By Sally J. Feltner, MS, Ph.D
The Pima Indians of Arizona have the highest rates of diabetes and obesity in North America. An estimated 50 percent of Pima adults are obese, and of those, 95% have diabetes type 2.
WHAT HAPPENED?
The story is not new – it more than likely began in the 1500’s when the Spanish explorers made contact with them in the New World. They and most Native tribes of that time were hunter-gatherers. They were lean, active and healthy people.
Pima Indians are believed to be descendants of people who crossed the Bering Strait from Asia to the Americas. Their traditional diet included meals made from the crops they cultivated including corn (maize), kidney beans, sunflower seeds, pumpkins and squash. Small game such as rabbit, was a staple part of their diet together with meat from their livestock such as sheep and goats. Larger game was also available such as deer, elk and bear. As they were in close proximity to rivers, fish, duck and many different types of shellfish were major elements of their diet, which was also supplemented with herbs, acorns and roots. Sadly, as the years went on, the Arizona group met with some unavoidable circumstances that changed their way of life considerably – especially their traditional diets, economics, and well-being.
- In 1859, the Arizona Pimas’ land along the Gila River was taken away by the U.S. government which left them to live on what land was left known as the Gila Reservation.
- In 1866, new settlers began to populate the Pima region and diverted the water from the Gila River for their own use.
- By 1869, the river had dried up and the Arizona Pimas were left with no water and less land to grow their food and crops resulting in an on – and – off – 40-year-old famine. As a result, the government exacerbated the problem again by providing subsidized foods to the tribe consisting of white flour, sugar, lard and canned goods, a far cry from their traditional diets of corn, beans and squash.
The timing of these significant changes in lifestyle and livelihood of the Arizona Pima population coincides with their development of diabetes type 2. At the turn of the nineteenth century, studies recorded only one case on the Gila River Reservation. In 1937, a study documented twenty-one persons with diabetes. By the 1950’s, however, the prevalence had increased ten-fold and a study initiated in 1965 documented in the Arizona Pima Indians the highest prevalence of diabetes ever recorded.
THE PIMA INDIANS IN MEXICO
The Pima Indians who had settled in Mexico resided in the small town of Maycoba. For decades they had been isolated until 1991 when a paved access to the town was constructed. Before that they grew a majority of their own food and still adhered primarily to their traditional diet that was similar to the Arizona tribe. Since they are genetically similar to the Arizona Pima, they present an opportunity to study and compare the two-lifestyle patterns of both tribes (diet and exercise) on their health statistics.
What Has Been Learned from Various Studies of these two Populations?
An Abstract from one study in 1994 that compared the two groups gives us the following details:
OBJECTIVE The Pima Indians of Arizona have the highest reported prevalence of obesity and diabetes type 2 In parallel with abrupt changes in lifestyle and the incidence in Arizona Pimas have increased to epidemic proportions during the past decades. To assess the possible impact of the environment on the prevalence of obesity and diabetes type 2, data were collected on members of a population of Pima ancestry living in a remote mountainous location in northwestern Mexico, with a lifestyle contrasting markedly with that in Arizona.
RESULTS The Mexican Pimas were significantly lighter and shorter with a lower Body Mass Index. They also had a significantly lower plasma total cholesterol level than the Arizona Pimas. Even more startling was that diabetes type 2 was less prevalent with only 2 women (11%) and 1 man (6%) in the Mexican group compared with a prevalence of 37% and 54% in male and female Arizona Pima Indians respectively.
CONCLUSIONS This preliminary investigation shows that obesity, and perhaps type 2 diabetes is less prevalent among people of Pima heritage living a “traditional” lifestyle than among Pimas living in an “affluent” environment. These findings suggest that, despite a similar potential genetic predisposition to these conditions, a traditional lifestyle, characterized by a diet including less animal fat and more complex carbohydrates and by greater energy expenditure in physical labor, may protect against the development of cardiovascular disease risk factors, obesity, and diabetes type 2.
DISCUSSION:
These results indicate that a more traditional lifestyle of the Mexican Pimas protects the group against obesity, diabetes and kidney disease, even though they may have a genetic predisposition for such health problems.
What explains the results of experiences of the Arizona Pima? One popular theory is one thing that drives obesity is a switch to a diet of highly refined carbohydrates that are so common in the Standard American Diet (SAD). When the Pima replaced traditional, unrefined carbohydrates with refined (sugar and flour), they became obese. It may not be the amount of food we eat but what kinds or quality we consume.
The lessons learned here support the theory that lifestyle factors appear to significantly influence the prevalence of obesity and diabetes type 2 in a population predisposed genetically to these conditions. Their story gives us all the opportunity to reassess our own current diets and lifestyle factors that may lead to healthier food environments and ultimately prevent our current situation of the diabesity dilemma.
SOURCES
Stephen Guyenet, Lessons From the Pima Indians. Whole Heath Source: Nutrition and Health Science.
Leslie O Schulz, PhD, Lisa S. Chaudhari, PhD. High-Risk Populations: The Pimas of Arizona and Mexico. Curr Obes Rep. 2015 March 1; 4(1): 92-98
Ravussin, et al. Effects of a Traditional Lifestyle on Obesity in Pima Indians, Diabetes Care 1994 September 17(9): 1067-1074
FOOD, FACTS and FADS 