Thursday, 28 March, 2024
HomeA FocusBolivian Amazon tribe has healthiest hearts in the world

Bolivian Amazon tribe has healthiest hearts in the world

AmazonFocusA high carbohydrate diet of rice, plantain, manioc and corn, with a small amount of wild game and fish – plus around six hours of exercise every day – has given the Tsimané people of the Bolivian Amazon the healthiest hearts in the world, reports The Guardian. But it may not be a life that everyone would choose.

 

The Tsimané live in thatched huts with no electricity or modern conveniences. Their lives are spent on hunts that can last for over eight hours covering 18km for wild deer, monkeys or tapir and clearing large areas of primal forest with an axe, as well as the gentler pastime of gathering berries.

But as a result of this pre-industrial lifestyle, the Tsimané have hardly any hardening of the arteries. Heart attacks and strokes, the biggest killers in the US and Europe, are almost unknown.

The study, presented at the American College of Cardiology conference, shows that an 80-year-old Tsimané man has the vascular age of an American in his mid-50s. Researchers, who investigated the lifestyles of the Tsimané and checked out their arteries with CT scanners, say that there are lessons for those of us who live sedentary lives in urban areas and eat packaged foods.

“This study suggests that coronary atherosclerosis (hardening of the arteries) could be avoided if people adopted some elements of the Tsimané lifestyle, such as keeping their LDL cholesterol, blood pressure and blood sugar very low, not smoking and being physically active,” said senior cardiology author Dr Gregory S Thomas from Long Beach Memorial Medical Centre in the US.

“Most of the Tsimané are able to live their entire life without developing any coronary atherosclerosis. This has never been seen in any prior research. While difficult to achieve in the industrialized world, we can adopt some aspects of their lifestyle to potentially forestall a condition we thought would eventually effect almost all of us.”

The researchers found that almost nine out of 10 of the 705 Tsimané adults who took part in the study had no risk at all of heart disease; 13% had a low risk and only 3% – 20 individuals – had moderate or high risk. Even in old age, 65% of those aged over 75 had almost no risk and only 8% (four out of 48) had a moderate to high risk.

By contrast, in the US, a study of more than 6,800 people found that half had moderate to high risk – five times as many as among the Tsimané people – and only 14% had no risk of heart disease at all.

The report says in the Tsimané population, heart rate, blood pressure, cholesterol and blood glucose were also low. The study suggests that genetic risk is less important than lifestyle.

“Over the last five years, new roads and the introduction of motorised canoes have dramatically increased access to the nearby market town to buy sugar and cooking oil,” said Dr Ben Trumble, of Arizona State University in the US. “This is ushering in major economic and nutritional changes for the Tsimané people.” Those whose lifestyle is changing have higher cholesterol levels than others who stick to hunting and fishing.

Senior anthropology author Professor Hillard Kaplan, from the University of New Mexico, said the loss of subsistence diets and lifestyles could be classed as a new risk factor for vascular ageing. “We believe that components of this way of life could benefit contemporary sedentary populations,” he said.

Tsimané people are more likely to get infections than those in the US, but even so, he said, “they have a very high likelihood of living into old age.”

The report says the researchers cannot yet say whether diet or the active lifestyle is the more important component, said Kaplan, but they want to go on to investigate that by following those of the community whose lifestyles change with exposure to the town. “My best guess is that they act and they interact,” he said.

And it could be as much the foods that the Tsimané do not eat that gives them healthy hearts as the food that they do. Their diet is high in unrefined carbohydrates (72%) with about 14% protein and it is very low in sugar and in fat – also 14%, which amounts to about 38g of fat a day including 11g of saturated fat. “In the evolutionary past, fat and dense energy in the form of sugar were in short supply,” Kaplan said.

Summary
Background: Conventional coronary artery disease risk factors might potentially explain at least 90% of the attributable risk of coronary artery disease. To better understand the association between the pre-industrial lifestyle and low prevalence of coronary artery disease risk factors, we examined the Tsimane, a Bolivian population living a subsistence lifestyle of hunting, gathering, fishing, and farming with few cardiovascular risk factors, but high infectious inflammatory burden.
Methods: We did a cross-sectional cohort study including all individuals who self-identified as Tsimane and who were aged 40 years or older. Coronary atherosclerosis was assessed by coronary artery calcium (CAC) scoring done with non-contrast CT in Tsimane adults. We assessed the difference between the Tsimane and 6814 participants from the Multi-Ethnic Study of Atherosclerosis (MESA). CAC scores higher than 100 were considered representative of significant atherosclerotic disease. Tsimane blood lipid and inflammatory biomarkers were obtained at the time of scanning, and in some patients, longitudinally.
Findings: Between July 2, 2014, and Sept 10, 2015, 705 individuals, who had data available for analysis, were included in this study. 596 (85%) of 705 Tsimane had no CAC, 89 (13%) had CAC scores of 1–100, and 20 (3%) had CAC scores higher than 100. For individuals older than age 75 years, 31 (65%) Tsimane presented with a CAC score of 0, and only four (8%) had CAC scores of 100 or more, a five-fold lower prevalence than industrialised populations (p≤0·0001 for all age categories of MESA). Mean LDL and HDL cholesterol concentrations were 2·35 mmol/L (91 mg/dL) and 1·0 mmol/L (39·5 mg/dL), respectively; obesity, hypertension, high blood sugar, and regular cigarette smoking were rare. High-sensitivity C-reactive protein was elevated beyond the clinical cutoff of 3·0 mg/dL in 360 (51%) Tsimane participants.
Interpretation: Despite a high infectious inflammatory burden, the Tsimane, a forager-horticulturalist population of the Bolivian Amazon with few coronary artery disease risk factors, have the lowest reported levels of coronary artery disease of any population recorded to date. These findings suggest that coronary atherosclerosis can be avoided in most people by achieving a lifetime with very low LDL, low blood pressure, low glucose, normal body-mass index, no smoking, and plenty of physical activity. The relative contributions of each are still to be determined.

Authors
Hillard Kaplan, Randall C Thompson, Benjamin C Trumble, L Samuel Wann, Adel H Allam, Bret Beheim, Bruno Frohlich, M Linda Sutherland, James D Sutherland, Jonathan Stieglitz, Daniel Eid Rodriguez, David E Michalik, Chris J Rowan, Guido P Lombardi, Ram Bedi, Angela R Garcia, James K Min, Jagat Narula, Caleb E Finch, Michael Gurven, Gregory S Thomas

[link url="https://www.theguardian.com/society/2017/mar/17/tsimane-of-the-bolivian-amazon-have-worlds-healthiest-hearts-says-study?CMP=Share_iOSApp_Other"]The Guardian report[/link]
[link url="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)30752-3/fulltext"]The Lancet article summary[/link]

MedicalBrief — our free weekly e-newsletter

We'd appreciate as much information as possible, however only an email address is required.