Chia: Rediscovering a Forgotten Crop of the Aztecs by Ricardo Ayerza and Wayne Coates. Tucson, AZ: University of Arizona Press; 2005. Paperback; 215 pages. ISBN13: 978-0816524884. $15.95.
The authors have compiled an excellent piece of work covering the anthropological, historical, and nutritional aspects of chia seed (Salvia hispanica, Lamiaceae). At the time the book was published, Ricardo Ayerza, Jr. was an associate at the University of Arizona’s Office of Arid Lands Studies, and Wayne Coates was a research professor at the same facility. They appear to have an extensive knowledge of chia, and they have done an admirable job in discussing the role of industrialization in limiting the food sources of much of today’s population.
In the first chapter of this book, the authors discuss the paradox of hunger despite over-abundance of agricultural crops, and they introduce the idea of going back to the past to review new sources of food for today.
In the second chapter, the authors explore changes in composition of food eaten by hunter-gatherers as compared to today’s Western diets. Hunter-gatherers ate high amounts of animal meat, yet this still provided lower fat content than today’s typical Western diet. This is due to differences in the composition of meat, since animals then were free-roaming and grazed on wild plants, as opposed to the rationfed cattle living in confined spaces that constitute the majority of meat in today’s Western diet. The diet of hunter-gatherers, depending on geographical location, also came from a large variety of plants (estimated in some cases to be over 200 species) compared to very limited number of agricultural crops in today’s diet.
Modern diets typically include consumption of far more omega-6 fatty acids than omega-3 fatty acids. The authors discuss the importance of dietary omega-3 fatty acids in maintaining health and the role of other lipids and fats on health. They state that an excess of omega-6 fatty acids, with deficiency of omega-3 fatty acids, leads to higher incidences of chronic heart disease and other inflammatory conditions. But in an attempt to simplify a complex message, the authors have made some errors. On page 35, they state that omega-6 fatty acids increase production of eicosanoids while omega-3 fatty acids decrease the production. This is not true. The omega-3 fatty acids decrease the production of series 2 prostaglandins and increase the production of series 3 prostaglandins. They just change the distribution of different eicosanoids, which lead to anti-inflammatory actions.
Chapter 3 includes a detailed discussion of crops used by Aztec Indians and the role of chia in the nahuatl culture’s food and medicine. The authors have done a commendable job in describing the old literature on the role of chia seeds. Chapter 4 describes the botany and agronomics of chia, with a great deal of discussion on production aspects.
Chapter 5 deals with chemistry of chia seed in comparison to other sources of omega-3 fatty acids like flax seed (Linum usitatissimum, Linaceae), algae, and marine oils. The authors have devoted significant discussion on superiority of chia seed over all other sources, though they have made some errors. They write that flax has never been used as a food. In the 8th century CE, the great Western European leader Charlemagne considered flax so important for the health of his subjects that he passed laws and regulations requiring its consumption.1 On page 120, the authors have raised an issue of toxicity of flax due to the presence of cyanogenic glycosides and other antinutritional factors. In discussing these, they have selectively used the literature, omitting the references to work done on safety of flax seed, which has concluded that up to 50 g per day of flax seed consumption is not associated with any safety concerns.2,3 The spellings of cyanogenic glycosides of flax are wrong (it is not “cianogicosides limarin”). On page 121, the authors have raised concerns on reproductive toxicity of SDG (secoisolariciresinol diglucoside) in animal studies. First, the authors have misspelled the compound’s name, and secondly, they have interpreted the studies incorrectly. The authors of those studies concluded that the minor effects observed in the animals have no clinical or physiological significance. The books’ authors have also claimed that chia has the highest source of omega-3 fatty acids. Chia oil has a higher amount of omega-3 fatty acids than flax oil (62% versus 58%), but the flax seed contains higher amounts of oil (38–42%) compared to 28–32% for chia seed. Hence, on weight basis, flaxs eed has higher amount of omega-3 fatty acids than chia seed.
On page 128, the use of chia is mentioned as a dietary strategy to increase omega-3 content of commercially-produced chicken eggs. Commercially, very little, if any, chia seed is used for this purpose. Commercial omega-3-enriched eggs are produced mainly by feeding flax meal or fish meal to poultry. The reference for table 6.3, “Cholesterol, Total Fat, Saturated Fatty Acid, and Omega-3 Fatty Acid Content of Eggs Produced by 2 Lines of Hens Fed 5 Different Omega-3 Diets,” is not easily accessible (the reference was not shown). For this study, the same amount of chia and flax were fed but the content of fish meal is not presented in the table. As flax seed contains a high amount of total and soluble fiber, total fat, and omega-3 fatty acid on weight basis, the diets were not equivalent. The effect of differential levels of fiber is not discussed. The data for table 6.1, “Cholesterol, Total Fat, Saturated Fatty Acid, and Omega-3 Fatty Acid Content of Eggs Produced by Shaver White Laying Hens Fed 4 Diets,” include 100% chia or a blend of chia and flax, while 100% flax was not studied. Data for tables 6.1 and
6.3 show different effects on DHA content of eggs, which is not explained. Also, data in table 6.1 demonstrate a dose-dependent inhibitory effect of chia on the DHA content of chicken eggs.
Excluding the shortcomings mentioned above, the book is a valuable resource about the emerging role and importance of chia as a healthy food and dietary supplement.
—Rakesh Kapoor, PhD Director, Science and Technology Bioriginal Food and Science Corp. Saskatoon, Canada
- Murray M, Pizzorno J, Pizzorno L. The Encyclopedia of Healing Foods. Memphis, TN: Atria Publishing; 2005.
- Cunnane SC, Thompson LU (eds). Flaxseed in Human Nutrition. AOCS Press, Champaign, IL: AOCS Press; 1995.
- Cunnane SC, Ganguli S, Menard C, et al. High a-linolenic acid flaxseed (Linum usitatissimum): some nutritional properties in humans. British Journal of Nutrition. 1993;69(2):443-453.