AbstractObjectiveTo compare dietary intake and sources of phylloquinone (vitamin K₁) in 4-year-old British children between 1950 and the 1990s, and report their variation by sociodemographic factors.DesignNationally representative samples of 4-year-olds from the longitudinal Medical Research Council National Survey of Health and Development (NSHD) (1950) and the cross-sectional National Diet and Nutrition Surveys (NDNS, 1992/93 and 1997).SettingGreat Britain.SubjectsSubjects were 4599 children born on 3–9 March 1946 (NSHD) and 307 children in the 1990s (NDNS).ResultsGeometric mean dietary phylloquinone intake was significantly higher in 1950 (39 μg day⁻¹, 95% confidence interval (CI) 37, 40) compared with the 1990s (24 μg day⁻¹, 95% CI 22, 25) (P < 0.001). This difference remained when intake was expressed per MJ energy intake and per kilogram body weight, and after accounting for sex, region and occupational social class of the family. In 1950, phylloquinone intake in Scotland was significantly lower than in the rest of Britain. By the 1990s these regional differences had disappeared. Food sources of phylloquinone intake changed significantly between 1950 and the 1990s, with fats and oils contributing more and vegetables less, although vegetables contributed most (60% and 48%, respectively) to phylloquinone intake in both surveys.ConclusionsPhylloquinone intakes of children have decreased significantly since 1950. With the suggested need for adequate phylloquinone intake for optimal development and maintenance of bone and the cardiovascular system, the substantially lower phylloquinone intakes reported in children of the 1990s, compared with 1950, may have implications for the health of these two systems in later adulthood.