The Way We Eat Now. Би Уилсон

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СКАЧАТЬ we actually are. Previous studies have summed together high consumption of healthy foods and low consumption of unhealthy foods. What made Imamura’s paper so innovative – and so much closer to the way we actually behave around food – was that he and his fellow researchers studied healthy and unhealthy foods in two parallel datasets.

      Imamura and his colleagues came up with a list of ten ‘healthy’ items: fruits, vegetables, fish, beans and legumes, nuts and seeds, wholegrains, milk, total polyunsaturated fatty acids (the kind of fat found in seed oils such as sunflower), plant omega 3s and dietary fibre. They created a separate list of ‘unhealthy’ items: sugary beverages, unprocessed red meats, processed meats, saturated fat, trans fat, cholesterol and sodium. (Imamura knows that some would quibble with the items on these lists. There is an ongoing debate among nutrition scientists about the healthiness or otherwise of saturated fats versus unsaturated fats. It looks as though the key question with saturated fat, as with other nutrients, is not whether it is unhealthy in absolute terms, but what you choose to eat instead of it. There is evidence that replacing saturated fats with processed carbohydrates can be harmful for heart health, whereas replacing it with olive oil or walnuts may have benefits.¹⁰ But based on everything that the epidemiologists currently knew about patterns of diet and health outcomes, these lists were the best they could do.) The researchers then tried to map a pattern of how much of these healthy and unhealthy foods are eaten in any given country.

      ‘We don’t know very much about what people consume, actually,’ Imamura tells me, disarmingly, sipping his black coffee. ‘Assessment of diet is very difficult.’ Almost all the data we have on what people eat is based on market figures: what commodities come into the country, or how many packets of an item people buy in any given year. This data on supply and production is used as a proxy for what people actually eat. It is useful for mapping big changes in our diets over time – the rise of salmon and the fall of herring, say. Often, food supply data reveals big truths about what we eat that are invisible to us in the daily bustle of shopping and cooking. Much of what I’ll tell you about food in this book will come from market data because often it’s the only hard data available.

      But this kind of market data has flaws: for one thing, it offers only a national average, and for another, it does not tell you what happens to the food after it enters the home. Did the consumer steam that bag of green beans and eat them with grilled sardines? Or leave it to rot at the back of the fridge?

      Another method of measuring diets is to ask people what they eat, whether over a 24-hour period or in a seven-day diary. Imamura tells me he much prefers survey data to market data because it gives a more detailed picture of how consumers actually behave around food. The snag is that one of the ways we behave around food is that we lie about it: No, I never bought and ate those extra-cheesy nachos. Yes, I eat five fruits and vegetables a day, every day. We also forget things, like that Snickers bar we devoured in haste between meetings.

      One way to get around this problem of accuracy is to measure biomarkers in the human body itself, like forensic scientists analysing a corpse. In recent years, epidemiologists have started searching for traces of our diets in blood serum, hair samples and even toenail clippings (toes are used instead of fingers because they are less exposed to outside environmental contamination). Toenail clippings are apparently the best way to measure levels of the mineral selenium in the body – a detail nutrition researchers are interested in, since low selenium correlates with type 2 diabetes and childhood obesity.

      The most versatile and commonly used biomarker to determine dietary intake is urine. Unlike toenails, which take weeks to grow back, urine is – how to put this delicately? – endlessly renewable, and it reveals traces of more different foods than any other measure. We haven’t quite reached the point yet where a sample of your urine could tell a researcher that you ate spinach gnocchi for lunch and pumpkin risotto for dinner, but that day may not be far off. In the meantime, urine has most often been used to measure how much salt we eat. Imamura and his colleagues looked at 142 surveys that measured sodium levels in urine, providing data on salt consumption for the majority of adult humans on the planet.¹¹

      At the time of writing, Imamura’s study is the most complete snapshot we have of diet quality on a truly global scale as it relates to patterns of ill health. In all, the researchers managed to find data to cover 88.7 per cent of the adult population of the whole world. From this, they built up a picture of what we eat from two different angles: on the one hand, how much healthy food countries eat and on the other hand, how much unhealthy food.

      A person may enjoy eating a slice of fresh melon but also enjoy munching on greasy fried onion rings. Countries, too, have contradictory tastes. Since 1990, the planet’s consumption of ‘healthy’ items has undoubtedly been growing, but this does not mean that people necessarily have a healthy pattern of eating. Take fruit. Since 1990, world vegetable consumption has remained static but the world’s fruit intake seems to have gone up by an average of 5.3 grams per person per day. For people who can afford to buy it, fresh fruit, from grapes to watermelon, has become one of the world’s favourite snacks. Fruit is expensive and it’s one of the first things parents buy as a treat for their children when they start to have disposable income. The rise of fruit gives credence to the fairy story about modern food (setting aside the fact that modern fruit is often not as nutritious as fruit used to be). Out of 187 countries, all but twenty or so have increased their intake of healthy foods, especially foods such as fruit and unsalted nuts which are eaten between meals.¹²

      But Imamura’s paper also supports the food horror story. The data clearly shows that diets high in sugary drinks, trans fats and processed meats became much more common in the world between 1990 and 2010. In 2010, around half the countries in the world were eating a diet higher in unhealthy items than in 1990, often drastically higher. The prevalence of unhealthy items in our diets is increasing more rapidly than our consumption of healthy foods. But it is not increasing everywhere to the same extent.

      The biggest surprise to come out of the data was that the highest-quality overall diets in the world are mostly to be found not in rich countries but in the continent of Africa, mostly in the less developed sub-Saharan regions. The ten countries with the healthiest diet patterns, listed in order with the healthiest first, came out as:

      Chad

      Mali

      Cameroon

      Guyana

      Tunisia

      Sierra Leone

      Laos

      Nigeria

      Guatemala

      French Guiana

      Meanwhile, the ten countries with the least healthy diet patterns, listed in order from the bottom up, were:

      Armenia

      Hungary

      Belgium

      USA

      Russia

      Iceland

      Latvia

      Brazil

      Colombia

      Australia

      The idea that healthy diets can only be attained by rich countries is one of the food myths, Imamura says. He found that the populations of Sierra Leone, Mali and Chad have diets that are closer to what is specified in health guidelines than those of Germany or Russia. Diets in sub-Saharan Africa are unusually low in unhealthy СКАЧАТЬ