High energy requirements and water throughput of adult Shuar forager‐horticulturalists of Amazonian Ecuador

Water connects the environment, culture, and biology, yet only recently has it emerged as a major focus for research in human biology. To facilitate such research, we describe methods to measure biological, environmental, and perceptual indicators of human water needs. This toolkit provides an overview of methods for assessing different dimensions of human water need, both well-established and newly-developed. These include:(a) markers of hydration (eg, urine specific gravity, doubly labeled water) important for measuring the impacts of water need on human biological functioning; (b) methods for measuring water quality (eg, digital colorimeter, membrane filtration) essential for understanding the health risks associated with exposure to microbiological, organic, metal, inorganic nonmental, and other contaminants; and (c) assessments of household water insecurity status that track aspects of unmet water needs (eg, inadequate water service, unaffordability, and experiences of water insecurity) that are directly relevant to human health and biology. Together, these methods can advance new research about the role of water in human biology and health, including the ways that insufficient, unsafe, or insecure water produces negative biological and health outcomes.

Section: Assessing Individual‐level Hydration and Water Needsmentioning

confidence: 99%

Measuring Human Water Needs

Wutich

Rosinger

Stoler

et al. 2019

“…Subjects provide two or more body water samples (urine, blood, or saliva) over the subsequent 7 to 14 days, and the change in deuterium enrichment in the samples over time is used to calculate the rate of water loss (L/d) from body water pool. Deuterium tracking is considered the gold standard for measuring water turnover precisely and accurately (IAEA, 2009), and the method is relatively easy to deploy in field settings (eg, Christopher et al, ; Kashiwazaki et al, ; Raman et al, ), but it is considerably more expensive than surveys or interviews. Further, water turnover calculated from deuterium depletion includes all sources of water gain and loss, and thus cannot distinguish, for example, water gained through food, drink, or metabolic water formation.…”

Section: Methods For Measuring Water Turnovermentioning

confidence: 99%

“…Johnson et al () have used this approach to validate a 7‐day fluid intake survey. Like deuterium tracking, the DLW method is relatively easy to use in the field (eg, Christopher et al, ; Kashiwazaki et al, ; Pontzer et al, 2015). However, it is more expensive than using deuterium alone due to the considerable expense of oxygen‐18 enriched water.…”

Section: Methods For Measuring Water Turnovermentioning

confidence: 99%

“…US measures were derived from two studies: † Raman et al () and ‡ Kant et al (). Measures for the Shuar (Christopher et al, ), Aymara (Kashiwazaki et al, ), Kenya (Keino et al, ), US † (Raman et al, ), and France (Blanc et al, ) were calculated using the deuterium depletion method. Tsimane (Rosinger & Tanner, ), Mestizo (Berti & Leonard, ), Indonesia (Laksmi et al, ), Greece (Athanasatou et al, ), Japan (Tani et al, ), Germany (Manz et al, ), and US ‡ (Kant et al, ) data were collected via nutritional survey.…”

Section: Population Variationmentioning

confidence: 99%

See 1 more Smart Citation

Water turnover among human populations: Effects of environment and lifestyle

Swanson

Pontzer

2019

Self Cite

Objectives: To discuss the environmental and lifestyle determinants of water balance in humans and identify the gaps in current research regarding water use across populations. Methods: We investigated intraspecific variation in water turnover by comparing data derived from a large number of human populations measured using either dietary survey or isotope tracking. We also used published data from a broad sample of mammalian species to identify the interspecific relationship between body mass and water turnover. Results: Water facilitates nearly all physiological tasks and water turnover is strongly related to body size among mammals (r2=0.90). Within humans, however, the effect of body size is small. Instead, water intake and turnover vary with lifestyle and environmental conditions. Notably, despite living physically active lives in conditions that should increase water demands, the available measures of water intake and turnover among small-scale farming and pastoralist communities are broadly similar to those in less active, industrialized populations.Conclusions: More work is required to better understand the environmental, behavioral, and cultural determinants of water turnover in humans living across a variety of ecosystems and lifestyles. The results of such work are made more vital by the climate crisis, which threatens the water security of millions around the globe.

“…However, variation has been documented in total water intake between and within populations across different environments ranging from 2 L per day among Greek adults to almost 10 L per day among Ecuadorian Shuar men (Braun et al, ; Christopher et al, ; Rosinger & Tanner, ; Tani et al, ). Additionally, the dietary constituents that make up total water intake, that is the percentage of water consumed from foods vs from beverages, vary.…”

Section: Introductionmentioning

confidence: 99%

Biobehavioral variation in human water needs: How adaptations, early life environments, and the life course affect body water homeostasis

Rosinger

2019

Body water homeostasis is critical for optimal physiological and cognitive function for humans. The majority of research has illustrated the negative biological consequences of failing to meet water needs. The human body has several mechanisms for detecting, regulating, and correcting body water deficits and excesses. However, variation exists in total water intake and how people meet those water needs as well as thirst thresholds and how well people tolerate water restriction. An evolutionary and developmental framework provides an underexplored perspective into human water needs by examining how adaptations, early life experiences and environments, as well as life course changes in health states and behaviors may shape these critical factors in body water homeostasis. This article first reviews biological and behavioral adaptations to water scarcity among animals and humans. It then examines human variation in water intake in a mostly water secure environment through the analysis of National Health and Nutrition Examination Survey dietary data and the link between water intake patterns and hydration biomarkers.Next, it reviews existing evidence of how maternal water restriction in utero and during lactation shape vasopressin release, thirst thresholds, drinking patterns, and body water homeostasis for the infant. Early life water restriction appears to have implications for hydration status, body size, and cardiovascular health. Finally, it examines how life course changes in health states and behaviors, including obesity, sleep, and parasitic infection, affect body water homeostasis. This article poses new questions about the plasticity and shaping of human water needs, thirst, and hydration behaviors.