Hydration in relation to water insecurity, heat index, and lactation status in two small‐scale populations in hot‐humid and hot‐arid environments

Abstract

Objectives This study compared the prevalence of concentrated urine (urine specific gravity ≥1.021), an indicator of hypohydration, across Tsimane' hunter‐forager‐horticulturalists living in hot‐humid lowland Bolivia and Daasanach agropastoralists living in hot‐arid Northern Kenya. It tested the hypotheses that household water and food insecurity would be associated with higher odds of hypohydration. Methods This study collected spot urine samples and corresponding weather data along with data on household water and food insecurity, demographics, and health characteristics among 266 Tsimane' households (N = 224 men, 235 women, 219 children) and 136 Daasanach households (N = 107 men, 120 women, 102 children). Results The prevalence of hypohydration among Tsimane' men (50.0%) and women (54.0%) was substantially higher (P < .001) than for Daasanach men (15.9%) and women (17.5%); the prevalence of hypohydration among Tsimane' (37.0%) and Daasanach (31.4%) children was not significantly different (P = .33). Multiple logistic regression models suggested positive but not statistically significant trends between household water insecurity and odds of hypohydration within populations, yet some significant joint effects of water and food insecurity were observed. Heat index (2°C) was associated with a 23% (95% confidence interval [CI]: 1.09‐1.40, P = .001), 34% (95% CI: 1.18‐1.53, P < .0005), and 23% (95% CI: 1.04‐1.44, P = .01) higher odds of hypohydration among Tsimane' men, women, and children, respectively, and a 48% (95% CI: 1.02‐2.15, P = .04) increase in the odds among Daasanach women. Lactation status was also associated with hypohydration among Tsimane' women (odds ratio = 3.35, 95% CI: 1.62‐6.95, P = .001). Conclusion These results suggest that heat stress and reproductive status may have a greater impact on hydration status than water insecurity across diverse ecological contexts.

Interactions between Climate Change and Infrastructure Projects in Changing Water Resources: An Ethnobiological Perspective from the Daasanach, Kenya

“…The main drinking water sources for the Daasanach in northern Kenya are traditional wells, boreholes, and waterholes dug in dry riverbeds (Bethancourt et al 2020; Figure 1C). Due to its salinity, the lake is rarely used as a source of drinking water (Bethancourt et al 2020), but wildlife and livestock drink water directly from the lake (Kaijage and Nyagah 2009) (Figure 1B). Herding is strongly dependent on the availability of pastures, maintained by seasonal rainfall.…”

Rapidly declining body temperature in a tropical human population

“…Fourth, we did not account for hydration status of participants. Tsimane show nontrivial prevalence of hypohydration (40), which may lead to increased core BT, especially during physical activity (41). Hydration status would only affect the temporal trend of lower BT if hypohydration became less common over the study period.…”

The toll of household water insecurity on health and human biology: Current understandings and future directions

“…Therefore, the resultant scores from the scale developed to measure water insecurity in this flood-prone setting may have also captured the effects of the flood and displacement resulting from water excess (Rosinger, 2018). New analyses indicate that the HWISE scale was positively, but not statistically significantly, associated with 5-29% higher odds of dehydration in both a hot-humid environment of Lowland Bolivia during a nonflood time and a hot-arid environment of northern Kenya (Bethancourt et al, 2020). However, water insecurity and food insecurity were jointly significant in this study in predicting higher odds of dehydration for women in northern Kenya and children in lowland Bolivia.…”