Members of a remote Bolivian tribe who gather, hunt and plant 98 percent of the food they eat may have the healthiest hearts in the world, according to a new study conducted in part by Kansas City researchers.
Tsimane tribe members spend much of their days in the Amazon jungle lowlands hunting, fishing, foraging, farming, felling trees, hand-carving canoes, caring for children and hauling buckets of water from rivers or wells.
Their active daily routines, combined with a low-fat, high-Omega 3 diet, may explain why their heart scan results mirror those of U.S. residents 28 years younger. Overall, the Tsimane’s levels of coronary artery disease are the lowest of any group studied in the world, researchers announced Friday.
The findings indicate that hardening of the arteries, a precursor to heart attacks and strokes, should not be accepted as simply part of growing older, the researchers say.
“This study shows that … atherosclerosis is virtually preventable if you have a lifelong control of risk factors and exercise like this,” said Randall Thompson, a cardiologist at St. Luke’s Mid America Heart Institute and one of the study’s lead researchers.
“If we could improve people’s health by that extent, really slowing the aging process by 25 or 30 years, obviously the (health care) savings would be enormous, the improvement to our health would be enormous.”
Researchers conducted cardio scans, which typically take less than five minutes, on 705 tribe members ages 40 to 94. Many of them had medical issues, such as bronchial infections, intestinal parasites, tuberculosis and low-grade anemia from hookworms.
Yet 85 percent overall, and 65 percent of octogenarians, had no calcium visible in their coronary arteries. Just 3 percent overall, and 8 percent of octogenarians, had calcification scores of 100 or higher, which would include moderate risk or higher levels.
The Tsimane avoid nearly all risk factors for heart disease: high blood pressure, high blood sugar, obesity, regular cigarette smoking, too much bad cholesterol and lack of physical activity.
More study is needed to determine which lifestyle factors most help the Tsimane, the researchers say.
Thompson, who made three trips to Bolivia, focuses on how seldom the Tsimane sit still.
They take at least twice as many steps a day as U.S. residents. Multiple that over a lifetime and the difference is enormous, he said.
“We have a hard time getting 5 percent of the (U.S.) population to exercise 30 minutes a day,” he said. “These people are exercising or walking or doing significant physical activity for four to eight hours a day. Their sedentary time is maybe 10 percent, versus 50 percent for most of us.…
“The exercise might be the most important ingredient. It might be more than people appreciate.”
The Tsimane, many of whom live in thatched-roof huts, use long guns, spears and bows to hunt boar, deer, monkeys, birds and other game. Hunts can last eight hours and cover 11 miles.
They catch fish using long arrows or poison. They raise some chickens and pigs. They gather nuts and fruit in the rain forest, in some cases from what Thompson said appear to be abandoned orchards. They clear small forest parcels to plant crops, such as maize, before the poor soil forces them perhaps two years later to clear new land for new plantings. The little food they buy amounts to about 5 percent of their diets.
Though carbohydrates make up 72 percent of what they eat, most of that is high in fiber and low in saturated fat and sugars.
Though they wear modern clothes, they live so remotely that they had to travel one or two days by canoe from their villages just to reach a town where they could climb into Jeeps for six-hour rides to the research site in Trinidad, Bolivia.
Researchers picked the Tsimane because anthropologists have been studying their lives for 15 years, already had gathered some health data and had built a rapport with the people. The researchers chose a scientific sample of villages and then tried to scan the hearts of every member age 40 and older in those villages. Only a few people refused.
“They were happy to cooperate but they did wonder why we were studying a disease they didn’t have,” said Thompson, who relied on Spanish and Tsimane interpreters to communicate with tribe members, who do not speak English.
Test participants received free lodging and travel, plus medical attention for their health issues. They also got gifts, such as simple tools, needles and yarn.
Thompson, who announced the Tsimane study results Friday at an American College of Cardiology conference in Washington, D.C., didn’t expect to find such a high percentage of older Tsimane adults with such young-looking hearts.
That’s because he previously helped an international team study CT scans of mummies’ arteries. Scans in 2009 of mummies of middle-aged and older Egyptians showed that more than half probably had hardening of the arteries. More recent CT scans on mummies from other regions, including Peru and Alaska’s Aleutian islands, found clear signs of hardening of the arteries in 34 percent of them.
Hardening of the arteries has been around thousands of years, that research showed. So perhaps a modern person couldn’t prevent it through diet and exercise, researchers said.
Yet many of the mummies were revered members of hierarchical societies, Thompson said. They probably exercised less than the Tsimane and ate diets richer in fat.
Some of Thompson’s research colleagues expected the Tsimane to score well on heart disease tests. Those doctors already believed that hunter-gatherer societies lived much more heart-friendly lifestyles than western societies.
But that lifestyle could be changing for Tsimane. In recent years, some have gotten small motors for their canoes. That allows them to travel farther and buy more of their food while doing less work getting places.
Meanwhile, their cholesterol levels have risen slightly, Thompson said. That suggests that genetics are not protecting them.
Though Kansas Citians cannot imitate the Tsimane hunting and foraging lifestyle, we can do something about exercise, Thompson said. Perhaps all office-bound workers need treadmills at their desks, for example.
“Everything I see tells me that exercise is a major health benefit,” he said.