THE OILY PRESS

By Michael I. Gurr

240 pages. Hard cover only. Published 1999.
ISBN-13: 978-0-9531949-1-9 (ISBN-10: 0-9531949-1-4).

Volume 11 in The Oily Press Lipid Library

Foreword | Preface | Reviews | Detailed contents list

Lipids in Nutrition and Health: A Reappraisal was conceived as an edited and updated compilation of the articles written by Dr Michael I. Gurr for Lipid Technology journal. During the months of writing it became more than this and is now an authoritative but very readable assessment of the role of lipids in nutrition and health. The Foreword is written by Professor Frank D. Gunstone (see the hyperlinks for this and the Preface above).

In summary, the contents are divided into 6 sections as follows. A more detailed contents listing is given later on this page.

• Influence of dietary fats on the concentration of lipids carried in the blood and the significance for health
• Dietary fats and cardiovascular disease
• Nutritional significance of lipid peroxidation
• Nutritional and biological properties of the polyunsaturated fatty acids
• Dietary fats in relation to weight control
• Lipids in foods and raw materials.

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"For ten years, Mike Gurr has written his nutrition article in Lipid Technology, amounting in all to nearly 60 articles. These have always been well received and have been one of the attractive features of the magazine. He writes clearly and carefully and with a light touch so that even those who might oppose his conclusions recognize his underlying knowledge, his ability, and the power of his arguments. It has now been agreed that all these articles should be organized into a single summarizing volume where they can be presented systematically, revising and updating only where this is necessary. The result is a powerful and critical survey of important aspects of lipid nutrition which will be appreciated by Lipid Technology readers and should be compulsory reading for those not familiar with the original articles. It also represents a convenient presentation of material spread through almost 60 issues.

"Since 80% of the global production of oils and fats — now exceeding 100 million tonnes — is consumed as food and a further 6% is eaten by animals to produce more human food it is not surprising that nutrition is one of the active areas in lipid science. Older aspects of this field such as the effects of saturated acids continue to be investigated while new aspects like conjugated linoleic acid provide excitement. What are our dietary needs? How do lipids as a whole and lipids as individual compounds affect us in respect of health and disease? These are important questions which attract a lot of attention. Most commentators — whether they be review writers, government health committees, or contributors to newspapers or magazines — are recycling what others have written, generally without careful assessment of the original articles. We are told what has been discovered. All the caveats of the original authors have got lost, suggestions become facts, arguments are simplified, and possibilities become certainties which are repeated and re-presented until they are part of received wisdom and no longer questioned.

"Mike Gurr belongs to that small group of writers who is not content with second-hand opinion but goes back to the original papers, reads them carefully, and re-assesses the conclusions on the basis of his extensive knowledge of nutritional science. His conclusions are sometimes unexpected and do not always accord with the nostrum of the day. They are always thoughtful and merit careful consideration.

"There is a growing awareness that some of the early nutrition experiments were not of the best design, that conclusions sometimes went beyond the experimental evidence, that the lipid hypothesis for cardiovascular disease, for example, is far from the whole story, and that early conclusions about cholesterol and saturated acids need to be reconsidered. Lipid Technology is pleased to have contributed to the new thinking through Mike Gurr's writing over 10 years and is proud to present this volume of collected revised papers in the belief that they will contribute powerfully to the on-going debate."

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Between 1989 and 1998, I contributed regular articles to Lipid Technology on nutritional aspects of lipids. Together these provide a clear picture of the development of concepts in lipid nutrition during this time and highlight some important advances in research in six main areas: influence of dietary lipids on blood lipid and lipoprotein concentration; dietary lipids and cardiovascular diseases; nutritional significance of lipid peroxidation; importance of polyunsaturated fatty acids in nutrition; dietary lipids and weight control; and lipids in foods and raw materials.

To provide coherent summaries for those interested in these topics, I have grouped together the Lipid Technology articles under these different headings, editing and updating where necessary. Some early articles have been omitted or considerably truncated where the material had become outdated and superseded by later articles.

Many articles did not fall neatly into these topics. These have been edited into the text of different chapters to provide introductory or background material (e.g. digestion and assimilation of lipids, consideration of dietary reference values, lipids and cancer). In the chapter on 'Lipids in foods and raw materials' I have grouped together such topics as lipids in meat, milk, infant foods, palm, or lipids of special interest (e.g. plant sterols, short-chain and medium-chain fatty acids).

For those who have not been regular readers of my Lipid Technology articles, I should point out that my interpretation of the scientific evidence for the significance of dietary lipids in the development of diseases such as heart disease, often differs considerably from those of my nutritionist colleagues. It certainly differs from the 'consensus view' adopted by most public health bodies. Shortly before putting pen to paper for one of my Lipid Technology articles, I was present at a meeting on new aspects of fats processing attended by people from the fats and oils industry. At dinner in the evening, my neighbour, by way of making conversation said "I enjoy your articles in Lipid Technology". My face glowed with pleasure; everyone likes praise! He continued: "I particularly like their facetious style". My face fell. My dictionary defines facetious as "characterized by flippant or inopportune humour". It certainly has not been my intention to be flippant or that my articles have anything other than serious scientific intent, although I hope they also make enjoyable reading. It is quite intentional however, that many of these articles are imbued with a certain scepticism (sceptical: "inclined to question the truth or soundness of accepted opinions" — my dictionary again!). The reason for this is that nutrition is a discipline which, as well as being underpinned by several fundamental sciences such as chemistry and physiology, also has distinct sociological attributes since it impinges necessarily on all our lives. It is therefore a subject in which it is all too easy to stray away from strict scientific reasoning, a topic on which I have expounded in another journal (Biologist, 1994, Vol.41, 191–194).

It has been my intention in these papers to examine critically the credentials of some popular beliefs about nutrition that have entered or are in danger of entering folklore, rather than to present bland and uncritical regurgitations of the literature. I have taken pains to try to point out why interpretations may differ so widely. I hope that these 'collected works' will provide a useful source of reference material on important lipid nutrition topics as well as being 'a good read'.

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Eddie Vos, owner of the independent nutrition web site `Nutrition, Health & Heart Disease: Cause & Prevention' (www.health-heart.org based in Sutton Quebec Canada), writes in his Amazon.com review on 11 January 2004.....

"Wonderful book for the medical or fat-interested reader....This is a primer about fats that should be required reading for any medical course and required knowledge for any one advising others about fats and cholesterol in health. Clearly written and up-to-date, it explores and goes beyond the fat and cholesterol phobia that has side tracked medical thinking for too long. A summary of articles written by Michael Gurr for Lipid Technology, a technical trade magazine about fats and oils. Main topics: digestion, cholesterol and fat, trans fats, heart disease, damaging fat oxidation, omega-3 and omega-6, weight control, where found in foods, and more...."

Professor Fritz Spener, Department of Biochemistry, University of Münster, Germany (President of the International Society for Fats Research [ISF]) writing in Lipid Technology, January 2000, p.22.....

"Gurr strengthens his views by thoroughly checking original literature and showing the reader how to do the same. Indeed, he rails against those who marshal nutritional `consensus views'....Thus the book does not repeat main-stream nutritional opinion. It reports well-researched literature. Gripping pro and contra arguments are presented in the context of the `lipid hypothesis'.... All this is intellectually enjoyable reading. And, in a practical way, it is highly informative....Gurr's book mirrors his scientific sincerity and engagement. It also displays his gifts in presenting information and argument...I can highly recommend Lipids in Nutrition and Health: A Reappraisal to both professionals and students alike. It brings you up to date in enjoyable fashion. And it is never boring, I can assure you." (See below for full review.)

Joyce Beare-Rogers, retired Chief of Nutrition Research for Health Canada, in Chemistry & Industry, 6 March 2000, p.187......

"If there were an award for the quality of writing in the lipid field, this book would be a strong contender.... It discusses the influence of dietary fats on health and disease in a clear and somteimes provocative manner....Readers should find the material in this book illuminating and challenging to some accepted orthodoxy....This book is a challenge to those who are comfortable with widespread advice linking dietary fats with cardiovascular disease."

Kurt Berger, fats & oils consultant, London, UK, writing in Food Science & Technology Today........

"This book provides an independent critical analysis of the most important topics concerning lipids and nutrition....It should be required reading for food technologists in industry and for students of food science and nutrition....It will be a valuable reference for managers who need to deal with questions arising out of media publicity on fats and nutrition."

Paula Yli-Jama writing in Lipidforum Newsletter, No.59, Spring 2000.......

"A critical view on the influence of lipids in nutrition is given...The text is entertainingly written and the author doesn't expect the reader to be a lipid expert in order to receive the message...He provokes by questioning most of the associations lipid research has provided during the last years between dietary fat - especially saturated - blood lipids, and coronary heart disease"

Oils & Fats International magazine, July 2000, p.31.......

"All chapters are well-referenced; the tone is outspoken, critical but, above all, even-handed, putting both sides of any story. Whether presenting the fundamentals of science or the latest debate in a contentious issue, the message is always clear...... Much received wisdom is questioned, but the questions are grounded in solid science, with the author citing original papers, never second-hand opinion. Overall, this is a refreshing book to read."

Sara Stanner, British Nutrition Foundation, writing in the BNF Nutrition Bulletin (Vol.24, Winter 1999) describes the contents of the book and ends.......

"This book provides a stimulating overview of current concepts in lipid nutrition. By reviewing the strength of the evidence in support of many popular beliefs, the book dispels several of the myths surrounding this subject. Whilst detailed and comprehensive, the book is written in an extremely readable style and will provide a valuable source of reference for anyone involved with lipids in food."

Dr Laurence Eyres, Massey University, New Zealand (and until recently Bluebird Foods) in The NZ Food Journal, 1999, 29 (6), p.226.........

"Mike Gurr writes in a knowledgeable, expert, disciplined and pragmatic style, leaving no topic untouched in his critical examination of evidence....The background discussions are marvellous for chemists who have minimal knowledge of physiology....The book is the latest in a series of publications from The Oily Press and is of the same high calibre as the previous books."

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Professor Fritz Spener, Department of Biochemistry, University of Münster, Germany (President of the International Society for Fats Research [ISF]). (Full review from Lipid Technology.)

Dr Gurr is well known to the readers of Lipid Technology for his more than 60 authoritative articles written over the last 10 years on issues of lipids affecting human nutrition and health. He has not merely compiled these articles in book form now. Rather, he has arranged them thematically in chapters, omitted out-dated material, and incorporated new findings. This careful editing becomes most obvious in the book's heading `A Reappraisal'. I do not mean to suggest, though, that the author has reappraised his own views. On the contrary, Gurr strengthens his views by thoroughly checking original literature and showing the reader how to do the same. Indeed, he rails against those who marshal nutritional `consensus views'. And I suspect the `Reappraisal' is meant to provoke writers and commentators in scientific journals, as well as members of public health committees, to avoid opinions based on the secondary literature — for example, reviews and comments that have been re-reviewed and re-commented over and over again — in favour of the original scientific literature.

Thus the book does not repeat main-stream nutritional opinion. It reports well-researched literature. Gripping pro and contra arguments are presented in the context of the `lipid hypothesis' (which Gurr describes as "the concept that over-consumption of saturated fatty acids results in an elevated concentration of cholesterol in the blood, which in turn increases the risk of coronary heart disease mainly causing severe narrowing of arteries supplying blood to the heart"), on which educational recommendations for the public, and their fine-tuning with regard to new knowledge, are commonly based. Understanding of this central theme is facilitated by introductory sections and explanations on the physiology and biochemistry of lipids, as well as on the art of epidemiology, meta analysis and medical jargon related to diseased states. All this is intellectually enjoyable reading. And, in a practical way, it is highly informative.

The text is organized into 6 chapters, each preceded by a succinct summary. Chapter 1, `Influence of dietary fats on the concentrations of lipids carried in the blood and the significance for health', sets the stage by addressing each fatty acid class and cholesterol in terms of nutritional and health issues, past and present. In Chapter 2, `Dietary fats and cardiovascular disease', the author disposes of the lipid hypothesis, I am inclined to say, on mainly two arguments: (i) inadequate statistics inherent to epidemiological studies, and (ii) neglect of thrombolytic events. Assessing the lipid hypothesis in the context of science and health policy, Gurr, a British subject, is fair to the world: he criticizes public health policy in Britain alone, but his lessons obviously apply worldwide.

The second half of the book is devoted to recent developments and advances in knowledge. Chapter 3, `Nutritional significance of lipid peroxidation', addresses the concept of oxidative stress and pathological implications. The current debate on essential fatty acids, and the adequacy of the nutritional ratio of n–3/n–6 polyunsaturated fatty acids is treated in Chapter 4 (`The nutritional and biological properties of polyunsaturated fatty acids'). To strengthen the thrombolytic aspect, a discussion on the potential of these fatty acids in blood clotting is included. `Dietary fats in relation to weight control' (Chapter 5) bears on everyone's daily discipline. The chapter thus reiterates, thoughtfully, basic facts certainly known to nutritionists but not necessarily to those engaged in borderline disciplines. Consuming non-digestible fats and fat substitutes raises the question of compensation that may differ between individuals. Considering individual predispositions in regulation of energy intake — implicit is energy expenditure — I would have expected a treatment on insights now available since the discovery of leptin and uncoupling proteins 2 and 3. The final chapter, `Lipids in food and raw materials', summarizes the latest findings about nutritional values of so-called minor compounds in fatty raw materials, such as phytosterols, and the application of innovative products, for example structured lipids, in niche markets. It is also a merit of this chapter that it castigates, in clear language, the scandal that consists of discrediting oils for commercial interests rather than on the basis of nutritional facts.

Gurr's book mirrors his scientific sincerity and engagement. It also displays his gifts in presenting information and argument. Notwithstanding the price, I can highly recommend Lipids in Nutrition and Health: A Reappraisal to both professionals and students alike. It brings you up to date in enjoyable fashion. And it is never boring, I can assure you.

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1. Influence of Dietary Fats on the Concentrations of Lipids carried in the Blood and the Significance for Health

Introduction
Fat digestion and assimilation
Prediction of lipid and lipoprotein responses to dietary fat and cholesterol
Cholesterol in the diet and in the blood: a more detailed appraisal
Saturated fatty acids and hypercholesterolaemia: are all saturated fatty acids equal?
Trans fatty acids: their influence on blood lipids and their wider health implications
Cis-Monounsaturated fatty acids: are they really 'neutral'?
Dietary fat, blood lipids and health. Which is more important: total amount of fat eaten or its composition?
Changes in blood lipid after a meal: significance for health
References

2. Dietary Fats and Cardiovascular Disease

Background to the debate
Evidence in support of the lipid hypothesis
Evidence against the lipid hypothesis
Dietary fat and cardiovascular disease: are current guidelines justified?
Epilogue: The politicization of science
References

3. Nutritional Significance of Lipid Peroxidation

Background
Lipid peroxidation
Significance of oxidation of lipids in foods
Lipid peroxidation and the body's defence against it
Antioxidant defence against damage by lipid peroxides
The concept of oxidant stress
Research into links between diet, oxidant stress and disease
Future directions
References

4. The Nutritional and Biological Properties of the Polyunsaturated Fatty Acids

Polyunsaturated and essential fatty acids — the distinction
Linoleic and alpha-linolenic acids as precursors of the n–6 and n–3 families of polyunsaturates
Long-chain polyunsaturated fatty acids of the n–6 family: gamma-linolenic and arachidonic acids
Long-chain polyunsaturated fatty acids of the n–3 family
Dietary n–6/n–3 polyunsaturates balance: is it important?
Dietary requirements for the essential fatty acids
Endpiece: What is 'essential' in regard to lipids?
References

5. Dietary Fats in Relation to Weight Control

Energy nutrients and body weight control
Fats and fattening: can we fool the system?
References

6. Lipids in Foods and Raw Materials

Meat lipids
Lipids of milk
A trans acid that is good to eat? Conjugated linoleic acid
Lipids in infant nutrition
Short-chain and medium-chain fatty acids in nutrition and metabolism
Oil palm lipids: edible oils with interesting nutritional attributes
Plant sterols in the diet
References

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