Michael Pollan has written some of my favourite foods books and now he has a new book “Cooked” and as part of the launch has written the following article for the Daily Mail…
For more than a century we have been engaged in a war on bacteria. We deploy an arsenal of antibiotics, hand sanitisers, pasteurisation and food regulations to tackle the moulds and bacteria and so, we hope, hold off disease and death.
I grew up on that field of battle. My mother instilled in our family a deep fear of botulism, and countless other unnamed germs possibly lurking in our food.
A touch of white on a wedge of cheese was enough to condemn it.
The slightest dent in a can of food consigned it to the rubbish, no matter that the dent came from being dropped on the floor. You never know, could be botulism; better safe than sorry.
In the decades since Louis Pasteur discovered bacteria, medical research has focused mainly on their role in causing disease.
The bacteria that reside in and on our bodies were generally regarded as either harmless freeloaders, or pathogens to be defended against.
But then in the early 2000s, researchers discovered hundreds of new species of bacteria in the human gut doing all sorts of unexpected things.
To their surprise, microbiologists discovered that we are made up of 90 per cent bacteria. Nine out of every ten cells in our bodies are not human but belong to these microbial species (most of them residents of our gut).
As one scientist put it to me, we ‘stand on the verge of a paradigm shift in our understanding of health as well as our relationship to other species’.
Metaphors about it being a ‘war’ no longer made much sense.
So what exactly are the 500 or so distinct species and countless different strains of those species that make up the kilogram or so of microbes in our gut doing there?
For most of these microbes, their survival depends on our own, and so they do all sorts of things to keep their host – us – alive and well.
Perhaps their most important function is to maintain the health of the gut wall, or epithelium. In the course of a lifetime, 60 tons of food pass through the gastrointestinal tract, an exposure to the world that is fraught with risk.
It appears that much of that risk is managed, most of the time brilliantly, by the gut bugs.
Taken as a whole, the organisms in the gut constitute the largest and one of the human body’s most important organs of defence.
So why would the body enlist bacteria in all these critical functions, rather than evolve its own systems to do this work? One theory is that because microbes can evolve rapidly they can respond with much greater speed and agility to changes in the environment.
Though we’ve tended to think of bacteria as agents of destruction, they are invaluable creators as well. Gut bugs manufacture essential vitamins (including vitamin K as well as several B vitamins) and a great many other compounds scientists are only just beginning to recognise.
Some of these compounds act on the central nervous system, moderating our appetite and the mechanisms that determine how we store fat.
So might changing the composition of our gut bacteria in turn change our weight?
Possibly: the researchers have found that when they transferred bacteria from the guts of fat mice into mice with no gut bacteria, they gained nearly twice as much weight as those that received gut bacteria from skinny mice.
But under the pressures of broad-spectrum antibiotics, food pasteurisation and a modern diet, the human microbe community has probably changed more in the past 100 years than in the previous 10,000, when the shift to agriculture altered our diet and lifestyle.
Children are exposed to fewer bacteria and the theory is that their immune system isn’t then ‘trained’ to accurately distinguish between good and bad microbes, which may explain the escalating rates of allergy, asthma and autoimmune disease in the developed world.
The average child in the developed world has also received between ten and 20 courses of antibiotics before their 18th birthday, an assault on the gut bugs the implications of which researchers are just beginning to calculate.
And then there is the diet. Put in a more scientific way, the diet should include both probiotics – beneficial bacteria – and prebiotics – something good for those bacteria to eat (such as fibre). Probiotics are what you should expect to find in fermented food, such as pickled vegetables, sauerkraut, cheese, yoghurt, breads, vinegar, soy sauce and beer.
But we’ve worked hard to eliminate bacteria from the diet, by sterilising our food, and by processing it we’ve removed much of the fibre – precisely the component of greatest value to the microbes.
With the exception of yoghurt, foods that contain live bacteria have all but vanished from our plates (the bacteria in sauerkraut, ketchup, pickled vegetables etc are killed off by pasteurisation).
The Western diet, with its refined carbohydrates, highly processed foods, and dearth of fresh vegetables, preserves foods by killing bacteria and then deprives our gut bacteria of much that is good for them to ferment and grow.
‘The big problem with the Western diet,’ Stephen O’Keefe, a gastroenterologist at the University of Pittsburgh, told me, ‘is that it doesn’t feed the gut, only the upper GI [gastrointestinal tract]. All the food has been processed to be readily absorbed, leaving nothing for the lower GI.
‘But it turns out that one of the keys to health is fermentation in the large intestine.’
The lack of fibre in our diet is, in effect, starving our gut and its microbial residents.
O’Keefe and many others are convinced the myriad intestinal disorders that have become common among people eating a Western diet can be traced to this imbalance.
We have changed the human diet in such a way that it no longer feeds the whole superorganism, as it were, only our human selves. We’re eating for one, when we need to be eating for a few trillion. But intestinal problems may be the least of it.
Populations that eat a Western diet consistently develop high rates of diseases such as heart disease and stroke, obesity, cancer, and type 2 diabetes. What remains subject to debate is exactly what about this diet makes it so lethal.
Lately, some researchers are beginning to suspect the problem is to do with inflammation, something in which our gut bugs may turn out to play a crucial role.
The case for getting more live-culture foods (especially of children) is already compelling and growing more so. Consider the research that has come out in the past decade or so.
Probiotics – beneficial bacteria ingested either in fermented foods or in supplements – have been shown to calm the immune system and reduce inflammation; shorten the duration and severity of colds in children; relieve diarrhoea and irritable bowel syndrome; reduce allergic responses; stimulate the immune response; possibly reduce the risk of certain cancers; and improve the health and function of the gut.
Mysteries remain, obviously, but the case for eating live-culture foods seems strong, perhaps strongest for fermented vegetables.
For in addition to bringing large numbers of probiotic guests to the party, the vegetables themselves also supply plenty of prebiotics – nourishment for the bacteria already there.
That’s why I have been busy with my pickling, working to perfect my sauerkraut – without pasteurisation.
2013 Miles in 2013
This year I am trying to complete 2013 miles self-powered miles. My 2013 miles in 2013 challenge is in aid of the Cystic Fibrosis Trust as I have been surprised since I started fundraising for the CF Trust just how many people are unaware of this disease and so I hope my efforts will not just raise money, but also awareness of the UK’s most most common life-threatening inherited disease.
The first person to commit to sponsoring my 2013 mile challenge has committed to 1p per mile (£20.13 in total) and this got me thinking. I am hoping that as many as possible of those reading this will commit to do the same and the best thing is, if each person does this on a “pay as you go” type approach all you will need to part with is approx £2 just after each pay day. In January I completed 205.9 miles, in February I completed a further 200.9 miles, in March I completed 185.7 miles, in April I completed 192.1 miles and in May I completed 168 miles. If you can please spare £9.53 to help the Cystic Fibrosis Trust it will be greatly appreciated.
The easiest way to give your sponsorship is to visit my Just Giving page: http://www.justgiving.com/2012-AYearWithoutBeer-CF.
2013 Miles in 2013 – The rules
The rules for my 2013 miles in 2013 challenge are quite simple:
- All miles must be completely self powered (no motors, sails, etc)
- I must be able to evidence all miles, either via GPS or with a picture of any static gym equipment
To complete my 2013 miles I will be running, cycling, rowing and who knows, I might even try a few other self powered methods along the way.