6 The Nonsense du Jour
Now we need to raise our game. Food has become, without question, a national obsession. The Daily Mail in particular has become engaged in a bizarre ongoing ontological project, diligently sifting through all the inanimate objects of the universe in order to categorise them as a cause of—or cure for—cancer. At the core of this whole project are a small number of repeated canards, basic misunderstandings of evidence which recur with phenomenal frequency.
Although many of these crimes are also committed by journalists, we will be reviewing them later. For the moment we will focus on ‘nutritionists’, members of a newly invented profession who must create a commercial space to justify their own existence. In order to do this, they must mystify and overcomplicate diet, and foster your dependence upon them. Their profession is based on a set of very simple mistakes in how we interpret scientific literature: they extrapolate wildly from ‘laboratory bench data’ to make claims about humans; they extrapolate from ‘observational data’ to make ‘intervention claims’; they ‘cherry-pick’; and, lastly, they quote published scientific research evidence which seems, as far as one can tell, not to exist.
It’s worth going through these misrepresentations of evidence, mainly because they are fascinating illustrations of how people can get things wrong, but also because the aim of this book is that you should be future-proofed against new variants of bullshit. There are also two things we should be very clear on. Firstly, I’m picking out individual examples as props, but these are characteristic of the genre; I could have used many more. Nobody is being bullied, and none of them should be imagined to stand out from the nutritionist crowd, although I’m sure some of the people covered here won’t be able to understand how they’ve done anything wrong.
Secondly, I am not deriding simple, sensible, healthy eating advice. A straightforwardly healthy diet, along with many other aspects of lifestyle (many of which are probably more important, not that you’d know it from reading the papers) is very important. But the media nutritionists speak beyond the evidence: often it is about selling pills; sometimes it is about selling dietary fads, or new diagnoses, or fostering dependence; but it is always driven by their desire to create a market for themselves, in which they are the expert, whereas you are merely bamboozled and ignorant.
Prepare to switch roles.
The four key errors
Does the data exist?
This is perhaps the simplest canard of all, and it happens with surprising frequency, in some rather authoritative venues. Here is Michael van Straten on BBC Newsnight, talking ‘fact’. If you prefer not to take it on faith that his delivery is earnest, definitive, and perhaps even slightly patrician, you can watch the clip online.
‘When Michael van Straten started writing about the magical medicinal powers of fruit juices, he was considered a crank,’ Newsnight begins. ‘But now he finds he’s at the forefront of fashion.’ (In a world where journalists seem to struggle with science, we should note that Newsnight has ‘crank’ at one end of the axis, and ‘fashion’ at the other. But that chapter comes later.) Van Straten hands the reporter a glass of juice. ‘Two years added to your life expectancy in that!’ he chuckles—then a moment of seriousness: ‘Well, six months, being honest about it.’ A correction. ‘A recent study just published last week in America showed that eating pomegranates, pomegranate juice, can actually protect you against ageing, against wrinkles,’ he says.
Hearing this on Newsnight, the viewer might naturally conclude that a study has recently been published in America showing that pomegranates can protect against ageing. But if you go to Medline, the standard search tool for finding medical academic papers, no such study exists, or at least not that I can find. Perhaps there’s some kind of leaflet from the pomegranate industry doing the rounds. He goes on: There’s a whole group of plastic surgeons in the States who’ve done a study giving some women pomegranates to eat, and juice to drink, after plastic surgery and before plastic surgery: and they heal in half the time, with half the complications, and no visible wrinkles!’ Again, it’s a very specific claim—a human trial on pomegranates and surgery—and again, there is nothing in the studies database.
So could you fairly characterise this Newsnight performance as ‘lying’? Absolutely not. In defence of almost all nutritionists, I would argue that they lack the academic experience, the ill-will, and perhaps even the intellectual horsepower necessary to be fairly derided as liars. The philosopher Professor Harry Frankfurt of Princeton University discusses this issue at length in his classic 1986 essay ‘On Bullshit’. Under his model, ‘bullshit’ is a form of falsehood distinct from lying: the liar knows and cares about the truth, but deliberately sets out to mislead; the truth-speaker knows the truth and is trying to give it to us; the bullshitter, meanwhile, does not care about the truth, and is simply trying to impress us:
It is impossible for someone to lie unless he thinks he knows the truth. Producing bullshit requires no such conviction…When an honest man speaks, he says only what he believes to be true; and for the liar, it is correspondingly indispensable that he considers his statements to be false. For the bullshitter, however, all these bets are off: he is neither on the side of the true nor on the side of the false. His eye is not on the facts at all, as the eyes of the honest man and of the liar are, except insofar as they may be pertinent to his interest in getting away with what he says. He does not care whether the things he says describe reality correctly. He just picks them out, or makes them up, to suit his purpose.
I see van Straten, like many of the subjects in this book, very much in the ‘bullshitting’ camp. Is it unfair for me to pick out this one man? Perhaps. In biology fieldwork, you throw a wired square called a ‘quadrat’ at random out onto the ground, and then examine whatever species fall underneath it. This is the approach I have taken with nutritionists, and until I have a Department of Pseudoscience Studies with an army of PhD students doing quantitative work on who is the worst, we shall never know. Van Straten seems like a nice, friendly guy. But we have to start somewhere.
Observation, or intervention?
Does the cock’s crow cause the sun to rise? No. Does this light switch make the room get brighter? Yes. Things can happen at roughly the same time, but that is weak, circumstantial evidence for causation. Yet it’s exactly this kind of evidence that is used by media nutritionists as confident proof of their claims in our second major canard.
According to the Daily Mirror, Angela Dowden, RNutr, is ‘Britain’s Leading Nutritionist’, a monicker it continues to use even though she has been censured by the Nutrition Society for making a claim in the media with literally no evidence whatsoever. Here is a different and more interesting example from Dowden: a quote from her column in the Mirror, writing about foods offering protection from the sun during a heatwave: ‘An Australian study in 2001 found that olive oil (in combination with fruit, vegetables and pulses) offered measurable protection against skin wrinkling. Eat more olive oil by using it in salad dressings or dip bread in it rather than using butter.’
That’s very specific advice, with a very specific claim, quoting a very specific reference, and with a very authoritative tone. It’s typical of what you get in the papers from media nutritionists. Let’s go to the library and fetch out the paper she refers to (‘Skin wrinkling: can food make a difference?’ Purba MB et al. J Am Coll Nutr. 2001 Feb; 20(1): 71-80). Before we go any further, we should be clear that we are criticising Dowden’s interpretation of this research, and not the research itself, which we assume is a faithful description of the investigative work that was done.
This was an observational study, not an intervention study. It did not give people olive oil for a time and then measure differences in wrinkles: quite the opposite, in fact. It pooled four different groups of people to get a range of diverse lifestyles, including Greeks, Anglo-Celtic Australians and Swedish people, and it found that people who had completely different eating habits—and completely different lives, we might reasonably assume—also had different amounts of wrinkles.
To me this is not a great surprise, and it illustrates a very simple issue in epidemiological research called ‘confounding variables’: these are things which are related both to the outcome you’re measuring (wrinkles) and to the exposure you are measuring (food), but which you haven’t thought of yet. They can confuse an apparently causal relationship, and you have to think of ways to exclude or minimise confounding variables to get to the right answer, or at least be very wary that they are there. In the case of this study, there are almost too many confounding variables to describe.
I eat well—with lots of olive oil, as it happens—and I don’t have many wrinkles. I also have a middle–class background, plenty of money, an indoor job, and, if we discount infantile threats of litigation and violence from people who cannot tolerate any discussion of their ideas, a life largely free from strife. People with completely different lives will always have different diets, and different wrinkles. They will have different employment histories, different amounts of stress, different amounts of sun exposure, different levels of affluence, different levels of social support, different patterns of cosmetics use, and much more. I can imagine plenty of reasons why you might find that people who eat olive oil have fewer wrinkles; and the olive oil having a causative role, an actual physical effect on your skin when you eat it, is fairly low down on my list.
Now, to be fair to nutritionists, they are not alone in failing to understand the importance of confounding variables, in their eagerness for a clear story. Every time you read in a newspaper that ‘moderate alcohol intake’ is associated with some improved health outcome—less heart disease, less obesity, anything—to gales of delight from the alcohol industry, and of course from your friends, who say, ‘Ooh well, you see, it’s better for me to drink a little…’ as they drink a lot—you are almost certainly witnessing a journalist of limited intellect, overinterpreting a study with huge confounding variables.
This is because, let’s be honest here: teetotallers are abnormal. They’re not like everyone else. They will almost certainly have a reason for not drinking, and it might be moral, or cultural, or perhaps even medical, but there’s a serious risk that whatever is causing them to be teetotal might also have other effects on their health, confusing the relationship between their drinking habits and their health outcomes. Like what? Well, perhaps people from specific ethnic groups who are teetotal are also more likely to be obese, so they are less healthy. Perhaps people who deny themselves the indulgence of alcohol are more likely to indulge in chocolate and chips. Perhaps preexisting ill health will force you to give up alcohol, and that’s skewing the figures, making teetotallers look unhealthier than moderate drinkers. Perhaps these teetotallers are recovering alcoholics: among the people I know, they’re the ones who are most likely to be absolute teetotallers, and they’re also more likely to be fat, from all those years of heavy alcohol abuse. Perhaps some of the people who say they are teetotal are just lying.
This is why we are cautious about interpreting observational data, and to me, Dowden has extrapolated too far from the data, in her eagerness to dispense—with great authority and certainty—very specific dietary wisdom in her newspaper column (but of course you may disagree, and you now have the tools to do so meaningfully).
If we were modern about this, and wanted to offer constructive criticism, what might she have written instead? I think, both here and elsewhere, that despite what journalists and self-appointed ‘experts’ might say, people are perfectly capable of understanding the evidence for a claim, and anyone who withholds, overstates or obscures that evidence, while implying that they’re doing the reader a favour, is probably up to no good. MMR is an excellent parallel example of where the bluster, the panic, the ‘concerned experts’ and the conspiracy theories of the media were very compelling, but the science itself was rarely explained.
So, leading by example, if I were a media nutritionist, I might say, if pushed, after giving all the other sensible sun advice: ‘A survey found that people who eat more olive oil have fewer wrinkles,’ and I might feel obliged to add, ‘Although people with different diets may differ in lots of other ways.’ But then, I’d also be writing about food, so: ‘Never mind, here’s a delicious recipe for salad dressing anyway.’ Nobody’s going to employ me to write a nutritionist column.
From the lab bench to the glossies
Nutritionists love to quote basic laboratory science research because it makes them look as if they are actively engaged in a process of complicated, impenetrable, highly technical academic work. But you have to be very cautious about how you extrapolate from what happens to some cells in a dish, on a laboratory bench, to the complex system of a living human being, where things can work in completely the opposite way to what laboratory work would suggest. Anything can kill cells in a test tube. Fairy Liquid will kill cells in a test tube, but you don’t take it to cure cancer. This is just another example of how nutri-tionism, despite the ‘alternative medicine’ rhetoric and phrases like ‘holistic’, is actually a crude, unsophisticated, old fashioned, and above all reductionist tradition.
Later we will see Patrick Holford, the founder of the Institute for Optimum Nutrition, stating that vitamin C is better than the AIDS drug AZT on the basis of an experiment where vitamin C was tipped onto some cells in a dish. Until then, here is an example from Michael van Straten—who has fallen sadly into our quadrat, and I don’t want to introduce too many new characters or confuse you—writing in the Daily Express as its nutrition specialist: ‘Recent research’, he says, has shown that turmeric is ‘highly protective against many forms of cancer, especially of the prostate’. It’s an interesting idea, worth pursuing, and there have been some speculative lab studies of cells, usually from rats, growing or not growing under microscopes, with turmeric extract tipped on them. There is some limited animal model data, but it is not fair to say that turmeric, or curry, in the real world, in real people, is ‘highly protective against many forms of cancer, especially of the prostate’, least of all because it’s not very well absorbed.
Forty years ago a man called Austin Bradford-Hill, the grandfather of modern medical research, who was key in discovering the link between smoking and lung cancer, wrote out a set of guidelines, a kind of tick list, for assessing causality, and a relationship between an exposure and an outcome. These are the cornerstone of evidence-based medicine, and often worth having at the back of your mind: it needs to be a strong association, which is consistent, and specific to the thing you are studying, where the putative cause comes before the supposed effect in time; ideally there should be a biological gradient, such as a dose-response effect; it should be consistent, or at least not completely at odds with, what is already known (because extraordinary claims require extraordinary evidence); and it should be biologically plausible.
Michael van Straten, here, has got biological plausibility, and little else. Medics and academics are very wary of people making claims on such tenuous grounds, because it’s something you get a lot from people with something to sell: specifically, drug companies. The public don’t generally have to deal with drug-company propaganda, because the companies are not currently allowed to talk to patients in Europe—thankfully—but they badger doctors incessantly, and they use many of the same tricks as the miracle-cure industries. You’re taught about these tricks at medical school, which is how I’m able to teach you about them now.
Drug companies are very keen to promote theoretical advantages (‘It works more on the Z4 receptor, so it must have fewer side-effects!’), animal experiment data or ‘surrogate outcomes’ (‘It improves blood test results, it must be protective against heart attacks!’) as evidence of the efficacy or superiority of their product. Many of the more detailed popular nutritionist books, should you ever be lucky enough to read them, play this classic drug-company card very assertively. They will claim, for example, that a ‘placebo-controlled randomised control trial’ has shown benefits from a particular vitamin, when what they mean is, it showed changes in a ‘surrogate outcome’.
For example, the trial may merely have shown that there were measurably increased amounts of the vitamin in the bloodstream after taking a vitamin, compared to placebo, which is a pretty unspectacular finding in itself: yet this is presented to the unsuspecting lay reader as a positive trial. Or the trial may have shown that there were changes in some other blood marker, perhaps the level of an ill-understood immune-system component, which, again, the media nutritionist will present as concrete evidence of a real-world benefit.
There are problems with using such surrogate outcomes. They are often only tenuously associated with the real disease, in a very abstract theoretical model, and often developed in the very idealised world of an experimental animal, genetically inbred, kept under conditions of tight physiological control. A surrogate outcome can—of course—be used to generate and examine hypotheses about a real disease in a real person, but it needs to be very carefully validated. Does it show a clear dose-response relationship? Is it a true predictor of disease, or merely a ‘co-variable’, something that is related to the disease in a different way (e.g. caused by it rather than involved in causing it)? Is there a well-defined cut-off between normal and abnormal values?
All I am doing, I should be clear, is taking the feted media nutritionists at their own word: they present themselves as men and women of science, fill their columns, TV shows and books with references to scientific research. I am subjecting their claims to the exact same level of very basic, uncomplicated rigour that I would deploy for any new theoretical work, any drug company claim and pill marketing rhetoric, and so on.
It’s not unreasonable to use surrogate outcome data, as they do, but those who are in the know are always circumspect. We’re interested in early theoretical work, but often the message is: ‘It might be a bit more complicated than that…’. You’d only want to accord a surrogate outcome any significance if you’d read everything on it yourself, or if you could be absolutely certain that the person assuring you of its validity was extremely capable, and was giving a sound appraisal of all the research in a given field, and so on.
Similar problems arise with animal data. Nobody could deny that this kind of data is valuable in the theoretical domain, for developing hypotheses, or suggesting safety risks, when cautiously appraised. But media nutritionists, in their eagerness to make lifestyle claims, are all too often blind to the problems of applying these isolated theoretical nuggets to humans, and anyone would think they were just trawling the internet looking for random bits of science to sell their pills and expertise (imagine that). Both the tissue and the disease in an animal model, after all, may be very different to those in a living human system, and these problems are even greater with a lab-dish model. Giving unusually high doses of chemicals to animals can distort the usual metabolic pathways, and give misleading results—and so on. Just because something can upregulate or downregulate something in a model doesn’t mean it will have the effect you expect in a person—as we will see with the stunning truth about antioxidants.
And what about turmeric, which we were talking about before I tried to show you the entire world of applying theoretical research in this tiny grain of spice? Well, yes, there is some evidence that curcumin, a chemical in turmeric, is highly biologically active, in all kinds of different ways, on all kinds of different systems (there are also theoretical grounds for believing that it may be carcinogenic, mind you). It’s certainly a valid target for research.
But for the claim that we should eat more curry in order to get more of it, that ‘recent research’ has shown it is ‘highly protective against many forms of cancer, especially of the prostate’, you might want to step back and put the theoretical claims in the context of your body. Very little of the curcumin you eat is absorbed. You have to eat a few grams of it to reach significant detectable serum levels, but to get a few grams of curcumin, you’d have to eat 100g of turmeric: and good luck with that. Between research and recipe, there’s a lot more to think about than the nutritionists might tell you.
Cherry-picking
The idea is to try and give all the information to help others to judge the value of your contribution; not just the information that leads to judgment in one particular direction or another.
Richard P. Feynman
There have been an estimated fifteen million medical academic articles published so far, and 5,000 journals are published every month. Many of these articles will contain contradictory claims: picking out what’s relevant—and what’s not—is a gargantuan task. Inevitably people will take shortcuts. We rely on review articles, or on meta-analyses, or textbooks, or hearsay, or chatty journalistic reviews of a subject.
That’s if your interest is in getting to the truth of the matter. What if you’ve just got a point to prove? There are few opinions so absurd that you couldn’t find at least one person with a PhD somewhere in the world to endorse them for you; and similarly, there are few propositions in medicine so ridiculous that you couldn’t conjure up some kind of published experimental evidence somewhere to support them, if you didn’t mind it being a tenuous relationship, and cherry-picked the literature, quoting only the studies that were in your favour.
One of the great studies of cherry-picking in the academic literature comes from an article about Linus Pauling, the greatgrandfather of modern nutritionism, and his seminal work on vitamin C and the common cold. In 1993 Paul Knipschild, Professor of Epidemiology at the University of Maastricht, published a chapter in the mighty textbook Systematic Reviews: he had gone to the extraordinary trouble of approaching the literature as it stood when Pauling was working, and subjecting it to the same rigorous systematic review that you would find in a modern paper.
He found that while some trials did suggest that vitamin C had some benefits, Pauling had selectively quoted from the literature to prove his point. Where Pauling had referred to some trials which seriously challenged his theory, it was to dismiss them as methodologically flawed: but as a cold examination showed, so too were papers he quoted favourably in support of his own case.
In Pauling’s defence, his was an era when people knew no better, and he was probably quite unaware of what he was doing: but today cherry-picking is one of the most common dubious practices in alternative therapies, and particularly in nutrition-ism, where it seems to be accepted essentially as normal practice (it is this cherry-picking, in reality, which helps to characterise what alternative therapists conceive of rather grandly as their ‘alternative paradigm’). It happens in mainstream medicine also, but with one crucial difference: there it is recognised as a major problem, and hard work has been done to derive a solution.
That solution is a process called ‘systematic review’. Instead of just mooching around online and picking out your favourite papers to back up your prejudices and help you sell a product, in a systematic review you have an explicit search strategy for seeking out data (openly described in your paper, even including the search terms you used on databases of research papers), you tabulate the characteristics of each study you find, you measure—ideally blind to the results—the methodological quality of each one (to see how much of a ‘fair test’ it is), you compare alternatives, and then finally you give a critical, weighted summary.
This is what the Cochrane Collaboration does on all the healthcare topics that it can find. It even invites people to submit new clinical questions that need an answer. This careful sifting of information has revealed huge gaps in knowledge, it has revealed that ‘best practices’ were sometimes murderously flawed, and simply by sifting methodically through pre-existing data, it has saved more lives than you could possibly imagine. In the nineteenth century, as the public-health doctor Muir Gray has said, we made great advances through the provision of clean, clear water; in the twenty-first century we will make the same advances through clean, clear information. Systematic reviews are one of the great ideas of modern thought. They should be celebrated.
Problematising antioxidants
We have seen the kinds of errors made by those in the nutri-tionism movement as they strive to justify their more obscure and technical claims. What’s more fun is to take our new understanding and apply it to one of the key claims of the nutrition-ism movement, and indeed to a fairly widespread belief in general: the claim that you should eat more antioxidants.
As you now know, there are lots of ways of deciding whether the totality of research evidence for a given claim stacks up, and it’s rare that one single piece of information clinches it. In the case of a claim about food, for example, there are all kinds of different things we might look for: whether it is theoretically plausible, whether it is backed up by what we know from observing diets and health, whether it is supported by ‘intervention trials’ where we give one group one diet and another group a different one, and whether those trials measured real-world outcomes, like ‘death’, or a surrogate outcome, like a blood test, which is only hypothetically related to a disease.
My aim here is by no means to suggest that antioxidants are entirely irrelevant to health. If I had a T–shirt slogan for this whole book it would be: ‘I think you’ll find it’s a bit more complicated than that’. I intend, as they say, to ‘problematise’ the prevailing nutritionist view on antioxidants, which currently lags only about twenty years behind the research evidence.
From an entirely theoretical perspective, the idea that antioxidants are beneficial for health is an attractive one. When I was a medical student—not so long ago—the most popular biochemistry textbook was called Stryer. This enormous book is filled with complex interlocking flow charts of how chemicals—which is what you are made of—move through the body. It shows how different enzymes break down food into its constituent molecular elements, how these are absorbed, how they are reassembled into new larger molecules that your body needs to build muscles, retina, nerves, bone, hair, membrane, mucus, and everything else that you’re made of; how the various forms of fats are broken down, and reassembled into new forms of fat; or how different forms of molecule—sugar, fat, even alcohol—are broken down gradually, step by step, to release energy, and how that energy is transported, and how the incidental products from that process are used, or bolted onto something else to be transported in the blood, and then ditched at the kidneys, or metabolised down into further constituents, or turned into something useful elsewhere, and so on. This is one of the great miracles of life, and it is endlessly, beautifully, intricately fascinating.
Looking at these enormous, overwhelming interlocking webs, it’s hard not to be struck by the versatility of the human body, and how it can perform acts of near alchemy from so many different starting points. It would be very easy to pick one of the elements of these vast interlocking systems and become fixated on the idea that it is uniquely important. Perhaps it appears a lot on the diagram; or perhaps rarely, and seems to serve a uniquely important function in one key place. It would be easy to assume that if there was more of it around, then that function would be performed with greater efficiency.
But, as with all enormous interlocking systems—like societies, for example, or businesses—an intervention in one place can have quite unexpected consequences: there are feedback mechanisms, compensatory mechanisms. Rates of change in one localised area can be limited by quite unexpected factors that are entirely remote from what you are altering, and excesses of one thing in one place can distort the usual pathways and flows, to give counterintuitive results.
The theory underlying the view that antioxidants are good for you is the ‘free radical theory of ageing’. Free radicals are highly chemically reactive, as are many things in the body. Often this reactivity is put to very good use. For example, if you have an infection, and there are some harmful bacteria in your body, then a phagocytic cell from your immune system might come along, identify the bacteria as unwelcome, build a strong wall around as many of them as it can find, and blast them with destructive free radicals. Free radicals are basically like bleach, and this process is a lot like pouring bleach down the toilet. Once again, the human body is cleverer than anybody you know.
But free radicals in the wrong places can damage the desirable components of cells. They can damage the lining of your arteries, and they can damage DNA; and damaged DNA leads to ageing or cancer, and so on. For this reason, it has been suggested that free radicals are responsible for ageing and various diseases. This is a theory, and it may or may not be correct.
Antioxidants are compounds which can—and do—‘mop up’ these free radicals, by reacting with them. If you look at the vast, interlocking flow chart diagrams of how all the molecules in your body are metabolised from one form to the next, you can see that this is happening all over the shop.
The theory that antioxidants are protective is separate to—but builds upon—the free radical theory of disease. If free radicals are dangerous, the argument goes, and antioxidants on the big diagrams are involved in neutralising them, then eating more antioxidants should be good for you, and reverse or slow ageing, and prevent disease.
There are a number of problems with this as a theory. Firsdy, who says free radicals are always bad? If you’re going to reason just from theory, and from the diagrams, then you can hook all kinds of things together and make it seem as if you’re talking sense. As I said, free radicals are vital for your body to kill off bacteria in phagocytic immune cells: so should you set yourself up in business and market an antioxidant-free diet for people with bacterial infections?
Secondly, just because antioxidants are involved in doing something good, why should eating more of them necessarily make that process more efficient? I know it makes sense superficially, but so do a lot of things, and that’s what’s really interesting about science (and this story in particular): sometimes the results aren’t quite what you might expect. Perhaps an excess of antioxidants is simply excreted, or turned into something else. Perhaps it just sits there doing nothing, because it’s not needed. After all, half a tank of petrol will get you across town just as easily as a full tank. Or perhaps, if you have an unusually enormous amount of antioxidant lying around in your body doing nothing, it doesn’t just do nothing. Perhaps it does something actively harmful. That would be a turn-up for the books, wouldn’t it?
There were a couple of other reasons why the antioxidant theory seemed like a good idea twenty years ago. Firsdy, when you take a static picture of society, people who eat lots of fresh fruit and vegetables tend to live longer, and have less cancer and heart disease; and there are lots of antioxidants in fruit and vegetables (although there are lots of other things in them too, and, you might rightly assume, lots of other healthy things about the lives of people who eat lots healthy fresh fruit and vegetables, like their posh jobs, moderate alcohol intake, etc.).
Similarly, when you take a snapshot picture of the people who take antioxidant supplement pills, you will often find that they are healthier, or live longer: but again (although nutritionists are keen to ignore this fact), these are simply surveys of people who have already chosen to take vitamin pills. These are people who are more likely to care about their health, and are different from the everyday population—and perhaps from you—in lots of other ways, far beyond their vitamin pill consumption: they may take more exercise, have more social supports, smoke less, drink less, and so on.
But the early evidence in favour of antioxidants was genuinely promising, and went beyond mere observational data on nutrition and health: there were also some very seductive blood results. In 1981 Richard Peto, one of the most famous epidemiologists in the world, who shares the credit for discovering that smoking causes 95 per cent of lung cancer, published a major paper in Nature. He reviewed a number of studies which apparently showed a positive relationship between having a lot of ?-carotene onboard (this is an antioxidant available in the diet) and a reduced risk of cancer.
This evidence included ‘case-control studies’, where people with various cancers were compared against people without cancer (but matched for age, social class, gender and so on), and it was found that the cancer-free subjects had higher plasma carotene. There were also ‘prospective cohort studies’, in which people were classified by their plasma carotene level at the beginning of the study, before any of them had cancer, and then followed up for many years. These studies showed twice as much lung cancer in the group with the lowest plasma carotene, compared with those with the highest level. It looked as if having more of these antioxidants might be a very good thing.
Similar studies showed that higher plasma levels of antioxidant vitamin E were related to lower levels of heart disease. It was suggested that vitamin E status explained much of the variations in levels of ischaemic heart disease between different countries in Europe, which could not be explained by differences in plasma cholesterol or blood pressure.
But the editor of Nature was cautious. A footnote was put onto the Peto paper which read as follows:
Unwary readers (if such there are) should not take the accompanying article as a sign that the consumption of large quantities of carrots (or other dietary sources of (3-carotene) is necessarily protective against cancer.
It was a very prescient footnote indeed.
The antioxidant dream unravels
Whatever the shrill alternative therapists may say, doctors and academics have an interest in chasing hints that could bear fruit, and compelling hypotheses like these—which could save millions of lives—are not taken lightly. These studies were acted upon, with many huge trials of vitamins set up and run around the world. There’s also an important cultural context for this rush of activity which cannot be ignored: it was the tail end of the golden age of medicine. Before 1935 there weren’t too many effective treatments around: we had insulin, liver for iron deficiency anaemia, and morphine—a drug with superficial charm at least—but in many respects, doctors were fairly useless. Then suddenly, between about 1935 and 1975, science poured out a constant stream of miracles.
Almost everything we associate with modern medicine happened in that time: treatments like antibiotics, dialysis, transplants, intensive care, heart surgery, almost every drug you’ve ever heard of, and more. As well as the miracle treatments, we really were finding those simple, direct, hidden killers that the media still pine for so desperately in their headlines. Smoking, to everybody’s genuine surprise—one single risk factor—turned out to cause almost all lung cancer. And asbestos, through some genuinely brave and subversive investigative work, was shown to cause mesothelioma.
The epidemiologists of the 1980s were On a roll, and they believed that they were going to find lifestyle causes for all the major diseases of humankind. A discipline that had got cracking when John Snow took the handle off the Broad Street pump in 1854, terminating that pocket of the Soho cholera epidemic by cutting off the supply of contaminated water (it was a bit more complicated than that, but we don’t have the time here) was going to come into its own. They were going to identify more and more of these one-to-one correlations between exposures and disease, and, in their fervent imaginations, with simple interventions and cautionary advice they were going to save whole nations of people. This dream was very much not realised, as it turned out to be a bit more complicated than that.
Two large trials of antioxidants were set up after Peto’s paper (which rather gives the lie to nutritionists’ claims that vitamins are never studied because they cannot be patented: in fact there have been a great many such trials, although the food supplement industry, estimated by one report to be worth over $50 billion globally, rarely deigns to fund them). One was in Finland, where 30,000 participants at high risk of lung cancer were recruited, and randomised to receive either ?-carotene, vitamin E, or both, or neither. Not only were there more lung cancers among the people receiving the supposedly protective ?-carotene supplements, compared with placebo, but this vitamin group also had more deaths overall, from both lung cancer and heart disease.
The results of the other trial were almost worse. It was called the ‘Carotene and Retinol Efficacy Trial’, or ‘CARET’, in honour of the high p-carotene content of carrots. It’s interesting to note, while we’re here, that carrots were the source of one of the great disinformation coups of World War II, when the Germans couldn’t understand how our pilots could see their planes coming from huge distances, even in the dark. To stop them trying to work out if we’d invented anything clever like radar (which we had), the British instead started an elaborate and entirely made-up nutritionist rumour. Carotenes in carrots, they explained, are transported to the eye and converted to retinal, which is the molecule that detects light in the eye (this is basically true, and is a plausible mechanism, like those we’ve already dealt with): so, went the story, doubtless with much chortling behind their excellent RAF moustaches, we have been feeding our chaps huge plates of carrots, to jolly good effect.
Anyway. Two groups of people at high risk of lung cancer were studied: smokers, and people who had been exposed to asbestos at work. Half were given 3-carotene and vitamin A, while the other half got placebo. Eighteen thousand participants were due to be recruited throughout its course, and the intention was that they would be followed up for an average of six years; but in fact the trial was terminated early, because it was considered unethical to continue it. Why? The people having the antioxidant tablets were 46 per cent more likely to die from lung cancer, and 17 per cent more likely to die of any cause,* than the people taking placebo pills. This is not news, hot off the presses: it happened well over a decade ago.
≡ I have deliberately expressed this risk in terms of the ‘relative risk increase’, as part of a dubious in-joke with myself. You will learn about this on page 240.
Since then the placebo-controlled trial data on antioxidant vitamin supplements has continued to give negative results. The most up-to-date Cochrane reviews of the literature pool together all the trials on the subject, after sourcing the widest possible range of data using the systematic search strategies described above (rather than ‘cherry-picking’ studies to an agenda): they assess the quality of the studies, and then put them all into one giant spreadsheet to give the most accurate possible estimate of the risks of benefits, and they show that antioxidant supplements are either ineffective, or perhaps even actively harmful.
The Cochrane review on preventing lung cancer pooled data from four trials, describing the experiences of over 100,000 participants, and found no benefit from antioxidants, and indeed an increase in risk of lung cancer in participants taking ?-carotene and retinol together. The most up-to-date systematic review and meta-analysis on the use of antioxidants to reduce heart attacks and stroke looked at vitamin E, and separately 0-carotene, in fifteen trials, and found no benefit for either. For ?-carotene, there was a small but significant increase in death.
Most recently, a Cochrane review looked at the number of deaths, from any cause, in all the placebo-controlled randomised trials on antioxidants which have ever been performed (many of which looked at quite high doses, but perfectly in line with what you can buy in health-food stores), describing the experiences of 230,000 people in total. This showed that overall, antioxidant vitamin pills do not reduce deaths, and in fact they may increase your chance of dying.
Where does all this leave us? There was an observed correlation between low blood levels of these antioxidant nutrients and a higher incidence of cancer and heart disease, and a plausible mechanism for how they could have been preventive: but when you gave them as supplements, it turned out that people were no better off, or were possibly more likely to die. That is, in some respects, a shame, as nice quick fixes are always useful, but there you go. It means that something funny is going on, and it will be interesting to get to the bottom of it and find out what.
More interesting is how uncommon it is for people even to be aware of these findings about antioxidants. There are various reasons why this has happened. Firstly, it’s an unexpected finding, although in that regard antioxidants are hardly an isolated case. Things that work in theory often do not work in practice, and in such cases we need to revise our theories, even if it is painful. Hormone replacement therapy seemed like a good idea for many decades, until the follow-up studies revealed the problems with it, so we changed our views. And calcium supplements once looked like a good idea for osteoporosis, but now it turns out that they probably increase the risk of heart attacks in older women, so we change our view.
It’s a chilling thought that when we think we are doing good, we may actually be doing harm, but it is one we must always be alive to, even in the most innocuous situations. The paediatrician Dr Benjamin Spock wrote a record-breaking best-seller called Baby and Child Care, first published in 1946, which was hugely influential and largely sensible. In it, he confidently recommended that babies should sleep on their tummies. Dr Spock had little to go on, but we now know that this advice is wrong, and the apparently trivial suggestion contained in his book, which was so widely read and followed, has led to thousands, and perhaps even tens of thousands, of avoidable cot deaths. The more people are listening to you, the greater the effects of a small error can be. I find this simple anecdote deeply disturbing.
But of course, there is a more mundane reason why people may not be aware of these findings on antioxidants, or at least may not take them seriously, and that is the phenomenal lobbying power of a large, sometimes rather dirty industry, which sells a lifestyle product that many people feel passionately about. The food supplement industry has engineered itself a beneficent public image, but this is not borne out by the facts. Firstly, there is essentially no difference between the vitamin industry and the pharmaceutical and biotech industries (that is one message of this book, after all: the tricks of the trade are the same the world over). Key players include companies like Roche and Aventis; BioCare, the vitamin pill company that media nutritionist Patrick Holford works for, is part-owned by Elder Pharmaceuticals, and so on. The vitamin industry is also—amusingly—legendary in the world of economics as the setting of the most outrageous price-fixing cartel ever documented. During the 1990s the main offenders were forced to pay the largest criminal fines ever levied in legal history—$1.5 billion in total—after entering guilty pleas with the US Department of Justice and regulators in Canada, Australia and the European Union. That’s quite some cosy cottage industry.
Whenever a piece of evidence is published suggesting that the $50-billion food supplement pill industry’s products are ineffective, or even harmful, an enormous marketing machine lumbers into life, producing spurious and groundless methodological criticisms of the published data in order to muddy the waters—not enough to be noteworthy in a meaningful academic discussion, but that is not their purpose. This is a well-worn risk-management tactic from many industries, including those producing tobacco, asbestos, lead, vinyl chloride, chromium and more. It is called ‘manufacturing doubt’, and in 1969 one tobacco executive was stupid enough to commit it to paper in a memo: ‘Doubt is our product,’ he wrote, ‘since it is the best means of competing with the ‘body of fact’ that exists in the minds of the general public. It is also the means of establishing a controversy.’
Nobody in the media dares to challenge these tactics, where lobbyists raise sciencey-sounding defences of their products, because they feel intimidated, and lack the skills to do so. Even if they did, there would simply be a confusing and technical discussion on the radio, which everyone would switch off, and at most the consumer would hear only ‘controversy’: job done.
I don’t think that food supplement pills are as dangerous as tobacco—few things are—but it’s hard to think of any other kind of pill where research could be published showing a possible increase in death, and industry figures would be wheeled out and given as easy a ride as the vitamin companies’ employees are given when papers are published on their risks. But then, of course, many of them have their own slots in the media to sell their wares and their world view.
The antioxidant story is an excellent example of how wary we should be of blindly following hunches based on laboratory-level and theoretical data, and naively assuming, in a reductionist manner, that this must automatically map onto dietary and supplement advice, as the media nutritionists would have us do. It is an object lesson in what an unreliable source of research information these characters can be, and we would all do well to remember this story the next time someone tries to persuade us with blood test data, or talk about molecules, or theories based on vast, interlocking metabolism diagrams, that we should buy their book, their wacky diet, or their bottle of pills.
More than anything it illustrates how this atomised, overcomplicated view of diet can be used to mislead and oversell. I don’t think it’s melodramatic to speak of people disempowered and paralysed by confusion, with all the unnecessarily complex and conflicting messages about food. If you’re really worried, you can buy Fruitella Plus with added vitamins A, C, E and calcium, and during Christmas 2007 two new antioxidant products came on the market, the ultimate expression of how nutritionism has perverted and distorted our common sense about food. Choxi+ is milk chocolate with ‘extra antioxidants’. The Daily Mirror says it’s ‘too good to be true’. It’s ‘chocolate that is good for you, as well as seductive’, according to the Daily Telegraph. ‘Guilt free’, says the Daily Mail: it’s ‘the chocolate bar that’s ‘healthier’ than 5lb of apples’. The company even ‘recommends’ two pieces of its chocolate a day. Meanwhile, Sainsbury’s is promoting Red Heart wine—with extra antioxidants—as if drinking the stuff was a duty to your grandchildren.
If I was writing a lifestyle book it would have the same advice on every page, and you’d know it all already. Eat lots of fruit and vegetables, and live your whole life in every way as well as you can: exercise regularly as part of your daily routine, avoid obesity, don’t drink too much, don’t smoke, and don’t get distracted from the real, basic, simple causes of ill health. But as we will see, even these things are hard to do on your own, and in reality require wholesale social and political changes.