Mayan ancestry may help explain the high risk of diabetes in Mexico

[Judi Lynn]

Mayan ancestry may help explain the high risk of diabetes in Mexico
By Emiliano Rodríguez Mega 5 June 2015 3:45 pm

Mexico has one of the highest rates of type 2 diabetes in the world, with 12% of the population suffering from the condition, compared with 9% of people in the United States. The Mexican government is so worried that it recently declared a state of emergency and introduced a tax on soda and junk food. But a new study shows that some Mexicans may be at higher risk for developing diabetes, no matter how healthy their diets are. The reason may be their Maya ancestry, which carries with it genetic variations associated with the disease.

“This is an important finding, because it could provide us clues about how to tackle the disease and plan public health strategies,” especially for Maya-speaking people, says María Guadalupe García, a geneticist at the Autonomous University of Yucatán (UADY) in Mérida, who was not involved in the research.

There may be fewer Maya today than at the culture’s height 3000 years ago, but they never disappeared. Today, Maya-speaking people constitute the second largest indigenous group in Mexico, with 800,000 people living mainly in the Yucatán Peninsula in the country’s southeast. Isolated culturally and geographically from other ethnicities for thousands of years, the Maya gene pool grew smaller and more homogeneous. As tends to happen with any isolated population, genetic variations that are rare in other groups became common among the Maya. Clinical biochemist Marta Menjívar of the National Autonomous University of Mexico (UNAM) in Mexico City wondered whether any of those variations might increase the Maya’s risk for diabetes, a growing problem in southeastern Mexico.

Menjívar’s team surfed through the genomes of 575 Maya individuals looking for 10 genetic variants that had been previously related to diabetes risk. They found that two are unusually common in the Maya, the researchers will report in next month’s issue of Gene.

More:
http://news.sciencemag.org/health/2015/06/mayan-ancestry-may-help-explain-high-risk-diabetes-mexico

[newfie11]

1. That's interesting

I know the Lakota Sioux have a very high level of Diabetes also.

[Warpy]

2. Locally, the Zuni tribe got proactive

They also had extremely high rates of diabetes, so they signed people up to do a trial of living on traditional foods of flint corn, beans, squash, chiles, and occasional small game meat. Diabetes rates among the test group plummeted. I do think they kept their coffee, they just ditched the sweeteners and dairy.

I don't know how many have signed up for this since the early program in the 90s. I only know the results they got, which were astonishing.

Weight loss also occurred, but down to a healthy weight, not a supermodel weight.

[Judi Lynn]

3. Never knew about this! Thank you, so much. n/t

[Warpy]

4. The study was started in the 80s, was continued by the tribe into the 90s

All I could find currently was CDC documentation of the IHS part of the program that stressed education and exercise classes. I was really hoping the dietary stuff was still out there somewhere, it was fascinating reading at the time.

[Igel]

5. The Huntington in Pasadena has cacti/succulent symposium each year. (Or did.)

The year I went for my C&SS in the mid-late '90s the focus was on ethnobotany and food. One of the larger issues was diabetes.

IIRC, they didn't discuss Mayans. They discussed the native populations in N. Mexico and S. Arizona, for the most part, where you get cacti and succulents. The diabetes rate among those populations is elevated and started increasing perhaps 20 years before (i.e., in the late '70s).

This corresponded to when tribes had a large-scale shift from native-plant and unrefined-food dominated diets to "Western" diets--high fat, high carb, high processing. Their average weight soared, esp. among the young. And their diabetes rate soared.

Several lines of research were explored. One was just weight, which wasn't sufficient. More weight = more diabetes, but that didn't account for much of the variance. That left lifestyle.

It was pointed out that the population had been more physically active, which not only kept the population thinner but also helped flat-line blood sugar levels after meals. The foods they had eaten had more complex carbs in it, helping also to reduce the diabetes rate. But also crucially pointed out in a series of papers that a variety of succulents provided oligosaccharides and other phytochemicals that inhibited rapid carb conversion and consequent sugar uptake and helped reduce the glycemic index even of other high-carb foods eaten at the same time. Eat those tunas and the refined wheat flour tortillas and your blood sugar increases at rates much lower than if you ate apples and the same tortillas, in other words. (A "tuna" is a prickly pear fruit.)

And, yes, one set of researchers actually asked some tribe members to alter their diets--it wasn't just a survey-based paper. And when they reverted to what some described as their "parents' food" the symptoms and incidence of diabetes declined.

One line of speculation was that a lot of the die-off in European populations because of a higher-carb diet happened in pre-history, selecting for a population that was more diabetes resistant. The current increase in European populations is because of a second dietary shift. This means that what we see is just two processes that are superimposed--response to very refined diets coupled with a shift much like what happened perhaps 9 kya in Europe (and at various other times elsewhere). This research sort of jabs at that: instead of it being evolution by survival of the fittest, there was a process by which certain populations became less fit. Perhaps that works for the Mayan (doubtful, but possible: Mexico has a number of genetic hot-zones because of inbreeding and founder effects). But it doesn't work for all the other populations. So we can assume two causations or one. By default, one involves fewer variables and is to be preferred in the absence of clear and unambiguous data.

[appalachiablue]

6. Interesting. There's a fairly high rate of diabetes among some ME, No. Indian & Pakistani groups.

Whether it's due to diet & lifestyle, genes or some close marriages to cousins & relatives I don't know.