The Diet Myth

The title of Tim Spector’s 2015 book The Diet Myth refers to one “myth”. The book begans with an Introduction that discusses the author’s midlife health crisis when his blood pressure rose suddenly, and present an overview of his research into the modern diet. The Introduction identifies the problems of deciding “what is good or bad for us in our diets” and several misconceptions about food that impair discussion of food and diet, and sensible decisions by consumers. In his later book Spoon-Fed, he discusses many other misconceptions or myths about food science, appetite, differences between individual metabolism, diet and health.

The Diet Myth‘s first chapter introduces discusses some of the gut microbiota (part of the human microbiome) that process food consumed by humans by breaking it down, releasing nutrients that the human gut absorbs and metabolizes. In reviewing Dr. Spector’s, 2020 book Spoon-Fed, the English writer Bee Wilson said it contains an overview of many medical and scientific studies of genetics, microbiology, biochemistry and food:

The book’s main argument is that to find the best way of eating we need to ignore much of what we are told. … Spoon-Fed is a worthy successor to Spector’s earlier bestselling book, The Diet Myth, which focused on the powerful role that the microbes in our guts play in determining our health. This new book is broader, but he manages to distil a huge amount of research into a clear and practical summary that leaves you with knowledge that will actually help you decide what to add to your next grocery shop.

Bee Wilson, the Guardian, August 5, 2020, review of Spoon-Fed

The Diet Myth suggests that

  • food science and popular writing has not absorbed the fact of the presence of an active microbiome in the human digestive tract,
  • the importance of a healthy and diverse gut microbiome,
  • the overuse of antibiotics and other medical errors that have harmed humans by affecting their microbiome,
  • medical and cultural practices that have contributed to the increasing incidence of food allergies. The book suggests that food science and popular writing has been inattentive to genetic variations of humans as affecting metabolism and interactions with food and microorganism.

The remaining 18 chapters discuss the topics addressed by the “Food Facts” labels used to disclose information about food: calories, fats, nutrients, and warnings, with reference to genetics and the microbiome.

The science of calories is based on the 1944-1945 Minnesota Starvation Experiment. Calorie-based thinking suggests that diets aimed at reducing weight or “curing” obesity should reduce the intake of calories. This has evolved into a proliferation of diet advice: avoiding all fats (or bad fats), avoiding carbohydrates. eating “paleo”, eating protein, eating “Mediterannean”, not eating cheese or nuts. The food industry dominated by corporate interests, is focussed on reducing foods into packaged commodities, processed to taste good, package well and sell. The food industry reduces food to “ingredients”. People try to make up for “missing” ingredients by taking supplements.

The book discussed the scientific “discovery” of “vitamins” with a brief reference to the illness known as beri-beri, caused by thiamine (vitaman B1) deficiency. One of the principal causes where the food supply is primarily “white” (milled or polished) rice is processing the rice:

Beriberi was known for millennia in Asia, but was not described by a European until the 17th century when Brontius in the Dutch East Indies reported the progressive sensorimotor polyneuropathy. The prevalence of beriberi increased greatly in Asia with a change in the milling process for rice in the late 19th century. In the 1880s, Takaki demonstrated the benefits of dietary modification in sailors, and later instituted dietary reforms in the Japanese Navy, which largely eradicated beriberi from the Japanese Navy by 1887. In 1889 Eijkman in Java serendipitously identified dietary factors as a major contributor to “chicken polyneuritis,” which he took to be an animal model for beriberi; the polyneuritis could be cured or prevented by feeding the chickens either unpolished rice or rice polishings. By 1901, Grijns, while continuing studies of beriberi in Java, suggested a dietary deficiency explanation for beriberi after systematically eliminating deficiencies of known dietary components and excluding a toxic effect.


By the 1950s synthetic forms of the vitamin were produced cheaply, allowing both therapeutic administration and prevention with food enrichment.

Abstract of Douglas J. Lanska “Historical aspects of the major neurological vitamin deficency disorders …” in Volume 95 of Handbook Clinical Neurology, Elsevier (2009), ScienceDirect portal.

The use of polished rice was culturally and economically embedded – it was easier to cook and digest, and conserved the fuel needed to cook rice. This problem was not an exclusively pre-modern or Asian problem American and European scientists criticized the use of bleached white wheat flour to bake bread and other cereal products. The public policy response was to require that white flour be “enriched” with nutrients. The book also mentions studies demonstrating that agricultural products harvested in modern times contain less nutrients than the products harvested several decades earlier. The book does not refer to studies about the causes and consequences of this fact. One consequence is that vitamin products are marketed as necessary to supplement foods available to consumers in markets – and that supplements have become a huge industry

The idea of enrichming some processed food is embedded in public health policy, and supplements are embedded in culture. The book touches the issues with criticism of the scientific and industrial idea of “reducing” food to a mixture of ingredients, and with criticism of fad diets. Food science in the 19th century and the 20th century failed to addressed dangerous unknowns, and failed to warn against risky agricultural and food processing practices. Science is now not exploring the known unknowns, and public policy remains uninformed. This area can be developed further – although it was beyond the scope of Dr. Spector’s book.

The Diet Myth

  • suggests that food science, as discussed in the popular media, has been static,
  • suggests that individuals might eat more vegetables,
  • recommends diversity of diet and expressly and implcitly endorsies Michael Pollan’s advice to “Eat food. Not too much. Mostly plants” and much of what Michael Pollan wrote in his books In Defence of Food (2008) and The Omnivore’s Dilemma (2006), and
  • suggests avoiding consuming processed foods,

The Diet Myth does not refer to the NOVA food classification system suggested by Carlos Monteiro, with his team at the Center for Epidemiological Research in Nutrition and Health at the University of São Paulo, Brazil in the 2009 paper “Nutrition and health. The issue is not food, nor nutrients, so much as processing” in the journal Public Health Nutrition. The NOVA system classifies many foods as ultra-processed.

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