The microbes that inhabit our bodies are intimately involved in human health and disease yet we still know relatively little about them. A new major census of these tiny symbionts has revealed that they are an even more diverse bunch than was once presumed.

We have long focused on single bacteria as sources of disease (E. coli or streptococcus, for example). But we have now been learning that, for the most part, these trillions of microbes that make their homes in and on us do an excellent job keeping us healthy (crowding out harmful microbes) and sated (breaking down a lot of the food we ingest).

Now that disturbances in this rich microbiome community have been linked to weight gain, inflammatory bowel disease, vaginal infections and risk for infection with harmful microbes (such as methicillin-resistant Staphylococcus aureus, or MRSA), the importance of understanding what makes up a "healthy" microbiome has become even more apparent.

We have been adding names to the attendee list for years, but scientists still do not have a full rundown of all of the bacteria, where they live in our bodies and their role in health and disease. "We need a reference to say what is normal before we can say what is abnormal," Eric Green, director of the National Human Genome Research Institute, said in a press briefing Wednesday.

Green and his colleagues at the Human Microbiome Project have taken a big step forward in charting this complex territory, publishing an extensive new survey of the microbial profiles of hundreds of individuals. The findings are described in two papers and an essay online June 13 in Nature and in more than a dozen papers in PLoS ONE. (Scientific American is part of Nature Publishing Group.) The findings only reinforce the suspicion that this invisible landscape is even more nuanced—and important—than we thought. For example, each person might carry around hundreds of thousands of species. These bugs bring with them some eight million different genes, which far outshines our own paltry 22,000.

"This is really a new vista on biology," Phillip Tarr, director of pediatric gastroenterology and nutrition at Washington University School of Medicine in Saint Louis and a collaborator on the research, said in the press briefing. "It opens up many opportunities to improve the health of our population."

To get their results, the team collected samples from 242 healthy adults aged 18 to 40 living in Houston or Saint Louis. From each person, researchers sampled 15 to 18 specific "habitats" (nine from the mouth, four from the skin, one from the nose and three from the female genitals) as well as from stool samples.

"Healthy humans carry a remarkable diversity of organisms," says Bruce Birren, director of the Genomic Sequencing Center for Infectious Diseases at the Broad Institute and study collaborator, said at the briefing. The oral and fecal samples had the highest microbe diversity, whereas the vaginal samples had the lowest.

Each person had a relatively different microbiome, reinforcing the notion that there is no single "healthy" microbiome profile. "Apparently there are many different ways to be healthy when it comes to our microbes," Birren said. The group found that even with so many different microbial communities at each location, the same metabolic functions seem to be getting done. Birren likens it to a potluck dinner, where everyone brings something different to the table so everyone gets to eat.

12 Comments

1. 1. hanmeng 09:35 PM 6/13/12

   So should I stop daily bathing to preserve my personal microbiome?

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2. 2. curmudgeon in reply to hanmeng 07:30 AM 6/14/12

   In all likelihood, yes! The prevalence of anti-bacterial products in modern washing products is certainly not helping with the increasing number of drug resistant strains of the nasties. And there's good evidence that increases in asthma and allergy sufferers are, at least in part, linked to the modern obsession with 'killing germs'. We are, as a species, now far too 'clean'! Regular hand washing makes good sense but daily stripping of all those helpful bacteria from your whole body and your home is doing nobody any good!

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3. 3. JamesDavis in reply to hanmeng 07:38 AM 6/14/12

   Well, actually, you should stop your daily baths to preserve your personal microbiome. People in the early and middle 19th and 20th Century only bathed once a week, month or year, and some never bathed at all, and they were healthier than we are today, and you should really stop going to the doctor every time you get a little sniffle. A healthy person doesn't go to doctors but, maybe, once a year for a checkup, so common sense should tell you that it is no longer in most doctors interest to keep you healthy...you stay healthy and they do not get paid.
   
   Virus and bacteria have been with us humans for millions of years and it is in their interest, since they live in and on us, to keep us healthy. The foods you eat helps the virus and bacteria keep you healthy. There was a very wise old man once said, "IF there are any among you are sick, let them turn to the fields for their healing." He said, "IF THERE ARE ANY AMONG YOU WHO ARE SICK"... The word "IF" tells me that there were not many people getting sick back then. Today, maybe 2/3 of our population is sick with something, and that tells me that we are not doing something right...maybe we have too many doctors who need to pay off their college loans. If we can pay a football player 25 to 30 million dollars to play a stupid game, why can't we pay off our doctors training debt so they can concern themselves more with our health and less with their 40 year debt that they accumulated in their training.

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4. 4. hanmeng 12:08 PM 6/14/12

   Wait till the EPA starts mandating how we treat our microbiomes.

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5. 5. evosburgh in reply to hanmeng 01:02 PM 6/14/12

   Ha ... yet another 'rule' to live by:)

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6. 6. JonathanEisen 01:08 PM 6/14/12

   For those interested I made a collection of links to the scientific papers discussed in this article: http://phylogenomics.blogspot.com/2012/06/human-microbiome-project-hmp-new-papers.html

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7. 7. frankboase 09:35 PM 6/15/12

   Morning James,
   "so common sense should tell you that it is no longer in most doctors interest to keep you healthy...you stay healthy and they do not get paid."
   Is there any truth in the story that in China, maybe not modern China) that patients paid doctors only for as long as they were healthy?

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8. 8. MarkB4 09:45 PM 6/15/12

   So that's why I never use soap, I love my microbes. :)
   
   Or should I use the auto dispensing microbial hand cleanser more often?

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9. 9. cybrzone 05:06 PM 6/16/12

   The people in the past century who seldom bathed did not live as long as now.. They had very poor dentists in those days...keeping plaque out of the blood stream is a big big factor in longevity... Trying to cleanse the world with handwipes everywhere is rather silly... The CHINESE have the correct paradym...no cure no pay....pure and simple...Motivation to perform is always good... I grew up in a Michigan rural area with well water and an outhouse...So called sponge bath every few days..heat a pot of water on the stove, and with washcloth clean underarms, private parts and feet...Toothpaste or Listerine???huh...teeth were cleaned by eating an apple and picking out particles with a toothpick....At age 70 I have all of my teeth except the so called wisdom teeth, and have been very consistent about the cleaning by a hygenist every six or seven months...Concerning doctors and hospitals, it is definitely the ol fashioned buyer beware...Many can testify that if one is not sick when entering the doc office or hospital, they will do everything to plug you into their system of pills and procedures until you are hooked for life...
   Herbs are the way to go...Ginko is very good for circulation and even ED. Myrrh, Goldenseal, Neem and a host of others are anti viral as well as antibacterial without damage to intestinal flora.....for anti-inflammatory herbs--tumeric is excellent..It is used in cooking and is perfectly safe to make a tea from it...Ginger and a host of other herbs are anti-inflammatory as well...Lysene for shingles or herpes cold sores....I can recomment Earl Mindell's book Herbal Bible.. Most healthfood stores carry it and there is often times more useful info on health available from your local health food store manager or owner...You can buy a few bottles of herbs which cannot hurt and should help, spend thirty bucks or so, or go to the doc's office, wait an hour, get a song and dance pony show for eighty or ninety, get some pills with side-effects and be back in the office again in a couple of weeks....The human body is a marvelous mechanism and will heal itself if given half a chance....proper rest, less stress, regular exercise, and a well balanced diet works well for most...but not all...If there is a serious existing condition then see a specialist for that condition and dont putz around with wannabees and referrals etc... Thats my two cents worth and hope someone in this group will benefit from my 70 years of experience...db

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10. 10. Gaspar_Ramsey 09:04 PM 6/16/12

    Back in the 1960's I worked for a world famous geneticist, Dr. Edgar Altenberg. In the 1930's he was interviewed on a nationwide program and expressed the opinion that people bathed too often. Subsequently, he received an offer to go on a nationwide tour extolling the virtues of not bathing. The person who made the offer claimed not to have bathed in 30 years and virtually exude health. Fearing that this person might also exude a effluvium thirty years in the making, Dr. Altenberg declined.

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11. 11. Gaspar_Ramsey 09:07 PM 6/16/12

    Back in the 1960's I worked for a world famous geneticist, Dr. Edgar Altenberg. In the 1930's he was interviewed on a nationwide program and expressed the opinion that people bathed too often. Subsequently, he received an offer to go on a nationwide tour extolling the virtues of not bathing. The person who made the offer claimed not to have bathed in 30 years and virtually exude health. Fearing that this person might also exude a effluvium thirty years in the making, Dr. Altenberg declined.

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12. 12. stevewriter 10:54 AM 6/20/12

    For several years I have considered myself as "bipedopolis," a city on foot. I have cell citizens that carry my genes, and a host of resident aliens that all work to keep the microbiological functions humming along smoothly. I am grateful that my rational mind can float on top of this marvelous community to guide it around in the meter-scale world.

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