First person accounts of fecal transplants – performed by the recipient with a turkey baster, no less – are not the everyday fare of much science writing. But that’s what the Human Food Project's Jeff Leach did during a research project in Tanzania. His attention grabbing first-person narrative bookends what is actually a fascinating discussion on the changing nature of gut bacteria in many Western societies.

Is the highly processed diets many in the West now eat adversely affecting the varied internal ecosystem? Might it be antibiotics? Are increased allergies the results of changing gut bacteria? Is there a connection to weight? Mr Leach writes that "scientists know very little about the connection between disease and the potential microbial culprits (these are early days). Science is hard and the human gut is a vast and diverse ecosystem."

The Human Food Project studies modern human diseases by studying the microbes that live in us now and those which may have decades or centuries ago. Leach, with a number of colleagues, spent more than a year studying the last hunter forager group in Tanzania – the Hadza – who still eat a diet a man from several thousand years ago might recognize. Their diet is very high in fiber and meat is eaten in only one of the two seasons, but is diverse and usually binged on when more available in the dry season (zebra, dik dik and monkey are a few of the seasonal menu options). Such research is not to argue for the superiority of one kind of diet – such as the caveman or Paleo diet espoused by some in the West – but rather to see the differences in gut bacteria in a hunter gatherer group of people. Also, to see how large seasonal variations in diet may change things.

Jeff Leach's first-person narrative bookends a fascinating discussion on the changing nature of gut bacteria in many Western societies

Leach's team took some 2,000 human and environmental samples in order to better understand the tribe’s microbial makeup. The official study is called The Effect of Seasonality and Transculturation on the Human Microbiome: a Pilot Study in Tanzania.

Laudable and possibly very important as this globe-spanning work is, where does Mr Leach’s self-administered fecal implant (stool supplied to him by an amenable Hadza man who had received a clean bill of health) come in? Just as more attention is being paid to the ecology of the human gut so too are ways to alter it, which go beyond fancy supermarket yoghurts.

Fecal transplants (they are temporary things; Mr Leach managed only 16 hours) between the healthy to the sick already occur in order to combat serious gut infections. They are not considered a way out or alternative therapy and can treat irritable bowel syndrome, colitis and constipation. There are some doctors who've found a more palatable way to administer the same bacteria, via a "Russian-doll" of a tablet containing bacteria gathered from healthy human feces. Most commonly the problem is a preponderance of the bacteria Clostridium difficile or C.diff (which for the record, Mr Leach does not have). According to the CDC C.diff infections can kill 14,000 people in the United States each year. They do not always respond to antibiotics and in some cases may occur after antibiotic bombardment has killed off harmless bacteria within the gut in the course of other, routine treatment. It should be noted Mr Leach's DIY transplant is not advised by medical professionals, as a rule.

In this case it was hoped there might be an effect upon his own microbial system. He also wondered if his daughter’s diabetes was not a result of an over-medicated world that was leaving many open to serious diseases. Leach does not, obviously, believe his fecal transplant will lead him on a path to cure his daughter's diabetes. Rather, he wants to know why she has it. He is worth quoting at length (though the engaging piece is very worth reading in its entirety anyway): "Was it because she was born via c-section, and thus skipped the time-honored seeding of microbes from her mothers birth canal? Was it because she was not breast fed for 2+ years like her ancestors? Was it some medication or the hyper-sterile environment that kids now grow up in the US? Is it because she had a lower diversity of gut microbiota than the ancestors who came before her – that is, is she a casualty of unintended consequences of the Anthropocene we all now live in?"

As Leach notes, there is now far greater interest not simply in what we are putting into our bodies but what is already living in there.

The many diseases, autoimmune deficiencies and allergies people in the West seem to suffer from these days are often blamed on more sterile environments. But whereas once understanding was limited to a preponderance of too-clean kitchens versus a lack of children still being allowed to drink from the dog's bowl, now understanding has progressed to the whole gut ecosystem and ten thousand years of change from hunter-gatherers to agricultural settlements through to filthy, overcrowded cities and now hyper-hygienic environments.

Though ostensibly warned against such a thing and against performing it himself (being beside a lake at sunset may have allayed any natural disgust he felt, but you get the sense from his writing that he is not a squeamish man), the colleagues and peers he quizzed were also fascinated to see the results. Having only posted about his experience at the end of September there are no real results for him to report yet. In November his Hadza donor will be able to supply a wet season sample for him to road test also. No doubt we will be updated then.

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