Total body phylloquinone and its turnover in human subjects at two levels of vitamin K intake

• Published in: British journal of nutrition 2002-06, Vol.87 (6), p.543-553
• Main Authors: Olson, Robert E., Chao, Jean, Graham, Donna, Bates, Margaret W., Lewis, Jessica H.
• Format: Article
• Language: English
• Subjects: Adult; Biochemistry; Biological and medical sciences; Blood Coagulation Factors - metabolism; Body Weight; Diet; Dietary restrictions; Drug Administration Schedule; Drug dosages; Exchangeable body pool; Excretion; Feces - chemistry; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Health care; Human subjects; Humans; Male; Medicine; Metabolic turnover; Metabolism; Metabolites; Middle Aged; Nutrition research; Plasma; Prothrombin Time; Radioactive phylloquinone; Radioactivity; Tritium; Turnover time; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vitamin K; Vitamin K 1 - administration & dosage; Vitamin K 1 - blood; Vitamin K 1 - pharmacokinetics
• ISSN: 0007-1145; 1475-2662
• DOI: 10.1079/BJN2002565

The aims of this study were to determine the total body phylloquinone and its metabolic turnover in human subjects using a tracer dose of [5-H3]phylloquinone containing 55·5×104 MBq/mmol. Seven subjects aged 22 to 49 years were given 0·3 μg isotopic phylloquinone intravenously on a control diet (75 μg phylloquinone/d) and blood, urine and faeces were sampled periodically for 6 d. Five of these subjects were studied a second time after 3–8 weeks on a low-vitamin K diet (8 μg/d). The changes in the radioactivity of plasma phylloquinone with time were analysed by the method of residuals and fitted to a curve composed of two exponential components. The size of the exchangeable body pool was calculated by isotope dilution. Plasma phylloquinone levels fell during vitamin K restriction but the vitamin K-dependent coagulation factors did not change. After injection the first exponential decay curve t1/2 was 1·0 (SD 0·47) H IN THE SUBJECTS ON THE CONTROL DIET AND 0·49 (sd 0·27) h after vitamin K restriction. On the control diet, the second exponential t1/2 was 27·6 (sd 124) h that did not change on the low-vitamin K diet (t1/2=25·1 (sd 13·5) h). These results indicate that the turnover time for phylloquinone in human subjects is about 1·5 d. Urinary excretion of 3H-metabolites ranged from 30 % of the administered dose on the control diet to 38 % on the restricted diet and had the same turnover rate as the second component of the plasma decay curves. The exchangeable body pool of phylloquinone declined from about 1·0 μg/kg before restriction to lower values after vitamin K restriction. The faecal excretion of phylloquinone and its metabolites fell from 32 % of the administered dose on the control diet to 13 % on the restricted diet.