In the first part of this essay, subtitled ‘Obesity &the Incoherence of Much Current Dietary Advice’, I cited a lecture by Dr Robert Lustig, Professor of Paediatrics at the University of California in San Francisco, in which he argues that, despite their widespread currency, the two most prevalent theories for explaining the increase in obesity, hypertension, Type 2 diabetes and cardiovascular disease in the second half of the 20th century are both fundamentally wrong.
The first of these theories – which gained broad acceptance in the early 1980s – says that one of the most important factors in the aetiology of all of the above diseases is the level of fat in our diets: a proposition that is now so well established in our collective belief system that it is not only generally accepted as a fact, but is the basis upon which much current dietary advice continues to be given.
According to Professor Lustig, however, not only was the international study, upon which this theory was initially grounded, seriously flawed – failing to take into account all the possible contributory factors – its continued status defies much of the evidence of the last thirty years. For while our intake of dietary fats has significantly fallen during this period – by around 25% – the incidence of each of the diseases with which these fats were believed to be causally related has continued to rise, reaching near-epidemic proportions.
Over the last ten to fifteen years, as a consequence, a second theory – one based less on scientific evidence than apparent common sense – has steadily gained greater currency. Instead of attempting to identify one particular substance or foodstuff as the principal culprit, it says that obesity – and all its other attendant diseases – is less the result of what we eat than simply how much. Based on the first law of thermodynamics, which tells us that, in a closed system, energy is never lost, it states that if we consume more in calories than we burn off in exercise and the sheer business of staying alive then the excess has to go somewhere. And the obvious answer as to where this might be is in our adipose tissue in the form of fat.
What this physics-based model fails to take into account, however, is that our bodies not only have different ways of dealing with excess dietary inputs – some of them hardly entering the closed system of our metabolism at all – they also have different ways of metabolising the different substances that do get that far.
In Part I of this essay, I illustrated this by taking the reader through the biochemistry involved in the metabolism of two common sugars: glucose and fructose. I shall not rehearse this excursion into the abstruse and wonderful world of human metabolism again here, not least because it would involve reproducing most of Part I all over again. The important point, however, is that it is quite possible for us to ingest identical amounts of two very similar substances, and for our bodies to treat them in completely differently ways. In the case of glucose, for instance, our bodies either use it to produce instantly available energy – in the form of ATP (adenosine triphosphate) – or turn it into the short-term energy store, glycogen. In contrast, if we ingest any significant amount of fructose, our bodies turn nearly all of it into fat.
And it is this that Professor Lustig believes to be the real problem: not the dietary fats which our metabolism largely breaks down into other (mostly) useful substances; but the non-fats which our bodies turn into fats, to be stored as such in adipose, skeletal muscle and cardiac tissue, where, if left unused and allowed to build up over time, they can do considerable harm. And chief among these harmful, ‘lipogenic’ non-fats, according to Professor Lustig, is indeed fructose.
More importantly, I have yet come across a single biochemist who disagrees with the basic science behind this contention. I can therefore state with a fair degree of confidence that, even if there are still some grains of truth in either of the other two theories used to explain the increase in obesity and heart disease over the last thirty years, if you want to avoid putting on fat, then the one thing you should certainly do is cut down on your consumption of fructose.
It is at this point, however, that we run into our first problem. For even if more people were to become aware of just how lipogenic – or disposed to fat formation – fructose truly is, it is unlikely that many of us would be able to tell you just how much of the stuff we are actually eating. This is because very little of our daily intake comes in a form that is readily identifiable as such. For most people, for instance, less than 5% of their fructose consumption comes in the form of fresh fruit – from which, in its broadest sense, all fructose is ultimately derived. A far greater proportion – the vast majority, in fact – is added to our food in the form of processed sugar.
Even in this regard, however, it is not always obvious how much we are consuming. For not all of the sugar we ingest is conspicuously spooned over strawberries or stirred into our tea or coffee. Most of it, in fact, is almost entirely hidden, not just in the cakes and biscuits we casually enjoy as mid-morning snacks, but in the ready-meals and fast-food takeaways – along with their accompanying soft drinks – that have become such a major part of our diet over the last thirty years.
To complicate matters further, different types of sugar contain different amounts of fructose: a fact which has led to the fairly widespread belief that there is one type of sugar – used exclusively in the industrial manufacture of food products – that is worse than all the others. The believed culprit is High Fructose Corn Syrup, or HFCS, which first made its appearance in the mid-1970s, after President Nixon asked his then Secretary of State for Agriculture, Earl Butz, to find a way of stabilising food prices so as to prevent them from becoming a political issue. Butz did this by subsidising the large scale production of HFCS made from maize grown in America’s Mid-West. 40% cheaper than sucrose – which is made from either sugarcane or sugar beet – it very quickly caught on with the food industry, especially with manufacturers of soft drinks such as Coca-Cola and Pepsi, which has further led to its demonization among certain campaigners, the view being that if Coca-Cola is using it, then it’s got to be evil.
This, however, is a very distorted view of what is actually going on here. For while it may not be entirely coincidental that the introduction of HFCS occurred more or less at the same time as the start of the period of rapid growth in obesity and CVD, to assume that this correlation is either simple or direct would be to make the same kind of mistake researchers in the 1970s made with respect to dietary fats. They saw a correlation and immediately assumed a cause.
One can see this more clearly if one steps back from the US context – where most of this debate is taking place – and takes a more global perspective. For despite what many campaigners seem to think, the production and consumption of HFCS is still very much a US phenomenon. In 2010, for instance, HFCS accounted for around 38% of the sugar – or ‘sweetener’ – consumed by the average American. In Europe, in contrast, it accounted for less than 5%. Yet Europe too – and the UK in particular – is experiencing a similar trend with respect to obesity and CVD. It may not be as pronounced as in the USA, where it started earlier, but it is following a very similar path.
Even more significantly, HFCS and sucrose are very similar in terms of their biochemistry. As can be seen in Figure 1, sucrose comprises a bonded pair of fructose and glucose molecules, which almost immediately breaks apart on digestion, producing one fructose molecule and one glucose molecule. One can therefore say that sucrose is more or less 50% fructose and 50% glucose. HFCS, in comparison, is 55% fructose and 42% glucose, with the other 3% being mostly water. The difference in the amount of fructose in each of these forms of sweetener may not be entirely trivial, but it is not enough, therefore, to blame one and not the other. In fact, singling out HFCS for attack, as many people seem to want to do, merely allows the food industry to counter by arguing that it is no more harmful than sucrose, which is more or less correct.
Figure 1: Molecular Structure of Sucrose
The real problem, therefore, is not the type of processed sugar we are consuming, but the total amount. Here, however, we have another problem. For obtaining reliable data on sugar consumption is not easy.
The first difficulty one encounters is in determining what counts as ‘sugar’ in the various datasets that are out there, and what is meant by ‘consumption’. A recent report by the Indian Council of Agricultural Research (ICAR), for instance, states that Brazil has the highest per capita consumption of sugar of any country in the world, with each Brazilian consuming 58 kg (128lbs) of the stuff per year. The USA, in contrast, comes in in seventh place, with each American only consuming half this amount, 29 kg (64lbs). It is only when one looks at the data in more detail that one starts to realise that this claim isn’t quite what it seems.
The first clue comes in the attribution of authorship on the title page. For while the report may have been published by ICAR, it was actually written by the Sugarcane Breeding Institute in Coimbatore. It will not, therefore, come as much of a surprise to discover that, under the heading ‘sugar’, the report only actually includes sucrose produced from sugarcane, which is a major agricultural crop in both India and Brazil. In Brazil, however, the sugar produced is not only sold in granulated form and used to sweeten manufactured foods and drinks; it is also used to produce Cachaça, one of Brazil’s most popular alcoholic beverages. This means that a large part of Brazil’s so-called ‘sugar consumption’ is not ingested as sugar at all – but as ethanol – and while it may make sense, from an economic and agricultural perspective, to include it as one of the more important raw materials consumed by the Brazilian economy, to include it as part of the country’s official per capita sugar intake gives one a totally distorted impression.
Of course, my selection of this rather extreme example to illustrate what is a fairly general point means that it is not entirely typical of most of the data on sugar consumption one finds on the internet. Statistically, it is a bit of an outlier. In many ways, however, it is actually far less misleading than quite a few reports I could have cited. For the vast majority of websites providing statistical information of this kind not only fail to reference their data’s provenance or define what it includes, in many cases they are produced on behalf of clearly vested interests, of which more trusting readers need to be aware.
There are, of course, plenty of scientific studies available, which, given peer-review, one can assume to be without intentional bias. But most of the ones at which I’ve so far looked are primarily concerned with correlating sugar consumption with the incidence of various specific diseases, and tend to be based on fairly small sample populations taken from a single geographical region, comprising a single sex in a fairly narrow age-range. In terms of helping us quantify per capita sugar consumption, they are therefore of little use. If we are looking for reliable data, as a consequence, all we really have to go on are official national statistics. And in the UK, even these are not very helpful.
The ONS, for instance – the Office of National Statistics – has absolutely nothing on the subject. DEFRA – the Department for Environment, Food and Rural Affairs – has figures for UK sugar production; but nothing on consumption. And while, for the purposes of ‘Health Education’, the Department of Health has published one or two papers on the dangers of high sugar diets, it appears not to have commissioned any real scientific work on the subject since 1999.
Part of the problem is that, in the UK, sugar consumption has not yet become a political issue. This, however, is certainly not something you can say about the USA, where the problem, if anything, is one of over-politicisation. Last year, for instance, it was announced that per capita sugar consumption in the USA had exceeded 100lbs (45kg) the first time ever – though, again, what was included under the heading ‘sugar’ is not absolutely clear. In October, however, the US Department of Agriculture, ever-mindful of the need to keep Midwest farming interests onside, announced that it was changing the way in which sugar intake would be calculated in future and duly revised the 2012 figure down to 76.7lbs (34.8kg).
Figure 2: US Per Capita Sweetener Consumption 1965-2010
(Source: US Department of Agriculture)
The irony is that, if one looks at the official figures which the Department of Agriculture published in September 2010 – before this change in methodology took place – they actually reveal a marked decline in per capita sugar consumption over the last decade, very possibly as a result of the growing campaign against HFCS which began in the early 2000s. Changing the method of calculation is therefore likely to obscure this.
What Figure 2 most strikingly reveals, however, is not only how rapidly HFCS substantially replaced sucrose (here designated as ‘Refined Sugar’) during the 1970s and early 80s, but how its per capita consumption still continued to grow even after the consumption of sucrose more or less levelled off, thereby leading to a marked increase in total sugar intake during a period in which the USA coincidentally experienced its most significant increase in the incidence of obesity and CVD.
To attribute this increase solely to the extra 5% fructose in HFCS, however, simply beggars belief, as does the argument that following the US consumer’s rejection of HFCS – and the subsequent decline in overall sugar consumption – the problem has now been resolved. For although some American consumers – having watched Professor Lustig’s lecture on YouTube perhaps – may be voting with their wallets and refusing to buy products containing HFCS, this does not mean that they have fundamentally changed their diet, or that the American food industry is now gearing itself up to produce food with a significantly lower sugar content. Indeed, it is questionable whether this latter is even possible. For having already reduced the amount of fat in foods they are producing – largely by replacing it with sugar – the question now facing all food manufacturers is with what – if they were forced to it – would they replace the sugar.
Not that they are in any imminent danger of being forced to make this decision, of course. For not only is the US Food & Drug Administration (FDA) still a long way from accepting that HFCS – or any other form of sugar – is harmful, but politicians and industry-insiders alike know full well that were they required to reduce the sugar content of their products, not only would many manufacturers go out of business, the effect on the overall US economy would be devastating.
This is because, as Earl Butz recognised, sugar is the key to cheap, mass-produced food. Without it, many manufactured foods would either be too lacking in flavour to be saleable, or too expensive for them to actually have a mass market.
To understand this, however, one needs to understand the economics of our food industry in the way that it is currently structured. And it is this that will be the subject of my third and last essay in this series, subtitled ‘Paying the Price.’
In it I shall not only describe how our food industry got itself – and us – into this extremely dire and possibly intractable predicament, I shall also attempt to outline the even more dire consequences that may follow if no solution can be found.