A Colombian indigenous man harvests plantains during the "First Intergenerational Summit on Traditional Knowledge and Leaders of the Amazon", held to discuss how to save indigenous culture and territories, on September 11, 2016 in Santa Sofia, Amazonas department, Colombia.
    Indigenous groups in Colombia's Amazonas department are threatened by logging, illegal mining and lack of governance. / AFP / LUIS ROBAYO (Photo credit should read LUIS ROBAYO/AFP/Getty Images)

    Do hunter-gatherer Bolivians really have the ‘world’s healthiest hearts’?

    20 March 2017

    Members of an Amazonian community have been found to have the healthiest hearts of any population group yet studied, according to a report in The Lancet.

    The lifestyle of the Tsimané has been described as pre-industrial; they spend most of their time farming, hunting and fishing, and eat a diet that is mostly carbohydrate-based and low in saturated fats.

    They are also far more physically active than the average Westerner. Men in the community were found to take an average of 17,000 steps a day and women 16,000. The figure remained high in old age.

    The researchers, from Long Beach Memorial medical centre in California, examined hundreds of members of the group. They found that almost nine out of 10 had clear arteries showing no risk of heart disease. Almost two thirds of those over the age of 75 were classed as having virtually no risk of heart disease and just eight per cent had a moderate-to-high risk level.

    The study’s lead author, Professor Hillard Kaplan, said: ‘Our study shows that the Tsimané indigenous South Americans have the lowest prevalence of coronary atherosclerosis [hardening and narrowing of the arteries] 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.’

    The study’s findings suggest that coronary atherosclerosis can be avoided in most people by achieving a lifestyle with very low cholesterol, blood pressure, glucose, maintaining a normal body-mass index, not smoking, and getting plenty of exercise.

    Instant analysis
    This was a cross-sectional cohort study looking at the heart health of individuals aged 40 or over belonging to a small forager-horticulturalist community in South America. The Tsimané are a Bolivian population living a subsistence lifestyle of hunting, gathering, fishing, and farming with few cardiovascular risk factors.

    Heart health was assessed via a CT scan looking at the degree of calcium in coronary arteries — the higher the amount of calcium, the greater the burden of calcified, or chronic, coronary artery disease.

    However, this doesn’t measure the amount of soft plaque, which is not calcified and therefore is not detected by such scans and is often unstable, leading to heart attacks. This why such calcium scoring is no longer performed alone in clinical practice, being superseded by a CT coronary angiogram, which assesses the amount of calcium first and then performs an assessment of the actual coronary arteries themselves, looking for soft plaque and the degree to which any plaque impinges into the lumen of the artery restricting flow.

    For reference, at the age of 45, almost no Tsimané had calcium in their coronary arteries while 25 per cent of Americans do, but at the age of 75, 66 per cent of Tsimané are free of calcium compared to only 20 per cent of Americans.

    The work does question the recent low-carb high-fat trend. The tribe’s diet consists of 17 per cent game, including wild pig, tapir and capybara, and seven per cent freshwater fish, with other foodstuffs from family farms growing rice, maize, manioc root and plantains and finally foraged fruit and nuts.

    As a result, 72 per cent of calories come from carbohydrates compared with 52 per cent in the US, while 14 per cent was from fat compared with 34 per cent in the US (and much less of this was saturated fat). Furthermore, even over-60s have a step count of over 15,000, much greater than the 10,000 that apps often recommend.

    Ethically, I wonder what happened to the individuals who were found to have coronary artery disease — were they offered follow up and treatment with statins, for example? Also, this was essentially screening, and there are no guidelines for screening for coronary artery disease. There could potentially be harm if small benign tumours such as lung nodules were discovered that might require further imaging, leading to more radiation exposure and higher risk of cancer.

    The ‘healthiest hearts in the world’ belong to those, unsurprisingly, with the least similar lifestyle to those in the West. While this study may be of anthropological and academic interest, I fail to see its usefulness. Most of us in the West may find it hard to go back to a semi-forager existence. Being more active and eating less processed foods are already familiar pieces of health advice.

    Finally, heart health isn’t just a factor of the coronary arteries, but also the endo-, peri- and myocardium, cardiac valves, specialised conduction tissues and other structures, which were not assessed in this study.
    Research score: 1/5