Currently the health of over half the adult population in the UK suffers because of fat. The UK is not alone: obesity is a global problem, but the populations of some countries are heavier than others. Based on an extensive review of scientific literature, this topical book is a presentation of the biochemical origins of obesity written in a way that is accessible to the non-specialist. Suitable for the general public, the principal focus of the book is to advance the public understanding and awareness of science through the high interest subject of obesity. However, many universities recommend public understanding of science texts to students as a means of broadening general knowledge and as a means to emphasise to students the importance of communicating their research to the public. This book will be key to developing this knowledge.
|Publisher:||Royal Society of Chemistry, The|
|Product dimensions:||5.98(w) x 8.98(h) x 0.91(d)|
About the Author
Claire Allardyce graduated in 1993 from the University of St Andrews, Fife, with a degree in Biochemistry and Biotechnology and then proceeded to do a PhD expecting this to start her career in rational drug design. During the course of her research, Claire became increasingly interested in how nutrition affected treatment, for example, the role of folic acid in decreasing the efficacy of certain anticancer drugs and the increased power of detoxification pathways after eating Brussels sprouts. Eventually her interest diverged towards presenting scientific findings to the general public, in particular, the chemistry of obesity.
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The Science behind Obesity
By Claire S. Allardyce
The Royal Society of ChemistryCopyright © 2012 Claire S. Allardyce
All rights reserved.
Why the Fuss about Obesity?
1.1 CLEARING THE NAME OF CHEMISTRY
Chemistry is a domain of science that often has negative connotations for the public. It is associated with poisoning, pollution, destruction and devastation. And yet there is another side to this science; a side on which the future of humanity depends.
If you take anything – plants, other animals or humans, the bacteria or viruses that cause disease, the sea we bathe in, the air we breathe or even the rock we stand on – and start chopping it down into smaller and smaller pieces, eventually you will make a mixture of atoms. Each type of atom is known as an element. Atoms are the basic units of everything on Earth and in space. In most materials, atoms are joined together to form molecules; few are poised enough to go it alone. Helium is. It is one of just six noble gases; elements so dignified that they reject liaisons with other atoms. They mix, but they do not merge.
Helium atoms are found naturally in the mixture of atoms and molecules we call air. True to type, they remain solitary and do not join with other atoms to form molecules. The union process – a chemical reaction – sometimes involves the exchange of heat: chemical reactions may suck energy in and trap it in the chemical bonds that link atoms together to form molecules, or they may release energy formerly trapped in the same; sometimes in anexplosive manner. Explosions are often based on the type of chemical reaction called combustion i.e. burning. In this type of reaction, fuel molecules are cleaved and fused with oxygen to release stored energy. This is the process that allows energy to be released from food to power the body, but because of the potentially violent nature of combustion, it needs to be tightly constrained to support life.
Helium's lack of interest in chemical reactions makes it very stable. It is reliable enough to give to children in balloons without a repeat of the Hindenburg disaster, when a much larger balloon, an airship to be exact, blew up dramatically back in 1937 killing many of its crew and passengers. The disaster is famed because it was one of the first tragedies to be caught on film and this footage is probably the main reason why airship travel became rather unpopular. Many more catastrophic events have been broadcast since 1937, but this old film continues to be viewed by those speculating on the cause of the blast. The favoured explanation is that the balloon leaked. The gas in the airship was hydrogen. Hydrogen is lighter than helium, therefore more effective at lifting airships or balloons off the ground, but unlike helium it is an explosive fuel; it loves liaisons. The explosion of the airship was caused by the burning of hydrogen, which is an ideal fuel, because, although this process releases plenty of energy, it produces no unwanted gases or residues, only water – super-clean combustion.
The chemical nature of hydrogen and helium gives these gases their similarities and differences: both gases are colourless, odourless and allow balloons to float in air; yet one is stably celibate and the other capriciously desperate for liaisons. This difference between the gases is determined by their electrons. Electrons are one of three types of particle that make up atoms; the other two are known as protons and neutrons. The protons are positively charged and packed in the centre of the atom between the similarly sized neutrons, which carry no charge at all. Together the protons and neutrons form a dense core known as a nucleus. Compared with protons and neutrons, electrons differ in size and space. In an attempt to explain them in pictorial terms, imagine tiny midges buzzing around a huge dung heap. The midges are the electrons and the dung is the nucleus of the atom. In the image, the heap needs to be at least 20 000 times bigger than an individual midge because that is the estimated size difference between the electrons and the nucleus of the smallest atom, hydrogen; it is estimated because electrons are really too small to measure. There are some differences between midges around a dung heap and atoms: for example, midges move in seemingly random ways, whereas the path of electrons follows a mathematical prediction called an orbital, and, whereas midges move alone, electrons prefer to be paired. Electrons are also charged, bearing a negative charge that neutralises the positive charge of the protons lodged in the nucleus of the atom. Take an isolated atom, which, outside the noble ranks of helium and its five kinsfolk, only exists in theory, and the fundamental unit would have the same number of protons and electrons. Whereas all the protons would be equivalent, the electrons would be found in two arrangements: those in stable, paired relationships with their own kind and those that are alone. It is the members of the singles club that are involved in bonds. Indeed, they are so desperate to make liaisons that they are seldom found alone in nature; rather they are given, received or shared between atoms to form chemical bonds and, fundamentally, it is the need to pair and share that sees few atoms going it alone. Helium's electrons are naturally paired – none is available to give or share – and so these atoms remain alone. In contrast, a lone hydrogen atom would have a single electron fidgeting and desperate to form a chemical bond. This desire is such that hydrogen gas is not made up of hydrogen atoms buzzing around on their own, but hydrogen molecules; two hydrogen atoms satisfy their needs by coming together so that the lonely electron in each atom can be paired and shared, and in so doing the hydrogen atoms form a molecule.
Like atoms, molecules are chemicals, but more complicated because they are made up of groups of atoms linked together. The smallest and arguably the simplest molecule is hydrogen gas. It is composed of the minimum number (just two) of the smallest type of atom (hydrogen). At the other end of the size scale are molecules so large that we can see them with the naked eye, for example strands of polymers, manmade fibres such as polythene or natural molecules, including our information storage molecule deoxyribose nucleic acid (DNA).
Chemistry is the science that strives to understand the behaviour of all chemicals, from the smallest to the largest, and their interactions with their surroundings. In light of this definition, it is possible to distil just about any part of science (and our lives) down to an essence of chemistry. However some powerful influences, in both science and marketing, dispute the dominance of chemistry. This opposition is mounted partly out of pride, claiming territory for other disciplines, but also because some factions want to put as much distance as possible between themselves and chemistry; chemistry has a certain reputation.
One particular industry that actively estranges chemistry is food manufacturing, demonstrated by the fact that marketing strategies often centre on listing groups of chemicals their products do not contain. Yet, despite the stand-off in public, chemistry and food manufacturing are closely intertwined; and have been so for many years.
Food science and chemistry grew up together. Virtually as soon as chemical know-how was developed, it was – and still is – translated into the domain of medicine and nutrition, improving the quality of our lives. Cooking is chemistry, despite what many chemists and cooks will have you believe. In the late 20th century, the close relationship between the food manufacturing and chemical industries came prominently into view, and the public did not like all that they found. A few decades before, the chemical industry had discovered some clever methods for processing, preserving and making food taste good. The methods generally involved adding extra ingredients; some were based on natural products and some were not. The food additives were (and are) tested for safety. For many tests the result was a "generally recognised as safe" (GRAS) categorisation. GRAS simply means that the chemical has no known detrimental health effects when used in the particular way evaluated, and in the particular quantities expected. For many food additives, the amounts in the final product are minuscule: tiny drops are added to vats of ingredients. At such low doses, even potential poisons can be generally recognised as safe. In this respect the GRAS categorisation is tried and tested: many natural poisons, such as cyanide, are found in the most natural of foods, but in such small amounts that they do not significantly affect health when the foods are incorporated into a balanced diet. Other chemicals that could poison the body in excess have health benefits in smaller doses. Take what we call vitamins as examples. In alphabetical order, vitamin A is the first: a fat soluble food component we need for good health, but an overdose, for example caused by one man eating an entire polar bear's liver, would be fatally toxic. There are many other examples of vital nutrients that become deadly poisons when consumed in excess, but generally there are few fatalities, because when they are part of the natural food source overconsumption is difficult. It is controlled by food availability, flavour and by our appetite. And with the food industry following such a tried and tested pathway, what could possibly go wrong? Perhaps too much success.
It is not clear whether the chemical industry ever imagined that their success in food production would be so sweeping – so revolutionary. But it was. And the consumers voted with their feet, selecting processed products over the fresh alternatives. Artificial flavours and flavour enhancers were central to this success. It is said that flavour is the reason why a particular food is bought repeatedly, and a few drops of the right chemical can make even the blandest products taste good. The cost of artificial flavours is often less than the packaging of the product. In addition, the most successful food products have been designed around innate preferences that optimise survival in the natural world: our partiality for salt, protein, fat and sugar. And so, with help from the chemical industry, some magic was woven in the factory kitchens and, for the first time, mass produced, low cost, convenient and tasty meal solutions became available. These products have enormous public appeal.
Within a decade convenience foods were incorporated into the daily diet of the majority of the population, in some cases to such an extent that certain food components were being consumed in excess of what had been anticipated. And health began to suffer. Nutritional deficiencies are one consequence of such dietary choices, but the odious links between chemical additives and health problems are more widely publicised; they are the consequences of excess. Towards the end of the 20th century, such links became headline material. History fuelled a rapid response. It was not the first time that the public had been shocked by food quality. Tampering with food began as soon as it was profitable, as soon as food production was outsourced beyond the family unit. But a lack of scientific understanding and a background of high levels of malnutrition and transmissible disease made the consequences difficult to trace. And so this first wave of dietary-induced illness festered for many centuries, until science became advanced enough to convict those who adulterated food. By that time – just outside living memory – special ingredients, from calves' brains to synthetic poisons, were being used to change the taste, texture or appearance of foods so that they fetched a higher price. When adulteration was at its height, few foods were untainted, from raw ingredients through to ready prepared products. Perhaps the most sickeningly ironic case was the use of toxic mineral dyes in lollipop treats for children. With hindsight it is clear that such practices significantly contributed to the poor growth and high rate of childhood death before the turn of the last century, when legislation was passed to protect the public. The public, logically, assumed the law would do what it set out to do; they were content and complacent. And so when the negative links between health and approved additives were revealed while the memory of the widespread and deadly incidents of food adulteration was still warm, much of society adopted a broad and bitter opinion of chemistry.
Decades on, the stigma associated with chemistry remains such that some manufacturers go to extreme lengths to distance themselves from this area of science; this can be so extreme it becomes ridiculous. For example, I was pleased that I had my camera with me on the day I purchased a coffee from a ready-to-eat food giant in the UK and found the following statement describing their organic milk plastered on the side of the cup: "it is natural, chemical-free and tastes good". This statement, if one will allow me the privilege of being pedantic, is meaningless: if their milk is free from chemicals then, technically, it is void of any atoms or molecules – a vacuum. Since molecules are what give our food flavour, how do they make a vacuum taste good, let alone put it in a paper cup? This enterprise has now modified its statement to say that it "creates handmade natural food avoiding the obscure chemicals", which again is not actually what I assume they mean to say. Recall the definition of chemistry: materials, both natural and synthetic, are all packed with chemicals. As a rule of thumb, synthetic chemicals are better characterised, more understood and less obscure than their natural cousins. Indeed, some of the current nutrition-linked health problems, including obesity, are not predominantly linked to synthetic food additives, but more to imbalances of natural chemicals – excesses and deficiencies of vital nutrients – often because of overconsumption of the same products that are rich in the synthetic additives.
Despite regularly having received a public flogging, just or unjust, chemistry has underpinned current nutrition and food safety. Only through advances in chemistry were cases of food adulteration proven such that legislation could be passed to protect the public from this type of poisoning. Only through chemical know-how is the food harvest preserved to prevent spoiling, protecting the public from some of the most deadly poisons known, including natural fungal toxins. Only through advances in chemistry have many nutritional deficiencies been identified and low-cost cures developed. Chemistry has been able to expand the food supply to provide an abundance to feed a growing population without ploughing up more natural habitat. And the role of chemistry in our lives does not stop there: this area of science is playing a principal part in determining the future of humanity. The current top four scientific challenges are energy, water, medicine and nutrition. Chemists are working in partnership with other scientists to tackle them all. This book focuses on the last two, although in truth they are all intertwined as increasing amounts of energy and water are being used to ensure that harvests are ample enough to feed well the growing population of the world.
1.2 CURRENT THREATS TO HUMAN HEALTH
In the domain of medicine, chemists are kept busy working on longstanding foes of humanity, and newcomers to the scene. If the truth be told, the human race currently faces major health scares that could wipe out a large percentage of the population if left unchecked. The World Health Organization (WHO) has been given the daunting responsibility of coordinating an integrated global alert and response system to contain what are considered to be the most prominent threats, should the need arise. On their hot list are the various forms of flu, severe acute respiratory syndrome (SARS), Ebola haemorrhagic fever, yellow fever, African trypanosomiasis, Crimean–Congo haemorrhagic fever, meningococcal disease, the return of the plague and so on. Other health threats currently challenging chemists include acquired immunodeficiency syndrome (AIDS) and the comeback of diseases formerly suppressed by vaccination, including tuberculosis and measles. In some cases a return is predicted to be accompanied by increased danger, due to drug resistance. Drug resistance is also causing new health threats, particularly in hospitals, where formerly controllable infections are becoming life threatening as they acquire defences against antibiotics; meticillin-resistant Staphylococcus aureus (MRSA) is one of the better known examples.
Some of WHO's hot-listed threats to human health come around in cycles, some are simmering away in remote parts of the world, while others just pop up out of the blue. An outbreak of any one of these diseases is likely to create fear amongst much of the population. Logically we need to be prepared for such events. To this end, scientists, including chemists, are busy trying to understand the mechanisms of initiation and progression of such diseases so as to develop new vaccines, treatments and containment programmes.
Excerpted from Fat Chemistry by Claire S. Allardyce. Copyright © 2012 Claire S. Allardyce. Excerpted by permission of The Royal Society of Chemistry.
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Table of Contents
Introduction; General fat; In the beginning; Stone Age obesity; Hardwired obesity; A thrifty genotype or human nature?; Softwired obesity; Beyond the helix; What we need; Death in the pot; The chemistry of food; Nutritional medication; Hidden under a blanket of fat; Your choice; Index