This article offers a comprehensive and well-grounded review of hydration and health, yet there are relevant perspectives worth adding — ones that complement, and in some points challenge, its conclusions. **1. The paradox of thirst as an insufficient guide in tropical climates** The article acknowledges that the thirst mechanism is sophisticated, but admits its limitations in the elderly. This critique could be extended to populations living permanently in hot and humid climates — such as much of sub-Saharan Africa and Brazil — where chronic heat desensitization may produce a habitual state of hypohydration that the body does not adequately signal through thirst. In these contexts, waiting for thirst before drinking is a physiologically inadequate strategy for a considerable portion of the world's population, one rarely addressed by recommendations built on North American and European data. **2. The biomarker gap and what it conceals** The authors are candid in stating that no adequate population-level biomarker exists for assessing hydration status. This gap, however, carries a silent consequence: water intake recommendations (the so-called *Adequate Intakes*) were constructed on a fragile methodological foundation — self-reported consumption medians. This is equivalent to setting a nutritional target based on what people already do, rather than what they should do. The article raises this problem, but could have been more forceful: we may be perpetuating a collective state of mild dehydration and calling it "adequate." **3. Water and cognition: methodological confusion has practical implications** The section on cognitive performance is one of the richest, yet also the most frustrating. Studies diverge because they combine heat, exercise, and fluid restriction in different ways. What becomes clear is that mild dehydration consistently affects *mood and alertness*, even when its impact on specific cognitive tasks is inconsistent. This is directly relevant to school and workplace settings: we do not need to wait for measurable cognitive deficits to justify better hydration practices — the impact on subjective well-being is already sufficient grounds for a public health argument. **4. The elephant in the room: who funds the research?** The article discloses funding from Nestlé Waters among its sources. This does not invalidate its conclusions, but deserves critical reflection. The bottled water industry has an obvious interest in recommendations that raise individual water consumption and question the adequacy of habitual intake. The gaps the authors identify — absence of long-term controlled trials, undefined biomarkers — conveniently create space for further industry-sponsored research. A discerning reader should weigh this when evaluating the strength of the final recommendations. **5. Water versus caloric beverages: a matter of supply, not just choice** The article documents the growth of caloric beverage consumption as a substitute for water and points to its negative effects on energy balance. However, the analysis remains at the individual level, as though this were simply a matter of personal preference or nutritional education. The structural dimension is missing: in many low-income urban and rural communities, safe drinking water is inaccessible or of questionable quality, making industrially processed sugary drinks the most practical — and at times the safest — available option. Health policies that fail to address access to treated water are unlikely to shift consumption patterns through nutritional guidance alone. --- In summary, this article is a solid reference that remains relevant more than a decade after its publication. Its greatest contributions lie in its honesty about the field's gaps. Its greatest weaknesses lie in remaining within a narrow methodological and geopolitical frame — one that privileges data from wealthy nations and underestimates the social and environmental determinants of hydration.