The search for safe water remains an important challenge in the 21st century as more than 1.1 billion people lack access to clean water. Globally, many populations are experiencing rapid economic and environmental change, including many in the South American Amazon region. While the social sciences emphasize that lifestyle transitions, or changes to dietary, economic, and cultural activities, affect health, disease patterns, and body composition, the role of dietary water use has been widely overlooked during these transitions. Hydration strategies, or how people meet their daily dietary water needs through a full spectrum of foods and liquids, may serve as dietary adaptations that balance nutrition and risk of infection. Lifestyle transitions may create a mismatch between hydration strategies and the nutritional landscape. This research will explain how hydration strategies are related to variation in hydration levels, pathogen exposure, and nutritional status among Tsimane' Amerindians in lowland Bolivia, where access to clean water is scarce.
This study by doctoral candidate Asher Rosinger (University of Georgia), under the guidance of Dr. Susan Tanner, will collect dietary, anthropometric, ethnographic, and biological biomarker data to address the following aims: 1) Determine if differences in hydration strategies are associated with variation in hydration levels, water-related diseases and immune activation, and body composition; 2) Investigate how market participation is related to variation in hydration strategies; and 3) Document how people without access to clean water interact with their environment to meet their daily water needs.
Responses to lifestyle transitions are critical to understand because they provide insight into past and future trends of human variation in nutrition and health. Because dietary hydration sources can expose people to pathogens but also provide calories, this research will provide insight into both diarrheal prevalence and the recent pattern of over-nutrition in Amazonia, information which can guide global health interventions. This study will inform water intake recommendations, which rely almost exclusively on data from industrialized countries. In addition to supporting the training and professional development of a US doctoral student, the project's results will be discussed with communities, turned into research posters to be disseminated to Tsimane' schools, and published in academic journals.
The search for safe water is an ongoing and critical global health problem among rural and indigenous populations in developing countries. Many of these same people are simultaneously experiencing rapid lifestyle transitions through increased participation in national and global markets, which research in global health and the social sciences links to changes in disease patterns and weight gain. Examining hydration strategies during transitions may help explain differences in disease risk, health, and energetic reserves within and between populations. The research supported by this award examined how hydration strategies relate to variation in hydration levels, water-related diseases, immune activation, and body composition during lifestyle transitions among Tsimane’ forager-horticulturalists in the Bolivian Amazon. My fieldwork spanned 13 months between July 2012 and June 2014 in two Tsimane’ communities, one a short taxi ride from the nearest market town and the other a two-day canoe ride away. My research found that Tsimane’ have flexible hydration strategies that rely on their environment for water. Using diet recalls, nutritional databases, health recalls, and anthropometrics, I found that increased water intake from foods was associated with a decreased risk of diarrheal illness among adults, which may represent a nutritional adaptation to an environment with very limited access to clean water. Through focal follow, anthropometrics, and biomarker methods, I also found that Tsimane’ who live in a market integrated community were significantly more dehydrated than Tsimane’ living in a traditional community, controlling for temperature and physical activity. To assess hydration status, I measured the biomarker of urine specific gravity through urinalysis. These findings contribute to human biology theory by suggesting that lifestyle transitions may create conditions that increase vulnerability to dehydration among rural populations. Additionally, lactating women were significantly more dehydrated than non-lactating women controlling for environmental and lifestyle factors. This work illustrates the nutritional challenges lactating women face in stressful physical environments and raises important evolutionary questions dealing with maternal buffering during chronic dehydration. While I was in the field in 2014, the worst flood event in recent memory occurred in Lowland Bolivia. This event underscored other aspects of water access problems, such as water insecurity, and served as an important natural experiment to evaluate how decision-making affects disease patterns. I collaborated with the environmental health laboratory SEDES Beni in Bolivia to analyze water quality of raw water sources in the communities. Through surveys, anthropometrics, health recalls, parasitological analyses, and doctor examinations, I found that primary water sources, age, and market integration were significantly associated with level of water insecurity and that the flooding affected multiple dimensions of water insecurity. Additionally, high water insecurity was associated with higher risk of diarrhea for the adults and with dehydration for their children. These findings illustrate the connections between natural disasters and water-related morbidities. My research provides context for public health interventions and water intake policy recommendations for countries without clean water, and contributes to the body of evidence for the health implications of global climate change.
