10% Human: How Your Body’s Microbes Hold the Key to Health and Happiness. Alanna Collen
as if they are germs that need to be attacked and removed. It hasn’t always been this way. In the 1930s, asthma was rare, affecting perhaps one child in every school. By the 1980s, it had shot up, and one child in every class was affected. In the last decade or so, the rise has levelled off, but it has left a quarter of children with asthma. The same goes for other allergies: peanut allergies, for instance, trebled in just ten years at the end of the last century, and then doubled again in the next five years. Now we have nut-free zones in schools and workplaces. Eczema and hay fever too were once rare and are now a fact of life.
This is not normal.
What about autoimmune diseases? Your sister-in-law’s insulin habit is common enough, with type 1 diabetes affecting, as it does, about 4 in every 1,000 people. Most people have heard of the multiple sclerosis (or MS) that’s destroyed your wife’s aunt’s nerves. And then there’s rheumatoid arthritis wrecking joints, coeliac disease attacking the gut, myositis shredding muscle fibres, lupus pulling apart cells at their core, and about eighty other such conditions. As with allergies, the immune system has gone rogue, attacking not just the germs that bring disease, but the body’s own cells. You might be surprised to learn that among them, autoimmune diseases affect nearly 10 per cent of the population in the developed world.
Type 1 diabetes (T1D) makes for a great example, because it is an unmistakable condition, so records are relatively reliable. ‘Type 1’ is the version of diabetes that usually strikes early, often in the teenage years, attacking the cells of the pancreas, and completely preventing the production of the hormone insulin. (In type 2 diabetes, insulin is produced, but the body has grown less sensitive to it, so it doesn’t work as well.) Without insulin, any glucose in the blood – whether that’s from the simple sugars in sweets and desserts or from the carbohydrates in pasta and bread – cannot be converted and stored. It builds up and quickly becomes toxic, bringing with it a raging thirst and constant need to urinate for the unfortunate teenager. The patient wastes away, and weeks or months later, death follows, often from kidney failure. That is, unless insulin is injected. Pretty serious, then.
Fortunately, compared to most conditions, it’s straightforward to diagnose, and always has been. These days, a quick check of the amount of glucose in the blood after fasting usually gives it away, but even 100 years ago diabetes could be detected by a willing doctor. I say willing, because the test for it involved tasting the patient’s urine. A sweetness within the tang indicated that there was so much glucose in the blood that it had been forced out into the urine by the kidneys. Though undoubtedly more cases were missed in the past than now, and many would have gone unrecorded, our understanding of the prevalence of type 1 diabetes over time is a reliable indicator of the changing status of autoimmune diseases.
About 1 in 250 people in the West are stuck playing the role of their own pancreas, calculating how much insulin they need and then injecting it, to store away the glucose they have consumed. What’s extraordinary is that this high prevalence is new: type 1 diabetes was almost non-existent in the nineteenth century. Hospital records for Massachusetts General Hospital in the US, kept over seventy-five years until 1898, log only twenty-one cases of diabetes diagnosed in childhood, out of nearly 500,000 patients. It’s not a case of missed diagnosis, either – that urine-taste test, the rapid weight loss and the inevitable fatal outcome made the disease easy to recognise even back then.
Once formal records had been set up just before the Second World War, the prevalence of type 1 diabetes could be tracked. Around 1 or 2 children in every 5,000 were affected in the US, UK and Scandinavia. The war itself altered nothing, but not long afterwards, something changed, and cases began to rise. By 1973, diabetes was six or seven times as common as it had been in the Thirties. In the Eighties, the rise levelled off at its current figure of about 1 in 250.
The rise in diabetes is matched by rises in other autoimmune conditions. Multiple sclerosis destroyed the nervous systems of twice as many people at the turn of the millennium as it did two decades previously. Coeliac disease, in which the presence of wheat prompts the body to attack the cells of the intestine, is a startling thirty or forty times as common now as it was in the 1950s. Lupus, inflammatory bowel disease and rheumatoid arthritis too have been on the rise.
This is not normal.
What about our collective battle with excess weight? Odds are I’m right in my flippant assumption that you struggle with your weight, as well over half of us in the Western world are either overweight or obese. It’s astonishing to think that being a healthy weight puts you in the minority now. Being fat is so typical that old shop mannequins have been replaced by larger versions, and television shows turn weight loss into a game. These changes are perhaps to be expected: statistically speaking, being overweight is the reality for most people.
But it didn’t use to be. To us now, looking back at black and white photographs of the skinny young men and women of the Thirties and Forties enjoying a spell of hot weather in shorts and swimwear, these healthy people appear emaciated, with prominent ribs and lean bellies. But they are not – they are simply not carrying our modern baggage. At the start of the twentieth century, human body weights were uniform enough that few thought to keep records. But, prompted by a sudden rise in weight gain in the 1950s at the epicentre of the obesity epidemic – America – the government began keeping track. In the first national survey in the early 1960s, 13 per cent of adults were already obese. That is, they had a Body Mass Index (weight in kilograms divided by height in metres squared) of over 30. A further 30 per cent were overweight (a BMI between 25 and 30).
By 1999, the proportion of obese American adults had more than doubled to 30 per cent, and many previously healthy adults had piled on the pounds, keeping the overweight category at a plump 34 per cent. That’s a total of 64 per cent overweight or obese. Trends in the UK followed the same pattern, with a bit of a lag: in 1966, just 1.5 per cent of the adult population were obese and 11 per cent were overweight. By 1999, 24 per cent were obese and 43 per cent overweight – that’s 67 per cent of people now heavier than they should be. Obesity is not just about excess weight, either. It can lead to type 2 diabetes, heart disease and even some cancers, all of which are increasingly common.
You don’t need me to tell you, this is not normal.
Tummy troubles too are on the rise. Your cousin may be awkward for trying out a gluten-free diet, but she’s possibly not the only one at the table who suffers from irritable bowel syndrome, which affects up to 15 per cent of people. The name implies a similar level of discomfort to a midge bite, and belies the ruinous impact of the condition on the quality of life of its sufferers. Proximity to a toilet takes priority over more meaningful pursuits for most sufferers, and a near-absence of need for one makes pursuit of anything but colonic relief worthless for the remaining patients. Inflammatory bowel diseases like Crohn’s disease and ulcerative colitis too are on the rise, leaving the worst affected with a bowel so damaged it has to be replaced by a colostomy bag outside the body.
This is definitely not normal.
And finally we come to mental health conditions. Your dentist’s autistic son has more company than ever before, as 1 in 68 children (but 1 in every 42 boys) are on the autistic spectrum. Back in the early 1940s autism was so rare it hadn’t even been given a name. Even by the time records began in 2000, it was less than half as common as it is now. You’d be right in thinking that at least some of these extra cases are due to increasing awareness and perhaps some over-diagnosis, but most experts agree that the rise in autism prevalence is genuine – something has changed. Attention deficit disorders, Tourette’s syndrome and obsessive–compulsive disorder are all also on the rise. Depression and anxiety disorders too.
This increase in mental suffering is not normal.
Except these conditions are now so very ‘normal’, you might not even have realised that they are new illnesses, rarely encountered by our great-grandparents and those before them. Even doctors are often unaware of the histories of the conditions they treat, having received their medical training only in the context of today’s doctors’ experiences. As with the rise in cases of appendicitis, a change forgotten by today’s medics, what matters most to front-line carers is the patients in their charge and the treatments available to them. Understanding the provenance of illness