To investigate water contributors in relation to dietary and serum micronutrient profiles.

A cross-sectional study. The main exposures were water contributors. Selected dietary and serum micronutrient levels were outcome measures.

The US population and its subgroups.

US adults (n 2691) aged ≥20 years from the National Health and Nutrition Examination Survey 2005–2006.

The daily mean total water intake was 3·1 (se 0·047) litres, with 68 % of adults consuming below the Adequate Intake level. Total water intake was higher in adults with higher BMI and physical activity, those taking dietary supplements and alcohol consumers (P < 0·05). Plain water intake was positively associated with food moisture and negatively with beverage moisture (P < 0·001). Beverage moisture was negatively associated with food moisture (P < 0·001). In multivariate regression analyses, plain water and food moisture intakes were positively associated with Fe, Ca, vitamins A, B, C, E and K and carotenoid intakes (P < 0·05). However, beverage moisture was unrelated to Ca, niacin and vitamin B6 intakes, and negatively associated with Fe, vitamin A, folate, vitamins C, E and K and carotenoid intakes (P < 0·05). Concentrations of serum vitamins A and C and carotenoids increased with plain water and food moisture intakes (P < 0·05) but decreased (P < 0·01) or were unrelated to beverage moisture intake.

Various contributors of total water intake differed in their associations with dietary and serum micronutrient profiles in US adults. The study provides evidence of plain water benefits on micronutrient adequacy over beverages.