Books and Arts

Nature 444, 425 (23 November 2006) | doi:10.1038/444425a; Published online 22 November 2006

Healthy fats

Asim K. Duttaroy1

BOOK REVIEWEDThe Queen of Fats: Why Omega-3s Were Removed from the Western Diet and What We Can Do to Replace Them

by Susan Allport

University of California Press: 2006. 232 pp. $22.50, £14.95

Two series of polyunsaturated fatty acids, the omega-6 and the omega-3 fatty acids, are essential dietary nutrients. Two major omega-3 fatty acids, eicosa-pentaenoic acid (EPA) and docosa-hexaenoic acid (DHA), are increasingly being seen as important modulators of biological pathways that affect growth, development and health. Consumption of these omega-3 fatty acids, which are found in fatty fish and fish oils, has been linked to the low incidence of coronary heart disease in the Inuit people of Greenland. An omega-3 fatty acid with a shorter chain, alpha-linolenic acid (ALA), found in some plant oils and sometimes converted to EPA and DHA, may also be beneficial. Omega-3 fatty acids may protect against cardiovascular disease by several mechanisms, such as lowering blood pressure; reducing plasma triglycerides; lowering the platelet aggregation response, inflammation and arrhythmias; and improving endothelial function, insulin sensitivity and atherosclerotic plaque stability.

Susan Allport discusses the history of using omega-3 fatty acids in her well-written book The Queen of Fats. She has done an excellent job in describing the events and the international collaboration involved in discovering the effects of omega-3 fatty acids. She covers almost every aspect of omega-3s, including the importance of an appropriate ratio of omega-6 and omega-3 fatty acids in the diet, which has been biased towards omega-6 fatty acids over the past 50 years, and the consequences for our health of changes in the ratio. There is considerable controversy over how much omega-6 and omega-3 fatty acids are needed in the diet, and which ones.

Many studies have shown a correlation between omega–3 fatty acids and diseases, but translating these findings into recommended amounts for individuals and populations requires careful consideration. Meta-analyses of the effects of omega–3 fatty acids are not conclusive on total mortality, combined cardiovascular events, or cancer. However, some of these meta-analyses failed to take into account many of the pitfalls that must be addressed if a clear picture of the benefits of omega-3 fatty acids is to be obtained.

Healthy fats

DESGRIEUX/PHOTOCUISINE
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Something fishy: mackerel is a good source of omega-3s.

Allport does not discuss recent meta-analyses of several large studies on fish oils, and fails to mention some of the possible health risks associated with a high intake of fish oils, such as increased bleeding and haemorrhagic stroke. In addition, the oxidation of omega-3 fatty acids can increase the level of low-density lipoprotein, reduce glycaemic control in diabetics, and reduce immunocompetence. She could also have elaborated on the significance of another omega-3 fatty acid, DPA, and on adverse health effects in infants and adults of lipid-soluble toxins (such as dioxins and polychlorinated biphenyl) and of heavy metals in fish oils. I also expected her to say more about the possibility of switching to new sources of omega-3 fatty acids, such as genetically modified oils, as a way of delivering more highly concentrated sources of omega-3 fatty acids. The advent of algal sources of DHA provides one of the few terrestrial sources of this fatty acid in a concentrated form. All this has been made possible by new technologies and improved processing techniques that ensure the stability and preserve the integrity of these unstable fatty acids.

These omissions aside, however, Allport's book provides an interesting and comprehensive account of the history of omega-3 fatty acids. It not only provides a clearly reasoned case for the benefits of having more omega-3 fatty acids in the diet, but also offers practical advice about how to add these fats to our diet. The book is also well organized, with a clear contents list, comprehensive notes, time lines and index to enable readers to quickly locate a required topic.

  1. Asim K. Duttaroy is in the Department of Nutrition, University of Oslo, PO Box 1046 Blindern, Oslo N-0316, Norway.

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