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* Department of Preventive Medicine and Biometrics, University of Colorado School of Medicine, Denver, CO and Navajo Area Indian Health Service, Window Rock, AZ
INTRODUCTION
FOOTNOTES
LITERATURE CITED
INTRODUCTION 
Research among American Indian populations has often not been tied directly to programs intended to improve the health status of the populations studied. Consequently, medical research has often been seen by American Indians and Alaska Natives as exploitation. In the past 100 years, there have been over 1200 studies of subjects and topics relating to clinical and health status investigations of the Navajo (Indian Health Service 1992). Research among the Navajo has been for many purposes, including anthropologic descriptive studies, studies of unusual occurrences of diseases and even randomized trials to test new vaccines. In the past, research was often done on small convenience samples, resulting in too little useful information for the Navajo people or for the programs that serve them.
In recent years, the Indian Health Service (IHS), in close collaboration with tribal governments, has established systems for more careful review of research conducted among Native Americans. The Navajo Nation Research Review Board now oversees all research conducted within its boundaries and has established a research policy to encourage the conduct of research on high priority health issues. Consequently, a more proactive research agenda is now being promoted to encourage research that can lead to improvements in the health of the Navajo people.
The Navajo Health and Nutrition Survey (NHNS) had a clear purpose, namely, to characterize the health and nutritional status of the Navajo in order to guide IHS and Tribal efforts in disease prevention, health promotion and clinical treatment services for the people of the Navajo Nation. The NHNS was conducted by the IHS with approval by the Health and Social Services Committee of the Navajo Nation Council. The findings from this survey that are now being reported in this supplement to The Journal of Nutrition have been reviewed and approved by the Navajo Nation Research Review Board.
The health history of the Navajo is inextricably related to Navajo social, political and economic history (Kunitz 1983
). The traditional historic lifestyles of gathering, cultivating and hunting for foods required high levels of physical activity. Even though meat intake increased substantially after the introduction of sheep-herding by the Spaniards, the maintenance of an active lifestyle allowed the Navajo to maintain good health until the forces of poverty, U.S. government Indian policies and infectious diseases began to take their toll in the late 19th century. Warfare and forced relocation led to undernutrition and infectious diseases from the last half of the 19th century, well into the early 20th century. In the last half of the 20th century, a more sedentary lifestyle, coupled with poorer nutritional habits, has now replaced starvation as the major nutritional concern among the Navajo. Changes in mortality among the Navajo in recent years reflect these trends (Table 1). Even in the brief 4-year time period between 1988 and 1992, mortality from heart disease increased by over 22% among the Navajo, whereas there was a decrease of ~10% in the U.S. as a whole (U.S. Department of Health and Human Services 1992, 1996a and 1996b). Mortality from diabetes mellitus is high and rising as well among the Navajo.
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Table 1. Mortality from selected chronic diseases among Navajos, 1988 and 19921 |
It is likely that much of the increase in chronic diseases among the Navajo is due to nutritional factors. A survey of Navajo dietary intake by Steggerda and Eckardt in 1934-1936 concluded that the Navajo, though eating high amounts of fat from mutton, may have reached a point of dietary balance, with ample physical activity contributing to their apparent high levels of physical fitness (Steggarda and Eckardt 1941). Because of concerns about possible undernutrition, another nutrition survey was conducted among the Navajo by the Rockefeller Foundation in the summer of 1955. The Journal of Nutrition published that landmark study in 1956: "A study of the dietary background and nutriture of the Navajo Indian" (Darby et al. 1956). That report was only the second supplement ever published by The Journal of Nutrition. Darby made the following observation in 1955: ". . . The Navajo . . . has abandoned his primitive diet 
he no longer depends on the hunt, on Indian corn, on the gathered wild plants, berries, and fruits for his food." That survey found little evidence of nutritional deficiency diseases and documented an apparently physically fit population.
Now, over 40 years after the Darby survey, The Journal of Nutrition is publishing another landmark survey of the health and nutrition status of the Navajo the Navajo Health and Nutrition Survey (NHNS). The Darby study was based on a convenience sample from only two Navajo communities, whereas the NHNS is based on a representative sample of the entire population residing on the Navajo reservation. The NHNS is the first comprehensive health and nutrition survey that is truly representative of the entire Navajo Nation. The NHNS was carried out by the IHS, in cooperation with the Navajo Nation government. The Centers for Disease Control and Prevention assisted with the data analysis. The NHNS therefore represents not only the state-of-the-art in health and nutrition survey methodology, but also represents health research that is designed and conducted collaboratively within the health care and political governance systems serving the Navajo Nation. The findings from the NHNS were presented to a meeting of tribal officials and health care workers in the autumn of 1995. The major findings from this survey are therefore already being incorporated into plans for improving the prevention and treatment services for the people of the Navajo Nation. We consider the following findings from the NHNS to be of particular importance for the planning and evaluation of prevention and clinical services.
, White et al. 1997a). The substantial increase in the prevalence of obesity among the Navajo in recent years, particularly the high prevalence of central adiposity (Gilbert et al. 1992), suggests a nutritional imbalance. Both the diet and the levels of physical activity have to be addressed (Byers 1992). Decreasing physical activity, experienced by most groups in the U.S. in recent decades, may be especially hazardous for the Navajo and other Native Americans, who appear to be metabolically sensitive to caloric overload (Popkin 1994). For those who are already overweight, preventing additional weight gain and achieving modest weight loss offer meaningful benefits to health, but the dismal results from weight loss programs in the U.S. in the past suggest that the prevention of excessive weight gain should be the primary goal for the Navajo. These efforts can target the entire lifespan but should begin early in life, with sensible school policies for good nutrition and ample physical education.
Diabetes.
Diabetes is an even greater health problem than previously realized among the Navajo (Will et al. 1997). Over 40% of Navajos ages 45 and older are now diabetic, although a third of those are unaware of their condition. In addition, another 18% of Navajos are glucose intolerant and therefore at high risk for the development of diabetes in the future. Therefore, the majority of Navajo adults are now either diabetic or prediabetic. Our understanding of the problem of diabetes among the Navajo has a tragic history. Diabetes was once rare among the Navajo (Salsbury 1937). Later, when diabetes emerged, it was erroneously regarded as a benign condition (Prosnitz and Mandell 1967). Now the full manifestation of diabetes is becoming evident increasing rates of heart disease, amputations, blindness and renal failure. Both primary prevention and improved clinical care must be pursued to address the growing problem of diabetes among the Navajo.
Coronary heart disease.
The NHNS showed that unfavorable risk factors for cardiovascular disease are common among the Navajo (Mendlein et al. 1997). The recent increases seen in heart disease mortality among the Navajo are therefore likely to continue unless prevention efforts are increased. The decline in heart disease mortality in the U.S. over the past 20 years has apparently been due to both primary prevention and improved treatment. These dual efforts of primary prevention and clinical preventive services will be required to influence obesity, hypertension, diabetes, cholesterol levels, tobacco use and diet to reverse the adverse trends in heart disease among the Navajo.
Tobacco.
Tobacco use may be increasing among Navajo youth and young adults (Freedman et al. 1997). Therefore, it cannot be assumed that the low rates of tobacco abuse among the Navajo in the past will continue into the future. Evidence from other populations has shown that the abuse of tobacco can act in concert with factors already common among the Navajo (diabetes, obesity, hypertension and elevated cholesterol) to greatly increase the risk of heart disease. Navajo policy makers, educators and health care providers cannot be complacent about the evidence that the use of tobacco products among young people is increasing.
Diet.
There is increasing evidence of the importance of diet in the prevention of many chronic diseases. Dietary intake of fruits and vegetables is low among the Navajo, and intake of fats is high (Ballew et al. 1997). However, it cannot be assumed that future improvements in the socioeconomic status among the Navajo will necessarily lead to improved diets. A recent analysis of diet trends in the U.S., for example, showed that improvements in economic conditions for African Americans over the past 30 years have actually been accompanied by a less healthful diet (more high fat foods and fewer foods from plant sources) (Popkin et al. 1996). The very low levels of fruits and vegetables in the Navajo diet are a particularly important problem. To remedy this situation is challenging, however, because only half of the households have refrigeration, and stores that sell fruits and vegetables are very distant from many homes.
Women's health.
Clearly, the most important women's health issues among the Navajo are now chronic diseases. Although reproductive health issues related to traditionally high parity, including iron deficiency anemia, continue to be a problem (Strauss et al. 1997), these issues do not appear to be as important as the trends in obesity, diabetes and heart disease risk factors among Navajo women (Mendlein et al. 1997, White et al. 1997a, Will et al. 1997). Continued efforts to improve coverage for Pap smears and mammography are necessary, but categorical programs to accomplish these goals should be implemented in a way that also meets the needs of Navajo women for the primary prevention of other more common chronic diseases.
Clinical services.
Many of those already diagnosed with hypertension and diabetes are not in adequate clinical control (Percy et al. 1997, Will et al. 1997). The approach to the delivery of clinical treatment services for diabetes and hypertension must be re-examined to improve treatment and control of these chronic conditions. Improved patient and family education is needed, but perhaps more important are outreach services to provide chronic care and patient monitoring for those who live far from clinical care centers.
). The findings from the NHNS should be useful in stimulating the design of a more efficient and effective future health care system, emphasizing health promotion, disease prevention and effective clinical services for the Navajo Nation (White et al. 1997b).
FOOTNOTES
LITERATURE CITED
1886-1996. Navajo Area Indian Health Service, Window Rock, AZ.
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