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The increased prevalence of coronary heart disease, diabetes, and hypertension among indigenous people can probably be partly explained by an increasing shift in dietary habits away from locally available food sources (bush foods) towards non-local refined and packaged foodstuffs. This factor among Australian Aborigines has been linked to the prevalence of malnutrition and infections in Aboriginal infants and children, maternal malnutrition and health problems, cardiovascular diseases, and diabetes (Gracey, 1986). A survey conducted among Aborigines living in six missions, five government settlements, and six cattle stations in the Northern Territory during the 1950s noted that the amount of indigenous foods consumed was not large. However, the mean consumption of bread, cereals, and flour was approximately twice the average Australian consumption; while the consumption of meat was 30 per cent higher. Milk products, fruit, vegetables, fats, and eggs were on average consumed less often than by other Australians (Wilson, 1953).
Furthermore, significant differences in dietary habits seem to exist even among urbanized Aborigines. A study of dietary patterns in an Aboriginal community in southwestern Australia noted that nutrient intakes were closely related to several social factors including employment, education, and the standard of housing. Caloric and other nutrient intakes were the lowest in households on the reserve; while households in town and between town and the reserve had much higher intakes (Hitchcock and
Gracey, 1975). Although Kamien and colleagues (1975a) also noted similar differences in the nutrient intakes of Bourke Aborigines, they concluded that the families living both on the reserve and in town had unsatisfactory diets. Overall, the high costs of food in remote towns and communities may help to encourage these unsatisfactory dietary patterns and socio-economic differentials (Sullivan et al., 1987).
Not all Aboriginal dietary intake studies support the view that dietary intakes are unsatisfactory or inconsistent with the wider society. A recent dietary recall study
conducted by Sibthorpe (1988) among Kempsey Aborigines noted that fat, sugar, and vitamin intakes were on the whole not inconsistent with results for all Australians. Evidence from the United States supports Sibthorpe's findings. A dietary intake study of Pima Indians aged 25 to 44 years showed that dietary habits met or exceeded American recommended allowances for calories, protein, calcium, iron, and
magnesium. The ratio of polyunsaturated to saturated fat was also lower. Furthermore, no link could be made between the intake of selected nutrients and the high prevalence of gall bladder disease and diabetes among the Pima (Reid et al., 1971).
In Canada, several researchers argue that large-scale development quickens the
acculturation of traditional Indian dietary habits. For example, in northern Manitoba the Churchill-Nelson River Hydro Project has been shown to have indirectly increased the dependence of local Indians on non-local food sources. This dietary void has been filled by an increased consumption of store-bought meats and other foodstuffs which are generally less nutritious than locally available bush foods (Waldram, 1985). A similar pattem of change towards store-bought foods has occurred among the Cree and Inuit of northern Quebec. Again these changes were brought on by a major
hydroelectric development in the area (Thouez et al., 1989).
A dietary intake analysis among the Dogrib Indians in Canada noted that dietary differences by community and age demonstrate a consistent but different pattem of dietary acculturation. The traditional food base is stable between communities, as neither total grams of traditional foods consumed nor the total calories derived from them vary significantly. However, non-traditional intakes do differ, producing a pattern of variable amounts of 'new food' being added to a traditional food base. The net result by community or age is more a matter of change in the quantity of food eaten than the substitution of new foods for native foods (Szathmary et al., 1987: 801).
In New Zealand, a study conducted by the National Heart Foundation during the mid- 1970s (Birkbeck, 1977) remains to this day the only comprehensive dietary study
Page 69 undertaken. Overall, the findings were that Maoris consume more energy and fat, particularly saturated fat, and significantly less fruit and vegetables than the non-Maori population (Pomare and de Boer, 1988).
Economic and social changes brought about by migration also have an important bearing on the availability and use of food and ultimately on nutrition and health status. For example, in New Zealand the dietary habits of migrants from the Cook Islands have been shown to shift from a diet high in fibre content and low in refined carbohydrates and salt to one low in fibre content and high in refined carbohydrates and salt. These dietary changes reflect the social adaptations the migrants have to make in the new environment, including adjustments to an increased income, the availability of new and familiar foods, and shifting work patterns (Fitzgerald, 1986).
The high prevalence rates of hypertension, heart disease, and cerebrovascular disease among Nauruans are presumed to be related to the high prevalence of obesity and high salt intake (Taylor et al., 1985); while the prevalence of obesity is probably related to high caloric intake coupled with reduced physical activity (Ringrose and Zimmet,
1979). The move from a traditional diet of coconut products and fish to a reliance on store-bought foods (particularly polished rice, sugar, condensed milk, and canned meat and fish) became significant by the mid-1920s. Such changes in diet, suggest Taylor and Thoma (1985: 153), are usually associated with increased salt intake, both from purchased salt and from highly salted foods.
Although this literature review makes no clear link between diet and heart disease in indigenous people, the evidence presented does indicate that acculturation can greatly alter dietary habits. Overall, there seems to be a shift away from traditional bush foods to prepackaged store-bought foods which are higher in salt, fat, and refined
carbohydrates and lower in dietary fibre, all of which have been shown to be dietary risk factors of coronary heart disease.