Reply to SC Cunnane

Department of Health and Exercise Science
Colorado State University
Fort Collins, CO 80523
E-mail: cordain{at}cahs.colostate.edu

S Boyd Eaton

Departments of Radiology and Anthropology
Emory University
Atlanta, GA

Anthony Sebastian

Department of Medicine and
UCSF/Moffitt General Clinical Research Center
University of California, San Francisco
San Francisco, CA

Neil Mann

Department of Food Science
Royal Melbourne Institute of Technology University
Melbourne
Australia

Staffan Lindeberg

Department of Medicine
Lund University
Lund
Sweden

Bruce A Watkins

Food Chemistry and Molecular Biology Laboratory
Department of Food Science
Purdue University
West Lafayette, IN

James H O'Keefe

Mid America Heart Institute
Kansas City, MO

Janette Brand-Miller

Human Nutrition Unit
Department of Biochemistry
University of Sydney
Sydney
Australia

Dear Sir:

We thank Dr Cunnane for his congratulatory words about our recent article in the Journal (1). Clearly, in a review article of a somewhat limited nature, it would not be possible to comprehensively document all diseases and maladies of civilization that have been linked to the typical Western diet. Instead, we referred interested readers to Cordain's earlier, more exhaustive review of the numerous health problems and illnesses associated with the consumption of cereal grains, a food introduced in the relatively more recent Neolithic period (2). We agree with the notion that normal human brain development and function require a diet adequate in iron, iodine, and long-chain polyunsaturated fatty acids (PUFAs) of both the n–3 and n–6 families. Moreover, there is little doubt that animal foods, which were the dietary staples for historically studied hunter-gatherers (3, 4), are rich sources of these nutrients (1, 5, 6).

With respect to iodine and the brain's development and function, it should be pointed out that a wide variety of staple foods domesticated during the Neolithic period and later (ie, millet, maize, soy, cassava, sweet potatoes, lima beans, turnips, cabbage, cauliflower, rapeseed, mustard, onion, garlic, bamboo shoots, and palm tree fruit) contain a variety of goitrogens (7, 8) that may elicit symptoms of iodine deficiency despite adequate iodine intakes (7, 9). Hence, plant food–dominated diets containing goitrogens, which were adopted by humanity after the agricultural revolution, may play a significant role in impairing thyroid function and thereby adversely influencing human brain development (10). In contrast, iodine deficiency is rare among traditional societies that consume animal-based diets (11).

For reasons we outlined previously (6, 12), we respectfully disagree with Cunnane's suggestion that seafood would have represented the primary source of long-chain PUFAs (22:6n–3 and 20:4n–6) and other micronutrients necessary to the relaxation of the selective pressure previously constraining encephalization in hominins. Exploitation of the marine environment is first documented in the archaeologic record during the Middle Paleolithic period (110 000 y BP), and stable isotope data show that inland aquatic foods were not utilized by hominins living in Europe until the mid-Upper Paleolithic period (28 000–20 000 y BP) (13). Hence, aquatic animal foods, whether ocean- or inland-derived, would have played a minor role in providing nutrients that were crucial to the rapid hominin brain expansion that occurred during the Early Paleolithic period (2.5–2.0 million y BP). Rather, terrestrial animal foods (including muscle, brain, marrow, thyroid gland, and other organs) would have represented the primary source of long-chain PUFAs, iron, zinc, iodine, and other nutrients that were necessary for encephalization and normal brain development (6, 12, 14).

ACKNOWLEDGMENTS

None of the authors had a conflict of interest.

REFERENCES

1. Cordain L, Eaton SB, Sebastian A, et al. Origins and evolution of the Western diet: health implications for the 21st century. Am J Clin Nutr 2005;81:341–54.
2. Cordain L. Cereal grains: humanity's double-edged sword. World Rev Nutr Diet 1999;84:19–73.
3. Cordain L, Brand Miller J, Eaton SB, Mann N, Holt SHA, Speth JD. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. Am J Clin Nutr 2000;71:682–92.
4. Cordain L, Eaton SB, Miller JB, Mann N, Hill K. The paradoxical nature of hunter-gatherer diets: meat based, yet non-atherogenic. Eur J Clin Nutr 2002;56(suppl):S42–52.
5. Andersen S, Hvingel B, Laurberg P. Iodine content of traditional Greenlandic food items and tap water in East and West Greenland. Int J Circumpolar Health 2002;61:332–40.
6. Cordain L, Watkins BA, Mann NJ. Fatty acid composition and energy density of foods available to African hominids: evolutionary implications for human brain development. World Rev Nutr Diet 2001;90:144–61.
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9. Lakshmy R, Rao PS, Sesikeran B, Suryaprakash P. Iodine metabolism in response to goitrogen induced altered thyroid status under conditions of moderate and high intake of iodine. Horm Metab Res 1995;27:450–4.
10. Rao PS, Lakshmy R. Role of goitrogens in iodine deficiency disorders and brain development. Indian J Med Res 1995;102:223–6.
11. Andersen S, Hvingel B, Kleinschmidt K, Jorgensen T, Laurberg P. Changes in iodine excretion in 50–69-y-old denizens of an Arctic society in transition and iodine excretion as a biomarker of the frequency of consumption of traditional Inuit foods. Am J Clin Nutr 2005;81:656–63.
12. Cordain L, Miller JB, Eaton SB, Mann N. Reply to SC Cunnane. Am J Clin Nutr 2000;72:1585–6 (letter).
13. Richards MP, Pettitt PB, Stiner MC, Trinkaus E. Stable isotope evidence for increasing dietary breadth in the European mid-Upper Paleolithic. Proc Natl Acad Sci U S A 2001;98:6528–32.
14. Cordain L, Watkins BA, Florant GL, Kehler M, Rogers L, Li Y. Fatty acid analysis of wild ruminant tissues: evolutionary implications for reducing diet-related chronic disease. Eur J Clin Nutr 2002;56:181–91.