Horizon on allergies

I have to admit to turning on last night’s Horizon programme on allergies with a bit of a sinking heart – expecting the usual perfectly worthy but not really helpful selection of talking heads. But indeed not! Led by the wonderfully avuncular but authoritative Prof. Graham Rook, they took a leisurely and in depth look at all of the very latest, and very exciting, theories and therapies focusing, primarily, on the microbiome.

For those who have not yet quite caught up with microbiota and the microbiome, they are the millions, billions, indeed trillions of bacteria which inhabit (indeed go to make up) the human body and which are concentrated in particularly massive numbers in the gut, especially the large intestine or colon.

As John Scott has been reporting to me for months, research on the microbiome – the community of bacteria that ‘share our body space’ – has gone mad. Indeed, he is, as we speak, compiling a ‘microbiome portal’ for the FoodsMatter site. Awareness of the importance of bacteria has been growing for some years (much of it focused on probiotics – the ‘good’ bacteria’) but it is only recently that researchers have really grasped the complexity of this bacterial population and started to understand the damage that going short on bacteria, or at least on some of them, may do to all body systems – including the immune system.

With reference to allergies, the theory is that the immune system had learnt, over many millennia, to live with a large and diverse population of both bacteria and of parasites. Because our forefathers lived in close proximity to the earth and to other animals, we could not avoid contact with the bacteria or the parasites that lived on them. But that was fine as the bacteria, the parasites and our immune systems had set up a good working partnership. It did the  bacteria and the parasites little good to multiply to the extent that they overwhelmed the human system – or to allow any one variety to multiply to the point where it unbalanced the system – because they would then have killed their hosts. So it was in everyone’s interests to allow the immune system to maintain a health balance.

The problem is that, with our obsession with man-made hygiene, our one sided view of parasites which were only seen as potential killers (which they are if they over grow), the popularity of Caesarean sections which mean that the infant does not come into contact with the vital population of bacteria found in the birth canal, and our industrial use of antibiotics for any and every medical condition, we have shot holes in this delicate balance. We have more or less wiped out our populations of parasites and we have seriously depleted, and in some cases actually wiped out, many of the bacteria which kept this whole system operational.

The result it would appear, is that the immune system, deprived of its day to day task of keeping the bacteria and parasites under control, has started to attack all kinds of harmless things such as foods and pollens. Meanwhile, the bacteria themselves have become so depleted that they are no longer able to perform their roles.

To illustrate this the Horizons programme took two families with highly allergic small children and examined their bacterial populations. Both children had a far lower diversity of bacteria than, for example, their parents and one child had no bacteria at all from the very important protective Bifido family. Both of the children had undergone numerous courses of antibiotics as babies.

In this context and before I had even heard about the Horizon programme John had sent me particularly interesting and relevant study that he had picked up over the weekend –  the latest research from the University of Chicago pointing to clostridia bacteria as a possible answer to food allergy. (It seems ironic that while one strain of clostridium, clostridium difficile, causes such havoc in health care facilities across the Western world, another strain could possibly solve the allergy problem!)

It would appear that the ‘clostridia cocleatum caused innate immune cells to produce high levels of interleukin-22 (IL-22), a signaling molecule known to decrease the permeability of the intestinal lining’. In other words, if you have enough of it, clostridia cocleatum will strengthen the body’s natural barriers (such as the gut wall) and prevent allergens getting into the blood stream where they cause so much damage.  While he was at it, John sent me two further studies (here and here) which suggest that Metformin, the  very popular diabetes drug appears to increase the population of clostridium cocleatum so might it also be used in the treatment of allergy?

But to return to Horizons. Having established that a reduced or unbalanced population of gut bacteria might well account for our current allergy epidemic, they did look at ways to improve the situation. Reduce the use of destructive antibiotics, discourage Caesarean section unless they are actually needed, eat foods with high bacterial populations (probiotics – although Prof Rook was a little dismissive of their efficacy – fermented foods etc), get down and dirty with animals and nature – and, possibly, have poo transplant!

Fecal microbiota transplant (FMT) – the transfer of faeces laden with healthy bacteria from the bowel of a health human to that of someone with a depleted population of bacteria in the hope that the healthy bacteria will recolonise the depleted bowl – has now been around for a while. (You can find out more here on the FoodsMatter site.) And while it is certainly sensible way to go, I was very agreeably surprised that  the BBC included it in the  programme – if only because the ‘yuck’ factor still puts off so many people who might seriously benefit from the treatment. I wonder how many complaints they got? Well, I suspect not as many as they will have got about the bacteria-free mice that they were experimenting on…

Anyhow, whatever about complaints, a really good programme – I recommend anyone to watch it on IPlayer where it will be available for the next three weeks.