Vitamin K status of older individuals in northern China is superior to that of older individuals in the UK

Abstract

To explore whether differences in vitamin K nutrition might, at least in part, underlie differences in fracture incidence between Asian and European populations, the vitamin K status of older individuals in Shenyang, China (eighty-six men, ninety-two women) and in Cambridge, UK (sixty-seven men, sixty-seven women) was compared. Dietary information was collected by food questionnaire in Shenyang and food diary in Cambridge and used to estimate the intake and sources of phylloquinone. Fasting blood was analysed for phylloquinone, triacylglycerol, total osteocalcin (tOC) and undercarboxylated osteocalcin (expressed as percentage of tOC; %ucOC). The mean intakes of green leafy vegetables were 127 (SD 90) g/d in Shenyang and 39 (SD 48) g/d in Cambridge. The estimated phylloquinone intakes (geometric means) were 247 (95% CI 226, 270) μg/d in Shenyang and 103 (95% CI 94, 112) μg/d in Cambridge. Plasma phylloquinone concentrations (geometric means) were significantly higher in the Shenyang subjects (2·17 (95% CI 1·95, 2·42) nmol/l) than in the Cambridge subjects (0·69 (95% CI 0·63, 0·76) nmol/l; P <0·001). Plasma phylloquinone concentration was positively related to phylloquinone intake in both the Shenyang (coefficient 0·17 (SE 0·08); P =0·03) and Cambridge subjects (coefficient 0·29 (SE 0·10); P =0·005). tOC concentration and %ucOC (after adjusting for tOC) were significantly lower in the Shenyang than in the Cambridge subjects (tOC 25·2 (SE 4·2) % and %ucOC 68·5 (SE 10·0) % lower respectively; P <0·001). After adjusting for tOC and triacylglycerol, %ucOC was negatively related to plasma phylloquinone concentration in both the Shenyang (coefficient −0·41 (SE 0·11); P =0·0003) and Cambridge subjects (coefficient −0·17 (SE 0·07); P =0·02). The present study demonstrates that older individuals in northern China have a better vitamin K status compared with their British counterparts in Cambridge, UK.