Chasing Good Heart Health in the Jungle

Headlines flowed this week from a study about people in a remote corner of the Amazon jungle who have exceptionally good heart health. This study, published in Lancet, tells us that the Tsimane people of Bolivia have the lowest rates of coronary artery plaque ever seen in any population.

This is one case where health reporters stuck with the facts better than the researchers did.

Findings in This Unusual Population

The Tsimane people are native to the Amazon jungle in the valley of the Maniqui River. They live a life of hunting, gathering, fishing, and farming. Modern industry plays virtually no role in their lives. Their diet consists of wild game, fish, and high-fiber plant foods. Monkeys, wild pigs, and piranha are notable features of that diet.

The researchers measured calcium plaques in the coronary arteries of 705 of these people. They also measured cholesterol, inflammation, and other risk factors for heart disease. For comparisons, the researchers used data from the landmark Multi-Ethnic Study of Atherosclerosis.

How low was the rate of atherosclerosis they found? It was five times less than the rates seen for people living in more industrial cultures. Likewise, this population had low rates of high cholesterol, blood pressure, blood sugar, obesity, and smoking. They live very active lives. In other words, risk factors for heart disease were low almost across the board.

Inflammation was the one exception. Infections in this population contribute to high measures of inflammation. Such inflammation is typically thought to contribute to atherosclerosis. But that was not the case in these people.

So What Does This Mean?

On this point, health reporters did a better job than the researchers.

By and large, health reporters stuck with the facts. They reported that this population has the lowest rate of risks for heart disease ever seen. For the most part, they did not try to say why. And of course, this study does not have the power to tell us anything about cause and effect. It might be diet. Or it might be physical activity. Freedom from modern stressors in a sedentary life might be the key factor.

All we have is a pattern of risk factors and markers for heart disease.

On the other hand, the researchers were not so shy. In a press release, lead author Hillard Kaplan said:

Our study shows that the Tsimane indigenous South Americans have the lowest prevalence of coronary atherosclerosis of any population yet studied. Their lifestyle suggests that a diet low in saturated fats and high in non-processed fibre-rich carbohydrates, along with wild game and fish, not smoking and being active throughout the day could help prevent hardening in the arteries of the heart. The loss of subsistence diets and lifestyles could be classed as a new risk factor for vascular ageing and we believe that components of this way of life could benefit contemporary sedentary populations.

All those factors are positives in the lives of these people. But the suggestion that this lifestyle “sets a new target in the prevention of coronary atherosclerosis” is speculation. It’s also worth noting that these people typically die at the age of 70. That’s about 15 years earlier than people in the U.S. So living in the jungle has a few downsides, too.

This story brings the cliché about the forest and the trees to life. Losing perspective is an easy thing to do in a dense jungle of data.

Will The Amazon Diet become the next New York Times bestseller? Let’s hope not. But don’t bet against it.

Click here for the study in Lancet. Read more from the Washington Post here, and from NPR here.

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March 22, 2017