DEATH BY FOOD PYRAMID

Like the book by Dr Leyla, this one is also based on the author's own experience and is subtitled 'how shoddy science, sketchy politics and shady special interests ruined your health… and how to reclaim it' - a description amply borne out by what follows. The foreword by Chris Masterjohn bears out of the experience of the author's own health worsening in many ways by following a strict vegetarian then vegan diet; he only recovered through eating high quality nutrient dense animal foods. This epitomises the difference in approach between advocates of the influential China Study (which I reviewed positively in 2006) and that of the Weston Price Foundation, which promotes the Paleo diet. Interestingly, during the detoxification phase, she felt and looked great, but later lacked energy, lost too much weight and suffered extensive dental problems.

Food is a province of competing experts, many of whom contradict each other. This makes it difficult for the layman to know what to believe, and one of the principal aims of this thorough and entertainingly written book is to provide us with the tools to take our own view by identifying bias, balancing open-mindedness with scepticism and challenging assumptions. The Food Pyramid of the title refers to the genesis of the USDA recommendations in the early 1990s, with a diagram showing what portions of food were recommended in the overall diet. As with other regulations, this soon fell foul of the food industry lobby and emerged in a very different form. In the final analysis, the USDA protects the interests of large farmers rather than promoting public health. More rigorous earlier versions of the pyramid were scotched by the food industry.

A key issue is the low-fat revolution initiated by Nathan Pritikin and others. The best-known research was carried out by Ancel Keys, who became a passionate advocate of the low-fat approach. Unfortunately, his data mistook cause for correlation and was extensively criticised by other scholars. Then John Yudkin comes along, making a similar case for the role of sugar, and in both cases the food industry weighs in. The author makes the observation that anyone who is certain about everything in nutrition is almost definitely wrong. She provides a series of test questions to help evaluate the status of experts and lists six logical flaws to look out for in an academic paper: ad hominem arguments, anecdotal evidence, appealed to authority, misplacing the burden of proof, cherry picking and setting up a straw man. In the following chapter, she gives a hitchhiker's guide to nutritional research and frequently used terminology, also explaining the status of different types of study and how to read a scientific paper.

She then looks in detail at the story of Ancel Keys and his lipid hypothesis for the genesis of heart disease. She provides a series of scientific critiques, even showing that countries with higher average fat intake and high cholesterol levels have the longest life expectancies. The overall error is mistaking one factor as exclusively causal without regard for the context and other potential factors. This kind of tunnel vision thinking is built into scientific reductionism but is inappropriate for complex and multifactorial situations. It is more probable that elements of affluence may form a toxic cocktail for heart disease and that the combination of various factors analysed, when combined with stress and a sedentary lifestyle, creates perfect storm conditions for heart disease. Long-term studies like Framingham in Massachusetts reinforce this conclusion.

It is equally hard to know with certainty the role played by individual elements of special diets, and it is particularly instructive to read the analysis of vegan diets and what they lack in essential nutrients. The final chapter presents three principal approaches: the Paleo, the Mediterranean and the Whole-Foods, Plant-Based. Each is explained in terms of its elements, claim to fame and caveats, with a corresponding pyramid diagram. The aha moment is finding where they all intersect and realising that their common exclusions are industrially produced vegetable oils, refined grains and refined sugar, which could explain their similar successes with health promotion and weight loss. So it's really as much about what we don't eat as what we do. In this chapter, there is also extensive discussion of the work of Weston Price and the differing communities he observed, which reinforces the conclusion about since none of these communities ate modern refined food - and their health declined when they began to do so, as Sir Robert McCarrison also discovered in India. Interestingly, the common prized foods contained high-density fat-soluble vitamins. On a practical level, this means that chasing a single ideal diet is the wrong route, and that one should pay as much attention to what one does not eat. This, moreover, is to some extent an individual matter, as the author explains while giving some very helpful overall advice. She also encourages us to remember that we are equipped with voting, spending and intellectual power, encouraging us to use it where we can. We can have what she calls a life of educated freedom rather than death by food pyramid, and her book provides a vital guide for interested people.