A preliminary assessment of vitamin K₁ intakes and serum undercarboxylated osteocalcin levels in 11-13 year old Irish girls

Low vitamin K₁ intakes have been associated with low bone mineral density in women and reduced bone turnover in girls. No European data exist on the relationship between vitamin K₁ and serum undercarboxylated osteocalcin (ucOC), an indicator of K₁ status in adolescents. The aim of the current study was to assess intakes of vitamin K₁ in relation to serum ucOC status in Irish girls. A detailed dietary history method, which measured habitual intakes from a typical 14-day period, was used to estimate vitamin K₁ intakes in 18 girls aged 11-13 years. Recently compiled and validated food composition data for vitamin K₁ were used to determine vitamin K₁ intakes. An enzyme immunoassay was used to measure ucOC in fasting serum samples. The mean (± SD) intake of vitamin K₁ in the girls was 72.4 μg/day (SD 34.4). Vegetables (particularly broccoli, composite dishes, and lettuce) contributed 53% of total vitamin K₁ intakes. Thirty-Seven percent of the girls failed to meet the current U.S. adequate intake for adolescents of 60 μg/day vitamin K₁. Serum ucOC levels were inversely related to body weight-adjusted vitamin K₁ intakes, controlling for energy intake (partial correlation r = -0.538; p = 0.026). The data indicate that large-scale studies to examine relationships between vitamin K₁ (and green vegetable) intakes and bone growth and development in adolescents are warranted.