Diabetes in Native Americans Linked to Prehistoric Diet
If you want to know why the rate of diabetes among Native Americans is so high, a research team believes it has found the answer in fossilized feces. It appears the prehistoric diet of Native Americans living in the Southwest led to the development of genes that store fat, called "thrifty genes."
Diabetes in Native Americans is epidemic
The theory about thrifty genes was proposed in 1962 by geneticist James Neel to help explain why the rate of diabetes among Pima Indians, a population that lives in the Southwest, is 50% among adults. Neel's theory is based on the fact that the Pima Indians experienced alternating periods of feast and famine for thousands of years, and that they developed a thrifty gene that allowed them to store fat during times of famine.
According to Karl Reinhard, professor of forensic sciences at the University of Nebraska-Lincoln's School of Natural Resources and the lead author of the new study, what he and his colleagues found in the fossilized feces (coprolites) indicate the thrifty genes did not develop in response to feast-or-famine scenarios, but in response to what the prehistoric Native Americans consumed on a daily basis, year round. "By looking at coprolites, we're seeing exactly what people ate," he said in a University news release.
The fossilized feces of Native Americans of the Southwest reveal that their diet would have been excellent for people who live with diabetes today: low in fat, high in fiber, and rich in foods low on the glycemic scale. Unfortunately, today's dietary habits include high-fat, low-fiber foods that are high on the glycemic index, and this clash between ancient genes and modern day poor diet contributes to diabetes.
The researchers analyzed coprolites from Antelope Cave, which is located in northern Arizona and which was home to a variety of Native American cultures. What the ancient Native Americans in this area ate included corn, seeds from sunflowers, wild grasses, amaranth, pigweed, and prickly pear--foods high in insoluble fiber and also low on the glycemic index.
The glycemic index ranks foods by their ability to have an impact on blood sugar. Foods ranked low (55 or lower) on the index are believed to be good while those with a value of 70 or higher can cause a person's blood sugar levels to rise and fluctuate, and to increase the risk of diabetes and obesity.
Native Americans and diabetes
Native Americans are 2.2 times more likely to have diabetes than are non-Hispanic whites, according to the US Department of Health and Human Services' Indian Health Service. Diabetes rates among Native Americans is 16.3% compared with 7.6% in non-Hispanic whites.
Among young Native Americans, there was a 68% increase in diabetes from 1994 to 2004 among those aged 15 to 19 years. In addition, an estimated 30% of Native Americans have prediabetes. Figures from 2008 show that Native Americans were 1.8 times more likely than non-Hispanic whites to die from diabetes.
The new study, which appears in Current Anthropology, suggests the so-called thrifty genes developed in Native Americans because of what they ate and not because of a feast-or-famine scenario. If so, helping Native Americans return to eating habits that are much closer to their prehistoric diet could be a significant benefit for those with diabetes and in preventing the disease.