5) Prof. Stavros Kavouras

Water, though essential for life, remains one of the least studied nutrients in human health. In dryland regions, where heat stress and water scarcity intersect, maintaining healthy hydration is a growing public health challenge. This presentation explores the physiological, behavioral, and environmental determinants of hydration, emphasizing how underhydration—distinct from overt dehydration—adversely affects health and resilience. Evidence from population studies shows that inadequate water intake is highly prevalent, particularly among older adults and marginalized groups, and is associated with elevated vasopressin levels, increased risk for kidney and metabolic diseases, impaired cognition, and reduced heat tolerance. Physiological mechanisms involving vasopressin, aldosterone, and renin highlight the body’s complex regulation of water balance under heat stress. Promoting healthy hydration—through accessible water sources, culturally appropriate education, and supportive policies—can reduce disease risk and enhance human adaptation to a warming, drying world. As global temperatures rise and desertification expands, understanding and implementing effective hydration strategies is critical for protecting health, productivity, and wellbeing in dryland communities.