DAVID GREENE, HOST:
A mystery in Bolivia. Scientists there have been studying this culture where heart disease barely exists. Here's NPR's Michaeleen Doucleff.
MICHAELEEN DOUCLEFF, BYLINE: Back in 1999, Michael Gurven was a young grad student in anthropology when he decided to take a daring trip deep in the rain forest. He hopped on a bus for 17 hours until the road ended.
MICHAEL GURVEN: Getting off the bus, you know, there was nothing - nowhere. So I just kind of started walking.
DOUCLEFF: And asking around about a group of farmers he had heard of called the Tsimane. They're an indigenous culture isolated from modern cities and still living like our ancestors did thousands of years ago.
GURVEN: And before long, I ended up at the house of the Tsimane government president.
DOUCLEFF: And instantly, Gurven was enchanted with the Tsimane lifestyle, hunting monkeys in the rain forest, fishing in rivers and drinking vats of beer made from fermented plantains. Gurven loved it so much, he decided to learn the language and live there.
GURVEN: It was really difficult. It was an intense time, and it was just amazing.
DOUCLEFF: And revealing. Over time, Gurven started to notice something about the Tsimane culture, that something was missing.
GURVEN: People just kind of clutching their chests and falling of heart attacks just isn't something that you ever really hear about.
DOUCLEFF: People didn't seem to have heart attacks, ever, which seemed kind of impossible, given that heart disease is common all around the world. So Gurven teamed up with a few cardiologists and started studying the Tsimane's hearts. Specifically, they measured the hardening of the arteries. What they found was striking.
GURVEN: Compared to the Americans, compared to a variety of countries in Europe, compared to Korea and even Japan, the Tsimane had the lowest level of atherosclerosis.
DOUCLEFF: In fact, the levels weren't just low. They were the lowest ever recorded in the world. Eighty-five percent of the Tsimane had no signs of heart disease at all.
GURVEN: And it wasn't only at age 50, 55, 60. But even up until, you know, past age 75, only 8 percent of Tsimane had atherosclerosis.
DOUCLEFF: So basically, even people that were in their 80s showed no signs of heart disease?
GURVEN: Yes, correct.
DOUCLEFF: Gurven and his collaborators recently published the findings in The Lancet journal. One of the cardiologists who helped with the study is Gregory Thomas at Long Beach Memorial in California. He says they're not 100 percent sure why that Tsimane have such spectacular hearts. But he thinks two major factors are at play. First off, the Tsmiane walk a lot. And I mean a lot.
GREGORY THOMAS: They exercise a huge amount, 17,000 steps for the men and 16,000 for the women.
DOUCLEFF: Sixteen thousand steps every day. That's like walking about seven miles every day. But here's the thing about this walking. It's easy, just like what you do naturally while fishing, farming or looking after the kids.
THOMAS: It's really the low intensity exercise for a long period of time. And we can do that really at any age. We don't have to be a 30-year-old at the gym looking strong. We can be going slow, but go long.
DOUCLEFF: And then there's the Tsimane diet. Thomas says it's very low in fat, especially saturated fat.
THOMAS: About 17 percent of their diet is wild game and 10 percent fish.
DOUCLEFF: But the rest, about 70 percent, is from carbohydrates. Now, we're not talking about bagels and baguette but unprocessed carbohydrates packed with fiber, like corn, plantains and tubers. Thomas says Americans can learn a lot from the Tsimane.
THOMAS: We don't necessarily want to go back to every family hunting and fishing for their self. It would be pretty dangerous to be doing that in most cities. But if we can practice some of that, we can benefit a lot.
DOUCLEFF: For starters, don't just go for 10,000 steps a day. Go for 15,000. And when selecting meat to eat, keep it lean. Maybe try some wild game. Michaeleen Doucleff, NPR News.
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