Читать книгу The Way We Eat Now - Би Уилсон - Страница 10

The light is fading on a cold winter’s day. I am sitting in a café at the top of the Cambridge University graduate students’ union with Fumiaki Imamura, a 38-year-old scientist. He drinks black coffee; I drink English Breakfast tea. Imamura, who has a Beatles haircut and a bright purple tie, is originally from Tokyo but has spent the past fifteen years in the West, studying the links between diet and health. ‘There are so many myths about food,’ Imamura says. One of the myths he refers to is the notion that there is such a thing as a perfectly healthy diet.

Every single human community across the globe eats a mixture of the ‘healthy’ and the ‘unhealthy’, but the salient question is where the balance falls. Imamura’s research shows that most countries in the world are currently eating more healthy food than we ever did; but also more unhealthy food. Many of us have a split personality when it comes to food, but then this is hardly surprising given how schizophrenic our food supply has become. We have access to more fresh fruit nowadays than we ever did; plus more sugar-sweetened cereals and French fries.

Imamura is a nutritional epidemiologist, meaning that he studies outlines of diet across whole populations to arrive at a more accurate account of how food and health are related. He works in the MRC Epidemiology Unit on the Cambridge Biomedical Campus. Imamura is one player in a much larger research team which straddles multiple universities in the United States and Europe. The overall project is based at Tufts University in Boston and is led by Professor Dariush Mozaffarian, one of the leading scholars currently using big data to measure nutrition in countries worldwide.

In 2015, Imamura was the lead author on a paper in medical journal The Lancet which caused a stir in the world of nutrition science. This team of epidemiologists have been seeking to map the healthiness, or otherwise, of how people eat across the entire world, and how this changed in the twenty years between 1990 and 2010.⁹

At this point, you might ask, what counts as a good quality diet? Some would define healthy food in positive terms: how many vegetables and portions of oily fish a person eats. Others define it more negatively, judging it by an absence of sugary drinks and junk food. Clearly, these are two very different ways of looking at the question. Most research on diet and health has lumped the two together, assuming that a high intake of ‘healthy’ fish will automatically go along with a low intake of ‘unhealthy’ salt, for example. But, alas, human beings are inconsistent creatures.

The Japanese, who are generally considered to eat an outstandingly ‘healthy’ diet as rich nations go, consume large amounts of both fish and salt: the one ‘healthy’ and the other ‘unhealthy’. They consume much refined polished white rice (‘unhealthy’) along with copious amounts of dark green vegetables (‘healthy’). Imamura himself still eats a diet centred on vegetables and fish, he tells me, but also a lot of salt in the form of soy sauce, even though as an epidemiologist he is aware that high sodium intake has been linked in numerous studies to high blood pressure. But he is conscious that no population in the world eats exactly the combination of healthy foods that nutritionists might recommend.

There have been many attempts to measure the healthiness of the world’s diet in the past but most studies have treated human eaters as more rational than 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 items and high in healthy ones. If you want to find the people who eat the most wholegrains, you will either have to look to the affluent Nordic countries where they still eat a lot of rye bread or to the poor countries of southern sub-Saharan Africa, where a range of nourishing grains such as sorghum, maize, millet and teff are made into healthy main dishes usually accompanied by some kind of stew, soup or relish. Sub-Saharan Africa also does very well on consumption of beans, pulses and vegetables. The average Zimbabwean eats 493.1 grams of vegetables a day, compared with just 65.1 grams for the average person in Switzerland.¹³

It was Imamura’s conclusion about the high quality of African diets that ruffled feathers in the world of public health. What about African hunger and scarcity? Zimbabweans may eat more vegetables than the Swiss, but there is more to health than vegetables, given that life expectancy in Zimbabwe in 2015 was just fifty-nine years of age compared with eighty-three for the average Swiss person. Some scientists argue that the low score for unhealthy foods in some African and Asian countries is actually a sign of diets that are ‘poor’ in various ways. If the people of Cameroon consume low amounts of sugar and processed meat, it is partly because they are consuming low amounts of food all round.¹⁴

Imamura does not deny, he tells me, that the quantity of food available is very low in some of the African countries, but adds, ‘That’s not the point of our study. We were looking at quality.’ His paper was predicated on the assumption that everyone in the world was consuming 2,000 calories a day. Imamura was well aware that is far from the case in sub-Saharan Africa, where the prevalence of malnourishment is around 24 per cent according to the Food and Agriculture Organisation. But he and his colleagues wanted to isolate the question of food quality from that of quantity. Traditional public health nutrition, he observes, was so fixated on the question of hunger that it paid too much attention to the quantity of food people had access to without considering whether the food itself was beneficial for human health.¹⁵

Africa’s hunger can easily blind us to the sheer quality and variety of food that people enjoy in much of the continent. The findings of Imamura’s paper came as no surprise to Graeme Arendse, a South African journalist at the Chimurenga Chronic, a magazine celebrating pan-African culture. In 2017 Arendse helped put together a special food issue of the magazine which challenged the Western idea that African food was all about deprivation and suffering. On a sunny winter’s day, sitting in his offices in Cape Town above the pan-African market in the city centre, Arendse tells me that ‘this story of scarcity is not true’. Arendse sees traditional African food as deeply diverse, with much of it very healthy. A short walk from his office in Cape Town, Arendse can pick up a takeaway of fish and brown rice at a Malian place where he likes to go. Other days, when the mood hits, he goes to a different café to buy a bowl of Nigerian egusi soup made from melon seeds with seafood and bitter greens, for the same price as a fast food meal from McDonald’s.

Arendse worries that unless traditional African cuisine with its soups and stews of many kinds is celebrated more, it will lose out even more to the fast foods and convenience foods that he notices becoming so popular now in South Africa. On the bus into work, in just the past couple of years, he has started to see some commuters breakfasting on crisps and cans of cola. ‘I never saw that in the past.’

Dietary patterns are getting rapidly worse in much of Africa, including South Africa. In recent years, monied South Africans have abandoned the old dinners of mealy maize and have started to drink bottles of sparkling mineral water and to eat salads of roasted vegetables and feta cheese, and, yes, many kinds of avocado toast. But there has also been a colossal rise in the consumption of packaged snack foods and sugary drinks. The balance of what South Africans eat is tipping away from the old vegetables and stews of the rest of sub-Saharan Africa and towards a Westernised diet of fried chicken and burgers and oversized portions of pasta.¹⁶

‘These young people have stretched their stomachs,’ observed an old black South African in 2016, startled by the way that children suddenly expected to eat fried foods and meat every day. Middle-income countries such as South Africa have experienced the full fairy tale and the full horror story of food at the same time. Rates of both under-nutrition and over-nutrition in South Africa exceeded 30 per cent of the population as of 2016. In the old days, South Africans ate many wild fruits and breakfasted on a thick maize or sorghum porridge, seasoned to taste with a few drops of vinegar. Now, breakfast is more likely to be nutrient-poor white industrial bread with margarine or jam. With escalating sugar consumption, tooth decay is rising in South Africa at an alarming rate.¹⁷

Eating in South Africa, a parched land with relatively poor soil quality, has never been ‘heaven on earth’, as South African dietitian Mpho Tshukudu has written. There is no golden age of food to return to. But nor have South Africans ever had to face food dilemmas quite like the ones they face today on a daily basis. One mother in her forties who came to Tshukudu’s clinic recalled that as a child growing up in a rural village, she walked for miles and ate home-cooked foods every day, always with a vegetable or some kind of legume. She knew no one who was obese and never needed to visit a doctor. But now, this woman lived in the city with her husband and three children and they all ate a lot of takeaway food and were frequently unwell. Her nine-year-old daughter was already so big that, to her distress, she had to buy her clothes in the grown-up section of the store.¹⁸

In some ways, South Africa’s new unhealthy pattern of eating is distinctive to the country itself, and to the injustice of the apartheid years. During apartheid, the state controlled who moved to towns and who stayed in the country and no black farmers were allowed to own land outside the ‘homelands’. Adults living in black townships often had long commutes to jobs in the white cities which left less time for cooking than in the past and as a result, some of the old traditional dishes died out.

But the most extreme and sudden changes to South African eating happened after the end of apartheid in the mid-1990s, during and after Nelson Mandela’s presidency, when thousands of black South Africans were lifted out of poverty for the first time. People were free to move to the cities; and they did. By many metrics, life got better and easier, but much of what people were eating now was less healthy than it had been before. As a newly open economy, the country was flooded with fast food and processed food from both home and abroad. From 2005 to 2010, the sales of processed snack bars in South Africa increased by more than 40 per cent.¹⁹

New freedom and city living; new snacks and abundance; new obesity and type 2 diabetes: the patterns of both eating and health have shifted fast in South Africa since the 1990s. The speed at which diets are changing here is vertiginous, yet the pattern is a familiar one. It is almost as if South Africa – along with so many other countries in the world – is following a script for eating set by America fifty or so years ago.