Research in context
Evidence before this study
We searched both PubMed and Google Scholar for articles with terms “coronary calcium” and “CAC” (coronary calcium scoring) published after 1990 with no language restrictions. We searched for all population-based studies of coronary artery disease using CAC to determine whether data have been published on prevalence and severity of disease in small-scale subsistence populations and to integrate all available data. We included studies that were either population-representative or of very large sample size with explicit sampling methodologies described.
Added value of this study
The findings of the present study show that, in comparison to existing evidence, Tsimane indigenous South Americans have the lowest prevalence of coronary atherosclerosis of any population yet studied. This was achieved despite a high infectious inflammatory burden.
Implications of all the available evidence
The available evidence suggests that a lifetime with very low LDL cholesterol, a subsistence diet of wild game, fish, and high-fibre carbohydrates that are very low in saturated fat, combined with physical activity throughout much of the day sets a new target in the prevention of coronary atherosclerosis. Although consuming a subsistence diet is generally not feasible in urban industrialised populations, adoption of certain aspects of subsistence lifestyles could benefit individuals in sedentary industrialised populations. Urbanisation and the elimination of a subsistence diet and lifestyle might represent a novel risk factor for coronary artery disease. The general lack of prediction of CAC by inflammatory biomarkers in this study suggests the potential of a threshold effect for either degree of coronary atherosclerosis or LDL cholesterol level required for inflammation to either cause or predict coronary artery disease. Alternatively, inflammation secondary to infection might not be causal.