What I have learned about dietary health slogans

Photo by Possessed Photography on Unsplash

In popular jargon, diet and health advice is usually presented as a series of rebukes in the form of slogans, such as: eat less saturated fat; eat more polyunsaturated ‘vegetable’ oils (even though they’re not made from vegetables); eat less salt; eat more fibre; eat more grains (and cereals made from them); eat less cholesterol; eat less ‘red’ and processed meat; drink more water; eat more fruits and vegetables or; eat a ‘Mediterranean’ diet or some-such thing. Authorities imagine that adhering to these simplistic slogans is going to solve the complex mystery of individual health and longevity. There’s a purpose to these simplifications though — dumb down complex science to increase the persuasiveness of the message and to leave no room for doubt. I’ll come back to persuasion later.

But, what if the science underlying these slogans hasn’t even been done, or is more inconclusive than reported, or is poorly done science, or uses weak study designs, or applies only to a subset of the population, or is subject to biased analysis, or misrepresents the significance of the findings, or is not scientifically published if it doesn’t conform to prevailing opinion, or is overblown sensationally in the popular media?

These considerations not only apply to, but are at the core of, mainstream nutrition science. None of the slogans I listed are founded on strong scientific evidence.

Saturated Fat

Take one example to highlight the lack of science: the saturated fat (sat-fat) hypothesis. Surely, there must be substantial science to support the health benefits of eating less saturated fat by now!

Well, no, not from definitive scientific studies. The best scientific evidence we have available indicates that dietary saturated fat does not increase the risk of heart disease or stroke. The biggest risk it poses is an increase in the enjoyment of food.

If nutrition science was following the fundamental principles of science, then the sat-fat hypothesis would have been rejected as false decades ago, and other risk factors for heart disease sought (such as sugar or insulin resistance). Instead, there have been shenanigans aplenty to prop up this hypothesis, including not publishing data that don’t support it. The first major randomised control trial (RCT) of the sat-fat hypothesis was carried out in Minnesota between 1968–73 in almost 10,000 participants, 20–97 years of age. A RCT is a sound scientific method. The trial tested whether replacing saturated fat with polyunsaturated corn oil would lower blood cholesterol and thereby reduce heart disease. They found that corn oil did lower blood cholesterol, however this increased mortality (all-cause death) — the lower that blood cholesterol was driven, the greater the mortality. This dietary substitution (oil for fat) also worsened survival in the elderly (> 65 years of age).

Rather than publishing these findings, the investigators (who expected their study to support the sat-fat hypothesis) bundled everything into archive boxes and stored it in the basement, where it remained for ~40 years. The data were rediscovered recently (~2011), recovered from magnetic tapes and punch cards, analysed using modern methods, and the full results finally published (2017). However, the sat-fat hypothesis has become unassailable, and the results of the study have had little impact. Science alone is not enough, and I will explain why later.

The 1960s-era Sydney Diet Heart Study was set up to answer the same question and ultimately suffered the same fate — it found that replacing dietary saturated fat with polyunsaturated oils increased the risk of death from coronary heart disease. The data were never published by the investigators, but were recovered and independently published in 2013.

Failure to publish undermines truth, but that only matters if the truth matters. There have been many other shenanigans over the decades.

Advocates for the sat-fat hypothesis will always be able to find studies to support it. However, these studies are invariably observational (not RCTs), meaning they are statistical rather than scientific. They look for association and cannot show causation, they are confounded by numerous uncontrollable factors any of which could variably contribute to causation, and they produce ‘evidence’ so weak it should be dismissed in any case.

These considerations are endemic to mainstream nutritional science. Certainly, there are scientists doing good work in diet and health, but they are not mainstream, and they rarely get on the radar. If they do, they soon get shot at. Mainstream nutritional science is ruthlessly protective of its hegemony.

Here’s an example from as recent as 2019. An international group of scientists revisited the evidence against dietary red meat. They noted that the evidence was from observational studies and therefore weak. Their analysis of all available studies led them to the conclusion that eating red meat was not harmful and that there is no reason to alter our eating patterns. They published 6 papers on various aspects of this topic in the Annals of Internal Medicine — a prestigious peer-reviewed medical journal. Mainstream nutritional science reacted with hostility to this conclusion and demanded the articles be retracted. In other words, that the papers be removed from the journal and quashed. Retraction is a serious step for a scientific journal to take, and usually only enacted for scientific fraud or serious flaws. In this case, the journal rejected the demand — this one got under the nutritionist radar. Still, there will be instances where discordant studies can be sidelined by other means (e.g. restricting funding, manipulation of the peer-review system, editorial pressures, academic intimidation, etc.).

Nutritional Scientism

The problem is with the term ‘Nutritional Science’ — just calling something science doesn’t necessarily make it so. Still, nutrition started out with good scientific intentions, building on the life sciences (biology, chemistry, physiology). The first success, from the 19th century, was in recognising the importance of macronutrients (protein, fat, and carbohydrate) for energy and health. Then, the beginning of the 20th century saw what was arguably nutrition’s greatest moment — the identification of nutrient-deficiency diseases and their causes. Vitamins were discovered, the importance of minerals recognised, and several significant medical conditions treated (scurvy, beriberi, rickets etc).

However, by the mid 20th century, nutrition started to lose its way by thinking that it could go beyond nutrient-deficiency to predict and manage life itself, in the form of determining what constituted the elements of diet and health. This advice was formulated over time, and influenced by various factors such as the rise of nutritional epidemiology (observational studies), the expansion of large-scale crop agriculture and food processing, the involvement of the State and an increasing interest in ‘health’. It took a while, but during this process, nutritional science morphed into a kind of nutritional scientism — the superficial and simplistic use of science in the service of nutritional ideology. Instead of an accumulating evidence-base, dietary advice was increasingly built around a sense of righteousness — e.g. the virtue of plants, the decadence of meat and the embrace of modernity.

Once nutritional scientism had decided, by whatever means, the rules of diet and health, the onus was on us to obey those rules and to lead healthy lives without being a burden on society. The State became involved, issuing guidelines and establishing expert committees to direct population health, and using health to justify their social and political interventions in our lives. We are expected to respect these authorities. Big Food, Big Ag, Big Pharma and Big Marketing were unleashed — commercial entities not much interested in our health. Reputations, and money, were made. The State widened its omniscience.

And yet, we know we are living through an unprecedented era of non-communicable diseases (NCDs) that were once rare (type 2 diabetes, Alzheimer’s disease, heart disease, cancer, non-alcoholic fatty liver disease…). For decades, nutritional scientism has run an uncontrolled, and unrepentant, experiment on our health that has failed us. The scale of the failure, and the horrendous consequences for individuals living with advanced NCDs, qualifies this experiment as a crime against humanity.

Nutritional Bullshit instead

I’ve used the term Nutritional Scientism up to now, but that’s rather dry and academic. Nutritional Bullshit is a term more to the point. Furthermore, I will now show that it is a theoretically appropriate term, not just colourful language.

The concept of bullshit has received academic attention — there’s a theory of bullshit. In 2005, a Princeton University Professor of Analytic Philosophy, Harry Gordon Frankfurt, published a short monograph with the title “On Bullshit”. It became a New York Times bestseller. His opening sentence reads:

One of the most salient features of our culture is that there is so much bullshit.”

Hear-hear. He goes on with the intention “to begin the development of a theoretical understanding of bullshit […] the most basic and preliminary questions about bullshit remain, after all, not only unanswered but unasked.”

His central thesis is that there is a fundamental difference between bullshit and lying. To lie, one must at least know the truth. “It is impossible for someone to lie unless he thinks he knows the truth. Producing bullshit requires no such conviction.” Bullshit may be true or false, it doesn’t matter — Frankfurt regarded the essence of bullshit to be an indifference to the truth. The bullshitter is interested in persuading the listener to his view instead.

Which explains why Nutritional Bullshit is an appropriate term. I don’t believe that most mainstream nutritionists are deliberately lying — they are bullshitting. They have formulated their rules on diet and health and it doesn’t matter if they are true or false, it matters that they persuade us to their way of thinking. It matters that they matter.

This perspective can also explain why newer and more rigorous scientific studies (debunking the sat-fat hypothesis, for example) don’t make a difference. It’s because the truth doesn’t matter, the bullshitter is indifferent to how things really are. There is a futility in trying to convince people with facts alone, if they’ve already been persuaded by bullshit.

In Closing

Conventional diet and health advice are not science-based, they represent an abuse of the scientific method. The essence of nutritional bullshit is persuasion. We can also see the benefits of defining our terms — rather than use ‘bullshit’ merely to disparage mainstream nutrition, the theory of bullshit gives us new insights into the relevance to nutrition. Of course, the relevance is not only confined to nutrition.

Further reading:

Minnesota Coronary Study: https://www.bmj.com/content/bmj/353/bmj.i1246.full.pdf

Sydney Heart Study: https://www.bmj.com/content/bmj/346/bmj.e8707.full.pdf

Detailed summary of the red meat papers: https://www.zoeharcombe.com/2019/10/meat-guidelines-the-evidence

Summary editorial of the red meat papers: https://annals.org/aim/fullarticle/2752329/meat-consumption-health-food-thought

Nutritional Scientism (pay-walled): https://doi.org/10.1007/s11673-015-9670-4

Harry Frankfurt, book: “On Bullshit

Harry Frankfurt, YouTube https://youtu.be/_D9Y-1Jcov4




Science of cooking, eating and health. Retired neuroscientist.

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Science of cooking, eating and health. Retired neuroscientist.

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