Innholdsfortegnelse for EG09 i New Scientist - The Essential Guides

THERE has never been a greater appreciation than there is now for the importance of what we eat – not just for our physical health, but for our mental health and the health of the planet, too. Even so, with supermarkets, magazines, social media and all manner of celebrities bombarding us with advice on what to eat and how to buy sustainably, you would be forgiven for not having a clue about what should be on your weekly shopping list. The aim of this latest New Scientist Essential Guide, the ninth in the series, is to bypass fashion and faddery and give an overview of what science says about healthy nutrition and a sustainable diet. We start with the origins of the current obesity crisis and working through what is…

Our discussion about why we’re getting fatter in the previous section missed out a big, complicating factor that we’re only just getting to grips with: our genes. Subtle differences in how we respond to food, driven by our genes, may be why many of us struggle to keep to the weight we want to be. IT IS no secret that people have big differences in appetite – some eat like birds, others like horses. But only some of these differences reflect our energy needs. The driving factors for weight gain tend to get oversimplified: studies show that most people still think obesity is down to laziness and gluttony. Others tend to shrug and blame “big bones” or “bad genes”. For many people, that second point might not be too far…

FOR many people, sweet treats are the way to happiness. Doughnuts are particularly difficult to resist. Recent studies show why: treats that are high in both carbs and fats trigger a supercharged amount of activity in our brain’s reward centre that releases the “feel-good” chemical dopamine. The researchers behind this study think that we may have separate systems in the brain to evaluate fatty or carb-heavy foods. If both get activated at the same time, this tricks the brain to produce a larger amount of dopamine – and a bigger feeling of reward – than there should be based on the food’s energy content. This could be because when the human brain evolved, our hunter-gatherer ancestors ate a diet consisting mainly of plants and meat, and never encountered food that…

WHAT DOES SATURATED / UNSATURATED MEAN? The bulk of a fatty acid is a long string of carbon atoms with hydrogen atoms attached. In a saturated fatty acid, this chain does not have any carbon-carbon double bonds, meaning it has the maximum possible number of hydrogens: it is “saturated”. Unsaturated fatty acids have at least one double bond. Triglycerides containing only saturated fatty acids are also called saturated; those with one or more double-bonded acids are unsaturated. As a rule, the more unsaturated a fat, the better it is for you – though this orthodoxy is being challenged. WHAT ABOUT ANIMAL AND VEGETABLE FATS? Fats from animals tend to be saturated, while those from vegetables are usually unsaturated. But this is only a rough guide. Meat, eggs and dairy contain…

IN 1911, Polish chemist Casimir Funk made one of the most influential biomedical discoveries of all time. He learned that a disease called beriberi affected those who ate a diet of mainly white rice, but not those who ate mostly brown rice. He isolated a chemical from rice bran, showed it could prevent beriberi and called it “vitamine”. This compound, the organic molecule thiamine, now goes by the name vitamin B₁. It is one of many organic molecules that are essential nutrients the human body can’t produce in sufficient quantities and that we must obtain from food. Casimir’s breakthrough led to similar discoveries, including the compounds that prevent scurvy and rickets. In 1920, the British chemist Jack Cecil Drummond proposed dropping the “e” and using the umbrella term “vitamin”. Vitamins…

LOW-CARB diets first became popular in the 1970s through New York cardiologist Robert Atkins, who lost weight himself this way and recommended it in diet and cookery books. His advice to fill up on steaks, cream and butter, while shunning most fruit and vegetables, made him a medical pariah. Critics said people wouldn’t be able to stick to it, and if they did, it would kill them, says Eric Westman, an obesity specialist at Duke University in North Carolina, who studied under Atkins. By the early 1990s, however, randomised trials were showing that such diets are at least as good as low-fat ones for weight loss, often a little better. In one trial, people on a low-carb diet lost an average of 4.4 per cent of their body weight after…

FASTING has been part of religious practices around the world for millennia. It has slipped into the consumer mainstream over the past decade, in various forms: take the 5:2 diet, where you fast for two days a week and eat normally for the others; the 16:8, where you eat within an 8-hour window and fast for 16 hours; and alternate-day fasting. That comes on the back of animal studies that have found that organisms from single celled yeasts to rodents age more slowly and live longer when their calorie intake falls to 40 per cent of that of a group of animals eating normally. Research in people who are overweight also suggests that skipping meals could have numerous health benefits. There is growing evidence, too, that periodically going without food…

While moving towards a more plant-based diet is undoubtedly good for us, the evidence of health and environmental benefits from the recent trend towards organic food grown without artificial fertiliser and pesticide is rather less clear-cut. On the health side, it is as simple as saying that there is no convincing evidence that organic food is better for you than conventionally farmed food. On the environmental side, one huge problem is that organic farming requires far more land than conventional farming to produce the same amount of food. According to a 2017 study, going all-organic would require up to a third more land to feed the world by 2050, as opposed to 6 per cent more if we feed people conventionally. If climate impacts are high, 55 per cent more…

Whatever diet we adopt for ourselves or for the planet, here is a startling fact to bear in mind. In 2019, around 931 million tonnes of food went into the waste bins of households, retailers, restaurants and other food services – something like a sixth of all the food we produce. That is the conclusion of the 2021 Food Waste Index Report produced by the United Nations Environment Programme and UK charity WRAP, which promotes sustainability. The study looked at food waste in retail outlets, restaurants and homes by reviewing government data and academic studies across 54 countries with a mix of incomes. Most of this waste – 11 per cent of all the food produced – occurs in homes. Globally, the average person throws away 121 kilograms of food,…

IF YOU love eating a grilled burger perfected into juicy, salty, fatty heaven… then you’re probably struggling right now, painfully aware that as a population, we need to reduce how much meat we consume. Plant-based meat analogues aren’t your standard meat substitutes, such as tofu, Quorn and soya mince; nor are they the much-hyped but still experimental meats grown in the lab from stem cells. They are plant products processed to look, smell, taste and feel like meat – and they are aimed squarely at diehard meat-eaters. ↓The next section has more on lab-cultured meat San-Francisco-based firm Impossible Foods, maker of the Impossible burger, is a big player in this new market. “We’re not going to be able to just talk people into a plant-based diet,” says its chief scientist…

While obesity is a growing public health crisis in many parts of the world, hunger and malnutrition have been far from banished. Nine children die every minute because their diet lacks essential nutrients, according to humanitarian NGO Médecins Sans Frontières. In fact, malnutrition is the single greatest threat to the world’s public health, with 178 million malnourished children across the world. If we could eliminate malnutrition, we would prevent 35 per cent of child deaths globally, according to the UN children’s agency UNICEF. Food insecurity – not having enough of the right stuff to eat – obviously plays a huge part. But it seems there is more to the issue than that. One new avenue of research suggests that a person’s risk of developing severe malnutrition may come down to…

WHEN we eat something, what we experience is its flavour, a combination of taste, smell and other sensory inputs. But while the scent of food is derived from a palette of 10,000 volatile chemicals, taste is much simpler. Millennia of experience and centuries of data identified four familiar, traditional, fundamental tastes: salt, sweet, bitter and sour. These primary tastes can be combined to beautiful effect, but not broken down further. An early hint of other primary tastes came in 1908 when a Japanese scientist extracted a compound called monosodium glutamate (MSG) from seaweed. Kikunae Ikeda at Tokyo’s Imperial University considered MSG the embodiment of what he called umami, which can be translated as “delicious taste”. People often describe it as the savoury quality of meats and cheese. The following year,…

SOURCE: AMERICAN JOURNAL OF CLINICAL NUTRITION, VOL 86, P901 I MAGINE you are sitting at a table with a bag of sugar, a teaspoon and a glass of water. You open the bag and add a spoonful of sugar to the water. Then another, and another, and another, until you have added 20 teaspoons. Would you drink the water? Even the most sweet-toothed child would find it unpalatably sickly. And yet that is the amount of sugar you are likely to eat today, and every day – usually without realising it. “Sugar” refers to a large class of sweet-tasting, energy-dense carbohydrates. The simple sugars glucose, fructose and galactose, and the more complex sucrose and lactose, are the most familiar to us. Whatever form it takes, sugar has become a large…

GROUP 1: UNPROCESSED AND MINIMALLY PROCESSED FOODS Edible parts of plants, animals or fungi, such as meat, fruit or mushrooms. GROUP 2: PROCESSED CULINARY INGREDIENTS Substances including oils, butter, sugar and salt that are derived from group 1 foods through processes such as refining, grinding or drying. They aren’t normally consumed by themselves, instead being used in combination with group 1 foods. GROUP 3: PROCESSED FOODS Foods made by adding ingredients from group 2 to items from group 1. This includes cheese, canned fish, bottled vegetables and freshly made breads. GROUP 4: ULTRA - PROCESSED FOODS Foods made from base ingredients, such as lactose, oil, whey and gluten, that may have been extracted from foods but have usually undergone modern processing to create things like hydrogenated oils, hydrolysed proteins and…

Carbohydrates are one of the three main constituents of the food we eat, along with fat and protein. Carbohydrates can be further divided into sugars, starches and fibre, also known as roughage. Chemically, sugars are small, simple molecules, such as glucose and fructose. Starches are built from chains of sugar molecules strung together, while indigestible fibre is made of more complex, cross-linked chains. Standard dietary guidelines generally advise that we try to get most of our energy from starch, by eating foods such as potatoes, bread, pasta and rice. The thinking is that fat makes us put on weight as it has more calories, and saturated fats found in meat and dairy are particularly bad for us as they increase blood cholesterol levels, which blocks our arteries and causes heart…

MANY of us have, at one time or another, at least thought about giving up meat and fish and going vegetarian. If you are one of those people, there is another villain on your plate that you may not have considered. Hard, soft, runny, blue, smelly – cheese. The cheese industry is a gigantic success story. World production is at least 22 million tonnes a year, up from 15 million tonnes in 2000, and is projected to keep on expanding as people in traditionally cheeseless cultures in parts of Asia catch on. Of course, you don’t have to be a vegetarian to love the stuff. But there is some evidence that, in some Western countries, a meat-cheese switch is happening. In the UK at least, studies show that people who…

SOURCE: WORLD ECONOMIC FORUM THE dream of growing meat in a lab instead of on a farm goes back 25 years. The first patents were issued in 1995. In the early 2000s, NASA funded research with the aim of finding new ways to make nutritious food for long-distance space travellers. Things got more serious in 2013, when a patty made from cow muscle fibres grown in a lab was cooked and eaten at a press conference. Companies quickly sprang up all over the world, driven by a desire to right the wrongs of livestock farming. Unlike the real thing, cultured meat is almost cruelty-free: aside from biopsies to obtain stem cells, no animals are harmed. In theory, the environmental footprint – all that land, water and pollution – shrinks to…

IN NEARLY every country in the world, average weight is on the increase. We are getting fatter for a multitude of reasons. First, and most simply, people are eating more. Abundant, cheap food means average daily calorie intake has gone up in high-income nations, from around 3000 calories a day in the 1960s to 3400 in the past decade, according to the World Health Organization. Second, we may be eating the wrong sorts of food. For a long time, the chief villain was seen as too much fat in our diet. More recently, attention has shifted more towards sugar and highly processed fast foods, with many doctors citing a shift from eating home-cooked food as an underlying factor in bulging waistlines. → Chapter 2 has more on nutritional villains such…

IT IS often easy to wonder whether we should believe anything we read about food – when we see the latest headline claiming that eating eggs increases our risk of a heart attack, say, or that a piece of dark chocolate a day keeps the doctor away. Advice about what to eat (or not to eat) seems to change every week. Many of the apparent contradictions stem from the fact that most food studies are of a certain kind that makes them easier to carry out, but more likely to lead to false conclusions. The gold standard for human medical trials is a randomised controlled trial, or RCT. Here, doctors ask a random half of their subjects to take a medicine, while the rest take identical dummy pills so no…

THERE is a famous scene in Woody Allen’s film Sleeper in which two scientists in the year 2173 are discussing the dietary advice of the late 20th century. “You mean there was no deep fat, no steak or cream pies or hot fudge?” asks one, incredulous. “Those were thought to be unhealthy,” replies the other. “Precisely the opposite of what we now know to be true.” We aren’t quite in this territory yet, but the idea that saturated fat is bad for your heart is no longer the uncontested truth it once was. The right answer matters. According to the World Health Organization, cardiovascular disease is the world’s leading cause of death, killing more than 17 million people annually, about a third of all deaths. It predicts that by 2030,…

SALT – or, more accurately, its constituent ions sodium and chloride – is a vital nutrient. Sodium and chloride help maintain fluid balance, and sodium is one of the ions that nerve cells use to create electrical impulses. The typical food available to our hunter-gatherer ancestors was low in salt, so we have evolved an exquisite system for detecting it in our diet. One of our (at least) five types of taste bud is dedicated to salt, the only one tuned to a single chemical. Unlike energy, our bodies can’t readily store salt, so we are experts at hanging on to it, largely through a recycling unit in the kidneys. It is possible to survive perfectly well on very little salt. Until recently, most humans ate no salt other than…

Besides vitamins and minerals, some fatty acids derived from what we eat are known to be essential for good health. Chief among them are so-called omega-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These act as building blocks for nerve and brain tissue, and keep our hearts beating regularly and our brains firing. Without these nutrients, our bodies can’t make the hormones that control artery expansion and blood clotting. If you are habitually consuming negligible amounts of omega-3s, it can affect cognitive function. In childhood, low omega-3 levels can be associated with attention deficit disorder and issues like hyperactivity, anxiety and temper tantrums. Omega-3s have been found to help with sustained attention in adults too. Eating high levels of omega-3s has been linked with a reduced…

WE HAVE known for a long time that the protein we get from food is vital. Proteins are assembled from a repertoire of 20 amino acids, the basic building blocks of bone, muscle, skin and blood. It is especially important that we get enough of the eight so called essential amino acids because, unlike the others, our bodies can’t make them. In recent years, however, many of us have become convinced we need more of the stuff. All of which is a bit strange, because pretty much everyone is getting enough protein already. Daily average consumption of protein in the UK is 87 grams for men aged between 19 and 64 and 67 grams for women. This is about 50 per cent more than they require, according to official guidelines.…

THE basic principle of veganism is to abandon all animal-derived products, particularly in food. That means no meat, fish, milk, cheese or eggs – even those laid by free-range chickens, which are still debeaked and can be packed as densely as nine birds per square metre. There is little doubt that it is a good move for the planet. As we saw in the previous section, livestock farming is responsible for 14.5 per cent of global greenhouse gas emissions. According to the UN Food and Agriculture Organization, a quarter of the ice-free land on the planet is used to graze livestock. On top of that, a third of all cropland is used to produce additional food for them. Studies show that if we all went vegan, two of the biggest…

“OUR understanding of how diet affects health is limited to 150 key nutritional components,” says Albert-László Barabási at Harvard Medical School. “But these represent only a small fraction of the biochemicals present in our food.” It was Barabási who coined the term “nutritional dark matter” for all the rest, in analogy to the 85 per cent or so of material in the universe that physicists say is there but can’t be observed directly. There are thousands and thousands of compounds that are in food but were, until recently, totally unknown, and that may be affecting our health The official source of information on this complex biochemical soup is the National Nutrient Database for Standard Reference, maintained by the US Department of Agriculture (USDA). It contains information on the composition of…