Coronary atherosclerosis in indigenous South American Tsimane: a cross-sectional cohort study.
Level 3 - non-randomized controlled study
Cross-sectional comparative cohort study comparing an indigenous population to an external industrialized cohort (MESA)
PubMed 28320601 · doi:10.1016/S0140-6736(17)30752-3
What was done
This cross-sectional cohort study assessed coronary artery disease in 705 self-identified Tsimane adults aged 40 years or older living a subsistence lifestyle in the Bolivian Amazon. Coronary artery calcium (CAC) was measured using non-contrast CT between July 2014 and September 2015, defining CAC > 100 as significant atherosclerotic disease. Blood lipid panels and inflammatory biomarkers were collected. Results were compared against 6,814 participants from the Multi-Ethnic Study of Atherosclerosis (MESA).
What was found
Of 705 Tsimane adults, 596 (85%) had a CAC score of 0, 89 (13%) scored 1–100, and 20 (3%) scored > 100. Among individuals older than 75 years, 31 (65%) had a CAC score of 0 and only 4 (8%) had CAC ≥ 100, representing a five-fold lower prevalence than industrialized populations (p ≤ 0.0001 across all MESA age categories). Mean LDL was 2.35 mmol/L (91 mg/dL) and mean HDL was 1.0 mmol/L (39.5 mg/dL), with low rates of obesity, hypertension, hyperglycemia, and smoking. High-sensitivity C-reactive protein was elevated (> 3.0 mg/dL) in 360 (51%) participants.
Why it matters
The findings demonstrate that a subsistence lifestyle characterized by high physical activity, low LDL cholesterol, and absent conventional cardiometabolic risk factors can maintain exceptionally low levels of coronary atherosclerosis, even amidst high systemic infectious inflammatory burden.
Limits
The study uses an observational cross-sectional design, precluding causal inference. Non-contrast CT assesses calcified plaque but does not measure non-calcified soft plaque. Survival bias may affect the older cohort in a population with lower life expectancy, and findings in an isolated indigenous population may not fully generalize to other genetic or cultural backgrounds.
Cited by
- supports Paleolithic humans and traditional populations rarely experienced chronic diseases or cancer, dying primarily from infant mortality, infections, and injuries.