Something good to chew on, for a change
In his new book, Mike Gibney aims to ‘challenge food controversies’, sprinkling a large pinch of salt over the claims of food fearmongers.
Given much of the popular discussion about food, it would be easy to despair that we face a future where half the world’s people starve to death while the other half drown in their own fat. The words ‘new food research’ in a news report are often just the lead into another sorry tale about how some aspect of what we eat is going to kill us or how some specific food will provide ‘miracle’ protection against the chronic illnesses of our age.
Professor Mike Gibney’s new book, Something to Chew On, is a welcome step back from all this noise, offering an expert take on many of these claims. Gibney is director of the Institute of Food and Health at University College Dublin and has served on many national and international advisory committees.
He usefully offers some historical perspective on the idea that there was some ‘golden age’ of food in the past and that everything has gone to hell in a handcart since. He contrasts ‘today’s highly regulated food supply to bygone eras of food shortage, more erratic food security, widespread food adulteration, utterly unregulated food control and a diet that was based on a narrow range of foods so that nutritional deficiencies were very common, contributing to poor post-natal survival and poor growth’.
He points to two major changes that have benefited humanity over the past century or so. One was a major investment in agricultural research and production, such that food is now produced far more efficiently than ever before. The other was in nutrition research, so that we have a better – if still imperfect – understanding of what we should eat.
Yet there has been a reaction against these important progressive trends. There is fear that the new science applied to agriculture and nutrition is unnatural. Gibney offers a factual rebuttal of some of these fears.
Take pesticides, for example. Many people are prepared to pay through the nose to buy organic food which is free of artificial pesticides. But as Gibney points out, those people are actually consuming a far greater weight in natural, plant-produced pesticides that are potentially every bit as cancer-inducing as modern chemicals. ‘Nature abounds with chemicals which, while beautifully natural, are nevertheless risk-laden’, he says, from the deadly poison ricin, found in castor beans, to substances in fava beans that induce a lethal form of anaemia in some susceptible people. The key is in the dose: for both natural compounds and their highly regulated artificial counterparts, the amounts that we actually eat are too small to represent any threat to health.
Indeed, Gibney goes on to make mincemeat of all of the claims made for organic foods: they don’t taste better than conventional crops, they offer no nutritional advantage, and, by being less productive, they are actually wasteful of land. That’s hardly environmentally friendly.
Equally irrational is the squeamishness about genetically modified crops. After all, as Gibney reminds us, many of the older crop varieties touted by greens and organic-food promoters are themselves the product of a fairly sledgehammer approach to creating mutations in seeds: irradiation. A wide variety of foods, including numerous types of rice, barley, cotton, pulses and grapefruit, are the result of ‘genomes blown to bits’ by large doses of radiation. By contrast, modern transgenic methods are much more subtle, changing specific genes. All these things are tools for plant scientists to apply to produce new, better crops and they all deserve to be embraced.
A particularly useful chapter looks at the problems of conducting nutrition research. While trying to figure out the effect of eating, or not eating, a particular kind of food on cancer or heart disease, for example, there are numerous confounding factors that get in the way of drawing robust conclusions. People lie about what they eat or simply don’t record it accurately; factors that look like cause and effect can turn out to be mere associations. Even finding enough subjects to look at the effect of diet on a relatively unusual disease, like ovarian cancer, can be very difficult.
For Gibney, the best evidence comes from intervention trials. Randomly assign people to two different groups, one eating a control diet and one eating an ‘intervention’ diet. If the two groups stick to their respective diets and there is a clear difference between the groups in relation to some particular condition, like high blood pressure, then you may feel confident that you can advise people to change their habits based on your results. The trouble is that people often don’t stick to the diets, and the studies involved may make multiple changes to what people eat at the same time, making the results tricky to interpret.
The truth is that every study’s results need to be treated with caution and there needs to be open-mindedness about other possible explanations. While it is relatively easy to see the effects of vitamin deficiency, for example, for the most part nutrition research moves forward on the basis of a lot of evidence that is unsatisfactory in one way or another. The endless stream of claims that red meat, sugar, eggs and myriad other foodstuffs cause harm should be treated with an almighty pinch of salt (as do claims about salt, for that matter).
Along the way, Gibney offers his thoughts on personalised nutrition – the possibility of creating diets specifically suited to our own DNA – and epigenetics – the idea that different elements of our DNA can be switched on or off by environmental factors in the womb or the first years of life. He also offers a Jacques Cousteau-like tour of the human gut. Did you know there are 10 times more bacteria living in our guts – 100 trillion – than there are cells in the human body? Did you know those bacteria can sometimes switch on or off changes in our bodies to suit their own needs? Gibney describes our relationship to this mass of bugs as a permanent state of ‘armed peace’, with mutual benefits to both parties: body and bacteria.
He takes a suitably critical look at the many claims made around obesity, too. It is a very real problem, he argues, but one driven more by genetics than by junk food. Looking at Ireland, he notes that if eating chips is a major problem, then the youth of Ireland are eating a lot more of them from local chip shops and cafés than from McDonald’s – and yet it’s still the big multinational that gets the blame.
With our current eating habits, he writes, some of us react by piling on large quantities of weight. For most of us, however, we simply acquire a bit of a podge or stay relatively slim. This genetic foundation to obesity means that the usual attempts to reverse the problem are largely doomed to failure. He quotes the Council on Scientific Affairs of the American Medical Association’s gloomy assessment: ‘The five-year cure rate for obesity is worse than the five-year cure rate for the worst cancer.’
If that sounds like a death sentence, it’s not. The phenomenon of the ‘fat but fit’ suggests that most of the negative consequences of weight gain can be undone by regular and surprisingly modest exercise. Citing work by Stephen Blair at the Cooper Institute in Dallas, which looked at thousands of men diagnosed with diabetes, Gibney notes: ‘Higher levels of fitness minimised the risk of death from diabetes complications irrespective of body weight. The relative risk of mortality was four or five times higher in the least-fit group, whether one looked at perfectly lean subjects or those who were overweight or even obese.’
Those genetic foundations of obesity suggest another conclusion: that the threat of an obesity ‘timebomb’, with populations continually getting fatter and fatter, has been overstated. The people with a propensity to pile on weight in the dietary environment of wealthier countries have probably already got as fat as they ever will. That seems to be borne out by a recent major study Gibney points to in his reflective final chapter. ‘Among children and adolescents’, he writes, ‘there was a clear trend towards stabilisation of obesity across continents and, while the pattern among adults was less clear-cut, stabilisation was nevertheless generally evident’.
For me, the most interesting chapter is the one on ‘Greying matters’ and the problem of malnutrition among the elderly, a topic that receives relatively little attention. Food may be cheaper and more available than ever before, but that doesn’t mean that older people eat enough. The ability to taste and enjoy food often declines with age, which may lead many people to stop eating as much as they should. That can have a major impact on their ability to recover from the inevitable health problems that accompany old age. Other problems associated with old age, particularly osteoporosis, are not so readily dealt with by dietary changes in later life. In fact, our bones achieve their greatest density in our twenties and steadily decline thereafter. The ‘kingmakers’ in the world of bone density are vitamin D and calcium. For the record, it seems that plenty of summer sunshine in your teens and twenties (though not so much that you get sunburnt) and calcium-rich foods like dairy may be a wise investment.
In such a wide-ranging tour through food issues, it is always unlikely that every chapter will be strong. I think Gibney is too trusting of the Independent Panel on Climate Change’s claims about the potential effects of climate change, for example. That said, in his introduction he emphasises the importance of a critical outlook and a willingness to be open to new evidence. As such, he offers a valuable service in trying to give a clear-headed assessment of what are the real risks and problems in relation to food, and what is just so much panicky navel-gazing.