title: Hydration: certain basic aspects for developing technical and scientific parameters into the nutrition knowledge
abstract: Introduction: Hydration is defined as the water intake coming from food and beverages. Its study has become an area by itself, within the nutrition field. Meaning that in 2010 the European Food Safety Authority (EFSA) approved the water intake recommendations, but the study of this topic implies a rigorous methodology, which represents several issues.
  Objective: Showing as a glance the main methodological issues in hydration studies.
  Material and methods: Bibliographic revision of scientific literature.
  Results: The main methodological issues presented are: sample selection (investigation field and sample design), selection of the method to evaluate hydration status (dilution techniques, bioelectrical impedance, plasmatic and urinary indicators, changes in body composition, water losses and clinic symptoms) selection of the method to evaluate water intake (biomarker, questionnaires, informatics programs, smartphone use, 24-h register, dietary history and food frequency questionnaire), and the main sources of hydration.
  Conclusions: Hydration status should be understood as a routine model, with daily frequency, according to gender, age, physical activity and environmental conditions. Furthermore, the correct design of the methodology has a special importance in order to take into account all the aspects
authors: Grupo de investigación VALORNUT. Departamento de Nutrición. Facultad de Farmacia. Universidad Complutense de Madrid. Madrid. aperalesgarcia@gmail.com.
authors: Aránzazu
authors: A
authors: Perales-García
authors: Isabel
authors: I
authors: Estévez-Martínez
authors: Rafael
authors: R
authors: Urrialde
mesh_terms: D000818:Animals; D001834:Body Water / Q000502:physiology*; D003681:Dehydration / Q000517:prevention & control; D004326:Drinking / Q000502:physiology*; D006801:Humans; D009751:Nutritional Requirements
keywords: Hidratación. Metodología. Ingesta. Líquidos. Agua.