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Department of Health and Exercise Science Colorado State University Fort Collins, CO 80523 E-mail: cordain{at}cahs.colostate.edu
Department of Biochemistry University of Sydney Sydney, NSW 2006 Australia
Departments of Radiology and Anthropology Emory University Atlanta, GA 30322
Department of Food Science Royal Melbourne Institute of Technology University GPO Box 2476V Melbourne, VIC 3001 Australia
Dear Sir:
We disagree with the editorial (1) that accompanied our recent article on hunter-gatherer plant-animal subsistence ratios (2). Milton appears to have misinterpreted our findings as well as Lee's (3) original analysis of the Ethnographic Atlas (4).
Within the nutritional community, it is common knowledge that the quantitative and qualitative lipid composition of domesticated meats is vastly different from that found in wild game. Game meat contains lower proportions of fat, especially saturated fat, than does meat from grain-fed domesticated animals, even on a whole-carcass basis (5). Nowhere in our article did we recommend that people should eat high-fat, domesticated livestock. Our take-home messages were that hunter-gatherer diets were higher in protein and lower in carbohydrate than are current Western diets or dietary guidelines and that this macronutrient balance may provide insight into potentially therapeutic diets. If any implication were to be inferred, it would be that dietary fat should emulate fat sources found in game meat and organs (high in n-3 fats, low in n-6 fats, and high in monounsaturated fats).
Milton's editorial repeated the same error that has occurred continually in the anthropologic community since Lee published his work 32 y ago (3). Lee did not report the total food intakes derived from animal sources because he did not sum hunted and fished animal foods. This is one of the reasons our reanalysis of the Ethnographic Atlas is original and noteworthy. Although we did not report it in our article, we analyzed Lee's sample of 58 hunter-gatherer societies as a subset and obtained results almost identical to those of our analysis of the entire sample (n = 229). The dependence on hunted and fished foods for subsistence was 86–100% (modal value) and 66–75% (median value). Milton's statement that "emphasis on hunting occurred only in the highest latitudes" is also inaccurate because our analysis of Lee's data showed that there is no correlation (Spearman's rho = 0.01) between dependence on hunting and latitude; on the contrary: as intakes of plant food decrease with increasing latitude, intakes of fished food increase and of hunted animal food stay constant—the same conclusion we reached with our original analysis. The editorial deemphasizes the importance of animal foods in hunter-gatherer diets by citing 2 extreme and nonrepresentative societies, the !Kung and the Hazda, both of which have been shown by the Ethnographic Atlas and modern quantitative studies to maintain high plant-animal subsistence ratios (67:33 and 56:44, respectively). Of the 229 hunter-gatherer societies listed in the Ethnographic Atlas, only 1 other society maintains a plant-animal subsistence ratio as high as that of the !Kung and only 13% maintain a ratio as high or higher than that of the Hazda. A compilation of the few available quantitative dietary studies in hunter-gatherers showed a plant-animal subsistence ratio of 41:59 (6), which is similar to the aggregate value (45:55) we reported in our article.
Increases in low-fat dietary protein at the expense of carbohydrate may have therapeutic effects. Wolfe and Piche (7) showed that the replacement of dietary carbohydrate with low-fat, high-protein animal foods improved blood lipids (LDL, VLDL, total cholesterol, triacylglycerol, and the ratio of total to HDL cholesterol). Furthermore, increased dietary protein may reduce the risk of coronary heart disease (8) and reduce serum homocysteine concentrations (9) while facilitating weight loss (10) and improving insulin metabolism (11).
Again, we do not recommend increases in intakes of domesticated animal fat, only of lean protein from lean animals, preferably protein that may also contain significant amounts of n-3 and monounsaturated fat such as that found in game meat. Consumption of low-fat dietary protein at the expense of carbohydrate is the nutritional pattern that is consistent with our species' evolutionary history and represents a viable dietary option for improving health and well-being in modern people. Further research is needed before this dietary pattern can be recommended without reservation, particularly in subjects with preexisting kidney disease.
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