Age- and brain region-specific effects of dietary vitamin K on myelin sulfatides.

Dysregulation of myelin sulfatides is a risk factor for cognitive decline with age. Vitamin K is present in high concentrations in the brain and has been implicated in the regulation of sulfatide metabolism. Our objective was to investigate the age-related interrelation between dietary vitamin K and sulfatides in myelin fractions isolated from the brain regions of Fischer 344 male rats fed one of two dietary forms of vitamin K: phylloquinone or its hydrogenated form, 2',3'-dihydrophylloquinone (dK), for 28 days. Both dietary forms of vitamin K were converted to menaquinone-4 (MK-4) in the brain. The efficiency of dietary dK conversion to MK-4 compared to dietary phylloquinone was lower in the striatum and cortex, and was similar to that in the hippocampus. There were significant positive correlations between sulfatides and MK-4 in the hippocampus (phylloquinone-supplemented diet, 12 and 24 months; dK-supplemented diet, 12 months) and cortex (phylloquinone-supplemented diet, 12 and 24 months). No significant correlations were observed in the striatum. Furthermore, sulfatides in the hippocampus were significantly positively correlated with MK-4 in serum. This is the first attempt to establish and characterize a novel animal model that exploits the inability of dietary dK to convert to brain MK-4 to study the dietary effects of vitamin K on brain sulfatide in brain regions controlling motor and cognitive functions. Our findings suggest that this animal model may be useful for investigation of the effect of the dietary vitamin K on sulfatide metabolism, myelin structure and behavior functions.

CYP4F2 is a vitamin K1 oxidase: An explanation for altered warfarin dose in carriers of the V433M variant.

Genetic polymorphisms in VKORC1 and CYP2C9, genes controlling vitamin K(1) (VK1) epoxide reduction and (S)-warfarin metabolism, respectively, are major contributors to interindividual variability in warfarin dose. The V433M polymorphism (rs2108622) in CYP4F2 has also been associated with warfarin dose and speculatively linked to altered VK1 metabolism. Therefore, the purpose of the present study was to determine the role of CYP4F2 and the V433M polymorphism in the metabolism of VK1 by human liver. In vitro metabolic experiments with accompanying liquid chromatography-tandem mass spectrometry analysis demonstrated that recombinant CYP4F2 (Supersomes) and human liver microsomes supplemented with NADPH converted VK1 to a single product. A screen of all commercially available P450 Supersomes showed that only CYP4F2 was capable of metabolizing VK1 to this product. Steady-state kinetic analysis with recombinant CYP4F2 and with human liver microsomes revealed a substrate K(m) of 8 to 10 microM. Moreover, anti-CYP4F2 IgG, as well as several CYP4F2-selective chemical inhibitors, substantially attenuated the microsomal reaction. Finally, human liver microsomes genotyped for rs2108622 demonstrated reduced vitamin K(1) oxidation and lower CYP4F2 protein concentrations in carriers of the 433M minor allele. These data demonstrate that CYP4F2 is a vitamin K(1) oxidase and that carriers of the CYP4F2 V433M allele have a reduced capacity to metabolize VK1, secondary to an rs2108622-dependent decrease in steady-state hepatic concentrations of the enzyme. Therefore, patients with the rs2108622 polymorphism are likely to have elevated hepatic levels of VK1, necessitating a higher warfarin dose to elicit the same anticoagulant response.

Menadione is a metabolite of oral vitamin K.

Phylloquinone is converted into menaquinone-4 and accumulates in extrahepatic tissues. Neither the route nor the function of the conversion is known. One possible metabolic route might be the release of menadione from phylloquinone by catabolic activity. In the present study we explored the presence of menadione in urine and the effect of vitamin K intake on its excretion. Menadione in urine was analysed by HPLC assay with fluorescence detection. Urine from healthy male volunteers was collected before and after administration of a single dose of K vitamins. Basal menadione excretion in non-supplemented subjects (n 6) was 5.4 (sd 3.2) microg/d. Urinary menadione excretion increased greatly after oral intake of the K vitamins, phylloquinone and menaquinone-4 and -7. This effect was apparent within 1-2 h and peaked at about 3 h after intake. Amounts of menadione excreted in 24 h after vitamin K intake ranged, on a molar basis, from 1 to 5 % of the administered dose, indicating that about 5-25 % of the ingested K vitamins had been catabolized to menadione. Menadione excretion was not enhanced by phylloquinone administered subcutaneously or by 2',3'-dihydrophylloquinone administered orally. In archived samples from a depletion/repletion study (Booth et al. (2001) Am J Clin Nutr 74, 783-790), urinary menadione excretion mirrored dietary phylloquinone intake. The present study shows that menadione is a catabolic product of K vitamins formed after oral intake. The rapid appearance in urine after oral but not subcutaneous administration suggests that catabolism occurs during intestinal absorption. The observations make it likely that part of the menaquinone-4 in tissues results from uptake and prenylation of circulating menadione.

The biological activity and tissue distribution of 2',3'-dihydrophylloquinone in rats.

2',3'-Dihydrophylloquinone (dihydro-K1) is a hydrogenated form of vitamin K1 (K1), which is produced during the hydrogenation of K1-rich plant oils. In this study, we found that dihydro-K1 counteracts the sodium warfarin-induced prolonged blood coagulation in rats. This indicates that dihydro-K1 functions as a cofactor in the posttranslational gamma-carboxylation of the vitamin K-dependent coagulation factors. It was also found that dihydro-K1 as well as K1 inhibits the decreasing effects of warfarin on the serum total osteocalcin level. In rats, dihydro-K1 is well absorbed and detected in the tissues of the brain, pancreas, kidney, testis, abdominal aorta, liver and femur. K1 is converted to menaquinone-4 (MK-4) in all the above-mentioned tissues, but dihydro-K1 is not. The unique characteristic of dihydro-K1 possessing vitamin K activity and not being converted to MK-4 would be useful in revealing the as yet undetermined physiological function of the conversion of K1 to MK-4.

Effects of a hydrogenated form of vitamin K on bone formation and resorption.

BACKGROUND: Hydrogenation of vegetable oils affects blood lipid and lipoprotein concentrations. However, little is known about the effects of hydrogenation on other components, such as vitamin K. Low phylloquinone (vitamin K1) intake is a potential risk factor for bone fracture, although the mechanisms of this are unknown. OBJECTIVE: The objective was to compare the biological effects of phylloquinone and its hydrogenated form, dihydrophylloquinone, on vitamin K status and markers of bone formation and resorption. DESIGN: In a randomized crossover study in a metabolic unit, 15 young adults were fed a phylloquinone-restricted diet (10 microg/d) for 15 d followed by 10 d of repletion (200 microg/d) with either phylloquinone or dihydrophylloquinone. RESULTS: There was an increase and subsequent decrease in measures of bone formation (P = 0.002) and resorption (P = 0.08) after dietary phylloquinone restriction and repletion, respectively. In comparison with phylloquinone, dihydrophylloquinone was less absorbed and had no measurable biological effect on measures of bone formation and resorption. CONCLUSION: Hydrogenation of plant oils appears to decrease the absorption and biological effect of vitamin K in bone.

Dietary vitamin K1 requirement and comparison of biopotency of different vitamin K sources for young turkeys.

In a preliminary experiment, the inclusion of vitamin K1 (K1) at a dietary level of 0.1 mg/kg was as effective as 1 or 2 mg/kg in reducing plasma prothrombin time (PT). To obtain an estimate of the dietary K1 requirement and to compare the biopotency of different vitamin K sources for poults, three additional experiments were conducted. In Experiment 1, an incomplete factorial arrangement of treatments was used in which five dietary concentrations of K1 (0, 0.1, 0.25, 0.5, or 2.0 mg/kg) were tested and two concentrations of neomycin (0 or 75 mg/L) in drinking water were used in conjunction with 0, 0.1, and 0.5 mg of K1/kg of diet. Thus, we used a total of eight treatments. Each treatment was given to two pens of poults, with eight poults per pen. Prothrombin time and prothrombin concentration (PC) in plasma were not influenced by inclusion of neomycin in drinking water. The K1 requirement was estimated, on the basis of PT and PC, to be 0.099 and 0.13 mg/kg, respectively, in Experiment 1. Dietary K1 concentrations tested in Experiment 2 were 0, 0.08, 0.31, or 0.44 mg/kg. A similar protocol to that of Experiment 1 was used in this experiment. The results of Experiment 2 indicated that the dietary K1 requirement was 0.079 mg, based on the influence of dietary K1 on PT. In Experiment 3, dietary treatments consisted of the equivalent of 0.22, 0.55, or 1.11 microM of menadione equivalent/kg from vitamin K1, menadione dimethypyrimidinol bisulfite (MPB) or menadione nicotinamide bisulfite (MNB), respectively, and a control without supplementation of any vitamin K source. The results of Experiment 3 showed that the biopotency of K1 was greater than that of MPB or MNB. The biopotencies of MPB and MNB were similar, although MNB was more potent in reducing plasma PT when supplemented at the level of 0.1 mg of menadione/kg. A nadir of PT and a plateau of PC were evident with a dietary supplementation of MPB or MNB at a level of 0.25 mg of menadione/kg. Results of this research show that the dietary K1 requirement of young turkeys is in the range of 0.079 to 0.13 mg/kg, and ingestion of neomycin did not affect estimates of the requirement. The biopotency of vitamin K1 in reducing plasma PT and increasing plasma PC was greater than that of MPB or MNB. The biopotency of MNB was greater than that of MPB when menadione supplementation was equivalent to 0.10 mg of K1/kg.

Effect of vitamin K1 supplementation on vitamin K status in cystic fibrosis patients.

BACKGROUND: Patients with cystic fibrosis are at risk for impaired vitamin K status due to fat malabsorption from pancreatic insufficiency. This study was designed to assess vitamin K status and measure the effect of vitamin K1 supplementation in cystic fibrosis patients. METHODS: Eighteen outpatients participated in a crossover study to determine the effect of vitamin K1 (phylloquinone) supplementation. After obtaining initial data, each subject was randomly assigned to either a 4-week study treatment of 5 mg oral vitamin K1 supplementation per week, or no supplementation and then crossed over to the other treatment for a second 4 week period. Plasma, serum and urine samples were collected and analyzed pre-study and at the end of each study period. RESULTS: The mean concentration of plasma vitamin K1 for the supplemented group was significantly higher than the unsupplemented group, [0.34 nmol/L and 0.21 nmol/L, respectively (p < 0.05)]. The percent of undercarboxylated osteocalcin increased on supplementation from 17% to 31%, (p < 0.005). Prothrombin induced in vitamin K absence (PIVKA-II) increased on supplementation from 5 ng/mL to 22 ng/mL, (p < 0.005). The ratio of urinary gamma-carboxyglutamic acid/creatinine was similar for both study periods. CONCLUSIONS: In contrast to other studies in cystic fibrosis, this study demonstrated a need for vitamin K1 supplementation. The carboxylation state of osteocalcin and PIVKA-II were the most sensitive indices of changes in vitamin K1 status. Although the 5 mg vitamin K1/week dose improved these vitamin K parameters, normal levels were not achieved.

Plasma concentrations of dihydro-vitamin K1 following dietary intake of a hydrogenated vitamin K1-rich vegetable oil.

Dihydro-vitamin K1 is a dietary form of vitamin K1 (phylloquinone) produced during the hydrogenation of vegetable oils. To determine if dihydro-vitamin K1 is present in plasma following dietary intake of a hydrogenated fat, eight healthy adults consumed each of two diets containing 30% of calories from fat, of which 20% was either soybean oil or a partially hydrogenated soybean oil-based stick margarine. Of the fats and oils analyzed, dihydro-vitamin K1 was only found in the hydrogenated products. The soybean oil diet contained 180 +/- 12 micrograms (mean +/- SD) of vitamin K1/day and nondetectable levels of dihydro-vitamin K1, whereas the stick margarine diet contained 199 +/- 7 micrograms of vitamin K1/day and 23 +/- 2 micrograms of dihydro-vitamin K1/day. After consuming each diet for five weeks, plasma dihydro-vitamin K1 concentrations were higher (P = 0.002) in all eight subjects when consuming the stick margarine diet (0.56 +/- 0.33 nmol/L) compared to the soybean oil diet (0.12 +/- 0.11 nmol/L). There was no significant change in plasma vitamin K1 concentrations when the two diets were compared. In conclusion, dihydro-vitamin K1 is detectable in plasma following dietary intake of a hydrogenated vitamin K1-rich vegetable oil.

Dihydro-vitamin K1: primary food sources and estimated dietary intakes in the American diet.

Dihydro-vitamin K1 was recently identified as a dietary form of vitamin K produced during the hydrogenation of vitamin K1-rich vegetable oils. Dihydro-vitamin K1 is absorbed, with measurable levels in human plasma following dietary intake. To determine the primary food sources of dihydro-vitamin K1 in the American diet, 261 foods from the U.S. Food and Drug Administration's (FDA) Total Diet Study (TDS) were analyzed by high-performance liquid chromatography. Of these foods, 36 contained dihydro-vitamin K1. Fast-food items that were otherwise poor sources of vitamin K1, such as french fries and fried chicken, contained appreciable amounts of dihydro-vitamin K1 (36 and 18 micrograms/100 g, respectively). These nutrient values were then applied to the FDA TDS consumption model to determine average dietary intake of dihydro-vitamin K1 in 14 age-gender groups. With the exception of infants, all age-gender groups had estimated mean daily dihydro-vitamin K1 intakes of 12-24 micrograms, compared to mean daily vitamin K1 intakes of 24-86 micrograms. The vitamin K1 and dihydro-vitamin K1 intakes were summed, and the dietary contribution of dihydro-vitamin K1 was expressed as a percentage of total vitamin K intake. Children reported the highest intakes of dihydro-vitamin K1 (30% of total vitamin K intake), followed by a progressive decrease in percentage contribution with age. There are currently no data on the relative bioavailability of dihydro-vitamin K1 but given its abundance in the American diet, this hydrogenated form of vitamin K warrants further investigation.

Changes in hepatic vitamin K1 levels after prophylactic administration to the newborn.

We undertook a study of hepatic concentrations of vitamin K (vitamin K1 or phylloquinone, vitamin K1-epoxide, and menaquinones) in 18 infants, ages 1-8 days, with or without vitamin K1 supplementation. The infants who had no supplementation had a total hepatic storage ranging between 0.1 and 0.9 micrograms. Also, hepatic storage of phylloquinone was poor (< 1 microgram) when compared with daily requirements. Moreover, we did not detect any menaquinone in the livers of these infants in our study. The prophylaxis applied to the other infants was very efficient. Hepatic vitamin K1 concentrations, obtained < 24 h after administration, were very high (62.8-93.5 micrograms/g). Vitamin K1-epoxide concentrations were high, which proved the efficiency of the vitamin K cycle. In contrast, the decrease in vitamin K1 concentrations was also very rapid, since the median value after 48 h was 8.4 micrograms/g and only 2.9 micrograms/g 5 days after administration. However, hepatic total storage after 5 days in one infant with vitamin K1 supplementation was much higher (112 micrograms) than in infants who had not received supplementation. In conclusion, hepatic phylloquinone storage at birth was poor (< 1 microgram). The newborn infant might be in a situation of potential deficiency. After prophylactic oral administration of phylloquinone, uptake by the liver was quite satisfactory, but concentrations dropped quickly. However, phylloquinone hepatic storage remained elevated (112 micrograms) after 5 days.

The effect of ubiquinone-7 and its metabolites on the immune response. II. Adjuvant activity on the circulating antibody production and the effect on the liver lysosomal membrane.

The effects of the fat-soluble vitamins (retinol, alpha-tocopherol, phylloquinone and ubiquinone) and their related compounds were investigated on the immune response in vivo. E acid-I, dihydro E acid-I, ES-6, K acid-I, Q acid-II and QS-3 act as adjuvants on the production of circulating antibody to bacterial alpha-amylase in mice when they are immunized with in the water phase of water-in-oil emulsion. These compounds, however, can not act as adjuvants in enhancing helper activity of carrier-primed T-cells using an adoptive transfer system in mice. It is also shown that these compounds have no adjuvant activity on the development of delayed type hypersensitivity to ABA-N-acetyltyrosine in guinea pigs. No definite correlation between the adjuvant activity of these compounds and their labilizing activity on rat-liver lysosomal membrane was found.