What Can We Learn About Heart-Healthy Lifestyle From The Tsimane People of the Amazon Rainforest ?

The skeptical cardiologist has been in Washington, DC attending the Scientific Sessions of the American College of Cardiology for the last three days in an attempt to upgrade his cardiology knowledge and obtain CMEs for all the various areas he needs CME (echo/nuclear/CT/vascular).
I’ve written some posts for SERMO, a physician social media site,  on interesting presentations from the meeting.
Here’s my take on one paper (published simultaneously in The Lancet) that is of general interest:
I’m a big advocate of coronary artery calcium (CAC) scans for helping make decisions on individual patients with intemediate risk for CAD. Several speakers at this year’s American College of Cardiology Meetings presented convincing data supporting this approach, providing more information to get patients off the fence about taking statins.
However, CAC apparently would be a useless test in the Tsimane (pronounced chee-MAH-nay) people according to a study presented at  the ACC meeting and published simultaneously in The Lancet.
Researchers performed CT scans on 700 of  these “forager-horticulturalist”  people, indigenous to the Bolivian Amazon Rainforest and found very little calcium suggesting that they have an amazingly low rate of atherosclerosis compared to we who have to live in the industrialized world.
Obviously CT scanners are not portable so the Tsimane traveled by river and jeep from the Amazon rainforest to Trinidad, a city in Bolivia and the nearest city with a CT scanner. It took tribe members one to two days to reach the nearest market town by river, and then another six hours driving to reach Trinidad.
85% of the Tsimane people studied had CAC scores of 0. In those over age 75 years, 65% had CAC scores of 0, and just four individuals in their 80s had moderately elevated CAC (> 100). The incidence of CAC > 100 in the entire Tsimane population was 3%, which is about one tenth the prevalence in a matched industrialized population. In addition, incidences of obesity, hypertension, high glucose concentrations, and cigarette smoking were rare overall.
The Tsimane live a subsistence lifestyle that includes hunting, gathering, fishing, and farming. They don’t eat at McDonalds and the men spend almost 7 hours pers day on physical labor. Their diet consists mostly of unprocessed fiber-rich carbohydrates with rice, plantain, manioc, corn, wild nuts, and fruit composing their staples. Fat consumption is 9% of calories versus 23% in the U.S.
Supporters of plant-based diets, of course, seized on these data to support the unsubstantiated claim that meat and dairy consumption is the main cause of atherosclerosis in western civilization.
Hillard Kaplan, one of the authors and a Professor of anthropology at the University of New Mexico said:

 “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 aging and we believe that components of this way of life could benefit contemporary sedentary populations.”

However, the real cause of the low levels of coronary artery calcification in the Tsimane remains a mystery because this kind of observational study cannot establish causality. Perhaps it is the 17,000 steps a day that they walk  engaging in foraging and horticulturalism. Could it be due to the absence of processed food and added sugar? The Tsimane have high levels of parasitic infections: perhaps that is protecting them.
Of two things I am certain:
-The Tsimane don’t need statins.
-I prefer my lifestyle to munching on manioc and foraging all day.
Semihorticulturally Yours,
-ACP