James McCormack, Marcie Gray Independently published, 2022, PB, 462pp, £16.39, 979-8449768575
How much do our food choices really matter? Eating is a necessity, but for the well fed everything we eat is a decision. Our choices reflect our preferences, cultures, diseases (and disease awareness), our symptoms, concerns for animal welfare, and our desires to reduce greenhouse gas emissions and help eliminate food waste.
What we need to eat should be common knowledge, but our knowledge about diet and nutrition does not keep any better than fish. We have to understand the difference between our diets (the kinds of foods we habitually eat) and our nutrition (the foods we need for our health and growth), and how to tweak our diet for optimum nutrition. All this is based on legacies of misinformation about food, and a constant, steady stream of new and confusing information.
This is not a topic that is usually taught well, even in medical education. Most of us struggle with knowing what is the best diet for a healthy and long life. A Google web search asking: ‘What is the best diet?’ produces millions of results. Diets are everywhere and can be like tyrants — promising you great things, expecting your obedience, but in the end usually disappointing you. The hard-talking demands of diet enthusiasts are often supported by the softer-spoken advocates for mechanisms of action aiming to make the claims of a diet seem rational. There is no shortage of news articles promoting the latest nutritional ‘research’ on how to live longer, lose weight, and be more fit.
If you feel baffled by the science and pseudoscience, and want to read an easy-to-understand book to be more confident and competent with your own knowledge and advice to others, then this is the one to read. James McCormack and Marcie Gray have written a review of the evidence about the known health effects of food. McCormack has had extensive experience talking to health professionals and consumers about the rational use of medication, both in Canada and internationally. His background is in pharmacy and for years he has been a leading advocate for shared, informed decision making using evidence-based information and rational therapeutic principles. Now he has focused his investigations, clear thinking, and explanations on nutrition.
This book can be read at different levels of expertise and interest. Each chapter is written as a conversation with the reader, explaining the evidence available, supported by summary tables of trial results, and with succinct takeaway summaries at the end of each chapter. Most of the current questions about nutrition and diets that can be answered from the available evidence are answered.
There are chapters on beverages, carbohydrates, fat, protein, fruit and vegetables, meat, desserts, condiments, dairy and eggs, fast/convenience food, specialty diets, and much more, with added explanations on evidence-based medicine. For example, in a chapter on side orders, allergies and food intolerances are discussed.
Non-coeliac gluten sensitivity occurs in 5%–10% of the population but in a re-challenge with a gluten trial as reported in the book, only 30% of participants had a relapse. In another trial with a re-challenge using either gluten or placebo, with gluten, 36% of participants had a relapse, but with placebo, 31% had a relapse. This evidence is hard to understand but it is interesting.
Because this book has been self-published on digital platforms, mistakes can be easily corrected and updates can be added. When it was first published there had only ever been four large nutrition trials, but a fifth was reported a few weeks after publication. The book has since been updated with this new trial information and the context provided. Anyone who had purchased a Kindle version automatically received the update. Purchased paperback versions cannot be updated but any new paperback will be the revised version. So, if you want to stay up-to-date buy the Kindle version.
In summary, McCormack believes that as an evidence-based clinician any nutrition decision ‘is best taken when informed by the best available evidence. That evidence tells us, in moderation you can eat the food you enjoy without fear or worry.’
As the food writer and chef Mary Berry says, ‘Cakes are healthy too, you just eat a small slice.’
- © British Journal of General Practice 2022
