James A. Sadowski

Food Sources and Dietary Intakes of Vitamin K-1 (Phylloquinone) in the American Diet

OBJECTIVE To identify important food sources and estimate dietary intake of vitamin K-1 (phylloquinone) in the American diet. DESIGN Core foods from the US Food and Drug Administration (FDA) Total Diet Study (TDS), which was based on the 1987-88 Nationwide Food Consumption Survey (NFCS), were analyzed for vitamin K-1. These nutrient values were then applied to the FDA TDS consumption model. SUBJECTS Of the NFCS participants within the 14 selected age-gender groups, 3,634 who had 3 days of dietary data were included in the FDA TDS consumption model. MAIN OUTCOME MEASURES Vitamin K-1 intakes were estimated for each of the age-gender groups; the percentage contribution of each food item to total intake of vitamin K-1 was calculated from the FDA TDS model. RESULTS Of the 14 age-gender groups selected, the 25- to 30-year-old women and men consumed less than the current Recommended Dietary Allowance (RDA) for vitamin K. In contrast, formula-fed infants had estimated vitamin K-1 intakes six times greater than the RDA. All other groups consumed amounts within the recommended daily intakes but lower than 90 micrograms/day. The top contributors to total vitamin K-1 intake were dark-green vegetables, although the fats and oils added to mixed dishes and desserts were also important contributors. The proportion of vitamin K-1 obtained from vegetables increased with age. APPLICATIONS The data identify important dietary sources of vitamin K-1 in the American diet. This knowledge can be used to develop dietary assessment instruments for use in epidemiologic studies.

Dietary induced subclinical vitamin K deficiency in normal human subjects

A subclinical vitamin K deficiency was induced in 32 healthy subjects (four groups of eight males and females) aged 20-40 and 60-80 yr residing in the Metabolic Research Unit of the Human Nutrition Research Center on Aging at Tufts University. Volunteers were initially fed (4 d) a baseline-period diet containing the recommended daily allowance for vitamin K which is equivalent to 80 micrograms/d of phylloquinone (vitamin K1). During the baseline period various parameters of vitamin K nutritional status were monitored. The baseline period was followed by a 13-d depletion period during which the subjects were fed a very low vitamin K1 diet (approximately 10 micrograms/d). After depletion, the subjects entered a 16-d repletion period (four stages lasting 4 d each) during which time they were repleted with 5, 15, 25, and 45 micrograms of vitamin K1 per day. Vitamin K1 depletion dramatically and significantly decreased plasma vitamin K1 levels (P < 0.0001) in both elderly and young groups to values 13-18% of day 1 (elderly 0.22 nM, young 0.14 nM). Repleting the subjects with up to 45 micrograms of vitamin K1 per day failed, in the case of the young subjects, to bring plasma vitamin K1 levels back into the normal range. Dietary vitamin K1 restriction induced different responses in the urinary excretion of gamma-carboxyglutamic acid between the young and the elderly subjects with values decreasing significantly (P < 0.03) in the young while remaining unchanged in the elderly. The vitamin K1 depletion period had no significant effect on either prothrombin and activated partial thromboplastin times, or Factor VII and protein C (as determined by antigenic and functional assays). By using a monoclonal antibody, decarboxy prothrombin was found to increase slightly but significantly in both groups (P < 0.05) as a consequence of the low vitamin K1 diet. This study clearly shows that a diet low in vitamin K1 can result in a functional subclinical deficiency of vitamin K (decreased urinary gamma-carboxyglutamic acid excretion) without affecting blood coagulation.

Delay of UV-induced eye lens protein damage in guinea pigs by dietary ascorbate.

Large accumulations of postsynthetically oxidized proteins are observed in the aged and cataractous eye lens. Ascorbate has previously been used to delay photooxidative damage in vitro. The goals of this study were to confirm that dietary ascorbate can be used to enhance lens ascorbate levels and to determine if lenses with enhanced ascorbate can better withstand photooxidative stress in the form of ultraviolet (UV) light exposure. Guinea pigs were placed on high dietary ascorbate (HDA), 50 mg/day, and low dietary ascorbate (LDA), 2 mg/day, for 21 weeks. Lenses from HDA animals were found to contain 3.3 times more ascorbate than LDA animals. Prior to irradiation, SDS-PAGE protein profiles and exopeptidase activity in HDA and LDA lens soluble proteins were indistinguishable. However upon exposure to UV light, more protein damage (e.g., high-molecular-weight aggregates and enhanced loss of exopeptidase activity) was seen in lens preparations from LDA as compared to HDA animals. These results suggest that ascorbate protects lens components against cataract-like and age-related postsynthetic changes in vivo. As in previous tests on lens preparations, attenuated exopeptidase activity was observed before protein aggregation.

Fat-Soluble Vitamin Nutriture in primary Biliary Cirrhosis

We measured serum levels of vitamins A, E, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D, as well as levels of abnormal (des-gamma-carboxy) prothrombin, in 52 patients with primary biliary cirrhosis. Decreased serum levels of retinol (vitamin A) and 25-hydroxyvitamin D and elevated levels of abnormal prothrombin were common in these patients and correlated with the histologic stage of the disease and with the clinical severity of disease as judged by elevated serum bilirubin levels and decreased serum albumin levels. The increased levels of abnormal prothrombin were due primarily to vitamin K deficiency but also, in part, to the severity of the liver disease itself. Vitamin E deficiency was rare. Only 1 patient had clinical manifestations of fat-soluble vitamin deficiency, night blindness, and gastrointestinal bleeding related to a marked prolongation of the prothrombin time. Deficiencies of fat-soluble vitamins are most likely to be present in jaundiced patients with long-standing, severe cholestasis. We suggest that fat-soluble vitamin status be determined in all patients with primary biliary cirrhosis by appropriate blood tests and that vitamin supplements be given only to those patients who require them.

The association of vitamin K status with warfarin sensitivity at the onset of treatment

We investigated the association of vitamin K status with warfarin sensitivity among 40 orthopaedic patients beginning perioperative algorithm‐dosed warfarin. Baseline vitamin K status was assessed using plasma vitamin K‐1 and vitamin K‐1 2,3 epoxide concentrations, and a questionnaire‐based estimation of usual vitamin K intake. Warfarin sensitivity was assessed as the increase in the International Normalized Ratio (INR) after two doses of 5 mg of warfarin and as the 4‐d accumulation of under‐γ‐carboxylated prothrombin (PIVKA‐II), adjusted for warfarin dose requirement. Multivariate models were used to assess vitamin K variables as predictors of warfarin sensitivity. The mean INR increase was 0·53 U and the mean PIVKA‐II increase was 771 ng/ml/mg warfarin. Demographic factors were not associated with warfarin response. For each 1 standard deviation (SD) lower value of plasma vitamin K‐1, but not the other vitamin K variables, the INR rose 0·24 U (P ≤ 0·01). A higher usual vitamin K intake and plasma vitamin K‐1, and lower plasma vitamin K‐1 2,3 epoxide, were all associated with a lower PIVKA‐II increase over 4 d. Respective differences in PIVKA‐II accumulation per SD increase of each variable were −165, −218 and 236 ng/ml/mg warfarin (all P ≤ 0·05). We concluded that dietary and biochemical measures of vitamin K status were associated with early warfarin sensitivity.

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.

Chemical reduction sytem for the detection of phylloquinone (vitamin K1) and menaquinones (vitamin K2

Both isocratic and gradient elution systems for fluorometric detection of K vitamins after post-column reduction with zinc metal to their hydroquinones are described. The reaction detection system for K vitamins (phylloquinone and menaquinones) in liquid chromatography is based on reduction of K vitamins to their corresponding hydroquinones with zinc metal in the presence of zinc ions. It was found that 95% of the injected quinones (K vitamins) could be reduced to their corresponding hydroquinones with zinc metal compared to 60% reduction for electrochemical detectors. Menaquinones could be detected down to 100 pg with relative ease during gradient elution.

DETERMINATION OF PHYLLOQUINONE IN FOODS BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Publisher Summary This chapter describes the high-performance liquid chromatography (HPLC) determination of phylloquinone in various food matrices. Phylloquinone is generally present in low concentrations relative to other lipophilic compounds, so crude lipid extracts cannot be used for direct HPLC analysis. Owing to their instability under alkaline conditions, vitamin K compounds cannot be isolated from triglycerides using saponification. Different analytical conditions have been successfully used for HPLC analyses of phylloquinone in foods. Whereas adsorption HPLC is required for separation of the cis from the trans form of phylloquinone, reversed-phase HPLC separates phylloquinone from the menaquinones. For the analysis of phylloquinone in foods, a reversed-phase HPLC system is used with postcolumn reduction of the quinone, followed by fluorometric detection. The application of HPLC in the determination of phylloquinone in various food matrices has facilitated the routine analyses of food items, thereby allowing accurate description of the phylloquinone and, more recently, the dihydrophylloquinone content of common food items.

The Vitamin K Content of Intravenous Lipid Emulsions

Commercially available intravenous lipid emulsions are largely derived from vegetable oils, a natural source of phylloquinone (vitamin K1). We therefore examined the concentration of vitamin K1 in two widely used intravenous lipid emulsions by using a previously validated high performance liquid chromatography technique. The vitamin K1 concentrations of 10% emulsions of Intralipid and Liposyn II were 30.8 and 13.2 micrograms/dL, respectively. The concentration of vitamin K1 in the 20% emulsions of these products was essentially double that in the 10% emulsions. The coefficients of variation between the vitamin K1 content in three different lots of each product were consistently less than 7.0%. The observed concentrations of the vitamin in these lipid emulsions paralleled the predicted content on the basis of the type of vegetable oil(s) used to make the product. The type of vegetable oil used for production therefore seems to be a major determinant of the final vitamin K1 content. The vitamin K1 contained in these intravenous lipid emulsions is substantial and may have great impact on the vitamin K status of the recipient.

The Effect of Orlistat on the Pharmacokinetics and Pharmacodynamics of Warfarin in Healthy Volunteers

To assess the effect of orlistat on the pharmacokinetics and pharmacodynamics of warfarin, a third‐party blind, placebo‐controlled, randomized, two‐way crossover study was performed in 12 healthy volunteers. Each participant received single 30‐mg oral doses of racemic warfarin sodium (Coumadin; DuPont Pharma, Wilmington, DE) administered on the eleventh day of treatment with 120 mg orlistat (treatment A) and placebo (treatment B) three times a day for 16 days; the two treatments were separated by a 3‐week washout period. Serial blood samples were collected before and at appropriate intervals after each dose of warfarin to determine plasma concentrations of R‐warfarin and S‐warfarin and blood prothrombin time (PT) and plasma Factor VII concentration. In addition, serum concentrations of vitamin K1 and its epoxide and of osteocalcin and its undercarboxylated form were measured before breakfast on days −7, 1, 4, 6, and 10. Equivalent results between treatments with orlistat and placebo were found with regard to all pharmacokinetic parameters of R– and S‐warfarin (except for time to maximum concentration of R‐warfarin). Pharmacodynamic parameters of warfarin (PT and Factor VII) and vitamin K nutritional status parameters (ratios of vitamin K1 to vitamin K1 epoxide and undercarboxylated osteocalcin to osteocalcin) also were unaltered by orlistat. Orlistat administered at doses of 120 mg three times daily did not significantly alter the pharmacokinetics and pharmacodynamics of a single 30‐mg oral dose of warfarin in healthy volunteers.