The Gut Microbes of African Hunter-Gatherers

http://www.wired.com/2014/04/hadza-hunter-gatherer-gut-microbiome/

by rosser • 12 years ago

103 38 12 years ago

I am now curious to see what happens when you switch some of the Hazda group to an Italian diet, and some of the Italians to a Hazdan diet.

Florin_Andrei3• 12 years ago

That would be interesting - but, as the article says, the environment where you're living is also important.

manmal• 12 years ago

That's what they say, but I'm sceptical this is really the case. What do bacteria behind strong barriers (stomach acid, small intestine) care about external factors?

marshray• 12 years ago

That would make a great new reality TV show: Baby Swap!

daemin• 12 years ago

I'm sure if you had to survive in a different environment your gut flora and fauna would adapt to the new conditions given enough time. But unless you were forced to adapt with your survival at stake you'd just revert to eating whatever didn't cause you to become ill.

This does remind me of an Anthony Bourdain No Reservations episode where they ate with the bushmen, and they gave Tony the "best" part of the hog - the anus - unwashed, uncooked. If nothing else then eating those parts of animals with all their attached microbes would introduce them to you over time. Tony did get violently ill for a few days after filming the segment.

logfromblammo2• 12 years ago

And that reminds me of a This American Life, where the show's producers were unable to actually uncover conclusive evidence that fried hog bung was being used as imitation calamari rings, but they did find in a blind taste test that you probably wouldn't notice if it were. So I wouldn't say it's the best part of a hog, but it certainly wouldn't be as awful as you might think. When prepared appropriately, of course. Nobody wants to eat raw swine manure as a condiment.

tim3332• 12 years ago

Really you'd want to send a few Hazda to live in Rome for a couple of months and send a few Italians the other way. It would be a good experiment - I'd watch the reality TV show.

Mz8• 12 years ago

Excerpt:

In westerners, Bifidumbacterium is a microbe that many nutrition scientists thought was essential to good gut health, but it is almost completely absent in the foragers. Likewise, high counts of the bacteria Treponema have been linked to maladies like Crohn’s disease and irritable bowel syndrome. Neither of these diseases exist among the Hadza, but their guts contain abundant Treponema.

As someone who has consciously and intentionally altered my gut so it would work closer to normal, to me, this suggests a lot of questions that I do not see being asked.

1) Perhaps modern diets are the problem and the biochemistry they foster rather than microbes per se. How can that be tested?

2) What actually causes "disease"? This implies to me that germs per se are not really the explanation.

3) I would be interested in seeing some data on biochemistry and cell structure of this group as compared to people with modern/Western diets.

4) I would be interested in seeing information related to genetics and how that impacts how their bodies deal with gut flora, etc.

tokenadult2• 12 years ago

I'll upvote your set of questions and reply here rather than make my own top-level comment in this interesting thread.

1) The way to test a causal hypothesis is always, at bottom, to do a controlled experiment.[1] So we will tease out the effects of diet on different people by finding experimental volunteers, after institutional review boards approve the experiments, and subjecting the volunteers to controlled diets. This is very difficult to do, as almost all human beings eat when they feel like eating WHAT they feel like eating. Earlier human experiments on effects of diet have actually required the experiment subjects to live in the laboratory long-term, and to have every gram of everything they ate during the experiment measured exactly. Even at that, those experiments came up with few clear conclusions, perhaps because the experiments weren't lengthy enough or didn't include enough subjects for strong inferences.

2) Lots of different things cause lots of different diseases. Both poor diets and infections by microbes can cause some kinds of disease, each independently of the other. It is a fallacy of human thinking to think that there is only one true cause of disease.[2]

3) Yes, it would indeed be interesting to gather more data about biomarkers and tissues of people from more human groups, and especially so after experimental interventions as mentioned in my reply to your first question. It will take very detailed data-gathering to figure out what is going on at the causal level that makes the gut biomes different, and what the different gut biomes do.

4) Your "gut reaction" is correct that this study does not have what human geneticist Robert Plomin would call a "genetically sensitive design," such as what a study of twins[3] would have. The human behavior geneticists with whom I participate in a journal club during the school year have made me very sensitive to how much information is missed if studies of human subjects don't take into account genetic similarity and dissimilarity of the study subjects. Much more work needs to be done on this.

My comment to a friend on Facebook after I posted this same story and friends started talking about it was "One tricky thing for you and me doing 'research' on this is distinguishing short-term effects from long-term effects. My life expectancy here in the United States is already a lot longer than that of most people in the world." It may be that you and I, with the health problems we have today in the United States, are still much better off sticking with our current diets rather than emulating the diets of hunter-gatherers in Africa.

[1] http://escholarship.org/uc/item/6hb3k0nz

[2] http://www.sciencebasedmedicine.org/the-one-true-cause-of-al...

[3] http://www.hup.harvard.edu/catalog.php?isbn=9780674055469

Mz8• 12 years ago

Thank you.

You said: Lots of different things cause lots of different diseases.

Due to my genetic disorder, I am supposed to be overrun with disease and simply accept dying from it. I have been steadily getting well for the last thirteen years, which is very frequently met with incredibly dismissive feedback. (My favorite being: Thirteen years of steady forward progress is not evidence I know anything, it is mere wild coincidence. Stranger things have happened.)

My genetic disorder is known to cause the tissues to be too acid. There are multiple books about how the typical American diet is too acid. If you get certain kinds of sudden acidosis (this comes to mind: http://en.wikipedia.org/wiki/Diabetic_Ketoacidosis), they will promptly hospitalize you because it can be deadly within 72 hours. Yet, it is not standard practice to treat or even test for acidosis with my condition. Ant-acids are only prescribed for gut issues like GERD and acid reflux which can occur with my condition. Anecdotally, other people with CF report that they have fewer lung issues when on acid blockers and similar for their gut issues.

Altering my diet to make my body less acid has been one of the cornerstones of getting myself well. I have seen articles linking anti-biotic resistance and biofilms to high acidity and seen research that biofilms can be broken up and anti-biotic resistance reversed if acidity is addressed. Yet, again, this remains not a standard treatment for my condition, which kills you by fostering infections and, ultimately, antibiotic resistance in those infections.

My life expectancy is not supposed to be that high for a modern Westerner. It is supposed to be roughly mid-thirties (granted, my form of CF has an undetermined life expectancy, yet I did nearly die in my mid thirties).

Anyway, I just know of lots of different bits of information linking inflammation, acidity, infection and many of the issues typical of my disorder. So a) I would really like to see more biochemical data (like ph balance of sample tissues) in studies of this sort and b) I am ...flummoxed as to why people seem to think we do not have enough data to say, yea, verily, acidity is a primary issue we should treat for to control symptoms of various conditions. (Because there are a lot of conditions associated with my genetic disorder but not unique to it, such as early onset osteoporosis, diabetes, arthritis and on and on.)

vacri3• 12 years ago

2) A "disease" really means just that: "dis"/not (at) "ease". It's a generic catch-all for something that makes you not at ease. It can have many causes, from microbial or viral sources (eg common cold), to inorganic toxins (eg lead poisoning), to genetic abnormalities (eg psoriasis), malnutrution and bad nutrition (eg fatty arteries), even social problems are sometimes considered a disease (eg gambling addiction). While there are some things that don't fall into the catch-all term, such as damage done by physical trauma, 'disease' has a great variety of causes and does not have to be communicable.

You seem to be intentionally looking for confirmation bias, trying to find a way to place blame on 'modern'.

Mz8• 12 years ago

No, I am not looking for confirmation bias. I am wondering about something complex that we don't seem to have good language for -- or perhaps that I don't personally have good language for.

I have spent a lot of years reversing symptoms of my genetic disorder as well as reversing issues in my special needs sons. Altering my diet is a very big part of that. Humans have been around a long time. Some of the issues my sons and I have are relatively "new." I spend a lot of time wondering how much that is a product of "new" environments rather than "new" biological issues within humans themselves, if that makes any sense.

My dad was old enough to be my grandfather. He grew up on a farm, without the constant noise of modern life. When I lived with my parents during my divorce, I realized my oldest son had many things in common with my father. I had never before realized. The sensitivity to noise that is viewed as pathological and worthy of labeling as ASD or as having sensory issues is something both my parents had. They were just old, grew up in a different era, and expected the house to be kept quiet. No on acted like their preferences were a "special need" requiring a label...etc.

Sorry if that is not very clear. I wonder a lot at how much our modern "ills" are really a product of our modern lives -- of environments that did not exist until recently but which we view as something "normal" that "everyone" should be capable of coping with. It isn't looking for confirmation bias. It is wondering how much bias exists in some of the assumptions we make in how we frame certain kinds of problems.

Steuard2• 12 years ago

I don't think it's fair to say that "modern diets are the problem". The availability of modern diets is, after all, largely responsible for modern civilization (which was enabled by agriculture).

But I think it's fair to say that the many benefits of modern diets are accompanied by some serious negative side effects, and that the human microbiome has not yet had enough time to evolve into an optimal state for coping with them. (It probably doesn't help that the "modern diet" isn't at all a stable target to optimize for, either.) Perhaps in another 20,000 years, evolution would naturally shape our microbiome to eliminate things like Crohn's disease and tooth decay.

Mz8• 12 years ago

"I don't think it's fair to say that "modern diets are the problem"."

Yeah, see, I didn't say that. You edited that to mean something completely different from what I said/meant. My sentence started with "perhaps", had no italics and I went on to ask how that could be tested. So I think this is a not great comment. It feels almost slanderous to me.

That's part of my assumption. But, also, it seems to me that the modern diet has chemical impacts that are pretty well-established as promoting disease. Not that we have to eat crap, but a lot of us do, in fact, live on rather crappy food -- microwave meals, food "products", etc. I think it's complicated and that the impact of food chemistry is not well studied or taken all that seriously. People who think relatively small changes may have big impacts tend to dismissed as quacks.

alsocasey• 12 years ago

2) What actually causes "disease"? This implies to me that germs per se are not really the explanation.

IBS (and Crohn's, which is really just a type of IBD), is an immune disorder characterized by chronic, uncontrolled inflammation. All the disease's symptoms stem from this state, so the specific germs involved may or may not be all that important, the body's reaction to them is. When you get down to it, many disease states are just a consequence of regulation of inflammation failing at a critical location.

bmm6o• 12 years ago

That's essentially the defining characteristic of a "syndrome". It is predicated on the condition or symptoms and not on the underlying cause, which isn't always known. As knowledge grows, more specific diseases can be removed from the classification.

shanev• 12 years ago

This is not surprising to me at all. Pathogenic bacteria linked to diseases such as Crohn's and IBS are only pathogenic if we get them later in life. When we get these bacteria in childhood, before the age of 7, they grow symbiotically with us and help ward off disease. Check out the book An Epidemic of Absence by Moises Valesquez-Manoff [1] if you guys want to learn more about this stuff. It's a fascinating account of a man who experiments with altering his gut biome to overcome Alopecia areata (total hair loss). The book is loaded with science and references a lot of other studies dealing with the gut biome.

[1] http://www.amazon.com/Epidemic-Absence-Understanding-Allergi...

tokenadult2• 12 years ago

I would ask my friends here on Hacker News to be cautious about taking the statements in that book at face value without a lot of careful follow-up.[1] And I write that, with chagrin, as a participant here who previously submitted an opinion piece by the author to Hacker News, where it reached the front page and sparked a lot of discussion. The claims in the book are very far from settled science, and many of the anecdotes have not been independently verified or replicated.

[1] http://www.emilywillinghamphd.com/2012/08/autism-immunity-in...

coopermor• 12 years ago

There's a small public biotech company Coronado Biosciences that just announced a trial to study their drug (pig whipworms) in autism http://ir.coronadobiosciences.com/Cache/1001185864.PDF.

They have other studies in a couple different autoimmune diseases in various stages http://www.coronadobiosciences.com/research-development/pipe...

So we'll have some more data regarding this soon.

mtew• 12 years ago

I found the book straightforward about how unproven the science is, and thought it did a good job of being clear about how speculative the theories are. Were there areas where you thought the book's claims were stronger than what is warranted?

ds9• 12 years ago

Somewhat related: presence or absence of diseases in an area may influence social and political systems, according to one theory (http://www.psmag.com/navigation/health-and-behavior/bugs-lik...)

contingencies• 12 years ago

I wonder if there is any kind of feedback loop between long term gut flora makeup and taste preferences?

VeejayRampay• 12 years ago

A somewhat related and fascinating read is Dr Daniel Lieberman's "The Story of the Human Body: Evolution, Health, and Disease". He develops the concept of mismatch diseases and goes into a lot of details about evolution and diets across different eras and cultures (there's a part in the book dedicated to hunter-gatherers IIRC).

pistle• 12 years ago

Gut flora-related disease could have also exerted pressure on an insulated population leading to tolerance for elevated levels of bacteria which are observed as being related to unwanted symptoms in other populations.

It takes more than a load of crap to tell the whole story.

davidw• 12 years ago

Here's how to make a startup out of it: you could sell exclusive trips to Hollywood types to Africa to get a hunter-gatherer biome "transfusion", proclaiming the various health benefits - "slimming! rejuvinating! all natural!".

I think I'm joking, but who knows :-)

tim3332• 12 years ago

Stranger schemes have worked. Travelling to those sorts of places and eating with the locals often leads to effective and rapid weight loss thorough slightly unpleasant mechanisms. On a more serious note my sister had IBS for a couple of years and it went away completely and permanently after visiting Indonesia - presumably some gut flora transfer thing.

tragic• 12 years ago

I might show this to my mother. She is of the opinion that no disease is sufficiently severe that it cannot be cured through large quantities of probiotic yoghurt.

The Gut Microbes of African Hunter-Gatherers

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