Inflammaging is minimal among forager-horticulturalists in the Bolivian Amazon.

An increase in chronic systemic inflammation in later life, termed inflammaging, is implicated in health risk. However, it is unclear whether inflammaging develops in all human populations, or if it is the product of environmental mismatch. We assessed inflammaging in Tsimane forager-horticulturalists of the Bolivian Amazon, using serum cytokines in a primarily cross-sectional sample (1134 samples from n = 714 individuals, age 39-94, 51.3% female). IL-6 was positively associated with age (β = 0.013, p < 0.01). However, other pro-inflammatory markers, including IL-1β and TNF-α, did not increase with age (β = -0.005 and β = -0.001, respectively). We then compared the Moseten, a neighbouring population that has experienced greater market integration (423 samples from n = 380 individuals, age 39-85, 48.2% female). The Moseten also showed a positive age association for IL-6 that attenuated at later ages (age β = 0.025, p < 0.01; age² β = -0.001, p < 0.05). Further, IL-1β and TNF-α were both positively associated with age (β = 0.021, p < 0.05 and β = 0.011, p < 0.01, respectively). Our results demonstrate minimal inflammaging in the Tsimane, highlighting variation across populations in this age-related process. They also suggest that inflammaging is exacerbated by lifestyle shifts.