A high carbohydrate diet of rice, plantain, manioc and corn, with a small amount of wild game and fish – plus around six hours’ exercise every day – has given the Tsimané people of the Bolivian Amazon the healthiest hearts in the world.
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 published in the Lancet medical journal and being 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.”
Coronary atherosclerosis is the build-up of plaque in the arteries leading to the heart, which slows the blood flow and can cause blood clots – which may in turn lead to a heart attack. 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.
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, 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 Prof 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 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.
