Advances in water intake assessment

water intake. Water intake assessment methods have yet to be validated against objective biomarkers, such as water turnover. Unknown potential for measurement error limits interpretation of existing water intake data. Bardosono et al. [2] explore the potential for error in water intake estimates derived by 24-h recall. Although one 24-h diet recall is generally understood to adequately estimate the energy and macronutrient intake of a group, these authors report significant underestimation of absolute beverage intake for groups of adolescents and adults, relative to a 7-day diet record. One 24-h recall appears to only yield valid estimates of relative fluid intake for groups, i.e. drinking water expressed as a percentage of total fluid intake. Although the data support use of one 24-h recall to evaluate interventions promoting relative beverage change, i.e. drinking water instead of caloric beverages, at the communityor group-level, it remains to be determined if and how sources of error in water intake estimation can be reduced. While a 7-day record appears to be a more reliable method to capture fluid intake, the burden associated with this instrument may impact its usability and acceptance in the general population. Monnerie et al. [3] provide data of a study comparing an online version of a 7-day record with a paper version of this instrument. They report that the online version resulted in higher water intake from fluids and a higher acceptance of the online version by the respondents. Lack of standardization and potential for measurement error, notwithstanding, water intake datasets are emerging from various countries worldwide. Iglesia et al. [4], Guelinckx et al. [5], and Ferreira-Pêgo et al. [6] describe absolute and relative water intake in children, adolescents, and adults from surveys with similar 7-day water intake assessment methodologies in 13 countries. In the 1990s, water intake was not a priority area for nutrition research. Water intake data were used by public health dentists to inform fluoridation initiatives, and by cancer and infectious-disease epidemiologists to estimate the risk of water-borne contaminants and carcinogens. Nutrition researchers, in reaction to the global obesity epidemic, focused data collection on macronutrient and energy intake, without tracking water. Over the past decade, nutritionists’ interest in water intake has grown along with increasing awareness of the effects of beverage consumption on obesity and chronic disease risk. The World Health Organization, European Food Safety Authority (EFSA), the American Medical Association, US Centers for Disease Control, and national Dietary Guidelines in many countries began recommending drinking water instead of caloric beverages to reduce obesity and chronic disease risk. Debate over water intake recommendations drew attention to gaps in the water intake evidence base. The articles in this supplement describe recent methodological and substantive developments in nutrition research on water intake and outline remaining gaps in knowledge. Gandy [1] describes inconsistent water intake assessment between countries, a lack of validated methods, and the need to standardize international efforts to estimate