Inflammation and infection do not promote arterial aging and cardiovascular disease risk factors among lean horticulturalists - PubMed (original) (raw)

Inflammation and infection do not promote arterial aging and cardiovascular disease risk factors among lean horticulturalists

Michael Gurven et al. PLoS One. 2009.

Abstract

Background: Arterial aging is well characterized in industrial populations, but scantly described in populations with little access to modern medicine. Here we characterize health and aging among the Tsimane, Amazonian forager-horticulturalists with short life expectancy, high infectious loads and inflammation, but low adiposity and robust physical fitness. Inflammation has been implicated in all stages of arterial aging, atherogenesis and hypertension, and so we test whether greater inflammation associates with atherosclerosis and CVD risk. In contrast, moderate to vigorous daily activity, minimal obesity, and low fat intake predict minimal CVD risk among older Tsimane.

Methods and findings: Peripheral arterial disease (PAD), based on the Ankle-Brachial Index (ABI), and hypertension were measured in Tsimane adults, and compared with rates from industrialized populations. No cases of PAD were found among Tsimane and hypertension was comparatively low (prevalence: 3.5%, 40+; 23%, 70+). Markers of infection and inflammation were much higher among Tsimane than among U.S. adults, whereas HDL was substantially lower. Regression models examine associations of ABI and BP with biomarkers of energy balance and metabolism and of inflammation and infection. Among Tsimane, obesity, blood lipids, and disease history were not significantly associated with ABI. Unlike the Tsimane case, higher cholesterol, C-reactive protein, leukocytes, cigarette smoking and systolic pressure among North Americans are all significantly associated with lower ABI.

Conclusions: Inflammation may not always be a risk factor for arterial degeneration and CVD, but instead may be offset by other factors: healthy metabolism, active lifestyle, favorable body mass, lean diet, low blood lipids and cardiorespiratory health. Other possibilities, including genetic susceptibility and the role of helminth infections, are discussed. The absence of PAD and CVD among Tsimane parallels anecdotal reports from other small-scale subsistence populations and suggests that chronic vascular disease had little impact on adult mortality throughout most of human evolutionary history.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1

Figure 1. Median and interquartile values of (A) ABI (averaged across left and right sides), (B) systolic BP and (C) diastolic BP, for Tsimane by age group and sex.

Figure 2

Figure 2. Prevalence of (A) Peripheral Arterial Disease (ABI<0.9) and (B) Hypertension (SBP≥140 and/or/ DBP>−90), among Tsimane and other populations.

Data sources for ABI: urban China , urban Mexico , South Africa , southeast Spain , Sweden (Sigvant Birgitta pers comm), Thailand , United States . Hypertension data for the same countries come from the World Health Organization Global Infobase,

http://www.who.int/infobase/report.aspx

. Note: x-axis represents midpoints of age intervals because of the different age intervals reported among studies (e.g. 30–39 vs. 35–44); Hypertension defined as SBP≥140 and/or DBP≥90 except for Sweden where SBP≥160 and/or DBP≥95.

Figure 3

Figure 3. Comparison of cardiovascular disease risk factors among Tsimane and United States adults.

Mean levels of (A) C-reactive protein (CRP, mg/L), (B) white blood cell (WBC) count (cells/mm3), (C) body mass index (BMI,kg/m2), (D) total and HDL cholesterol (mg/dL). Total cholesterol correlates strongly with low-density lipoprotein (LDL) among both Tsimane (r = .82, p<.0001) and US (r = .91, p<.0001), and with triglycerides (Tsimane: r = .48, p<.0001; US: r = .43, p<.0001), and so are not illustrated here. See Table 6 for further details.

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