ONE THE ABORIGINE IN ALL OF US
In the summer of 1982, a group of ten middle-aged, overweight, and diabetic Aborigines living in settlements near the town of Derby, Western Australia, agreed to participate in an experiment to see if temporarily reversing the process of westernization they had undergone might also reverse their health problems. Since leaving the bush some years before, all ten had developed type 2 diabetes; they also showed signs of insulin resistance (when the body’s cells lose their sensitivity to insulin) and elevated levels of triglycerides in the blood—a risk factor for heart disease. “Metabolic syndrome,” or “syndrome X,” is the medical term for the complex of health problems these Aborigines had developed: Large amounts of refined carbohydrates in the diet combined with a sedentary lifestyle had disordered the intricate (and still imperfectly understood) system by which the insulin hormone regulates the metabolism of carbohydrates and fats in the body. Metabolic syndrome has been implicated not only in the development of type 2 diabetes, but also in obesity, hypertension, heart disease, and possibly certain cancers. Some researchers believe that metabolic syndrome may be at the root of many of the “diseases of civilization” that typically follow a native population’s adoption of a Western lifestyle and the nutrition transition that typically entails.
The ten Aborigines returned to their traditional homeland, an isolated region of northwest Australia more than a day’s drive by off-road vehicle from the nearest town. From the moment they left civilization, the men and women in the group had no access to store food or beverages; the idea was for them to rely exclusively on foods they hunted and gathered themselves. (Even while living in town, they still occasionally hunted traditional foods and so had preserved the knowledge of how to do so.) Kerin O’Dea, the nutrition researcher who designed the experiment, accompanied the group to monitor and record its dietary intake and keep tabs on the members’ health.
The Aborigines divided their seven-week stay in the bush between a coastal and an inland location. While on the coast, their diet consisted mainly of seafood, supplemented by birds, kangaroo, and witchetty grubs, the fatty larvae of a local insect. Hoping to find more plant foods, the group moved inland after two weeks, settling at a riverside location. Here, in addition to freshwater fish and shellfish, the diet expanded to include turtle, crocodile, birds, kangaroo, yams, figs, and bush honey. The contrast between this hunter-gatherer fare and their previous diet was stark: O’Dea reports that prior to the experiment “the main dietary components in the urban setting were flour, sugar, rice, carbonated drinks, alcoholic beverages (beer and port), powdered milk, cheap fatty meat, potatoes, onions, and variable contributions of other fresh fruits and vegetables”—the local version of the Western diet.
After seven weeks in the bush, O’Dea drew blood from the Aborigines and found striking improvements in virtually every measure of their health. All had lost weight (an average of 17.9 pounds) and seen their blood pressure drop. Their triglyceride levels had fallen into the normal range. The proportion of omega-3 fatty acids in their tissues had increased dramatically. “In summary,” O’Dea concluded, “all of the metabolic abnormalities of type II diabetes were either greatly improved (glucose tolerance, insulin response to glucose) or completely normalized (plasma lipids) in a group of diabetic Aborigines by a relatively short (seven week) reversion to traditional hunter-gatherer lifestyle.”
O’Dea does not report what happened next, whether the Aborigines elected to remain in the bush or return to civilization, but it’s safe to assume that if they did return to their Western lifestyles, their health problems returned too. We have known for a century now that there is a complex of so-called Western diseases—including obesity, diabetes, cardiovascular disease, hypertension, and a specific set of diet-related cancers—that begin almost invariably to appear soon after a people abandons its traditional diet and way of life. What we did not know before O’Dea took her Aborigines back to the bush (and since she did, a series of comparable experiments have produced similar results in Native Americans and native Hawaiians) was that some of the most deleterious effects of the Western diet could be so quickly reversed. It appears that, at least to an extent, we can rewind the tape of the nutrition transition and undo some of its damage. The implications for our own health are potentially significant.*
The genius of Kerin O’Dea’s experiment was its simplicity—and her refusal to let herself be drawn into the scientific labyrinth of nutritionism. She did not attempt to pick out from the complexity of the diet (either before or after the experiment) which one nutrient might explain the results—whether it was the low-fat diet, or the absence of refined carbohydrates, or the reduction in total calories that was responsible for the improvement in the group’s health. Her focus instead was on larger dietary patterns, and while this approach has its limitations (we can’t extract from such a study precisely which component of the Western diet we need to adjust in order to blunt its worst effects), it has the great virtue of escaping the welter of conflicting theories about specific nutrients and returning our attention to more fundamental questions about the links between diet and health.
Like this one: To what extent are we all Aborigines? When you consider that two thirds of Americans are overweight or obese, that fully a quarter of us have metabolic syndrome, that fifty-four million have pre diabetes, and that the incidence of type 2 diabetes has risen 5 percent annually since 1990, going from 4 percent to 7.7 percent of the adult population (that’s more than twenty million Americans), the question is not nearly as silly as it sounds.