes of the Human Body. (Credit: National Human Genome Research Institute






Sources: (AOBiome, 2014), (Wikipedia, 2014), and (Baylor College of Medicine, 2013-2014)
  • There are 100’s of trillions of micro-organisms in the various microbiomes in and on our bodies, our Second Genome.
  • The number of non-human micro-organisms (bacteria, viruses, fungi, archaea and single-celled leukaryotes) inhabiting a healthy human adult is estimated to outnumber human cells by a ratio of 10 to 1.
  • The human microbiome contains about 3,000,000 non-human bacterial cells to our 23,000 human cells. (See correction below)
  • The total number of genes in our microbiome exceeds the number of genes in our human genome by a factor of at least 200.
  • So, even though the microbial cells making their home in and on us are only 1/10th to 1/100th the size of our human cells, they account for up to 5 pounds of an adult’s body weight.
  • To date, only a small percentage of the bacteria comprising our human microbiome have been identified.
Correction (8/22/2015): A reader named Stephen sent the following comment:

I just need to point out that you have one fact slightly, but importantly, inaccurate. You cite that:

The human microbiome contains about 3,000,000 non-human bacterial cells to our 23,000 human cells.

When in fact, you should replace the two occurrences of the word “cells” with the word “genes”. This fact is often misunderstood. What it means is that the human genome has about 23k unique genes, whereas the bacteria that inhabit us have about 3x10E6 unique genes, not that there are 3 million genes among them. The point is that the bacteria on our bodies possess incredible functional diversity and can do many things for our bodies that we cannot do ourselves.



(Source: welladjustedbabies.com)
(Source: welladjustedbabies.com)


And these miniscule critters aren’t invaders trying to harm us. The vast majority of them are necessary and beneficial to us – as we are to them.
Yet for a century, we’ve been unintentionally, but systematically, distorting and destroying the healthy workings of our various microbiomes with processed foods, pharmaceuticals – especially antibiotics, cleaning products, cosmetics, pesticides and herbicides, genetically modified foods and more, resulting in the degradation of our immune systems and huge increases in diseases and chronic medical conditions.
At the same time, and with many of the same products, we’ve also been degrading  healthy microbiomes in the soil and our water supplies – making not only humans ill but also wreaking havoc on the other fauna and flora on our planet.




Human Microbiome Map
Human Microbiome Map









The Zoo on Our Skin (Source: discovermagazine.com)
The Zoo on Our Skin
(Source: discovermagazine.com)


From the  AOBiome website (AOBiome, 2014):

Human skin, a large and heterogenous organ, harbors a fascinating array of species of bacteria, fungi, and other microorganisms. The specific makeup of the skin flora depends on many factors, such as whether the particular skin area is dry, moist, or sebaceous, the age of the host, external conditions, etc. Dry forearms and hairy, moist underarms are very distinct habitats, despite their relative proximity. People living together also seem to share a larger portion of their microbimes than those are not cohabitating, and pet owners share some with their animal companions.

Here are some of the most common microorganisms that reside on our skin:

Propionibacteria are the most prevalent on sebaceous, or oily skin, such as nostrils, scalp, upper chest and back. They are lipophilic anaerobes, decomposing oily sebum secreted by our glands, producing propionic acid. Although they are present in infants and babies, they become more dominant around the onset of puberty, as the sebaceous glands increase their output. One of the bacterial strains, Propionibacterium acnes, is thought to be responsible for inflammation of the glands that can lead to acne.

Staphylococci have their name derived from Greek word for grape, as their colonies resemble grape clusters. They reside predominantly in the moist areas of the body, such as the armpit, the elbow crease, etc. As aerobic bacteria, they produce lactic acid that lowers the pH of the skin and controls growth of other microorganisms. They are particularly prevalent on the skin of babies and infants, their relative abundance decreasing with age. While normally harmless, certain species of staphylococci, such as S. aureus, can act as human pathogens. Methicilin-resistant S. aureus (MRSA) infections are a difficult public health problem in hospitals and beyond.

Corynebacteria are rod-shaped, and mostly innocuous. They also prefer moist environments, such as the navel, or back of the knee. They grow slowly, even when the food is abundant.

Betaproteobacteria are a diverse group, which includes Nitrosomonas, currently excluded from human skin. They are the most prevalent group in the dry areas, such as the forearms. Also, these are the bacteria that the dog owners have the most in common with their dogs

Malassezia – as fungi, Malassezia get a honorable mention. They are found on our skin in large quantities, and are typically harmless, but certain species can cause dandruff or skin discoloration.



Skin Microbiome (Source: skinmicrobiome.wordpress.com
Skin Microbiome
(Source: skinmicrobiome.wordpress.com)






Horse Rolling in Dirt
Horse Rolling in Dirt
Ever wonder why horses love to roll around in dirt? We know horses, like humans, sweat a lot. We also know how unpleasant our skin can feel – and smell – after we’ve worked up a sweat. David Whitlock, the M.I.T.- trained chemical engineer who invented AO+, theorized that horses dirt bathe to manage their sweat. He reasoned, “The only way that horses could evolve this behavior was if they had substantial evolutionary benefits from it.”
The goal of using AO+ spray is to encourage the growth of a healthy colony of probiotic bacteria on the skin. This probiotic bacterial colony will then act as a built-in cleanser, deodorant, anti-inflammatory and immune booster by feeding on the ammonia in our sweat, converting it into nitrite and nitric oxide.
Scientists at AOBiome hypothesize that humans also had healthy, mutually beneficial, colonies of ammonia-oxidizing bacteria (AOB), such as Nitrosomonas eutropha, living on our skins. These AOBs regulated our nitrogen metabolism. Then in the 20th century, we began regarding all bacteria as dangerous and started trying to scrub them all away. (AOBiome, 2014)









The Hygiene Hypothesis – also called the Biome Depletion Theory or the Lost Friends Theory – states that a lack of early childhood exposure to infectious agents, symbiotic microorganisms (eg, probiotic gut flora – referred to as Our Old Friends), and parasites increases susceptibility to allergic diseases by suppressing the natural development of the immune system. In particular, the lack of exposure is thought to lead to defects in the establishment of immune tolerance. (Wikipedia, 2014).
The Hygiene Hypothesis is consistent with the destruction of the ammonia oxidizing bacteria (AOB) on our skins. Many ingredients in most of our personal care products have been found in laboratory tests to inhibit or have been found  toxic to AOB: sodium lauryl sulfate, sodium coco-sulfate, castile-type soaps, and amine oxides (such as lauryl dimethyl amine oxide). AOBiome’s laboratory is still in the process of testing the AOB toxicity of other ingredients commonly found in soaps, shampoos, skin creams, and deodorants.
The encouraging news is that AOBiome has found ingredients that ARE compatible with ammonia oxidizing bacteria. Their goal is to test, certify and develop a variety of hygiene products with these ingredients – including soaps and shampoos. (AOBiome on facebook, 2013-2014)





Here’s an explanation of why restoring healthy colonies of this bacteria on our skins is important – from the AOBiome website (AOBiome, 2014):

Modern hygiene has selectively depleted the natural balance of the skin microbiome particularly affecting AOB. By restoring the appropriate AOB levels, we believe a range of human health conditions could be impacted. AOBiome is interested in exploring potential physiologic effects including:

Improving skin architecture
Improving skin architecture


Preventing infection
Preventing infection


Improving vascularization
Improving vascularization



Before the advent of anionic surfactants, Nitrosomonas would have colonized our skin, our sweat glands in particular, constantly secreting low amounts of NO. Due to their particular sensitivity to detergents, however, they have been eradicated from our skin microbiome. As a consequence, we are dermatologically and systemically NO-deprived – in a mildly pro-inflammatory state, with a number of our systemic NO-mediated regulatory mechanisms out of balance. This deprivation may contribute to a number of skin conditions, such as eczema, psoriasis, potentially also neuropathies, and more. AOBiome aims to re-introduce Nitrosomonas to our skin’s bacterial flora, restoring natural NO levels, stabilizing the NO-dependent signaling pathways and alleviating symptoms resulting from NO imbalance.

Nitrosomonas are naturally occurring in most aquatic and soil environments and seem to totally lack pathogenic potential, as indicated by the absence of pathogenicity factors and also evidenced by the complete lack of human infections reported to date. Since Nitrosomonas depend on ammonia and urea for their growth, their numbers on the skin are necessarily limited, and are naturally regulated by the amount of sweat the body produces. This ensures that the amount of NO produced would be relatively low, without any adverse effects. Because of its reactivity, the Nitrosomonas-produced NO will exert most of its effects locally, in the skin of the host. If desirable, however, one could eliminate the bacteria using a simple soap treatment.

AOBiome’s scientists have also found that using concentrated AO+ led to a hundredfold decrease of Propionibacterium acnes, bacteria associated with acne breakouts. And they have found that a two week treatment with a formulation of AOB heals skin ulcers on diabetic mice.  (Scott, 2014)






AOBiome says NO. The probiotic bacteria in AO+ Refreshing Cosmetic Mist thrive in water so you can use it and also continue showering – just not lathering yourself up with soap or shampoo that will kill those useful bacteria. The ammonia oxidizing bacteria in AO+ can survive limited exposure to the chlorine and chloramine added to municipal water supplies to purify them. From the company’s facebook page (AOBiome, 2013-2014):
Our research shows that daily application along with normal showering in regular tap water produces a sustained level of AOB on skin. In our initial cosmetic study we showed that AOB are detectable and present in 95% of cases with daily showering and application and that AOB continue to survive in 60% of subjects for up to 7 days without additional applications as long as shampoo is not used. This is the basis for our recommendation that you apply AO+™ Refreshing Cosmetic Mist daily as part of your usual personal hygiene routine.
A note for those of you who’ve read the New York Times Magazine article, “My No-Soap, No-Shampoo, Bacteria-Rich Hygiene Experiment” (Scott, 2014), and came away from it thinking the choice will be between using the ammonia oxidizing bacterial spray or showering:
The article’s author was using the spray and not showering for 28 days as part of a clinical trial for AOBiome. When she started showering again but not also using the spray, the colony of ammonia oxidizing bacteria on her skin was quickly destroyed by showering with soap.
When the  Company has succeeded in bringing to market an AOB-friendly shampoo and AO+ Refreshing Cosmetic Mist is also readily available, we should be able to both shower and wash our hair with these products while maintaining a healthy colony of AOB. And when an AOB-friendly skin cream has been developed and approved for marketing to the public, we’ll also be able to nurture our AOB colonies by using it.










Credit: New York Times.com
Credit: New York Times.com


As Michael Pollan wrote in an excellent article last year titled Some of My Best Friends Are Germs (Pollan, 2013):

As a civilization, we’ve just spent the better part of a century doing our unwitting best to wreck the human-associated microbiota.

Now this brilliant biotech company, AOBiome, is working on a big piece of the solution to our ills. If you want to be wowed by the work they’re doing, take a look at their website.



(Credit: New York Times.com)
Credit: New York Times.com





Us - just 10% human





AOBiome. (2014). Pioneering bacterial therapy for the skin. See: https://www.aobiome.com/company

AOBiome. (2013-2014). facebook.  See:  https://www.facebook.com/AOBiome

Baylor College of Medicine, Department of Molecular Virology and Microbiology. (2013-2014). The Human Microbiome Project.  See:  https://www.bcm.edu/departments/molecular-virology-and-microbiology/microbiome

Hardin, J.R. The Gut Microbiome – Our Second Genome. AllergiesAndYourGut.com.  See:  http://allergiesandyourgut.com/the-gut-microbiome-our-second-genome/

Martinko, K. (2014). Could bacteria be the new beauty trend that actually makes us healthier?  See:  http://www.treehugger.com/health/could-bacteria-be-new-beauty-trend-actually-makes-us-healthier.html

Polan, M. (2013). Some of My Best Friends Are Germs. New York Times Magazine, May 15 2013. See:  http://www.nytimes.com/2013/05/19/magazine/say-hello-to-the-100-trillion-bacteria-that-make-up-your-microbiome.html?pagewanted=all&_r=0

Scott, J. (May 22 2014). My No-Soap, No-Shampoo, Bacteria-Rich Hygiene Experiment.  The New York Times Magazine. See:  http://www.nytimes.com/2014/05/25/magazine/my-no-soap-no-shampoo-bacteria-rich-hygiene-experiment.html?action=click&module=Search&region=searchResults&mabReward=relbias:r,%5B%22RI:6%22,%22RI:12%22%5D&url=http://query.nytimes.com/search/sitesearch/?action=click&region=Masthead&pgtype=Homepage&module=SearchSubmit&contentCollection=Homepage&t=qry545&_r=1

Wikipedia. (June 2 2014). Hygiene Hypothesis. See:  http://en.wikipedia.org/wiki/Hygiene_hypothesis

Wikipedia. (June 3 2014). Human Microbiome.  See:  http://en.wikipedia.org/wiki/Human_microbiome


© Copyright 2014 Joan Rothchild Hardin. All Rights Reserved.


DISCLAIMER:  Nothing on this site or blog is intended to provide medical advice, diagnosis or treatment.