You are what you eat: The "wicked hard" science of nutrition

In 1993, Collins & Pinch published a series of incisive essays on the nature of science entitled ‘The Golem: what everyone should know about science’. In a series of seven essays, they liken science to a ‘Golem’ – a creature of Jewish mythology that is made of clay.

 It does not understand truth, but is driven by it. Science is neither all good nor all bad; it is only a golem. The question is: how do people use this creature? Of course, science is not alone there, nor is it the ‘unique’ golem of humanity. The following is an examination of the ‘Nutrition’ golem. It is not the only clay-monster out there, but it is the one we’re all likely to encounter most frequently. We may get through our life without understanding the limitations and discoveries of particle physics –but we’re as sure as hell going to be ingesting food.

Introduction

We’ve all heard it, the ubiquitous, friendly, simplistic and comforting advice; ‘You are what you eat’. It makes you think twice about reaching for that donut, and simultaneously gives you an almost puritanical psychological rush when you chow down on a salad. Common sense tells you that it should be simple and easy. Humans have been ingesting and metabolizing food for millennia, right? It’s not like this is ‘new’. How can something so basic and natural to the human condition be so difficult to navigate?

A recent headline in the Washington Post offered a succinct answer: ‘Nutrition science isn’t broken, it’s just wicked hard’ (Gallegos, 2017). Nutrition science is a mess. It defines ‘messy’. It also provides the perfect example of the nature of the scientific process, its wonders and its shortcomings. It’s also worth remembering that, relatively speaking, it is a ‘new’ science. The field of Chemistry has been studied around ten times longer than the field of Nutrition, and its first 200 years were marked by what we would now call ‘limited’ progress. As Dr John Berardi (2018) puts it: “one could say the field of nutrition is in its “Alchemy Days”.

The simplest answer as to why it is so difficult for humans to make the most salient choices in food, is because, well –we’re humans. Our relationship with food is not just a matter of balancing energy intake and nutrients. Food intake encompasses the fields of biochemistry, sociology, ideology, psychology and ecology. It is genetic, emotional, spiritual, microbiological, political and more besides. How, why, where, when and with whom we choose to ingest food are equally as important to human beings as the food’s actual physical nature or its nutrient breakdown as elucidated by the unflinching microscope of scientific reductionist empiricism. Indeed, the inherently cross and multi-disciplinary nature of this field is both its greatest strength and its most fundamental challenge (Allison et al. 2015, Döring & Ströhle, 2015). 

Human beings and our relationship with food is an enormous, complex tapestry with thousands of interwoven, interlocking threads and none of them move in nice, predictable straight lines. This fine, intellectually or academically speaking –a marvellous puzzle, a delightful challenge – a life’s work (and then some), but there’s an elephant in the room…a big one. The incidence of diet-related non-communicable diseases (NCDs) is increasing at an exponential rate worldwide with alarming socio-economic impacts (WHO 2017). Despite our knowledge to date, Nutrition science is failing to make a dent in an enormous global health crisis (Walls, Johnston, Mazalate & Chirwa, 2018; Adams, 2015; Pollan, 2007). In order to focus our enquiry we will not attempt to analyse all potential and actual human foods, but look closely at one of humanity’s oldest food-sources to date, and one of the most controversial: the humble egg.

Which came first?

“Which came first, the chicken or the egg?” is, at first glance, one of those ubiquitous clever-clogs conundrums presented within an argument to imply infinite regress –an uncertainty as to delineation of cause and effect. Indeed, this was the purpose of the question as posed by philosophy in the writings of both Aristotle and Plutarch (Merrill, 2016; Sorenson, 2003). Of course, with the emergent tools of evolutionary biology and the work of a certain Mr Darwin, scientists have since deduced that it is not a matter of infinite regress, -the answer is ‘the egg’ (Sorenson, 1992). Despite this neat evolutionary summation of the egg’s place in time, the delineation of cause and effect when humans actually eat eggs is a little more complicated.

 Since the advent of farming, and the domestication of fowl, eggs have been a common staple across continents and socio-economic classes (Touissant-Samat, 1994). As a rich, relatively inexpensive form of both protein and energy, the humble egg was a boon to the human diet, especially pre-1885 when most Nutrition science was focused on either protein or energy –mostly due to the fact that these were often missing from people’s diets and resulted in obvious and devastating health outcomes (Carpenter, 2003). As the 20^th Century dawned and diseases of dietary deficiency began to wane, a Dutch scientist led the scientific community into a new field, -micronutrients and their effects on human health (Grijns, 1935). In the 20^th and 21^st Centuries, the Western world witnessed an entirely new phenomenon –compromised health due to over-eating. In a nutshell, people began to consume too many calories and too much low-quality (nutrient-poor) food and the incidence of chronic NCD’s (cancer, diabetes, obesity, heart disease) began its meteoric and as yet, unchecked exponential rise. Unlike the previous century’s deficiency-states (like scurvy), these new illnesses were more complex: they don’t develop overnight, and fixing them isn’t just a matter of iodising salt, or adding an orange to a person’s diet (Bhatt, 2010), but old habits die hard and science continued to do what it does, -break down large problems into component parts and answerable parameters in order to provide meaningful data.

Dietary fat and Cardiovascular Disease (CVD), the early years.

In the late 1950’s Ancel Keys undertook the now famous/infamous Seven Countries Study, an epidemiological investigation into the incidence of coronary heart disease. Serum cholesterol was identified as a universal risk factor (Keys, 1980). The study was largely based on Keys’ previous work (Keys, 1953) as well as published investigations into the effects of lipids and lipoproteins on serum cholesterol levels in animal studies (Gofman et al., 1950). According to the scientific knowledge of the time, high dietary cholesterol led to high blood (serum) cholesterol which resulted in a high risk of developing cardiovascular disease (Kritchevsky, 1998). There were three distinct and convincing lines of evidence presented:

1.     1.  Animal studies (rabbits) showing that cholesterol in the diet increased serum cholesterol and the development of atherosclerosis;

2.     2.  Epidemiological evidence that high cholesterol intake was positively correlated with CVD incidence, and;

3.    3.   Clinical studies showing that high cholesterol intake led to increased serum cholesterol levels.

As a result of the available evidence, in 1968 the American Heart Association took the first real leap into demonizing one particular food –the egg. The public were advised to consume absolutely no more than three egg yolks per week (McNamara, 2015). The egg industry took a serious hit. Why did all the focus land on the egg and not any other source of dietary cholesterol? Perhaps because the researchers were using powdered egg as their cholesterol source in the studies. This, in itself turns out to be a slight problem when it comes to data interpretation. Powdered egg that has been through the processes of liquefying, pasteurizing and spray-drying contains oxidized cholesterol (Yang & Chen, 2001), fresh eggs don’t. Oops. The important distinction that oxidised cholesterol causes atherosclerosis was missed. Quite simply, because science didn’t know that yet, and wouldn’t until thousands of further studies on the wider behaviour of cholesterol in human metabolism had been undertaken. The second slightly problematic aspect to the evidence that informed public dietary recommendations here is the dubious applicability of animal studies to human outcomes (Bracken, 2009). In this case, rabbits are herbivores, and as such, have problems metabolizing cholesterol (Fan. Et al., 2015). This is a useful quality for researchers as it leads to fast and dramatic somatic results, but the ethical questions surrounding the applicability of force-feeding a creature a substance that isn’t naturally part of their diet and then drawing conclusions about the resulting arterial cholesterol deposits to human health are numerous, and ongoing.

The end of the ‘Egg Wars’ ?

Despite the unquantified damage that had been done by encouraging the public to see eggs as ‘taboo’ (Meyer-Rochow, 2009), more recent studies have broadened their research scope and rather than reducing the egg to a mere vessel containing cholesterol, have embraced both the complexity of the food-matrix and the resultant collinearity of certain nutrients within eggs, -like saturated fat and cholesterol. The conclusion? –that dietary cholesterol is not an independent risk factor for CVD (Hegsted & Ausman, 1988; Kromhaut et al., 1995; McNamara, 2000). Further, cholesterol size, distribution and ratio (High-density lipoproteins and low-density lipoproteins) substantially altered the risk-benefit ratio of egg consumption (Howell. Et al., 1997; Clarke et al., 1997; Greene et al., 2005; Mutungi et al., 2008).

It turns out that eggs are far more than just ovulate vehicles of lurking cholesterol, and that many of the macro and micronutrients within them are of enormous benefit to humans. Egg protein is extremely useful for satiety and weight-control (Pelletier et al. 1996; Vander et al., 2005), and an excellent bioavailable source of choline, lutein and zeaxanthanin (Chung, Rasmussen & Johnson, 2004; Ribaya-Mercado & Blumberg, 2004; Wenzel et al., 2006; Zeisel, 2006).

The effect on public opinion?

One can only assume that the egg industry breathed a huge and collective sigh of relief, but the ‘damage’ had been done. The story of the egg and its subsequent investigations, public recommendations and retractions is a telling microcosm of public interaction with scientific method. The inherent uncertainty and mutability of scientific discovery, and the way it is communicated/reported makes people anxious (Pidgeon, 2014). Suddenly, studies that were once published in journals meant for peer-to-peer discussion are flashy headlines promising ‘cures’ and ‘breakthroughs’ (Belluz, 2017). The unfortunate result is often complete denouncement/abandonment of intellectual achievement (Nichols, 2017) and resultant emotionally-driven attachment to other readily available sources of variable trustworthiness (Rowe & Alexander, 2012). ‘Post-truth’, defined as “relating to or denoting circumstances in which objective facts are less influential in shaping public opinion than appeals to emotion and personal belief’ (Oxford University Press, 2017) was the Oxford Dictionary’s 2016 Word of the Year. The public are now more enamoured with ‘Scienciness’ than science –especially when it comes to nutrition and health (Burke, 2017).

The new egg war…

Just when you thought it was safe to go back into the coop…

                                         

While physical nutrition science was travelling well-worn paths of hypothesis, trial and publication regarding nutrient effects on human digestion and metabolism, social science wasn’t exactly asleep. Edging along beside her more empirical sister were emergent social ideologies that once again challenged the ‘science’. Human nutrition choices are no longer just about the food and its effect on personal or population health.

 Eggs have become complicated again. Are they Free-Range? Organic? Do we trust the labelling system either way? Is egg production sustainable? Are chickens indeed as intelligent as toddlers? What of institutionalized animal cruelty within layer breeding practises? Is it necessary to macerate day old male chickens en masse? When science pops its head up again with potential solutions to some of the aforementioned questions, it is often dealt a stinging blow by a very angry and reactive ‘public’ (Urwin, 2014; ABC Bush Telegraph, 2014). Indeed, Nutrition has been cited as ‘Science’s biggest fail’ (Adams, 2015).

 Is it? Or it a particularly toothsome example of a newly formed Golem, -not inherently evil, but “a little daft” (Collins & Pinch, 1993). In their seminal book introduction, Collins and Pinch warned that science/The Golem requires careful control, or “it may destroy its masters with its flailing vigour”. Have we indeed lost control of our Golem as some critics suggest (Rosenbaum, 2017)? –and if we are to change its story/narrative to regain control –how? Perhaps simple honesty regarding the nature of the beast is part of the solution.

 On the first day of medical school at Harvard, Professor Daniel Gilbert’s students are told the following: “Half of what we’re going to teach you is wrong –the problem is we don’t yet know which half” (Rosenbaum, 2017). Like the formula for a successful romantic relationship, openness and honesty may be the key. The ‘veil’ must be rent in twain, and locked doors flung open. “When the door is locked, we may knock it down; when the door is open, we may choose to come in” (Sandman, 2003). The work of the future in Nutrition science is to ensure that The Golem, its creators and its witnesses enter into a true understanding of each other, for our own sake and that of the amazing blue ‘egg’ we call home.

REFERENCES

ABC Bush Telegraph (2014). GM recipe saves millions of male chicks. [Interview with Dr Urwin]. Retrieved from: https://www.abc.net.au/radionational/programs/bushtelegraph/gm-eggs/5236662

Adams, S. (2015, February 2). Science’s Biggest Fail [Blog post]. Retrieved from: https://blog.dilbert.com/2015/02/02/sciences-biggest-fail/

Allison, D. B., Bassaganya-Riera, J., Burlingame, B., Brown, A. W., le Coutre, J., Dickson, S. L., …Vögele, C. (2015). Goals in Nutrition Science 2015-2020. Frontiers in Nutrition, 2(26) doi: 10.3389/fnut.2015.00026

Berardi, J. (2018). Why nutrition science is so confusing [Blog post]. Retrieved from: https://www.precisionnutrition.com/nutrition-science-is-so-confusing.

Belluz, J. (2017, February 27). This is why you shouldn’t believe that exciting new medical study [Blog Post]. Retrieved from: https://www.vox.com/2015/3/23/8264355/research-study-hype.

Bhatt, A. (2010). Evolution of Clinical Research: A History Before and Beyond James Lind. Perspectives in Clinical Research, 1(1), 6-10. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3149409

Bracken, M. B. (2009). Why animal studies are often poor predictors of human reactions to exposure. Journal of the Royal Society of Medicine, 102(3), 120-122 doi: 10.1258/jrsm.08k033

Burke, L. M. (2017). Communicating Sports Science in the Age of the Twittersphere. International Journal of Sport Nutrition and Exercise Metabolism, 26, 1-5 doi: 10.1123/ijsnem.2017-0057

Chung, H. Y., Rasmussen, H. M., Johnson. E. J. (2004). Lutein bioavailability is higher from lutein-enriched eggs than from supplements and spinach in men. Journal of Nutrition, 134(8), 1887-1893.

Clarke, R., Frost, C., Collins, R., Appleby, P., Peto, R. (1997). Dietary lipids and blood cholesterol: Quantitative meta-analysis of metabolic ward studies. The British Medical Journal (BMJ), 314. 112-117 doi: 10.1136/bmj.314.7074.112

Collins, H. & Pinch, T. (1993). The Golem: what everyone should know about science. Cambridge University press, Cambridge UK. ISBN: 0 521 33602 6

Döring, F. & Ströhle, A. (2015). Nutritional biology: a neglected basic discipline of nutritional science. Genes and Nutrition, 10(6) doi: 10.1007/s12263-015-0505-2.

Fan, J., Kitajmia, S., Watanabe, T., Xu, J., Zhang, J., Liu, E., Chen, Y. E. (2015). Rabbit models for the study of human atherosclerosis: from pathophysiological mechanism to translational medicine. Pharmacology and Therapeutics, 146. 104-119 doi: 10.1016/j.pharmthera.2014.09.009

Gallegos, J. (2017, July 22). Nutrition Science Isn’t Broken, It’s Just Wicked Hard [Blog post]. Retrieved from: https://www.sciencealert.com/nutrition-science-isn-t-broken-it-s-just-wocked-hard

Greene, C. M., Zern, T. L., Wood, R., Shrestha, S., Aggarwal, D., Sharman, M., Volek, J. S., Fernandez, M. L. (2005). Dietary cholesterol provided by eggs does not result in an increased risk for coronary heart disease in an elderly population. Journal of Nutrition, 135(8), 2793-2798

Grijns, G. (1935). Researches on Vitamins, 1900-1911. J.Noorduyn en Zoon. P.38. Gorinchem, The Netherlands. Retrieved from: https://www.delpher.nl/nl/boeken/view?coll=boeken&identifer=MMKB05%3A000037697%3A00010

Gofman, J. W., Lindgren, F., Elliott, H.., Mantz, W., Hewitt, J., Strisower, B., Herring, V., Lyon, T. P. (1950). The role of lipids and lipoproteins in atherosclerosis. Science, III. 166-171. Retrieved from: https://pdfs.semanticscholar.org/2633/aa514f948c20d6d7047e007949324de78dc,pdf

Hegsted, D. M. & Ausman, L. M. (1988). Diet, alcohol and coronary heart disease in men. Journal of Nutrition, 118(10), 1184-1189 doi: 10.1093/jn/118.10.1184

Howell, W. H., McNamara, D. J., Tosca, M. A., Smith, B. T., Gaines, J. A. (1997). Plasma lipid and lipoprotein responses to dietary fat and cholesterol: a meta-analysis. American Journal of Clinical Nutrition, 65(6), 1747-1764

Keys, A. (1953). Atherosclerosis: a problem in new public health. Journal of the Mt. Sinai hospital, 20(2), 118-139.

Keys, A. (1980). The Seven Countries Study. Retrieved from: https://www.sevencountriesstudy.com/study-findings/publications/#books

Kritchevsky, D. (1998). History of Recommendations to the Public about Dietary Fat. The Journal of Nutrition, 128(2), 4495-4525 doi: 10.1093/jn/128.2.4495

Kromhaut, D., Menotti, A., Bloemberg, B., Aravanis, C., Blackburn, H., Bucina, R., Duntas, A. S., Fidanza, F., …Jansen, A. (1995). Dietary saturated and trans fatty acids and cholesterol and 25-year mortality from coronary heart disease. The seven countries study. Preventative Medicine, 24(3), 308-315 doi: 10.1006/pmed.1995.1049

McNamara, D. J. (2000). Dietary cholesterol and atherosclerosis. Biochimica et Biophysica Acta, 1529(2000), 310-320 doi: 10.1016/S1388-1981(00)00156-6 Retrieved from: https://www.aeb.org/images/website/documents/food-manfacturers/order-aeb-resources/Dietary_Cholesterol_and_Atherosclerosis.pdf

McNamara, D. J. (2015). The Fifty Year Rehabilitation of the Egg. Nutrients, 7(10), 8716-8722 doi: 10.3390/nu7105429

Merill, F. (2016, March 13). Now you know: Which came first, the chicken or the egg. [Blog post] Time Magazine. Retrieved from: https://www.wonderideas.club/2018/03/09/now-know-came-first-chicken-egg.

Meyer-Rochow, V. B. (2009). Food taboos: their origins and purposes. Journal of Ethnobiology and Ethnomedicine, 5. 18-19 doi: 10.1186/1746-4269-5-18.

Mutungi, G., Waters, D., Ratliff, J., Puglisis, M. J., Clark, R. M., Volek, J. S., Fernandez, M. L. (2008). Eggs distinctly modulate plasma carotenoid and lipoprotein subclasses in adult men following a carbohydrate restricted diet. Journal of Nutritional Biochemistry, 21(4), 261-267 doi: 10.1016/j.jnutbio.2008.12.011

Nichols, T. (2017). The Death of Expertise. Oxford University Press: New York.

Oxford University Press (2017): https://en.oxforddictionaries.com/word-of-the-year/word-of-the-year-2016 accessed March 9, 2018

Pelletier, X., Thouvenot, P., Belbraouet, S., Chayvialle, J. A., Hanesse, B., Mayeux, D., Debry, G. (1996). Effect of egg consumption in healthy volunteers: Influence of yolk, white or whole-egg on gastric emptying and on glycemic and hormonal responses. Annals of Nutrition and Metabolism, 40(2), 109-115 doi: 10.1159/00177903

Pidgeon, N. (2014). Risk, Uncertainty and Social Controversy: From Risk Perception and Communication to Public Engagement. In Bammer, G. & Smithson M (eds) Uncertainty and Risk: Multidisciplinary Perspectives. Taylor & Francis Group, London & New York

Pollan, M. (2007, January 28). Unhappy Meals [Blog Post]. Retrieved from: https://www.nytimes.com/2007/01/28/magazine/28nutritionism.t.html

Ribaya-Mercado, J. D., Rasmussen, H. M., Johnson, E. J. (2004). Lutein and zeaxanthin and their potential roles in disease prevention. Journal of The American College of Nutrition, 23(7), 5675-5875 doi: 10.1080/07315724.2004.10719427

Rosenbaum, L. (2017). The March of Science –The True Story. New England Journal of Medicine, 377. 188-196 doi: 10.1056/NEJmms1706087

Rowe, S. & Alexander, N. (2012). Nutrition communication essentials: (hint: we can’t talk to each other if we can’t trust each other). Nutrition Today, 47(2), 55-57

Sandman, P. M. (2003, June 12). Stakeholders [Blog post]. Retrieved from: https://www.psandman.com/col/stakeh.htm

Sorenson, R.A. (1992). The Egg came before the chicken. Mind, 101(403), 541-542 doi: 10.1093/mind/101.403.541

Sorenson, R. (2003). A Brief History of the Paradox: Philosophy and the Labyrinths of the Mind. Oxford University Press, Oxford, UK. 4-11. Retrieved from: https://www.ketabnak.com/redirect.php?dlid=64404

Touissant-Samat, M. (1994). History of Food. Blackwell Publishers, Oxford UK. ISBN 0-631-17741-8 p 355-362

Urwin, N. A. R. (2014, June 17). Would you prefer to eat genetically modified eggs, or see day-old chicks destroyed? [Blog Post]. The Guardian: Farming Opinion. Retrieved from: https://www.theguardian.com/commentisfree/2014/jun/17/would-you-prefer-to-eat-genetically-modified-eggs-or-see-day-old-chicks-destroyed

Vander, J. S., martin, J. M., Khosla, P., Jen, K. L., Dhurandar, N. V. (2005). Short term effects of eggs on satiety in overweight and obese subjects. Journal of the American College of Nutrition, 24 (6), 510-515 doi: 10.1080/07315724.2005.10719497

Walls, H. L., Johnston, D., Mazalate, J., Chirwa, E. W. (2018). Why are we still failing to measure the nutrition transition. BMJ Global Health, 3(1), e000657, doi: 10.1136/bmjgh-2017-000657

Wenzel, A. J., Gerweck, C., Barbato, D., Nicolosi, R. J., Handelman, G. J., Curran-Celentano, J. A. (2006). A 12-wk egg intervention increases serum zeaxanthin and macular pigment optical density in women. Journal of Nutrition, 136 (10), 2568-2573

WHO (2017). Noncommunicable diseases. https://www.who.int/mediacentre/factsheets/fs355/en/ accessed 11^th March 2018

Yang, S. C. & Chen, K. H. (2001). The Oxidation of Cholesterol in the Yolk of Selective Traditional Chinese Egg Products. Poultry Science, 80. 370-375

Zeisel, S. H. (2006). Choline: critical role during foetal development and dietary requirements in adults. Annual Review of Nutrition, 26. 229-250 doi: 10.1146/annurevnutr.26.061505.111156