Friday, April 19, 2024

The Forensics of Pooh; the truth is in there.

Good mobility is essential to good motility. I.e. keep walking for a healthy bowel.
That's just a clumsy way of explaining why these pictures are on a blog that has nothing to do with them.
They are of a walk I took at ten o'clock on the morning of the 18th of April. The weather forecasters say that we are going to have 28 days of rain in April so I took the opperchancity of stealing this dryish thirty minutes to take some snaps.

Spring in Scotland. It's rather soggy.

 Compared to what is going on elsewhere in the world, we are fortunate.

So here is the blog. Any pictures of the subject of the actual blog might be ....unpalatable.


A very clever chappie called Lawrence David has been studying the human microbiome. He was chatting one day to an ecologist who was studying diets of large African herbivores by looking at their pooh. As well as having tons of excreta at his fingertips so to speak, the ecologist also had a huge amount of  precise and well researched data/ statistics. The precision of the results of his research made David rather envious. How did the ecologist get that degree of data without watching everything the animals ate?

By examining their pooh obviously. Or to be more specific, by sequencing the DNA of matter present in the ‘animal scat’ picked up from the savanna.

Could that work with humans?

There has been a few murders solved by examining the DNA in the pooh of pigs suspected of consuming the body of a victim but this research is talking about the DNA in pooh for the welfare of the live owner.

The MIE bloggers, as they read this, might have all sorts gurgling through their intestines (Is that the first time that sentence has been written in a blog?)

I think that three of us, maybe four, will have the DNA of plant materials only, maybe a dozen or so plants at any given time. Others might have the DNA of the various animals they have consumed during the past 24 hours. While the average John will have the DNA of around 12 species of plant, some hugely healthy vegivores may have up to forty types of DNA meandering through the gut.

The analysis of DNA in human faeces seems an obvious way to get some traction on the links between diet and health, digestion and digestives issues like IBS.

With the exception of vitamins, minerals and salts, everything we eat comes from something that once lived, and things that live all have genomes with coded DNA, and the majority of that DNA goes undigested.

From looking at the sequencing of the DNA in the output, then analysing that for patterns, the pattern will suggests the diet. The diet and the patient can then be connected to look at obesity, mal absorption syndromes, gastric irritability etc. Or the absence thereof.

Are some diets, the DNA of the diet and the DNA of the person interwoven in some way that could predict malignancy of the colon, Crohn’s disease, ulcerative colitis? The ability to lose weight or not? The ability to gain it?

Like the ability to taste coriander or to smell cyanide or to look good in a kilt,  are food allergies and intolerances DNA linked.

It has to be pointed out that mixed within the tissue being examined are the DNA of the gut cells and a massive amount belonging to the bacteria that hang around inside us, helping us to digest our lunch.

It’s often said that forensics don’t lie. And that’s true, but the way forensic evidence is interpreted is always open to interpretation. At the end of the working day, there will be trace elements of  skin cells of  15-20 of my patients somewhere about my person. That doesn’t mean I killed them, it means I treated them. If they are found dead at the bottom of somebody’s garden with my DNA on the skin of their neck… I treated them for a neck issue.


Patients do lie. They do it all the time. All physicians ask the same question more than once, often the other way round. ‘Did you do anything to hurt your back yesterday?’  ‘Oh no, had a nice day, relaxing.’

 Then two minutes later ask, ‘So were you busy at the weekend.’  ‘Oh yes, I cut the grass.’

They don’t mean to lie, they just do. They are often trying to be helpful, or just forget.  Smoking, drinking, how much exercise, what they eat, what they don’t eat. Are they sticking to their diet? Celiacs having a wee bit of toast?

David makes the good point that those patients most at risk from failure of nutrition- the very young, the very old, the very ill, those with cognitive issues - are the ones who cannot keep an accurate food diary. And DNA analysis of their pooh can help to rebalance any issues prescriptively.

It dawned on me while writing this that all this – the collection of pooh -  is normal to me, and to most Scottish people. I’m not sure about England. We have to do a pooh test every two years once over the age of 50.

A wee pack arrives at the house. You collect your pooh BEFORE it hits the water ( can I just point out that you do need half decent spinal mechanics for this- or a very close friend  - or cling film ), then you take a sample with the wee spoon provided, smear that onto the first sample pad and seal it and date it. Then 48 hours later you do all that again and then poop, sorry, pop it in the post.

The samples are then analysed for blood and evidence of any malignancies. Then a report comes back to you, calling you in for retest, or saying you have the all clear.

So basically, your pooh can say a lot about you.




  1. I think my time as a pharmacist might come to an end when customers claim to have a particular ailment and request I analyse their stool sample to check (only they're constipated and I'll need to fetch the sample myself).

    I took that too far, didn't I?

  2. To quote renown philosopher Forrest Gump, "Shit Happens," not to be confused with his equivalently famed observation that "Life is like a box of chocolates."

  3. It makes sense to me that doctors would do DNA analyses of human feces to find out about all kinds of health problems. I assume a lot of this work is already being done, isn't it?