SummaryThe relationship between dietary intake of vitamin K, fat, plasma vitamin K concentrations and anticoagulation response to warfarin within individuals, as well as the contribution of dietary vitamin K to differences in warfarin dose requirements between individuals were investigated in 53 patients on warfarin therapy who had stably controlled anticoagulation. Each patient completed a dietary record of all foods consumed on a daily basis for 4 weeks. Each week a blood sample was taken for measurement of the international normalized ratio (INR), plasma vitamin K, triglycerides and warfarin enantiomer concentrations. The patients' genotype for CYP2C9 was also determined. Regression analysis of the data showed that, for each increase of 100 lg in the daily dietary intake of vitamin K averaged over 4 d, the INR was reduced by 0AE2. There was no correlation between warfarin daily dose and average daily dietary vitamin K intake when calculated over 28 d. The regression model for warfarin dose showed that, while dietary vitamin K had no effect, CYP2C9 genotype (P ¼ 2%) and age (P < 1%) significantly contributed to inter-patient variability in warfarin dose requirements. A consistent intake of vitamin K could reduce intrapatient variability in anticoagulation response and thus improve the safety of warfarin therapy.
Current information suggests that dietary intake of nutrients declines with age and that undernutrition in elderly long-stay hospital patients may be under-recognized. We undertook to describe the daily dietary intakes of a group of elderly long-stay hospital patients (n = 92) (group A), using 7-day weighed dietary records. The aim of the study was to determine the adequacy of the diet and investigate whether any differences existed in the intakes of the hospital patients. An assessment of nutritional status was carried out by anthropometry, haematology and biochemistry and was validated by comparison with two further groups: fit young subjects (n = 41) (group B) and fit community elderly subjects (n = 92) (group C). Men in group B had the highest mean values for mid-arm circumference, arm-muscle circumference, corrected arm-muscle area and arm-fat area while women in group A had the lowest mean values for all measured anthropometric indices. There were significant correlations between daily energy intake and anthropometry for men in groups B and C. In group A 68% had intakes < 2/3 recommended daily allowance for energy, 100% for vitamin D, E, B6, folic acid; 98% for magnesium and zinc; and 90% for retinol. Serum calcium and serum alkaline phosphatase were correlated with vitamin D intake in men in group A. There was no biochemical or haematological evidence of undernutrition in the three groups. Elderly long-stay hospital patients were grossly undernourished and their dietary intake did not satisfy basal metabolic demands, based on recommended daily allowances.
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