In a recent study published in British medical journal The Lancet, the Tsimane, who live a subsistence lifestyle in the Bolivian Amazon, were found to have the healthiest arteries in the world.
American researchers found that the coronary arteries of an 80-year-old Tsimane are typically as supple as those of an American in his or her mid-50s – with hardly any signs of coronary atherosclerosis (hardening of the arteries).
The researchers, led by Hillard Kaplan, a professor of anthropology at the University of New Mexico, say the extremely low levels of vascular ageing are probably down to the Tsimane diet. It is very low in saturated fat and high in fibre. The Tsimane also have high levels of physical activity and almost no smoking.
However, the relative contributions of these lifestyle factors to the cardiac health of the Tsimane are still to be determined.
In their study, conducted between 2014 and 2015, the researchers examined 705 Tsimane adults aged 40 to 94.
They took CT scans of coronary arteries and measured cholesterol and blood sugar levels, as well as blood pressure, among other things.
85% of those tested had no coronary artery calcium (CAC).
By comparison, a similar US study of Americans aged 45 to 84 found only 14% to have no CAC.
Nearly three-quarters of the Tsimane diet consists of non-processed, high-fibre foods in the form of rice, manioc (a starchy root vegetable), maize, nuts and fruits such as plantain, a low-sugar relative of the banana.
Protein – via meat and fish – constitutes 14% of their diet, and fat, another 14%.
While people in industrialised societies typically spend more than half of their waking hours sitting, the Tsimane are sedentary just 10% of the time.
They spend the rest of the day hunting, fishing, foraging or farming.
The study also cast doubt on the link between inflammation and heart disease, as elevated levels of inflammation were found in slightly more than half of the Tsimane who were examined.
“Conventional thinking is that inflammation increases the risk of heart disease,” says Dr Randall Thompson, co-author of the study, and a cardiologist at Saint Luke’s Mid America Heart Institute at the University of Missouri-Kansas City.
“However, the inflammation common to the Tsimane was not associated with increased risk of heart disease, and may instead be the result of high rates of infection.”
The authors also say the Tsimane lifestyle is rapidly changing.
“Over the past five years, new roads and the introduction of motorised canoes have dramatically increased access to a nearby market town, where they can buy sugar and cooking oil,” says Benjamin Trumble from Arizona State University’s School of Human Evolution and Social Change, another of the report’s co-authors.
“This is ushering in major economic and nutritional changes for the Tsimane people.”
Some experts have pointed out that the study’s findings are fully in line with existing medical thinking.
“Current recommendations for the prevention of cardiovascular diseases and other lifestyle maladies target the same lifestyle and risk factors – such as diet, physical activity and body weight – that have proved so protective in this study,” says Dr Hans Hauner, a nutritional physician at Rechts der Isar Hospital in Munich, Germany.
The problem is that the general population do not have enough awareness of these recommendations, he adds, and every individual should take more personal responsibility for their cardiac health.
Many factors to consider
Dr Heribert Schunkert, medical director of the German Heart Centre, notes that multiple factors play a role in the hardening of the arteries. “It’s always a whole bundle of various aspects that add up,” he says.
Heart health depends on a mixture of genetic predisposition and lifestyle, he adds. Whether exercise or a low-cholesterol diet is more effective in preventing coronary artery disease depends on a person’s metabolic predisposition.
Clearly, only some aspects of the Tsimane lifestyle can be adopted in industrialised societies, and Dr Schunkert notes the difficulty of escaping the conventions of one’s environment.
Nevertheless, he concludes: “The study is a reminder of the importance of a natural way of life.” – dpa