Water Security and Nutrition: Current Knowledge and Research Opportunities

Water security encompasses four dimensions: availability, accessibility, use, and stability across time. Water insecurity can manifest due to problems with water scarcity, excess, or contamination, and can have a profound impact on nutrition-related behaviors and activities. The role of water in nutrition extends beyond its physiological necessity, with water security creating an enabling environment for good nutrition. Water is essential for agricultural food production and preparation, personal hygiene, and psychological well-being. However, few studies have considered the role of water security in nutrition, and a broader conceptualization of water and its diverse uses is needed to sustainably achieve global nutrition targets. Research has shown that water insecurity is a global phenomenon that occurs in both high- and low-income countries, and that it often co-occurs with food insecurity. Water insecurity may precipitate future food insecurity, and greater consideration of water security is necessary for improving nutrition and health globally. The development of validated experiential water-insecurity scales has demonstrated the importance of considering the complex lived experiences of individuals and households in understanding the intersections between water security and nutrition. The physiological importance of water cannot be overstated, with water serving as a universal solvent, aiding in nutrient digestion, absorption, transport, and metabolism, storing and dissipating heat for thermoregulation, maintaining osmotic gradients and action potentials, and providing protection as a physical shock absorber. Total body water accounts for more than 50% of body weight, and fluid balance is maintained by matching output with inputs, including direct fluid intake and consumption of foods that contain water. Dehydration can have a range of negative effects on health, including fatigue, impaired cognitive function, reduced brain volume, and increased risk of morbidities such as urolithiasis and chronic kidney disease. A 1-2% loss of body water can cause mild dehydration, which can impair cognitive function and reduce brain volume. Dehydration has also been inconsistently associated with worse mood and cognition. The intersections between water security and nutrition are complex and multifaceted, and a comprehensive review of the current knowledge and research opportunities in this area is necessary to inform policy and programmatic approaches for improving water security and nutrition synergistically. This review aims to synthesize available evidence on the physiological importance of water and the myriad intersections between water security and nutrition, and to guide readers toward foundational reports or reviews that cover particular topics in greater depth.