Peace, Love, and Gut Bacteria


How hippie food became mainstream.

“The Hippies Have Won.” That was the conclusion of a New York Times article on April 4th, which suggested that “just as yoga and meditation have gone mainstream, so have ideas and products surrounding health, wellness and eating that play like a flashback to the early 1970s.”

The nicely-observed piece supported its claims in part by explaining that fermented foods such as kombucha and kimchi are no longer fringe-fads, but are now considered by many to promote good gut health, supporting the development of a healthy microbiome.

Well, right on.

In fact, the NYT says that kombucha, for example, has gone from being “something your art teacher might have made in her basement [to where] the company GT’s Kombucha brews more than a million bottles annually and sells many of them at Walmart and Safeway.”

Fermented foods, as well as being undeniably tasty, tend to be rich in bacteria – particularly those strains that might be classified as probiotics, which, in general, are a good thing when they arrive in your gut.

But has the world of fermented food been entirely taken over by corporate giants?

Thankfully not.

While we’re definitely grateful that big business is banging the drum for these healthy diet additions, getting them into the hands (and mouths) of a wider market, it’s comforting to report that a great deal of grass-roots fermentation is still going on, and, indeed, there’s been something of a revival in this area.

Our attention was drawn to a new edition of the 2003 classic “Wild Fermentation,” written by a man named Sandor Katz, who describes himself as a “fermentation fetishist.”

Whatever tickles your pickle, one might say.

Sandor, who’s so into fermentation that he’s known and loved by many as Sandorkraut, has been described by food author and activist Michael Pollan as showing you “why an act as practical as making your own sauerkraut represents nothing less than a way of engaging with the world.”

There’s a delightful short documentary film on the NYT website, showing Sandor making sauerkraut in a satisfyingly “earthy” way.

A charming, messy kitchen.

Plenty of bare-handed squishing of shredded cabbage.

Repurposed old jars.

And splendidly-aged fermentation crocks in stone-walled basements.

The documentary directors even found a great old country song named “Sauerkraut” for the soundtrack.

The tune, incidentally, was sung back in 1926 by country music pioneer Riley Puckett, best known for being the first country artist to yodel in his performances.

What’s not to like about a yodelling country singer with a song about fermented cabbage?

Actually, he was probably on controversial ground, since sauerkraut had been renamed Victory Cabbage as a marketing move during World War I (1914-18) because of the word sauerkraut’s associations with Germany.

By 1926, however, it was clearly safe to go back to how things had been pre-war.

Sandor Katz explains that wild fermentation refers to the reliance on naturally-occurring bacteria and yeast to ferment food.

He points out that humans didn’t really discover fermentation, as it was already occurring in the wild.

We just found ways to harness this natural process.

So, fruit already has yeast on its surface, which enables the fermentation process to take place, as it does in the wild – much to the delight of certain species of tropical bats.

And cabbage leaves provide a home for bacteria that, in anaerobic conditions, produce carbon dioxide and lactic acid, the latter being what kickstarts fermentation.

Sandor grew up in New York City, but moved to rural Tennessee after a life-changing diagnosis of AIDS.

He’d originally been a “policy wonk,” so moving to an off-the-grid rural community was indeed a significant life change.

His new focus has led to him teaching hundreds of food workshops in the US and all over the world, and he now runs a fermentation school at Walnut Ridge, a restored 1820s log cabin in Liberty, Tennessee.

What do we know about the scientific basis of probiotics, though?

It’s often suggested that the microorganisms concerned may not actually reach the gut intact, and, of course, it’s their presence in the lower gut, in particular, that is believed to be beneficial.

Well, in an article published in The American Journal of Clinical Nutrition, Dr Anatoly Bezkorovainy, an assistant professor in the biochemistry department at Rush Medical College, reported that estimates suggest that 20-40% of selected strains of probiotics make it through the stomach into the gut.

Their main obstacles are gastric acidity and the action of bile salts.

Interestingly, however, Dr Bezkorovainy went on to report that there’s little evidence that probiotic bacteria adhere to the mucosal walls in the intestine, so they tend to pass through you, like sh**s in the night.

This seems to support the notion that the benefits of fermented food don’t really result from a “fix-it-and-forget-it” action.

Instead, it appears to be important to consume it on a regular basis.

Finally, returning to Riley Puckett, although he erroneously sang about vinegar being part of the sauerkraut-making process, when, in fact, the dear old cabbage just needs the addition of salt for it to make its own acid, it seemed apt to end on his words from 90 years ago, clearly not only a time when you could write a hit song about cabbage, but also a time of lower prices:

If you will only listen to who I speak about,
I ain’t no voice to tell you how to make that sauerkraut,
It’s made out of vinegar, so everyone suppose,
And of that little flower, they call that cabbage rose.

Oh sauerkraut is bully, I told you it was high,
I think I ought to know for why,
I eat him all the time.

Then it’s sauerkraut, then it’s sauerkraut,
Priced good you know, because you love it so.
Then it’s sauerkraut, then it’s sauerkraut,
Only five cents, one pint.


Salmon Sperm and Bee Venom in Your Eye?


Excuse us, you have something in your eye: bacteria.

Pop quiz. Which part of your body is just about the same size now as it was on the day you were born?

In fact, you’re almost certainly making use of it right now.

Yup, an eyeball remains around one inch in diameter from the minute we’re born until the day we die, and it’s why the small head of an infant can make us believe that babies have big eyes. It’s actually a matter of scale.

Unless you’re reading this via some kind of whizzy text-to-speech gizmo, you’re now using your eyes, and reading our words through a thin biofilm that contains bacteria. That could explain the fuzziness.

Welcome to your ocular microbiome.

Until pretty recently, it was widely believed that, unless they were infected, our eyes were bacteria-free. But studies now show that a healthy eye does indeed contain its own ecosystem of microorganisms that remain in place despite tears and the approximately twelve times a minute that we blink.

It was in 2009 that scientist Valery Shestopalov, from the Bascom Palmer Eye Institute at the University of Miami, founded the Ocular Microbiome Project, an initiative that now has twelve collaborators in five universities.

Dr. Shestopalov’s early work showed that the surfaces of what he termed the “exposed mucosal epithelium” in the eye are densely populated with microorganisms.

In the eye, the mucosal epithelium is the wet membrane that forms the surface of the eye, and the insides of the eyelids.

Around a dozen bacterial genera dominate the eye’s conjunctiva, which is the white of the eye (the “sclera”) and the eyelids.

Interestingly, on the corneal surface (the transparent part of your eye, which covers your iris and pupil) there’s likely to be a slightly different microbial community, although again with about twelve predominant genera.

You see? Even when you’re healthy, there’s a barn load of bacteria in your eye.

But what happens when you get an infection, though?

Well, the two most common eye infections are styes and conjunctivitis (sometimes called “pink eye”).

Styes are those pesky little bumps that can form on the eyelid, generally the result of skin bacteria getting into the hair follicle of an eyelash.

Conjunctivitis can indeed be caused by bacteria, but it’s also possible that a virus or allergy could be the culprit.

Other causes can be substances that cause irritation, contact lens products, eye-drops, or eye ointments.

More on contact lenses in a moment, but first some intriguing findings about infections of the cornea, which are known as keratitis (the eye is a complicated space when it comes to naming infections).

Research has shown that during keratitis, bacterial diversity on the cornea actually reduces rather than increases, and these changes typically occur before eye infections are diagnosed, making it possible that monitoring of the ocular microbiome might form some kind of future diagnostic tool.

But what of contact lenses, then?

The US Food and Drug Administration (FDA) reports that around 30 million Americans wear them, so does this affect the bacteria in their eyes?

Yes indeedy.

A study at New York University School of Medicine (NYU) compared the ocular microbiomes of lens-wearers with those of non-wearers, and found considerable differences.

In fact, contact lens wearers tend to have an ocular microbiome which is more like their skin microbiome.

It’s tempting to jump to the conclusion that this is simply because contact lens wearers are frequently poking their fingers into their eyes (an idea many non-wearers probably flinch at), but although the NYU researchers acknowledge that this could indeed be the reason, they say it’s actually too early to be sure.

It is, however, a good time to remind all lens-wearers of the importance of thorough hand-washing before dealing with contacts.

Dr. Shestopalov’s team sequenced bacteria from contact lenses used for one day, finding relatively little diversity on their surfaces, as well as further evidence that contact lens wearers have an ocular microbiome that differs from those who don’t wear contacts.

Wearing lenses can, in and of itself, be a cause of eye problems, and estimates suggest that anywhere between 7% and 25% of contact lens wearers experience irritation and redness.

Actually, some researchers hypothesize that contact lenses make it easier for pathogens to colonize the eye by giving bacteria something to adhere to.

However, if this gives you a lightbulb moment, and makes you think about inventing an antimicrobial contact lens – well, sorry to tell you this – someone else got there first.

A medical microbiologist at the University of New South Wales in Australia is heading a team of scientists who are developing antimicrobial contact lenses by coating them with a synthetic peptide called melimine.

That’s melimine with an “i,” rather than Melamine with an “a.”

One’s an antimicrobial agent, while the other is, well, the stuff that unbreakable tableware is made from, and you wouldn’t want picnic plates in your eyes.

Although, when you read the following, you may well think the same about melimine (with an i.)

You see, melimine is a combination of two other substances – protomine, and milletin – hence its portmanteau name.

And somewhat unbelievably, protomine was originally isolated from salmon sperm, while mellitin is the principal active component of bee venom.

Quite honestly, two stranger substances to place in your eye are difficult to imagine.

Despite the thoroughly odd provenance of this antimicrobial agent, early tests on humans by the Australian scientists suggest that the melimine-coated contacts are as safe as regular lenses, and seem to be effective as an antimicrobial against two major pathogens – Pseudonymous aeruginosa and Staphylococcus aureus.

What do you get if you cross salmon sperm and bee venom?

There’s probably one heck of a good one-liner answer to that (and we’d love to hear your suggestions) but the real truth is that it’s antimicrobial contact lenses.


Microbes in the Mansion: US Presidents and their Bacteria


The often surprising truth about presidential-bacterial connections.

With so much media coverage of presidential matters over the past year, and particularly with last week’s inauguration of the 45th President of the United States, you might think every possible presidential angle has been covered.

This, though, would be seriously underestimating your good friends here at uBiome.

For it is with considerable pleasure this week that we bring you a collection of presidential bacteria stories over a time period beginning with the first president, and ending with the 44th.

Let’s start with number nine, William Henry Harrison, who has entered the record books for at least two significant achievements.

The first was delivering the longest inaugural address in history, speaking for an hour and 45 minutes in a DC snowstorm, without an overcoat, gloves, or scarf.

The second (perhaps not entirely disconnected)?

Harrison was the first president to die in office – exactly one month after being sworn in – which for 150 years was widely claimed to be because of pneumonia he developed after standing in the cold for so long.

However, thanks to some excellent detective work by two researchers – Jane McHugh and Philip Mackowiak – it’s now believed that President Harrison died of enteric fever (also known as paratyphoid fever) brought on by gastroenteritis, a bacterial infection.

What’s more, the recent research uncovered the fact that two other presidents of that era, James Knox Polk and Zachary Taylor, are also believed to have died from gastrointestinal infections.

And the thinking is that this sickness came about through unsanitary conditions.

Very possibly, there may have been no hand-wash in the White House.

Actually, in the 1840s, Washington DC’s systems for the disposal of what was then euphemistically termed “night soil” were, to say the least, primitive.

Not to put too fine a point on it, barrels of fecal sludge were hauled through the streets of Washington DC at government expense, and dumped in a depository where the sludge stagnated and formed a marsh.

Unfortunately, this was just seven blocks from the White House water supply, and it was therefore probably no surprise that these three presidents became, well, ex-presidents.

As a matter of fact, bacteria probably also played a part in the demise of the very first president, George Washington.

His life was plagued by numerous serious diseases, mostly of a viral nature, but his death in 1799 at the age of 67 may have been partly the result of epiglottitis, a throat infection that can be caused by the Haemophilus influenzae bacterium, following a serious cold Washington developed.

Yet another presidential death associated with bacteria was the sad case of William McKinley, who was shot by an assassin at the 1901 Pan-American Exposition in Buffalo, New York.

Two bullets were fired into McKinley’s body, but only one was retrieved.

A projectile in his stomach was elusive, so a hastily-gathered surgical team, led by a gynecologist, stitched up the President with the ammo still inside him.

One of his aides, concerned about this laissez-faire surgical attitude got in touch with Thomas Edison, requesting that the inventor lend them an x-ray machine, which was delivered but never used.

Soon after, McKinley died – not from the bullet itself, but from septic shock caused by a bacterial infection which led to the development of gangrene along the pathway taken by the bullet.

A bacterial infection also took the life, not of Calvin Coolidge himself, but his son, Calvin Coolidge Jr.

Tragically, Coolidge Jr. developed a simple blister on his toe while playing lawn tennis on the White House grounds.

Unfortunately, the blister became infected with the very common Staphylococcus aureus, which most of us carry on the surface of our skin, but in the case of President Coolidge’s son, led to his rapid demise.

It’s sobering to note that, although a simple course of antibiotics would have almost certainly prevented this death in 1924, this occurred just four years before Alexander Fleming discovered penicillin, the first true antibiotic.

And it’s kind of ironic that less than a century later, the 44th President, Barack Obama, issued an Executive Order in 2014 seeking to combat antibiotic-resistant bacteria, a phenomenon that has been largely brought about by the overuse of antibiotics, with the Center for Disease and Prevention estimating that antibiotic-resistant bacteria cause 23,000 deaths annually in the US.

George W. Bush made one of two presidential addresses relating to bacteria in November 2011 after the US had experienced a series of deadly anthrax attacks just a week after 9/11. Anthrax is a bacterium that was first identified in 1875 by the German scientist Robert Koch.

The other microbe-related presidential speech was made by Bill Clinton in 1996 after a team of US meteorite hunters said they’d identified bacteria from Mars in a meteorite they’d discovered in Antarctica.

Unfortunately, their claims were subsequently rejected by the wider scientific community, but not before President Clinton had suggested that the find was “one of the most stunning insights into our universe that science has ever uncovered.”

Or not.

We end our exploration of presidential bacteria with, once again, the outgoing president who, just last year, announced the National Microbiome Initiative, that is now fostering the integrated study of microbiomes across all manner of different ecosystems, and which we at uBiome are of course happy to support with our Microbiome Impact Grants.

As for bacterial connections with our latest president, well, we’ll simply have to wait.


Extreme Dieting, and Meeces Who Eat Feces


Also: why it’s good to be cautious about study-based news stories.

As we noted last week, at this time of year, millions of Americans put themselves on diets, so it’s no big surprise to find books like Travis Stork’s The Lose Your Belly Diet, doing well on the New York Times Best Sellers list.

It’s also no surprise to see the media picking up on our fascination with losing weight, and part of this most recent onslaught of interest has come about through an intriguing paper published just last week in the journal Cell Host & Microbe.

In case you don’t have a subscription, and since we’re pretty certain you won’t find a copy in your local supermarket checkout line, we thought it might be interesting to report on it, investigating in a little more depth than you may find in other sources.

As ever, once you start looking under the hood of a paper, there’s some fascinating learning (as well as a few caveats) to be had along the way.

The headline finding of the research is that there appears to be evidence that switching from a typical unrestricted American diet to a more healthy calorie-restricted plant-based diet may not get an immediate response from your body.

In “pop” terms, going on a profoundly different diet may not deliver instant results.

Let’s begin by checking on the provenance of the study, and this one’s good. In fact, they don’t get much better.

It was led by Jeffrey Gordon of Washington University School of Medicine.

Professor Gordon runs the distinguished Gordon Lab in Washington and has been responsible for some of the research community’s most important work on human gut microbial communities. He also played a pivotal role in the foundation of the Human Microbiome Project.

So how did Professor Gordon’s team go about this new investigation?

Well, they began by inoculating gnotobiotic mice (animals that had been bred to be “germ-free”) with fecal matter sampled from two different groups of humans.

The first group were individuals consuming what might be considered a standard American diet, typically defined as one that’s low in vegetables, fruits, poultry, seafood, and whole grains but high in carbohydrates, saturated fats, red meats, sugar, and processed food.

You know, all the things that are bad for you and none of those that are good for you.

The second group of participants were eating the aforementioned “healthy, calorie-restricted, plant-based diet,” and stay tuned for more about them in a minute: it gets interesting.

Once the mice were dosed with one of two types of human fecal matter, which we’ll term “American” or “calorie-restricted,” the two groups were again subdivided, and placed on either a simulated American or calorie-restricted diet.

Mice with a microbiome they’d inherited from calorie-restricted humans responded strongly to both types of diet.

Mice with an American microbiome, however, responded only partially to being fed the calorie-restricted diet.

Their American microbiome appeared to prevent the calorie-restricted diet having much of an effect.

But wait, who were the individuals who supplied the calorie-restricted fecal samples?

Well, we said it gets interesting, and in fact they were all members of an intriguing organization known as the Calorie Restriction Society, founded in 1994.

Members of the society take the view (and these are their words, not necessarily ours) that the only valid life extension method that has any proven scientific backing behind it is calorie restriction – the consumption of a diet with adequate quantities of all essential nutrients, except that the energy content of the diet (its caloric intake) is safely reduced by as much as 10-40% below the amount of energy (calories) that the body would tend to naturally desire.

In fact, the group members who participated in this study habitually consumed nearly 50% fewer calories than their American diet counterparts.

Somewhat extreme, you may agree.

But while it makes a ton of sense for researchers to investigate such clearly defined individuals, perhaps it’s less reasonable for the mainstream media to then extrapolate this to suggest that individuals modifying their diet – a little – won’t see results?

Actually, the second stage of the research was also deeply interesting.

When mice with the American microbiome were co-housed with calorie-restricted animals, the former gradually acquired some of the bacteria from the latter.

In fact, the researchers went on to argue that we need to think of our microbial communities not as isolated islands, but as part of an archipelago where bacteria can move from island to island.

However, lest you imagine that humans might therefore lose weight simply by hanging out with lean individuals – through some kind of airborne bacterial osmosis – the researchers noted that the mice in the experiment were actually, uh, coprophagic.


Yup, they were poop-eaters.

We’ve not seen any mainstream media coverage of the study mention this, but it’s a good demonstration of the care that’s required when taking perfectly legitimate, completely sound research, and jumping to sometimes unlikely conclusions.

Our thinking?

If you want to lose weight this New Year, following Michael Pollan’s simple rule “Eat food. Not too much. Mostly plants.” may make sense for many, and, in fact, one conclusion we can pretty safely take away from this recent research is that the increased microbial diversity of the calorie-restricted individuals seems at least partly based on their higher consumption of fruit and vegetables.

Probably best steer clear of the whole coprophagia thing, though.

Unless you’re a mouse.


Losing Weight is Most Popular New Year’s Resolution – Could Probiotics Help?


Spoiler Alert: Maybe, maybe not.

Right now, like many, you may be reflecting on the rapidly receding holiday season, ruing that you ate more, and were less physically active, than usual.

Perhaps you’ve even needed to loosen your belt a notch or two.

Don’t worry, you aren’t the only one.

In fact, a 2012 survey reported that weight loss was the number one New Year’s resolution for Americans (for 21% of those who set goals).

Other popular focuses were on improving finances (14%), exercising (14%), and getting a new job (10%).

Dr. John Norcross, Distinguished Professor of Psychology at the University of Scranton, PA, estimates that between 40 and 50% of Americans make New Year’s resolutions, but his research suggests we’re not always successful at keeping them.

Dr. Norcross wrote the popular book Changeology, so he knows a thing or two about the psychology of behavior change.

In fact, he says, around a quarter of people make it no further than one measly week into the year before their resolve crumbles, and over a half have fallen off the wagon six months on.

Now, the food you ate toward the end of 2016 has probably had an impact on your microbiome, but is there any evidence that making deliberate changes to the bacterial composition of your gut can help you lose weight?

Well, perhaps – but as ever, it’s a very qualified perhaps.

Let’s look at one particular piece of research in detail, containing cautiously good news for women (sorry, guys). And along the way, we’ll also shine a light on the peculiar world of the patenting of bacteria.

This particular study was conducted by scientists from Laval University in Québec, Canada, alongside researchers from Nestlé in Switzerland (bet they had good chocolate in their meetings), and was published in the British Journal of Nutrition in December 2013.

Essentially, it explored the impact of swallowing a probiotic supplement – in capsule form – on obese men and women over a 24-week period.

The study was a double-blind, placebo-controlled, randomised trial. Half of the 125 participants received a probiotic, while the other half were administered an inert placebo, all in identical capsules.

During the first twelve weeks of the trial, participants were placed on personalized diet plans, which involved them consuming 500 calories per day less than they would need for weight maintenance.

This was followed by twelve weeks on a strict weight-maintenance diet.

So, what happened?

Well, as we hinted earlier, women in the study appeared to benefit from the probiotic supplement.

Those in the placebo group lost an average of 5.7 pounds in the first twelve weeks, but those receiving the probiotic experienced a greater average weight loss of 9.7 pounds.

What’s more, though, the probiotic recipients continued to lose weight after they stopped getting the supplement and were back on their weight maintenance diet. They ended up with an average loss of 11.5 pounds. Those on the placebo lost no further weight during the second half of the study.

But what about the men?

Disappointingly, those in the placebo group actually lost more weight than the participants who received the probiotic supplement during the first twelve weeks.

And by the end of 24 weeks, both groups of men had lost about the same – around 12.5 pounds.

Professor Angelo Tremblay, the study’s leader, said they didn’t know why the probiotics had no effect on men, but hypothesized that it may have been a question of dosage – or perhaps the study period was too short.

Even the study’s positive results on females have been questioned by some experts, who pointed out that the experiment was carried out on a very specific type of woman (e.g. none were pregnant, smoked cigarettes, had drug or alcohol problems, or took vitamins or supplements of any kind).

However, given such possible limitations, what was in those probiotic capsules?

They each contained 10 mg of a powdered version of a strain of Lactobacillus rhamnosus, known as Lactobacillus rhamnosus CGMCC1.3724, which provided 162 million colony-forming units.

This powder was accompanied by 300 mg of a mix of oligofructose and inulin (both dietary fibers/prebiotics) designed to help the active probiotic make it through the stomach’s acidity and into the gut.

Curiously, this particular strain of bacteria has since been patented by Nestlé.

In general, bacteria occur naturally, so they cannot be protected by patents, but in 1980, the US Supreme Court ruled that microorganisms created in the laboratory by genetic manipulation could indeed be patented.

This ruling followed an eight-year legal battle that began in 1972 after a microbiologist at General Electric created an oil-eating bacterium in the laboratory, and it allowed Nestlé to follow the now widely-adopted practice of obtaining a patent for a bacterial strain.

If you’re wondering about the “CGMCC1.3724,” it’s all to do with the Chinese General Microbiological Culture Collection (CGMCC), which is based in Beijing and acts as a kind of Library of Congress repository for those who wish to patent microorganisms.

The “1.3724” is simply the strain number, a label for a particular entry in the CGMCC catalog.

While this may be way more information than you’ll ever need, it fascinated us.

Nestlé refers to its bespoke strain as LPR, and uses it in certain yogurt products sold in European markets.

Professor Tremblay, however, believes that the probiotics found in dairy products in North America could have a similar effect to the Nestlé strain. (Don’t tell the company’s patent attorneys.)

Diet or not, good luck with your own New Year’s resolutions.

We’ve made one, too.

We’ll be doing our level best to keep you informed and, we hope, entertained with our weekly newsletters.

See you next time, and thank goodness for elasticated waists.

When Did You Last Clean Your Showerhead?



It could be time to get to work.

Apparently it was the Greeks who started it all. Part of an ancient Greek’s daily bathing routine consisted of emptying a jug of water over their head or, if they were wealthy, having a servant do it for them.

These days, of course, you don’t need a jug. It’s common to take a shower, and according to a 2016 survey by the market research company Euromonitor, around 70% of Americans start with one every single morning.

Surprisingly however, we aren’t quite as dedicated to our showers in the US as those in Colombia and Brazil, where just about 100% of adults make their way into the spray every morning.

Many hygiene experts say this may actually be overdoing it, though, as there’s some suggestion that daily showers rob our skin of important oils.

But there’s another reason to think twice about showering, which is that your showerhead might just be harboring bacteria, then blasting it onto your body, and possibly even into your lungs. This is one of the reasons why a study led by North Carolina State University is asking 500 people in the US and Europe to send them samples of the gunk they’ve collected from inside their showerhead.

Nicola Twilley, writing recently in The New Yorker, described what she found when she removed the faceplate of her own showerhead in order to participate in the study. It was “a slimy, slightly clotted dark film, covering the stainless steel interior.”


The North Carolina study is being run out of The Rob Dunn Lab, Rob Dunn being a professor of applied ecology at North Carolina State.

His website explains that microbes can colonize the insides of showerheads, raining down on you as you shower.

But showers also produce an aerosol effect – resulting in minute particles becoming suspended in the air, from where they can readily enter your lungs.

However, the site goes on to explain, there’s an enormous difference between the amount of gunk (biofilm is actually the scientific term) found from one showerhead to another. Appearances can be deceptive.

While some generously ooze with biofilm inside, others have none – and this can even apply, in the lab’s own words, to “old, gunky, terrible-looking ones of the sort you might find in the hostel of your nightmares.”

The researchers believe that some of this difference may be down to the municipal water shooting through the showerhead, but it’s thought that climate can also play a part.

Showerheads, of course, are wet at certain times, then generally dry out completely before their next use, and this wet/dry regimen can favor the growth of unusual sorts of microbes.

The lab says it is even possible that some showerheads may contain bacteria-eating amoeba which keep the plumbing clean.

One of the team’s researchers, Jennifer Honda, a microbiologist from University of Coronado Anschutz Medical Campus, will be looking for non-tuberculous mycobacteria (NTM), a pathogen that can cause lung disease in individuals with compromised immune systems.

She will be testing the hypothesis that NTM will be more likely in tropical climates than in temperate ones.

In tropical conditions, she explains, the showerhead has less of a chance to dry out.

If the genus Mycobacterium makes you think vaguely of mushrooms, that’s not an entirely misplaced idea.

“Myco” is Greek for “fungus,” and the genus was given its name because Mycobacteria tend to grow in a fuzzy, mold-like fashion.

Another study, involving a species from this genus – again involving showerheads – was carried out at the University of Colorado in 2009 by Dr. Norman Pace, a professor of molecular, cellular, and developmental biology.

In this case, he was interested in Mycobacterium avium, one of a collection of microorganisms that can cause pulmonary (lung) disease.

Dr. Pace explained that as well as those microbes that accumulate in the showerhead, others are continuously added via the water supply.

His research showed, however, that whereas Mycobacterium avium may be present at levels of 0.1-1% in the water coming into the shower, it may make up to 70-80% of the biofilm in the showerhead itself.

What about chlorine in the water supply? Shouldn’t this kill bacteria?

Well, some, but not all, since Mycobacterium avium is actually fairly resistant to chlorine.

In a 2009 interview, Dr. Pace suggested that breathing in this particular bacteria could cause a “low-grade cough that persists for months,” making you feel “lousy, weak,” and leading to, perhaps, “breathing difficulties.”

Dr. Pace explained that Mycobacterium avium pulmonary disease is “very undiagnosed” and is a condition that isn’t nationally reportable by the CDC.

If you are concerned about the possibility of Mycobacterium avium, Dr. Pace suggested you might think about taking a bath rather than a shower, significantly reducing the possibility of aerosolization.

Of course, as in all matters bacterial, there are both bad guys and good.

In fact, Rob Dunn’s research will also explore the possibility that shower-delivered bacteria might actually benefit us by introducing microbes that strengthen the human immune system.

The study’s website points out that showerheads are one of the few places from which we can get exposed to lots of weird microorganisms, which can be a good thing.

Rob Dunn seems to have built a career out of exploring the wilder side of micro-life.

His past work has involved: a study of bellybutton microbial diversity, looking at the population dynamics of facial mites, and a multi-year survey of household dust.

Alongside his showerhead research, he has also recently launched a study of sourdough bread, prompting him to conflate the two into the “Showerdough Project.”

Rob Dunn suggests that one possible reason for the belief that females make better-tasting bread than men is that their hands could be colonized with lactobacilli (which are more supportive of fermentation) originating from their own vaginas.

This fascinating reflection led one online commenter to claim, “I’d eat the vagina yeast bread, but I wouldn’t want to lick a showerhead.”



Handshakes: Sharing the Love, Sharing the Microbes


But could you ever seriously fist bump your physician?

The first official world record for handshaking was set by President Theodore Roosevelt on January 1, 1907, after he shook hands with a finger-crushing 8,510 people in the White House.

One hopes these 8,510 had thoroughly washed their hands, as engaging in intimate palm-on-palm contact is a well-known cause of spreading microbes from person-to-person, a process known scientifically as transmission.

Handshakes as social greetings date back to at least 5th century BCE Greece, which we know from depictions in carved slabs from around that time.

One theory is that the custom possibly originated as a peace gesture, since it demonstrated that the hand held no weapon.

But what of the handshake’s potential for spreading bacteria between individuals?

Would an official at, say, a graduation ceremony be placed at risk when shaking hands with dozens – perhaps hundreds – of people?

As ever, there’s a study on this, coming from Johns Hopkins Bloomberg School of Public Health.

The project’s leader had heard that some officials at Johns Hopkins graduations were “sneaking squirts of hand sanitizer behind the podium,” so his team set out to swab officials’ hands after ceremonies.

Actually they found a very low prevalence of pathogens, estimating that the rate of contamination was around 100 times lower than might be expected in those who were shaking hands in a healthcare setting.

Now this, of course, is excellent news for those officiating at graduation ceremonies.

But it’s perhaps less comforting for anyone in a healthcare environment, and it brings us to two other studies that sought to investigate whether something other than a conventional handshake might be more hygienic.

In 2013, researchers at West Virginia University noted that, partly thanks to President Obama’s use of the technique, fist bumping was becoming a popular form of physical greeting.

Could a fist bump transmit less bacteria from bumper to bumper than is transferred from shaker to shaker in a more conventional greeting?

The researchers engaged two participants, both healthcare workers, to shake hands with 20 colleagues, then got them to press their palms on specially prepared agar culture plates.

After thoroughly washing their hands, they went through a similar process, only this time using fist bumps.

Fist bumping resulted in a reduction in colony-forming units of around a quarter, compared to handshaking, a phenomenon the researchers said was mainly due to smaller areas of skin coming into contact.

The next year, a team of scientists at Aberystwyth University in the UK picked up the baton, and stepped up a gear, to continue where their American predecessors had left off.

Curiously, their paper referred to fist bumps as being a “dap greeting,” a term we’d never come across before.

As it turns out, neither had the experts in the Stanford University library, but we have them to thank for digging up that the phrase “giving dap,” describing fist bumps, high-fives, and other elaborate forms of handshaking, appears to date back to black soldiers fighting in the Vietnam War in the early 1970s.

Some suggest that “dap” may be an acronym for “dignity and pride,” associated with black power, but in all honesty, the jury’s out on its etymology.

Anyway, the British researchers approached the handshake vs. fist bump vs. high-five issue with commendable thoroughness, asking a participant they called a “greeting donor” to put on a sterile glove, then immerse their hand into a bucket containing a dense soup of E. coli.

On removing their hand, the glove was allowed to dry, then it was time for the greeting donor to interact with a sterile-gloved recipient.

After either shaking hands, fist bumping, or high-fiving, the recipient’s glove was checked to find out how much bacteria had been transmitted.

In fact, twice as many bacteria were transferred in a handshake than in a high-five, but a fist bump resulted in the lowest transfer of all.

You know we said they were thorough?

Well, the scientists determined the area of contact by copiously spraying a donor’s glove with acrylic paint before an interaction, in order to see how much was transferred to the recipient.

They also investigated whether the short duration of a fist bump led to less bacterial transfer, by having participants do awkward three second fist bumps.

And, yup, lengthy fist bumps do indeed transmit more bacteria.

They even looked at pressure, to see if firm handshakes are somehow “dirtier.”

Sure enough, a firm handshake does indeed increase the amount of bacteria transferred.

We really can’t leave the subject of handshakes without reporting briefly on an utterly riveting 2015 study from Israel, in which scientists covertly observed 271 participants after they’d met a researcher who greeted them either with or without a handshake.

It may sound hard to believe, but having first observed that we humans sniff our hands a lot, generally without realising it, the research showed that this behavior increases significantly after a handshake.

What’s more, there’s a remarkable gender difference.

After handshakes within gender (male-to-male, or female-to-female) sniffing of the right-hand – the one that did the shaking – increased by 100%.

But handshakes across gender led to a 100% increase in sniffing of the non-shaking hand.

While it’s unclear why this might happen, the researchers hypothesized overall that some kind of subliminal social “chemosignaling” is going on.

Rather like animals sniffing one another, humans may be investigating others – or checking in on themselves – after a handshaking encounter.

It’s always fun to research and write these newsletters, and we’re always happy to hear that people enjoy reading them, too.


(Well, perhaps a fist bump.)