Interdependence of serum concentrations of vitamin K1, vitamin E, lipids, apolipoprotein A1, and apolipoprotein B: importance in assessing vitamin status

Dietary, macronutrient, micronutrient, and nutrigenetic factors impacting cardiovascular risk markers apolipoprotein B and apolipoprotein A1: a narrative review

Genetic predisposition and dietary factors can impact cardiovascular disease (CVD) risk. Two important markers in assessing CVD risk are apolipoprotein (apo) B and apolipoprotein A1 plasma levels. These markers are measured as a ratio, with a high apoB:apoA1 ratio associated with increased CVD risk. Dietary and lifestyle recommendations are the cornerstone of managing primary and secondary CVD risk-mitigation strategies. One way to assess the impact of various dietary and lifestyle interventions on CVD risk is to evaluate the changes in CVD risk markers, such as apoB, apoA1, and apoB:apoA1 ratio. Various human studies have demonstrated the impact of dietary, macronutrient, and micronutrient interventions on apoB and apoA1 status. This review aims to elucidate dietary, macronutrient, micronutrient, and nutrigenetic considerations for impacting apoB and apoA1 levels. A low-carbohydrate, high-saturated-fat diet, low fiber intake, low vitamin and mineral intake, and zinc and iron deficiency are associated with an elevated apoB:apoA1 ratio. The Mediterranean diet, vegan diet, fermented dairy products, lower sugar intake, higher protein intake, higher polyunsaturated fat intake, and an omega-3-rich diet are associated with a decreased apoB:apoA1 ratio. Micronutrients associated with a decreased apoB:apoA1 ratio include vitamin D sufficiency, increased serum vitamin C, and magnesium. Variants in the APOE, APOA1, and FADS2 genes may alter the apoB:apoA1 ratio in response to various dietary interventions. When accounting for factors that may favorably alter the apoB:apoA1 ratio, researchers should consider a healthy diet sufficient in polyunsaturated fats, vitamins, minerals, trace minerals, and lower excess sugars.

Serum Vitamin Levels and Their Relationships with Other Biomarkers in Korean Breast Cancer Patients

Numerous studies have shown that vitamins reduce the risk of cancers, but the relationship between serum vitamin levels and breast cancer is still controversial. In this study, we evaluated serum levels of vitamins in Korean patients with benign breast disease or breast cancer and investigated their associations with clinical and laboratory parameters. Concentrations of vitamin A, D, and E, together with homocysteine and methylmalonic acid as biomarkers of vitamin B12 deficiency, were measured by high-performance liquid chromatography (HPLC) or liquid chromatography with tandem mass spectrometry (LC-MS/MS) in the serum of 104 breast cancer patients, 62 benign breast disease patients, and 75 healthy Korean females. We further assessed possible associations between vitamin levels and breast cancer subtypes, the presence of lymph node metastasis, and tumor stages. Serum concentrations of vitamins A and E were significantly lower in breast cancer patients and in benign breast disease patients than in healthy controls. Severe vitamin D deficiency was more prevalent in breast cancer patients than in healthy controls. Vitamin D level was significantly lower in breast cancer patients with estrogen receptor-negative or triple-negative subtypes than in those with other subtypes. Further research with a larger study population is required to elucidate the role of vitamins in breast cancer.

Vitamin K plasma levels determination in human health

Vitamin K (phylloquinone or vitamin K1 and menaquinones or vitamin K2) plays an important role as a cofactor in the synthesis of hepatic blood coagulation proteins, but recently has also aroused an increasing interest for its action in extra-hepatic tissues, in particular in the regulation of bone and vascular metabolism. The accurate measurement of vitamin K status in humans is still a critical issue. Along with indirect assays, such as the undercarboxylated fractions of vitamin K-dependent proteins [prothrombin, osteocalcin (OC), and matrix gla protein], the direct analysis of blood levels of phylloquinone and menaquinones forms might be considered a more informative and direct method for assessing vitamin K status. Different methods for direct quantification of vitamin K serum levels are available. High-performance liquid chromatography (HPLC) methods coupled with post-column reduction procedures and fluorimetric or electrochemical detection are commonly used for food and blood analysis of phylloquinone, but they show some limitations when applied to the analysis of serum menaquinones because of interferences from triglycerides. Recent advancements include liquid chromatography tandem mass spectrometry (LCMS/MS) detection, which assures higher specificity. The optimization and standardization of these methods requires specialized laboratories. The variability of results observed in the available studies suggests the need for further investigations to obtain more accurate analytical results.

Measurement of plasma vitamin K1 (phylloquinone) and K2 (menaquinones-4 and -7) using HPLC-tandem mass spectrometry

BACKGROUND

Given the growing interest in the health benefits of vitamin K, there is great need for development of new high-throughput methods for quantitative determination of vitamin K in plasma. We describe a simple and rapid method for measurement of plasma vitamin K1 (phylloquinone [PK]) and K2 (menaquinones [MK]-4 and -7). Furthermore, we investigated the association of fasting plasma vitamin K with functional vitamin K insufficiency in renal transplant recipients (RTR).

METHODS

We used HPLC-tandem mass spectrometry with atmospheric pressure chemical ionization for measurement of plasma PK, MK-4, and MK-7. Solid-phase extraction was used for sample clean-up. Mass spectrometric detection was performed in multiple reaction monitoring mode. Functional vitamin K insufficiency was defined as plasma desphospho-uncarboxylated matrix Gla protein (dp-ucMGP) >500 pmol/L.

RESULTS

Lower limits of quantitation were 0.14 nmol/L for PK and MK-4 and 4.40 nmol/L for MK-7. Linearity up to 15 nmol/L was excellent. Mean recoveries were >92%. Fasting plasma PK concentration was associated with recent PK intake (ρ=0.41, p=0.002) and with plasma MK-4 (ρ=0.49, p<0.001). Plasma PK (ρ=0.38, p=0.003) and MK-4 (ρ=0.46, p<0.001) were strongly correlated with plasma triglyceride concentrations. Furthermore, we found that MK-4-triglyceride ratio, but not PK-triglyceride ratio, was significantly associated with functional vitamin K insufficiency (OR 0.22 [0.07-0.70], p=0.01) in RTR.

CONCLUSIONS

The developed rapid and easy-to-use LC-MS/MS method for quantitative determination of PK, MK-4, and MK-7 in human plasma may be a good alternative for the labor-intensive and time-consuming LC-MS/MS methods and enables a higher sample throughput.

Bone Health and Osteoporosis: The Role of Vitamin K and Potential Antagonism by Anticoagulants

BACKGROUND

Vitamin K's effects extend beyond blood clotting to include a role in bone metabolism and potential protection against osteoporosis. Vitamin K is required for the gamma-carboxylation of osteocalcin. Likewise, this gamma-carboxylation also occurs in the liver for several coagulation proteins. This mechanism is interrupted by coumarin-based anticoagulants in both the liver and bone.

METHODS

A thorough review of the literature on vitamin K, osteocalcin and their role in bone metabolism and osteoporosis, as well as the potential bone effects of anticoagulant therapy was conducted.

CONCLUSIONS

Epidemiological studies and clinical trials consistently indicate that vitamin K has a positive effect on bone mineral density and decreases fracture risk. Typical dietary intakes of vitamin K are below the levels associated with better BMD and reduced fracture risk; thus issues of increasing dietary intakes, supplementation, and/or fortification arise. To effectively address these issues, large-scale, intervention trials of vitamin K are needed. The effects of coumarin-based anticoagulants on bone health are more ambiguous, with retrospective studies suggesting that long-term therapy adversely affects vertebral BMD and fracture risk. Anticoagulants that do not affect vitamin K metabolism are now available and make clinical trials feasible to answer the question of whether coumarins adversely affect bone. The research suggests that at a minimum, clinicians should carefully assess anticoagulated patients for osteoporosis risk, monitor BMD, and refer them to dietitians for dietary and supplement advice on bone health. Further research is needed to make more efficacious decisions about vitamin K intake, anticoagulant therapy, and bone health.

Determinants of vitamin K status in humans

To understand the role of vitamin K in human health, it is important to identify determinants of vitamin K status throughout the life cycle. Our current understanding of vitamin K physiology and metabolism only partially explains why there is wide interindividual variation in vitamin K status, as measured by various biochemical measures. Dietary intake of vitamin K is one of the primary determinants of vitamin K status, and intakes vary widely among age groups and population subgroups. How dietary sources of vitamin K are absorbed and transported varies with the form and food source of vitamin K. Likewise, the role of plasma lipids as a determinant of vitamin K status varies with the form of vitamin K ingested. There is also some evidence that other fat-soluble vitamins antagonize vitamin K under certain physiological conditions. Infants are at the greatest risk of vitamin K deficiency because of a poor maternal-fetal transfer across the placenta and low vitamin K concentrations in breast milk. During adulthood, there may be subtle age-related changes in vitamin K status but these are inconsistent and may be primarily related to dietary intake and lifestyle differences among different age groups. However, there is some suggestion that absence of estrogen among postmenopausal women may be a determinant of vitamin K, status. Genetics may explain some of the observed interindividual variability in vitamin K, but to date, there are few studies that have systematically explored the associations between individual genetic polymorphisms and biochemical measures of vitamin K status.

Familial hypobetalipoproteinemia in a Turkish family with hereditary spastic paraplegia

A 24-year-old male presented with progressive gait disturbance and was diagnosed with hereditary spastic paraplegia. His brother and possibly one uncle also had the condition. Routine biochemical testing found that the patient had unusually low plasma concentrations of low density lipoprotein (LDL) cholesterol and apolipoprotein (apo) B, the hallmark of familial hypobetalipoproteinemia. DNA sequencing showed that he, along with other family members (n=5; mean LDL cholesterol 0.8 mmol/L, apoB 0.31 g/L), were heterozygous for a single nucleotide deletion in exon 26 of the APOB gene. This mutation is predicted to form a truncated apoB species of 3545 amino acids, which we have designated apoB-78.2.

HPLC Method for Plasma Vitamin K1: Effect of Plasma Triglyceride and Acute-Phase Response on Circulating Concentrations

Background: The plasma concentration of vitamin K1 (phylloquinone) is the most reliable index for assessing vitamin K status. Our aim was to analytically validate an HPLC method for quantifying phylloquinone in plasma and to examine the effect of plasma triglyceride concentration on the phylloquinone reference interval. We also examined the effect of acute-phase response on phylloquinone concentration in plasma.

Methods: Phylloquinone was extracted from fasting plasma samples by deproteinization and C18 solid-phase extraction, separated by reversed-phase HPLC, and detected fluorometrically after postcolumn reduction with a platinum catalyst. We synthesized a novel internal calibrator, docosyl naphthoate.

Results: The recovery of phylloquinone was &gt;90%. Between-run imprecision was 8.7%–9.0%, and within-run imprecision was 3.8%–7.0%. The linearity was up to 44.8 nmol/L, limit of detection 0.08 nmol/L, and limit of quantification 0.14 nmol/L. The correlation between plasma phylloquinone and triglyceride concentrations was r = 0.7 in the reference population. The 95% reference interval for the phylloquinone:triglyceride ratio was 0.20 to 2.20 nmol/mmol. Plasma concentrations of C-reactive protein were significantly increased, whereas triglyceride and phylloquinone but not the phylloquinone:triglyceride ratio were transiently decreased &gt;50% after surgery.

Conclusion: Phylloquinone population reference intervals should be expressed as a ratio of the triglyceride concentration. Phylloquinone concentrations in plasma are decreased in acute-phase response and, unless corrected for plasma triglyceride concentration, are unlikely to be a reliable index of vitamin K status.

Violent behavior associated with hypocholesterolemia due to a novel APOB gene mutation

A 26-year-old male, the index patient, presented with persecutory delusions and suicidal behavior. He had 10 paternal male relatives in two prior generations. Five of them died by violent suicide and one, of the five, also committed a double homicide. The index patient was found to be hypocholesterolemic due to being heterozygous for a novel mutation of apolipoprotein B (apoB-29.4). His mother and paternal grandmother were normocholesterolemic, whereas a surviving paternal uncle was hypocholesterolemic and heterozygous for the apoB-29.4 mutation. This indicated that the index patient's father and paternal grandfather, both of which died by violent suicide, were obligate heterozygotes for the apoB-29.4 mutation and that the index patient inherited the mutation from his paternal grandfather. The odds ratio for the association between hypocholesterolemia and violent behavior in this family, where cholesterol status was known, was 16.9 (95% confidence interval 1.1-239.3). Therefore, our results support an inheritable relationship between violent behavior and hypocholesterolemia.

Plasma phylloquinone (vitamin K1) concentration and its relationship to intake in British adults aged 19-64 years

Plasma phylloquinone (vitamin K1) concentration from non-fasted blood samples was examined by season, smoking status, socio-demographic factors and phylloquinone intake in a nationally representative sample of 1154 British individuals aged 19-64 years from the 2000-1 National Diet and Nutrition Survey. Geometric mean plasma phylloquinone concentration was 0.94 (95% CI 0.88, 1.00) nmol/l, with 95% of values in the range 0.10-8.72 nmol/l. Plasma phylloquinone concentrations of 530 men were significantly higher than those of 624 women (1.13 (95% CI 1.04, 1.22) v. 0.81 (95% CI 0.74, 0.88) nmol/l; P<0.001), independent of other factors. Women aged 19-34 years had significantly lower plasma phylloquinone concentration than their older counterparts. Women were also found to have lower plasma phylloquinone concentrations during summer compared with winter and spring (each P<0.01). In contrast, plasma phylloquinone concentration in men did not vary significantly by season or any of the socio-demographic or lifestyle factors. Plasma phylloquinone concentrations were positively correlated with phylloquinone intake in men and women (r 0.26 and 0.32 respectively; each P<0.001). Overall, forward stepwise multiple regression analysis revealed that 8% of the variation in plasma phylloquinone concentration was explained by phylloquinone intake, with a further 10% of its variation explained by plasma concentrations of gamma-tocopherol (6%) and retinyl palmitate (4%). After adjustment for age and corresponding nutrient intakes, plasma phylloquinone concentration was significantly associated (each P<0.01) with plasma concentrations of total and LDL-cholesterol, alpha- and gamma-tocopherols, retinyl palmitate, beta-carotene, lycopene and lutein plus zeaxanthin in men and women.

Different effects of oral conjugated equine estrogens and transdermal estrogen on undercarboxylated osteocalcin concentration in postmenopausal women

OBJECTIVE

Undercarboxylated osteocalcin (ucOC) is a sensitive marker of vitamin K status, and triglyceride (TG) has been shown to be the main transporter of vitamin K. In the present study, we examined the difference between ucOC concentrations in postmenopausal women receiving hormone therapy (HT) with oral conjugated equine estrogens (CEE) and transdermal estradiol (TE2). We also examined the associations of ucOC concentration with estradiol concentration and TG.

DESIGN

Ninety-two postmenopausal women were recruited for this study. Serum concentrations of ucOC, intact osteocalcin, estradiol, and TG were measured before and after 12 months of HT. Forty-six women received oral administration of 0.625 mg of CEE and 2.5 mg of medroxyprogesterone acetate daily, and 46 women received transdermal administration of 50 mug of 17beta-estradiol twice weekly and 2.5 mg of medroxyprogesterone acetate daily.

RESULTS

The ucOC concentration in women during HT with oral CEE was significantly (P < 0.01) lower than that in women during HT with TE2. Serum estradiol concentrations during HT with CEE showed a significant inverse correlation with ucOC concentrations and the ratio of ucOC/OC during HT (P < 0.05 and P < 0.01, respectively). In addition, the serum ucOC concentration in women with an increased percentage of change in TG was significantly (P < 0.01) lower than that in women with a decreased percentage of change in TG during HT with oral CEE.

CONCLUSION

The effect of HT with TE2 on ucOC concentration in women is weaker than the effect of HT with oral CEE. Suppression of ucOC concentration in postmenopausal women during HT with oral CEE might be associated with the effect of vitamin K through increased TG induced by oral CEE.

Undercarboxylated osteocalcin concentration in postmenopausal women receiving hormone therapy daily and on alternate days

OBJECTIVE

Undercarboxylated osteocalcin (ucOC) is a sensitive marker of vitamin K status. The authors examined the difference in serum ucOC concentrations in postmenopausal women receiving hormone therapy (HT) daily and on alternate days, and assessed the association between ucOC and triglyceride concentrations, which are related to the transport of vitamin K.

DESIGN

Seventy-three postmenopausal women were recruited for this study. Thirty-seven women received 0.625 mg of conjugated equine estrogens (CEE) and 2.5 mg of medroxyprogesterone acetate (MPA) daily, and 36 women received 0.625 mg of CEE and 2.5 mg of MPA on alternate days. The concentrations of serum ucOC, bone turnover markers, lipid profiles, and hormones were measured before and after 12 months of HT.

RESULTS

The ucOC concentration in women taking HT daily was significantly (P < 0.01) lower than that in women taking HT on alternate days. Serum ucOC concentrations during HT showed a significant (P < 0.01) inverse correlation with estradiol concentrations during HT. Serum estradiol concentrations during HT showed a significant (P < 0.01) positive correlation with triglyceride concentrations during HT. Furthermore, ucOC concentrations during HT showed a significant (P < 0.05) inverse correlation with triglyceride concentrations in women receiving HT.

CONCLUSIONS

The effect of HT on alternate days on ucOC concentration was weaker than the effect of HT daily. In addition, ucOC concentration after 12 months of HT daily might be decreased due to the conversion of ucOC to carboxylated OC by the effect of vitamin K through increased triglyceride levels induced by oral CEE.

Apolipoprotein AI could be a significant determinant of epithelial integrity in rainbow trout gill cell cultures: A study in functional proteomics

The freshwater fish gill forms a barrier against an external hypotonic environment. By culturing rainbow trout gill cells on permeable supports, as intact epithelia, this study investigates barrier property mechanisms. Under symmetrical conditions the apical and basolateral epithelial surfaces contact cell culture media. Replacing apical media with water, to generate asymmetrical conditions (i.e. the situation encountered by the freshwater gill), rapidly increases transepithelial resistance (TER). Proteomic analysis revealed that this is associated with enhanced expression of pre-apolipoprotein AI (pre-apoAI). To test the physiological relevance, gill cells were treated with a dose of 50 microg ml(-1) human apolipoprotein (apoAI). This was found to elevate TER in those epithelia which displayed a lower TER prior to apoAI treatment. These results demonstrate the action of apoAI and provide evidence that the rainbow trout gill may be a site of apoAI synthesis. TER does not differentiate between the trans-cellular (via the cell membrane) and para-cellular (via intercellular tight junctions) pathways. However, despite the apoAI-induced changes in TER, para-cellular permeability (measured by polyethylene glycol efflux) remained unaltered suggesting apoAI specifically reduces trans-cellular permeability. This investigation combines proteomics with functional measurements to show how a proteome change may be associated with freshwater gill function.

Determination of the urinary aglycone metabolites of vitamin K by HPLC with redox-mode electrochemical detection

We describe a method for the determination of the two major urinary metabolites of vitamin K as the methyl esters of their aglycone structures, 2-methyl-3-(3'-3'-carboxymethylpropyl)-1,4-naphthoquinone (5C-aglycone) and 2-methyl-3-(5'-carboxy-3'-methyl-2'-pentenyl)-1,4-naphthoquinone (7C-aglycone), by HPLC with electrochemical detection (ECD) in the redox mode. Urinary salts were removed by reversed-phase (C18) solid-phase extraction (SPE), and the predominantly conjugated vitamin K metabolites were hydrolyzed with methanolic HCl. The resulting carboxylic acid aglycones were quantitatively methylated with diazomethane and fractionated by normal-phase (silica) SPE. Final analysis was by reversed-phase (C18) HPLC with a methanol-aqueous mobile phase. Metabolites were detected by amperometric, oxidative ECD of their quinol forms, which were generated by postcolumn coulometric reduction at an upstream electrode. The assay gave excellent linearity (typically, r2 > or = 0.999) and high sensitivity with an on-column detection limit of < 3.5 fmol (< 1 pg). The interassay precision was typically 10%. Metabolite recovery was compared with that of an internal standard [2-methyl-3-(7'-carboxy-heptyl)-1,4-naphthoquinone] added to urine samples just before analysis. Using this methodology, we confirmed that the 5C- and 7C-aglycones were major catabolites of both phylloquinone (vitamin K1) and menaquinones (vitamin K2) in humans. We propose that the measurement of urinary vitamin K metabolite excretion is a candidate noninvasive marker of total vitamin K status.

Dietary phylloquinone intake as a potential marker for a heart-healthy dietary pattern in the Framingham Offspring cohort

Abstract Associations were evaluated among self-reported dietary intakes of phylloquinone (vitamin K-1), lifestyle characteristics, and intermediary markers of cardiovascular disease risk in a population-based cohort of men and women. Dietary phylloquinone intakes were assessed by food frequency questionnaire in 1,338 men and 1,603 women (mean age, 54 years) participating in the Framingham Heart Study. Cross-sectional associations with lifestyle characteristics and lipid profiles, including total cholesterol, low-density lipoprotein and high-density lipoprotein cholesterol, and triglyceride concentrations, were estimated across increasing quintile categories of phylloquinone intakes. Participants in the highest quintile category of phylloquinone intake consumed more fruit, vegetables, fish, dietary fiber, and dietary supplements ( P <.001), and consumed less meat and less saturated fat ( P <.001). Higher phylloquinone intakes were also associated with lower triglyceride concentrations ( P <.001). In conclusion, a high phylloquinone intake may be a marker for an overall heart-healthy dietary pattern.

A novel nontruncating APOB gene mutation, R463W, causes familial hypobetalipoproteinemia

Familial hypobetalipoproteinemia (FHBL), an autosomal co-dominant disorder, is associated with reduced plasma concentrations (<5th percentile for age and sex) of apolipoprotein (apo) B and beta-migrating lipoproteins. To date, only mutations in APOB encoding prematurely truncated apoB have been found in FHBL. We discovered a novel APOB gene mutation, namely R463W, in an extended Christian Lebanese FHBL kindred. Heterozygotes for R463W had the typical FHBL phenotype, whereas homozygotes had barely detectable apoB-100. The effect of the R463W mutation on apoB secretion was examined using transfected McA-RH7777 cells that expressed one of two recombinant human apoBs, namely B48 and B17. In both cases, the mutant proteins (B48RW and B17RW) were retained within the endoplasmic reticulum and were secreted poorly compared with their wild-type counterparts. Pulse-chase analysis showed that secretion efficiencies of B48RW and B17RW were, respectively, 45 and 40% lower than those of the wild-types. Substitution of Arg(463) with Ala in apoB-17 (B17RA) decreased secretion efficiency by approximately 50%, but substitution with Lys (B17RK) had no effect on secretion, indicating that the positive charge was important. Molecular modeling of apoB predicted that Arg(463) was in close proximity to Glu(756) and Asp(456). Substitution of Glu(756) with Gln (B17EQ) had no effect on secretion, but substitution of Asp(456) with Asn (B17DN) decreased secretion to the same extent as B17RW. In co-transfection experiments, the mutant B17RW showed increased binding to microsomal triglyceride transfer protein as compared with wild-type B17. Thus, the naturally occurring R463W mutant reveals a key local domain governing assembly and secretion of apoB-containing lipoproteins.

Phylloquinone absorption from phylloquinone-fortified oil is greater than from a vegetable in younger and older men and women

Studies that have compared the absorption of phylloquinone from green vegetables and oils have equivocal results. To address differences in approaches used to assess absorption of phylloquinone, a 24-h absorption study was conducted in 18 younger (20-40 y) and 18 older (60-80 y) men and women as part of a larger metabolic study that compared changes in vitamin K status in response to broccoli and phylloquinone-fortified oil (377 +/- 46 and 417 +/- 45 micro g/d, respectively). Absorption was defined as the 24-h area under the curve (AUC) for plasma phylloquinone concentrations (both unadjusted and adjusted for triglyceride concentrations). The mean AUC for plasma phylloquinone concentrations (both unadjusted and adjusted) were significantly greater after consumption of the phylloquinone-fortified oil diet compared with the broccoli diet (P < 0.001). However, there were no differences between the two treatments in 24-h fasting plasma phylloquinone concentrations. Although there were no age differences in the AUC for plasma phylloquinone adjusted for triglycerides, older adults had significantly higher plasma phylloquinone concentrations (both unadjusted and adjusted) at 0 and 24 h than the younger adults (P < 0.001). These data emphasize that the use of different approaches for the assessment of vitamin K absorption can result in disparate conclusions.

Dietary and nondietary determinants of vitamin K biochemical measures in men and women

Few epidemiological studies that rely on the food frequency questionnaire (FFQ) for dietary assessment have measured biomarkers of vitamin K intake to independently confirm associations between self-reported dietary vitamin K intake and disease risk. Associations were examined between two sensitive biomarkers of vitamin K status, plasma phylloquinone and serum percent undercarboxylated osteocalcin (%ucOC), and self-reported usual phylloquinone intake as estimated from a FFQ. The influence of other dietary and nondietary factors on plasma phylloquinone concentrations was also examined. Dietary phylloquinone intake was estimated using a FFQ in 369 men and 468 women of the Framingham Offspring Study. The prevalence of high %ucOC concentrations (>/= 20%), suggestive of a low vitamin K status, was 44% in men and 54% in women, respectively. After multivariate adjustment, the odds of a high %ucOC was 2.5 greater for women (odds ratio: 2.5; 95% confidence interval [CI]: 1.2-5.1) and almost three times greater for men (odds ratio: 2.8; 95% CI: 1.3-5.9) in the lowest dietary phylloquinone intake quintile category compared to the highest quintile category. Fasting triglyceride concentrations, smoking status and season were associated with plasma phylloquinone concentrations, independent of dietary phylloquinone intake. Phylloquinone and green vegetable intake was linearly associated with plasma phylloquinone, after adjustment for potential confounding factors. There were limitations in the use of the FFQ to predict plasma phylloquinone, evident in an observed plateau effect and required nondietary adjustment factors. Despite these caveats, these findings support the use of a FFQ for a relative assessment of vitamin K status in population-based studies.

HPLC and GC/MS determination of deuterated vitamin K (phylloquinone) in human serum after ingestion of deuterium-labeled broccoli

The ability to intrinsically label plant constituents with stable isotopes has the potential to advance the study of vitamin K-absorption and metabolism in humans. Broccoli, a primary food source of phylloquinone (VK-1), was grown hydroponically using 31 atom % deuterium oxide in order to label VK-1 within the food matrix. Deuterium-labeled broccoli (115 g; 168 &mgr;g VK-1) was fed to one male subject in a single serving. Multiple serum samples were drawn throughout the subsequent 24-hr period. Reversed-phase HPLC was used to extract and purify VK-1 in both broccoli and serum. Ion abundances of the deuterium-labeled and unlabeled (endogenous) VK-1 were determined using GC/MS in negative chemical ionization mode. No sample derivatization was required. Endogenous VK-1 produced isotopomers from m/z 450 to m/z 453. The labeled VK-1 isotopomers in the broccoli were from m/z 452 to m/z 467, with the most abundant isotopomer being m/z 458 (14.1% of total labeled VK-1). The GC/MS chromatograms from serum revealed both endogenous VK-1 and VK-1 derived from the deuterium-labeled broccoli. The profile of labeled VK-1 isotopomers in serum was identical to the VK-1 isotopomer profile in labeled broccoli, indicating that no deuterium was lost due to exchange either in the body or in sample preparation. At 4 hr following broccoli intake, there was an 81.1% enrichment of phylloquinone in serum; labeled VK-1 was no longer detectable in serum at 24 hr. Use of isotope labeled vegetables enables one to discriminate exogenous intake of VK-1 from endogenous pools and ultimately to determine bioavailability of VK-1 from foods.