Living off the fat of the land

Get mothers overeating during pregnancy and you stand to gain customers as soon as they are born.

Drink and snack manufacturers used to be vilified for making a profit out of making us fat. With the new Health and Social Care Act starting to bite, we can look at this differently. Because of the reincarnation of the National Health Service as a path to private profit, obesity can now be reclassified as a marvellous opportunity to kick-start the economy.

Those who are overweight and obese will help generate annual revenues of £10bn by 2050, according to Public Health England. Surely this makes it even more important that we understand the causes of obesity.

On 14 April, researchers gathered in Cambridge to go over what we know. The truth is not much. The bottom line is that obesity seems to be becoming programmed into human biology in the developed world. Profit-hungry health providers should be punching the air.

Cambridge University’s Stephen O’Rahilly, who gave the opening keynote speech at the meeting, calls obesity a “heritable neuro-behavioural disorder” that is “highly sensitive to environmental conditions”. As much as 70 per cent of the difference between individual levels of fatness can be attributed to heritable factors but the rapid rise in obesity and diabetes over the past couple of decades shows that it’s not all genetic. There are ways to make people fulfil their potential for fatness.

Much of it has to do with failures in the signals between the brain and the gut – the messages that tell us when we are full and how much energy we feel we have and need. We don’t know a lot about what causes the failures but the bacteria living in your gut might be able to help. A study published in March showed how a microbe transplant can help weight loss. Transplant the microbes from the stomach of a mouse that has had a gastric bypass into the stomach of a mouse that hasn’t and the second mouse will begin to lose weight. No one knows exactly why, but some think that the mouse with the bypass has an altered gut flora and the most prevalent bacteria change the signalling from gut to brain.

Some of the metabolic failures seem to get programmed in before birth. It is becoming increasingly clear that a balanced diet is crucial to the unborn child. Research has shown that mothers who eat more fat than they should in pregnancy increase the risk of their offspring having liver and pancreas damage, heightening the chances of diabetes and early-onset obesity.

Maternal nutrition can affect the child’s mind as well as its body. Poor health and nutrition in pregnancy has been linked to anxiety, depression and attention deficit/hyperactivity disorder in the child. Improved nutrition in the run-up to conception could have an enormously beneficial effect on future generations.

It’s not entirely popular, O’Rahilly concedes, to blame genetics and environmental factors for obesity: as a society, we still want to characterise the obese as lazy or lacking self-control. Research even suggests that some obese people may be suffering from a progressive neurological disorder induced by factors in their environment: the brain machinery controlling energy balance is falling apart.

Anyway, viewed from a different perspective, this programmed obesity is wonderful, guaranteeing you a client base for generations. Get mothers overeating during pregnancy and you stand to gain customers as soon as they are born. They might end up in a mental health clinic rather than the obesity clinic but a customer’s a customer, right?

Maternal nutrition can affect the child’s mind as well as its body. Photograph: Getty Images

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 29 April 2013 issue of the New Statesman, What makes us human?

Davide Restivo at Wikimedia Commons
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Scientists have finally said it: alcohol causes cancer

Enough of "linked" and "attributable": a new paper concludes that alcohol directly causes seven types of cancer.

I don't blame you if you switch off completely at the words "causes cancer". If you pay attention to certain publications, everything from sunbeds, to fish, to not getting enough sun, can all cause cancer. But this time, it's worth listening.

The journal Addiction has published a paper that makes a simple, yet startling, claim: 

"Evidence can support the judgement that alcohol causes cancer of the oropharynx [part of the throat], larynx, oesophagus, liver, colon, rectum and [female] breast"

So what's especially significant about this? 

First, scientists, unlike journalists, are very wary of the word "causes". It's hard to ever prove that one action directly led to another, rather than that both happened to occur within the same scenario. And yet Jennie Connor, author of the paper and professor in the Preventive and Social Medicine department at the University of Otago, New Zealand, has taken the leap.

Second, alcohol not only causes cancer of one kind – the evidence supports the claim that it causes cancer at seven different sites in our bodies. There was weaker evidence that it may also cause skin, prostate and pancreatic cancer, while the link between mouth cancers and alcohol consumption was the strongest. 

What did we know about alcohol and cancer before?

Many, many studies have "linked" cancer to alcohol, or argued that some cases may be "attributable" to alcohol consumption. 

This paper loooks back over a decade's worth of research into alcohol and cancer, and Connor concludes that all this evidence, taken together, proves that alcohol "increases the incidence of [cancer] in the population".

However, as Connor notes in her paper, "alcohol’s causal role is perceived to be more complex than tobacco's", partly because we still don't know exactly how alcohol causes cancer at these sites. Yet she argues that the evidence alone is enough to prove the cause, even if we don't know exactly how the "biologial mechanisms" work. 

Does this mean that drinking = cancer, then?

No. A causal link doesn't mean one thing always leads to the other. Also, cancer in these seven sites was shown to have what's called a "dose-response" relationship, which means the more you drink, the more you increase your chances of cancer.

On the bright side, scientists have also found that if you stop drinking altogether, you can reduce your chances back down again.

Are moderate drinkers off the hook?

Nope. Rather devastatingly, Connor notes that moderate drinkers bear a "considerable" portion of the cancer risk, and that targeting only heavy drinkers with alcohol risk reduction campaigns would have "limited" impact. 

What does this mean for public health? 

This is the tricky bit. In the paper, Connor points out that, given what we know about lung cancer and tobacco, the general advice is simply not to smoke. Now, a strong link proven over years of research may suggest the same about drinking, an activity society views as a bit risky but generally harmless.

Yet in 2012, it's estimated that alcohol-attributable cancers killed half a million people, which made up 5.8 per cent of cancer deaths worldwide. As we better understand the links between the two, it's possible that this proportion may turn out to be a lot higher. 

As she was doing the research, Connor commented:

"We've grown up with thinking cancer is very mysterious, we don't know what causes it and it's frightening, so to think that something as ordinary as drinking is associated with cancer I think is quite difficult."

What do we do now?

Drink less. The one semi-silver lining in the study is that the quantity of alcohol you consume has a real bearing on your risk of developing these cancers. 

On a wider scale, it looks like we need to recalibrate society's perspective on drinking. Drug campaigners have long pointed out that alcohol, while legal, is one of the most toxic and harmful drugs available  an argument that this study will bolster.

In January, England's chief medical officer Sally Davies introduced some of the strictest guidelines on alcohol consumption in the world, and later shocked a parliamentary hearing by saying that drinking could cause breast cancer.

"I would like people to take their choice knowing the issues," she told the hearing, "And do as I do when I reach for my glass of wine and think... do I want to raise my risk of breast cancer?"

Now, it's beginning to look like she was ahead of the curve. 

Barbara Speed is a technology and digital culture writer at the New Statesman and a staff writer at CityMetric.