Dietary induced subclinical vitamin K deficiency in normal human subjects

Vitamin K: a potential missing link in critical illness-a scoping review

BACKGROUND

Vitamin K is essential for numerous physiological processes, including coagulation, bone metabolism, tissue calcification, and antioxidant activity. Deficiency, prevalent in critically ill ICU patients, impacts coagulation and increases the risk of bleeding and other complications. This review aims to elucidate the metabolism of vitamin K in the context of critical illness and identify a potential therapeutic approach.

METHODS

In December 2023, a scoping review was conducted using the PRISMA Extension for Scoping Reviews. Literature was searched in PubMed, Embase, and Cochrane databases without restrictions. Inclusion criteria were studies on adult ICU patients discussing vitamin K deficiency and/or supplementation.

RESULTS

A total of 1712 articles were screened, and 13 met the inclusion criteria. Vitamin K deficiency in ICU patients is linked to malnutrition, impaired absorption, antibiotic use, increased turnover, and genetic factors. Observational studies show higher PIVKA-II levels in ICU patients, indicating reduced vitamin K status. Risk factors include inadequate intake, disrupted absorption, and increased physiological demands. Supplementation studies suggest vitamin K can improve status but not normalize it completely. Vitamin K deficiency may correlate with prolonged ICU stays, mechanical ventilation, and increased mortality. Factors such as genetic polymorphisms and disrupted microbiomes also contribute to deficiency, underscoring the need for individualized nutritional strategies and further research on optimal supplementation dosages and administration routes.

CONCLUSIONS

Addressing vitamin K deficiency in ICU patients is crucial for mitigating risks associated with critical illness, yet optimal management strategies require further investigation.

IMPACT RESEARCH

To the best of our knowledge, this review is the first to address the prevalence and progression of vitamin K deficiency in critically ill patients. It guides clinicians in diagnosing and managing vitamin K deficiency in intensive care and suggests practical strategies for supplementing vitamin K in critically ill patients. This review provides a comprehensive overview of the existing literature, and serves as a valuable resource for clinicians, researchers, and policymakers in critical care medicine.

Drug interactions between ALK inhibitors and warfarin with concurrent use of bucolome: a case report

BACKGROUND

Alectinib, crizotinib, and ceritinib, are anaplastic lymphoma kinase-tyrosine kinase inhibitors (ALK-TKIs) that exhibit high protein binding, and their metabolism is associated with the cytochrome P450 (CYP) isoenzymes 2C9 or 3A4. The plasma protein binding rate of warfarin, which is used to prevent and treat venous thromboembolism, is also high. Warfarin is a racemate of S-warfarin and R-warfarin, which are metabolized by CYP2C9 and CYP3A4, respectively. Reports on the drug interactions between each of the above-mentioned ALK-TKIs and warfarin with concurrent use of bucolome are currently lacking.

CASE PRESENTATION

We report a case of a patient receiving warfarin and bucolome, whose international normalized ratio (INR) increased after sequential treatment with alectinib, crizotinib, and ceritinib. The patient was a 61-year-old man with a history of aortic valve regurgitation, who was receiving warfarin treatment following aortic valve replacement. Bucolome, which can enhance the effect of warfarin, was also used simultaneously. The patient was diagnosed with primary lung adenocarcinoma, and ALK rearrangement was detected during second-line chemotherapy. After progression of the disease with chemotherapy, sequential treatment with alectinib, crizotinib, and ceritinib was initiated. Pretreatment INR values were in the therapeutic range (target INR of 2-3) but increased to supratherapeutic levels each time after initiation of alectinib, crizotinib, or ceritinib treatment. Adjustment of warfarin dose or discontinuation of bucolome were necessary to maintain the therapeutic INR range. There were no serious bleeding events or substantial changes in dietary intake. Displacement of plasma protein binding or competitive inhibition of metabolism by alectinib, crizotinib, and ceritinib could increase the plasma concentration of the unbound form of warfarin, resulting in high INR values. In addition, alectinib, crizotinib, and ceritinib might cause displacement of bucolome from plasma proteins, followed by displacement of warfarin or inhibition of warfarin metabolism caused by the unbound form of bucolome.

CONCLUSIONS

Close monitoring of INR and adjustment of warfarin dosage are needed during treatment with alectinib, crizotinib, or ceritinib in patients who receive warfarin with concurrent use of bucolome.

The relationship between vitamin K and metabolic dysfunction-associated fatty liver disease among the United States population: National Health and Nutrition Examination Survey 2017-2018

Background

The effect of vitamin K is associated with several pathological processes in fatty liver. However, the association between vitamin K levels and metabolic dysfunction-associated fatty liver disease (MAFLD) remains unclear.

Objective

Here, we investigated the relationship between vitamin K intake and MAFLD risk by employing the American National Health and Nutrition Examination Surveys (NHANES) including 3,571 participants.

Methods

MAFLD was defined as hepatic steatosis with one or more of the following: overweight or obesity, type 2 diabetes, or >2 other metabolic risk abnormalities. The total vitamin K was the sum of dietary and supplement dietary intake. The relationship of between log₁₀(vitamin K) and MAFLD was investigated using survey-weighted logistic regression and stratified analysis, with or without dietary supplementation.

Results

The MAFLD population had a lower vitamin K intake than the non-MAFLD population (p = 0.024). Vitamin K levels were inversely associated with MAFLD in the fully adjusted model (OR = 0.488, 95% CI: 0.302-0.787, p = 0.006). Consistent results were seen in the group without dietary supplements (OR = 0.373, 95% CI: 0.186-0.751, p = 0.009) but not in the group consuming dietary supplements (OR = 0.489, 95% CI: 0.238-1.001, p = 0.050).

Conclusion

Vitamin K intake may be a protective factor for MAFLD, especially for individual not using dietary supplements. Nevertheless, more high-quality prospective studies are needed to clarify the causal relationship between them.

The Associations of Dietary Vitamin K Intake and Circulating Vitamin 25(OH)D with Serum Lipoprotein Levels: The Vitamin Deficiency Matters

A synergistic interplay between vitamins K and D appears to exist. We aimed to investigate for the first time whether the associations of dietary vitamin K intake and circulating 25(OH)D with serum lipoprotein levels are influenced by the existence of deficiency of either or both vitamins K and D. Sixty individuals [24 males, 36(18-79) years old] were examined. Vitamin deficiency of K1 and D were defined as vitamin K1 intake/body weight (BW)<1.00 μg/kg/day and circulating 25(OH)D<20 ng/ml, respectively. In individuals with vitamin K1 deficiency, the vitamin K1 intake/BW correlated positively with high density lipoprotein-cholesterol (HDL-C) (r=0.509, p=0.008) and negatively with serum triglycerides (TG) (r=-0.638, p=0.001), whereas circulating 25(OH)D correlated negatively with TG (r=-0.609, p=0.001). In individuals with vitamin D deficiency, the vitamin K1 intake/BW correlated positively with HDL-C (r=0.533, p=0.001) and negatively with TG (r=-0.421, p=0.009), while circulating 25(OH)D correlated negatively with TG (r=-0.458, p=0.004). The above-mentioned associations of vitamin K1 intake/BW and circulating 25(OH)D with serum lipoproteins were not detected in individuals without vitamin K1 deficiency or the ones without vitamin D deficiency. The vitamin K2 intake/BW correlated negatively with low density lipoprotein-cholesterol (LDL-C) (r=-0.404, p=0.001). In conclusion, the associations of vitamin K1 intake with TG and HDL-C and of circulating 25(OH)D with TG were more pronounced in individuals with deficiency of either or both vitamins K1 and D. Increased dietary vitamin K2 intake was associated with decreased LDL-C.

Role of Vitamin K in Bone and Muscle Metabolism

Vitamin K, a cofactor for the γ-glutamyl carboxylase enzyme, is required for the post-translational activation of osteocalcin and matrix Gla protein, which play a key role in bone and muscle homeostasis. In vivo and in vitro models for osteoporosis and sarcopenia suggest the vitamin K could exert a positive effect in both conditions. In bone, it increases osteoblastogenesis, whilst decreases osteoclast formation and function. In muscle, it is associated with increased satellite cell proliferation and migration and might play a role in energy metabolism. Observational trials suggest that high levels of vitamin K are associated with increased bone mineral density and reduced fracture risk. However, interventional studies for vitamin K supplementation yielded conflicting results. Clinical trials in sarcopenia suggest that vitamin K supplementation could improve muscle mass and function. One of the main limitations on the vitamin K studies are the technical challenges to measure its levels in serum. Thus, they are obtained from indirect sources like food questionnaires, or levels of undercarboxylated proteins, which can be affected by other environmental or biological processes. Although current research appoints to a beneficial effect of vitamin K in bone and muscle, further studies overcoming the current limitations are required in order to incorporate this supplementation in the clinical management of patients with osteosarcopenia.

Vitamin K Contribution to DNA Damage—Advantage or Disadvantage? A Human Health Response

Vitamin K is the common name for a group of compounds recognized as essential for blood clotting. The group comprises phylloquinone (K1)—a 2-methyl-3-phytyl-1,4-naphthoquinone; menaquinone (K2, MK)—a group of compounds with an unsaturated side chain in position 3 of a different number of isoprene units and a 1,4-naphthoquinone group and menadione (K3, MD)—a group of synthetic, water-soluble compounds 2-methyl-1,4-naphthoquinone. However, recent epidemiological studies suggest that vitamin K has various benefits that go beyond blood coagulation processes. A dietary intake of K1 is inversely associated with the risk of pancreatic cancer, K2 has the potential to induce a differentiation in leukemia cells or apoptosis of various types of cancer cells, and K3 has a documented anti-cancer effect. A healthy diet rich in fruit and vegetables ensures an optimal supply of K1 and K2, though consumers often prefer supplements. Interestingly, the synthetic form of vitamin K—menadione—appears in the cell during the metabolism of phylloquinone and is a precursor of MK-4, a form of vitamin K2 inaccessible in food. With this in mind, the purpose of this review is to emphasize the importance of vitamin K as a micronutrient, which not only has a beneficial effect on blood clotting and the skeleton, but also reduces the risk of cancer and other pro-inflammatory diseases. A proper diet should be a basic and common preventive procedure, resulting in a healthier society and reduced burden on healthcare systems.

A critical review of the effects of vitamin K on glucose and lipid homeostasis: its potential role in the prevention and management of type 2 diabetes

In recent years, our knowledge regarding the physiological role of vitamin K has expanded beyond regulation of coagulation to include many other aspects of human health. In the present review, we aimed to evaluate the existing evidence for beneficial effects of vitamin K on type 2 diabetes and components of the metabolic syndrome as risk factors for cardiovascular disease. Increased dietary intake of vitamin K has been linked to lower incidence of type 2 diabetes mellitus (T2DM), possibly through its enhancement of insulin production and sensitivity. Additionally, higher plasma levels of vitamin K1 have been associated with lower T2DM risk and decreased insulin resistance, and supplementation trials also suggest a positive influence of vitamin K on glucose regulation. Vitamin K might also beneficially affect serum lipids and lipid metabolism. However, the available data remain controversial. Additionally, different studies use different approaches to assess vitamin K status owing to the absence of a generally accepted marker, which further complicates data evaluation. In conclusion, vitamin K possibly improves glucose and lipid metabolism and could be an emerging target in the context of prevention and control of T2DM, insulin resistance, and dyslipidemia.

Vitamin K and cardiovascular complications in CKD patients

Vitamin K, well known for its role in coagulation, encompasses two major subgroups: Vitamin K1 is exclusively synthesized by plants, whereas vitamin K2 mostly originates from bacterial synthesis. Vitamin K serves as a cofactor for the enzyme γ-glutamyl carboxylase, which carboxylates and thereby activates various vitamin K dependent proteins. Several vitamin K-dependent proteins are synthesized in bone but the role of vitamin K for bone health in CKD patients, in particular the prevention of osteoporosis is still not firmly established. Here we focus on another prominent action of vitamin K, in particular vitamin K2, namely the activation of matrix Gla protein (MGP), the most potent inhibitor of cardiovascular calcifications. Multiple observational studies link relative vitamin K deficiency or low intake to cardiovascular calcification progress, morbidity and mortality. Patients with advanced chronic kidney disease (CKD) are particularly vitamin K deficient, in part because of dietary restrictions but possibly also due to impaired endogenous recycling of vitamin K. At the same time this population is characterized by markedly accelerated cardiovascular calcifications and mortality. High dose dietary supplementation with vitamin K2, in particular the most potent form menaquinone-7 (MK7), can potently reduce circulating levels of dephosphorylated uncarboxylated, i.e. inactive MGP in patients with end stage kidney disease. However, despite this compelling data basis, several randomized controlled trials with high dose MK7 supplements in patients with advanced CKD have failed to confirm cardiovascular benefits. Here we discuss potential reasons and solutions for this.

Perspective: Evidence before Enthusiasm-A Critical Review of the Potential Cardiovascular Benefits of Vitamin K

A protective role for vitamin K in cardiovascular disease (CVD), a leading cause of morbidity and mortality, has been proposed because vitamin K-dependent proteins, such as matrix Gla (γ-carboxyglutamic acid) protein (MGP), are present in vascular tissue. MGP functions as a vascular calcification inhibitor-but only when it is carboxylated, which requires vitamin K. There is more than one naturally occurring form of vitamin K. Phylloquinone (vitamin K1) is found in plant-based foods, whereas menaquinones (vitamin K2) are a class of vitamin K compounds found in animal-based and fermented foods. Phylloquinone and menaquinones are capable of carboxylating MGP and other vitamin K-dependent proteins. In rodent models, high intakes of either phylloquinone or menaquinone reduced vascular calcification. Evidence of the relative importance of phylloquinone and menaquinone to CVD in humans is limited and controversial. In some observational studies, higher dietary menaquinone intake, but not phylloquinone intake, was associated with less coronary artery calcification (a subclinical manifestation of CVD) and a lower risk for clinical CVD events. These findings have led to claims that menaquinones have unique cardiovascular health benefits compared with phylloquinone. However, this claim is not supported by the results of the limited number of intervention trials conducted to date. The purpose of this review is to evaluate the strengths and limitations of the available evidence regarding the role of vitamin K in vascular calcification, CVD, and mortality.

Vitamin K Analogs Influence the Growth and Virulence Potential of Enterohemorrhagic Escherichia coli

Enterohemorrhagic Escherichia coli (EHEC) causes serious foodborne disease worldwide. It produces the very potent Shiga toxin 2 (Stx2). The Stx2-encoding genes are located on a prophage, and production of the toxin is linked to the synthesis of Stx phages. There is, currently, no good treatment for EHEC infections, as antibiotics may trigger lytic cycle activation of the phages and increased Stx production. This study addresses how four analogs of vitamin K, phylloquinone (K1), menaquinone (K2), menadione (K3), and menadione sodium bisulfite (MSB), influence growth, Stx2-converting phage synthesis, and Stx2 production by the EHEC O157:H7 strain EDL933. Menadione and MSB conferred a concentration-dependent negative effect on bacterial growth, while phylloquinone or menaquinone had little and no effect on bacterial growth, respectively. All four vitamin K analogs affected Stx2 phage production negatively in uninduced cultures and in cultures induced with either hydrogen peroxide (H₂O₂), ciprofloxacin, or mitomycin C. Menadione and MSB reduced Stx2 production in cultures induced with either H₂O₂ or ciprofloxacin. MSB also had a negative effect on Stx2 production in two other EHEC isolates tested. Phylloquinone and menaquinone had, on the other hand, variable and concentration-dependent effects on Stx2 production. MSB, which conferred the strongest inhibitory effect on both Stx2 phage and Stx2 production, improved the growth of EHEC in the presence of H₂O₂ and ciprofloxacin, which could be explained by the reduced uptake of ciprofloxacin into the bacterial cell. Together, the data suggest that vitamin K analogs have a growth- and potential virulence-reducing effect on EHEC, which could be of therapeutic interest.IMPORTANCE Enterohemorrhagic E. coli (EHEC) can cause serious illness and deaths in humans by producing toxins that can severely damage our intestines and kidneys. There is currently no optimal treatment for EHEC infections, as antibiotics can worsen disease development. Consequently, the need for new treatment options is urgent. Environmental factors in our intestines can affect the virulence of EHEC and help our bodies fight EHEC infections. The ruminant intestine, the main reservoir for EHEC, contains high levels of vitamin K, but the levels are variable in humans. This study shows that vitamin K analogs can inhibit the growth of EHEC and/or production of its main virulence factor, the Shiga toxin. They may also inhibit the spreading of the Shiga toxin encoding bacteriophage. Our findings indicate that vitamin K analogs have the potential to suppress the development of serious disease caused by EHEC.

MK-7 and Its Effects on Bone Quality and Strength

Vitamin K acts as a cofactor and is required for post-translational γ-carboxylation of vitamin K-dependent proteins (VKDP). The current recommended daily intake (RDI) of vitamin K in most countries has been established based on normal coagulation requirements. Vitamin K1 and menaquinone (MK)-4 has been shown to decrease osteocalcin (OC) γ-carboxylation at RDI levels. Among the several vitamin K homologs, only MK-7 (vitamin K2) can promote γ-carboxylation of extrahepatic VKDPs, OC, and the matrix Gla protein at a nutritional dose around RDI. MK-7 has higher efficacy due to its higher bioavailability and longer half-life than other vitamin K homologs. As vitamin K1, MK-4, and MK-7 have distinct bioactivities, their RDIs should be established based on their relative activities. MK-7 increases bone mineral density and promotes bone quality and strength. Collagen production, and thus, bone quality may be affected by MK-7 or MK-4 converted from MK-7. In this review, we comprehensively discuss the various properties of MK-7.

Association of marked prolongation of prothrombin time-international normalized ratio with warfarin and endoscopic nasobiliary drainage for biliary fistula after left hemihepatectomy

WHAT IS KNOWN AND OBJECTIVE

Vitamin K deficiency is known to cause impaired coagulation. We report a case of marked prolongation of the prothrombin time-international normalized ratio (PT-INR) associated with warfarin and vitamin K deficiency caused by endoscopic nasobiliary drainage (ENBD).

CASE PRESENTATION

Oral administration of warfarin was initiated in a 67-year-old man after left hemihepatectomy. He developed a biliary fistula after surgery that was treated by ENBD, which resulted in significant prolongation of the PT-INR.

WHAT IS NEW AND CONCLUSION

The effect of warfarin was enhanced in this patient due to reduced absorption of vitamin K as a result of external biliary drainage.

Vitamin K-what is known regarding bariatric surgery patients: a systematic review

Vitamin K, a fat-soluble vitamin, is involved in blood coagulation, bone mineralization, inhibition of vascular calcification, and regulation of numerous enzyme systems. Patients who undergo bariatric surgery (BS), especially procedures that involve a malabsorptive component, are prone to develop vitamin K deficiency (VKD). The causes of VKD include decreased absorptive surface areas, steatorrhea, bacterial overgrowth, marked reduction of carriers of vitamin K, decrease in vitamin K intake, and modifications of gut microbiota. Data on vitamin K status among BS patients are scarce and the strength of evidence supporting vitamin K supplementation is weak. Thus, this systematic review summarized the scientific literature on vitamin K and examined the status among patients before and after BS, as well as among pregnant women with a history of BS. A MEDLINE/Pubmed and Embase electronic search was performed. After a thorough screening of 204 titles, 19 articles were selected by 2 independent reviewers. Five studies on BS candidates (n = 750), 12 studies after BS (n = 1442), and 4 studies on pregnant woman after BS (n = 83, of them n = 7 from case reports) were included. Results of the current review suggest that patients who undergo major malabsorptive surgeries are at a higher risk of developing VKD and should be better monitored. At this point, it is still unclear whether supplementation of vitamin K is required, and what oral dose or vitamer type should be used to normalize serum levels after different types of bariatric procedures. It should be noted that the current protocols for VKD treatment are still experiential in these patients. It is also unknown at what intervals screening tests for vitamin K should be performed and what assay is most appropriate for screening purposes. Future studies are needed to answer these unresolved issues.

Plasma Response to Deuterium-Labeled Vitamin K Intake Varies by TG Response, but Not Age or Vitamin K Status, in Older and Younger Adults

Background

Phylloquinone is the primary form of vitamin K in the diet and circulation. Large intra- and interindividual variances in circulating phylloquinone have been partially attributed to age. However, little is known about the nondietary factors that influence phylloquinone absorption and metabolism. Similarly, it is not known if phylloquinone absorption is altered by the individual's existing vitamin K status.

Objective

The purpose of this secondary substudy was to compare plasma response with deuterium-labeled phylloquinone intake in older and younger adults after dietary phylloquinone depletion and repletion.

Methods

Forty-two older [mean ± SD age: 67.2 ± 8.0 y; body mass index (BMI; in kg/m2): 25.4 ± 4.6; n = 12 men, 9 women] and younger (mean ± SEM age: 31.8 ± 6.6 y; BMI: 25.5 ± 3.3; n = 9 men, 12 women) adults were maintained on sequential 28-d phylloquinone depletion (∼10 µg phylloquinone/d) and 28-d phylloquinone repletion (∼500 µg phylloquinone/d) diets. On the 23rd d of each diet phase, participants consumed deuterated phylloquinone-rich collard greens (2H-phylloquinone). Plasma and urinary outcome measures over 72 h were compared by age group, sex, and dietary phase via 2-factor repeated-measures ANOVA.

Results

The plasma 2H-phylloquinone area under the curve (AUC) did not differ in response to phylloquinone depletion or repletion, but was 34% higher in older than in younger adults (P = 0.02). However, plasma 2H-phylloquinone AUC was highly correlated with the serum triglyceride (TG) AUC (r2 = 0.45). After adjustment for serum TG response, the age effect on the plasma 2H-phylloquinone AUC was no longer significant.

Conclusions

Plasma 2H-phylloquinone response did not differ between phylloquinone depletion and repletion in older and younger adults. The age effect observed was explained by the serum TG response and was completely attenuated after adjustment. Plasma response to phylloquinone intake, therefore, seems to be a predominantly lipid-driven effect and not dependent on existing vitamin K status. More research is required to differentiate the effect of endogenous compared with exogenous lipids on phylloquinone absorption. This trial was registered at clinicaltrials.gov as NCT00336232.

Acute Kidney Injury Masked by Malnutrition: A Case Report and the Problem of Protein

Acute kidney injury (AKI) is common among critically ill patients. There are a number of nutrition considerations in the management of AKI, including fluid balance, electrolyte and acid-base disturbances, protein provision, and management of comorbid conditions. The optimal amount of protein provision for patients with AKI who are not on renal replacement therapy (RRT) has been a topic of debate for years. Excessive protein provision may contribute to azotemia in these patients, but inadequate protein intake may harm nutrition status and result in poorer clinical outcomes. This review discusses a patient case of AKI masked by malnutrition and muscle loss and reviews the current literature on optimal protein intake in AKI (not on RRT). Based on a structured search strategy, 4 articles were reviewed. We conclude that the available evidence suggests that significant restrictions in protein intake are not necessary for those critically ill patients with AKI. However, the studies reviewed here showed significant heterogeneity in protein dose and delivery, estimation of protein needs, patient population, and definition of AKI, and thus further research is needed to systematically determine the optimal dose of protein for critically ill adults with AKI.

Vitamin K deficiency in critical ill patients; a prospective observational study

BACKGROUND

Vitamin K is a cofactor for proteins involved in cardiovascular health, bone metabolism and cancer. Measuring uncarboxylated prothrombin, also termed as "protein induced by vitamin K absence or antagonism for factor II (PIVKA-II)", has been used to assess vitamin K status. High levels may indicate vitamin K deficiency. The aim of this study was to measure PIVKA-II and prothrombin time (PT-INR) in intensive care (ICU) patients and correlate vitamin K status with mortality.

METHODS

Ninety-five patients admitted to the ICU had blood samples taken near admission and every third day. In addition to PIVKA-II and PT-INR, critical-care severity scores were computed.

RESULTS

The median baseline PIVKA-II was 4.97 μg/L compared to the upper reference of 2.0 μg/L. PIVKA-II further increased at days 3 and 6, (median 7.88 μg/L, p = .047 and median 8.14 μg/L, p = .011) predominantly in cardiac arrest patients (median 21.4 μg/L, day 3).

CONCLUSION

Intensive care patients have increased PIVKA-II levels at admission, which increases during the ICU stay, especially in cardiac arrest patients. There were no correlations between PIVKA-II and PT-INR, SOFA score or mortality. Further studies are needed to determine why PIVKA-II increases and whether high PIVKA-II levels in ICU patients affect long-term mortality or morbidity.

Desphospho-Uncarboxylated Matrix-Gla Protein Is Increased Postoperatively in Cardiovascular Risk Patients

BACKGROUND

Matrix Gla protein (MGP) is an extrahepatic protein that is dependent on glutamate carboxylation, a vitamin K-dependent process. Its dysfunctional form, desphospho-uncarboxylated-MGP, has been associated with increased arterial calcification and stiffness. The aim of this study was to measure the degree of postoperative carboxylation of MGP and two other Gla proteins in patients scheduled for abdominal or orthopaedic surgery.

METHODS

Forty patients undergoing abdominal or orthopaedic surgery were included. Blood samples were collected preoperatively and four days after the surgery. Desphospho-carboxylated MGP (dp-cMGP), desphospho-uncarboxylated MGP (dp-ucMGP), carboxylated osteocalcin (OC) (cOC), uncarboxylated OC (ucOC), and uncarboxylated prothrombin (PIVKA-II) were analysed.

RESULTS

Preoperatively, 29 patients had dp-ucMGP levels above the reference values. Patients with pre-existing cardiovascular comorbidities had higher dp-ucMGP preoperatively compared with patients with no record of cardiovascular disease. Postoperatively, this number increased to 36 patients, and median dp-ucMGP levels increased (p < 0.0001) and correlated to a PIVKA-II increase (r = 0.44). On the other hand, dp-cMGP levels did not significantly alter. Decreased levels of ucOC and cOC were seen after surgery (p = 0.017 and p = 0.0033, respectively). Comorbidities, possible nutritional defects, and complications affecting Gla protein activity and function were identified.

CONCLUSIONS

Dp-ucMGP was high preoperatively, and had further increased postoperatively. This pattern was linked to several comorbidities, possible nutritional defects, and postoperative complications, which motivates further research about potential interactions between perioperative corrective treatments with vitamin K supplements, cardiovascular biomarkers, and incidents of stroke and myocardial infarction events.

Nutritional Needs and Support for Children with Chronic Liver Disease

Malnutrition has become a dangerously common problem in children with chronic liver disease, negatively impacting neurocognitive development and growth. Furthermore, many children with chronic liver disease will eventually require liver transplantation. Thus, this association between malnourishment and chronic liver disease in children becomes increasingly alarming as malnutrition is a predictor of poorer outcomes in liver transplantation and is often associated with increased morbidity and mortality. Malnutrition requires aggressive and appropriate management to correct nutritional deficiencies. A comprehensive review of the literature has found that infants with chronic liver disease (CLD) are particularly susceptible to malnutrition given their low reserves. Children with CLD would benefit from early intervention by a multi-disciplinary team, to try to achieve nutritional rehabilitation as well as to optimize outcomes for liver transplant. This review explains the multifactorial nature of malnutrition in children with chronic liver disease, defines the nutritional needs of these children, and discusses ways to optimize their nutritional.

Vitamin K and cancer

Subclinical vitamin K deficits refer to carboxylation defects of different types of vitamin K-dependent hepatic and extrahepatic so-called Gla proteins without prolongation of the prothrombin time. This condition has been reported in different clinical situations due to insufficient supply or malabsorption of vitamin K as well as drug interactions. This review discusses the effects of different vitamin K subspecies on tumour growth and the possible anti-tumour effects of increased vitamin K intake. Blocking carboxylation of vitamin K-dependent proteins with warfarin anticoagulation - what are the risks/benefits for carcinogenesis? Previous studies on both heparin and low molecular weight heparin blocking of the vitamin K-dependent factors X and II have shown tumour suppressive effects. Vitamin K has anti-inflammatory effects that could also impact carcinogenesis, but little data exists on this subject.

Dietary reference values for vitamin K

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) derives dietary reference values (DRVs) for vitamin K. In this Opinion, the Panel considers vitamin K to comprise both phylloquinone and menaquinones. The Panel considers that none of the biomarkers of vitamin K intake or status is suitable by itself to derive DRVs for vitamin K. Several health outcomes possibly associated with vitamin K intake were also considered but data could not be used to establish DRVs. The Panel considers that average requirements and population reference intakes for vitamin K cannot be derived for adults, infants and children, and therefore sets adequate intakes (AIs). The Panel considers that available evidence on occurrence, absorption, function and content in the body or organs of menaquinones is insufficient, and, therefore, sets AIs for phylloquinone only. Having assessed additional evidence available since 1993 in particular related to biomarkers, intake data and the factorial approach, which all are associated with considerable uncertainties, the Panel maintains the reference value proposed by the Scientific Committee for Food (SCF) in 1993. An AI of 1 μg phylloquinone/kg body weight per day is set for all age and sex population groups. Considering the respective reference body weights, AIs for phylloquinone are set at 70 μg/day for all adults including pregnant and lactating women, at 10 μg/day for infants aged 7-11 months, and between 12 μg/day for children aged 1-3 years and 65 μg/day for children aged 15-17 years.

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.

Management of vitamin K deficiency after biliopancreatic diversion with or without duodenal switch

BACKGROUND

Reduced serum vitamin K levels are frequently observed after biliopancreatic diversion (BPD) and BPD with duodenal switch (BPD/DS). The criteria for treatment are not precisely defined.

OBJECTIVES

To assess the effects of standardized vitamin K supplementation in patients who develop vitamin K deficiency after BPD or BPD/DS.

SETTING

Teaching hospital specializing in bariatric surgery.

METHODS

Serum vitamin K levels, clotting times, and vitamin K-dependent coagulation factors were measured after an overnight fast at baseline and then at 4 days and 1, 4, and 52 weeks after the start of vitamin K supplementation in 10 consecutive patients who had developed severe vitamin K deficiency after BPD or BPD/DS. Vitamin K was administered in a dose of 5 mg/d for 1 week, followed by a maintenance dose of 5 mg once a week.

RESULTS

At baseline, all patients had serum vitamin K1 levels below the limit of detection, but none reported symptoms of easy bleeding. Minor prolongation of the prothrombin time and minimal decreases of some coagulation factors were observed in a minority of patients. During the first week of vitamin K loading, median serum vitamin K1 levels rose into the high normal range. During maintenance treatment, median vitamin K1 levels settled in the low normal range.

CONCLUSION

Vitamin K1 deficiency in patients with BPD or BPD/DS is not commonly associated with bleeding or clinically relevant decreases in coagulation factor activity. We hypothesize that vitamin K2 production in the large intestine is usually sufficient to compensate for vitamin K1 deficiency and to maintain total liver vitamin K stores within the range required for (near) normal coagulation factor production.

Perioperative changes in PIVKA-II

BACKGROUND AND AIMS

Proteins induced by vitamin K absence for factor II (PIVKA-II) is an enzyme-linked immunosorbent assay that monitors uncarboxylated prothrombin and responds to vitamin K deficits prior to changes in the prothrombin test. The aim of this project was to study perioperative PIVKA-II changes during various types of surgery in a prospective observational study.

METHODS

Patients undergoing abdominal or orthopaedic surgery were included. Blood was sampled on the day of surgery (preoperatively) and up to 5 days after surgery. The activated partial thromboplastin time, Quick and Owren prothrombin times were analyzed, together with PIVKA-II.

RESULTS

Thirty-nine patients were included, 27 +male and 12 +female. All but 7 +patients had elevated PIVKA-II levels preoperatively. PIVKA-II levels had already increased significantly (p < 0.017) on day 1 after surgery as compared to presurgery plasma levels. The median PIVKA-II was highest on day 5. Routine tests were mostly normal. No significant difference in PIVKA-II was seen when comparing patients undergoing abdominal versus orthopaedic surgeries. There was no significant correlation between PIVKA-II and routine coagulation tests. Patients with anterior resection, emergency laparotomy and emergency hip fractures had higher postoperative increases, which could be linked to increased gastrointestinal recovery times, paralytic ileus, peritonitis and comorbidities.

CONCLUSIONS

PIVKA-II levels increase during the perioperative period, despite mostly normal routine coagulation tests. Pre- and perioperative vitamin K supplementation in patients with elevated PIVKA-II levels should be studied, and its clinical significance be defined in future studies.

How I treat poisoning with vitamin K antagonists

Severe deficiency of vitamin K-dependent proteins in patients not maintained on vitamin K antagonists is most commonly associated with poisoning by or surreptitious ingestion of warfarin, warfarin-like anticoagulants, or potent rodenticides ("superwarfarins"), such as brodifacoum. Serious bleeding manifestations are common. Superwarfarins are 2 orders of magnitude more potent than warfarin and have a half-life measured in weeks. These rodenticides are readily available household environmental hazards and are sometimes consumed accidentally or as manifestations of psychiatric disease. Immediate diagnosis and proper therapy is critically important to minimize morbidity and mortality because this condition, affecting thousands of patients annually, is reversible. Treatment with large doses of oral vitamin K1, often over months to years, to maintain a near-normal prothrombin time can reverse the coagulopathy associated with superwarfarins. Although these patients initially present to various medical specialties, the hematologist is often consulted to offer the definitive diagnosis and proper therapy.

Menaquinones, bacteria, and the food supply: the relevance of dairy and fermented food products to vitamin K requirements

Vitamin K exists in the food supply as phylloquinone, a plant-based form and as menaquinones (MKs), a collection of isoprenologues mostly originating from bacterial synthesis. Although multiple bacterial species used as starter cultures for food fermentations synthesize MK, relatively little is known about the presence and distribution of MK in the food supply and the relative contribution of MK to total dietary vitamin K intake. Dairy products may be a predominant source of dietary MK in many regions of the world, and there is recent interest in enhancing the MK content of dairy products through identification and selection of MK-producing bacteria in dairy fermentations. This interest is increased by emerging evidence that current dietary recommendations based on the classic role of vitamin K as an enzyme cofactor for coagulation proteins may not be optimal for supporting vitamin K requirements in extrahepatic tissues and that MK may have unique bioactivity beyond that as an enzyme cofactor. Observational studies have reported favorable associations between MK intake and bone and cardiovascular health. Although randomized trials have provided some evidence to support the beneficial effects of MK on bone, the evidence to date is not definitive, and randomized trials have not yet examined MK intake in relation to cardiovascular outcomes. Food production practices provide a means to enhance dietary MK availability and intake. However, parallel research is needed to optimize these production practices, develop comprehensive food MK content databases, and test hypotheses of unique beneficial physiological roles of MK beyond that achieved by phylloquinone.

Diffuse alveolar hemorrhage in coumarin users: a fibrosing interstitial pneumonia trigger?

BACKGROUND

Fibrosing interstitial pneumonias (IPs) include idiopathic pulmonary fibrosis (IPF) and nonspecific interstitial pneumonia (NSIP). It has been suggested that oxidative damage plays a role in the pathophysiology of idiopathic interstitial pneumonias. Diffuse alveolar hemorrhage (DAH) can cause oxidative stress. Accordingly, we hypothesized that episodes of DAH might trigger fibrosing IP development.

METHODS

Patients using coumarins with confirmed DAH were retrospectively gathered during a 9 year period and reviewed for the development of IPF or fibrosing NSIP.

RESULTS

A total of 65 patients with DAH could finally be included, 31 (48 %) of whom subsequently developed a fibrosing IP. The majority of these 31 patients developed the fibrosing IP within 3 years after DAH confirmation. A total of 41 (63 %) patients died within 3.0 ± 0.9 (range 1.3-4.7) years after the DAH diagnosis had been confirmed. Twenty-two of the deceased (54 %) had finally developed fibrosing IP.

CONCLUSIONS

Almost half of the patients with established episodes of DAH developed fibrosing IP; therefore it seems that DAH might be a trigger for the development of fibrosing IP. This observation warrants prospective studies to further evaluate the clinical impact of these findings.

A single measurement of serum phylloquinone is an adequate indicator of long-term phylloquinone exposure in healthy older adults

Assessment of long-term phylloquinone exposure is challenging in studies investigating vitamin K in health. Data are equivocal as to whether a single measurement of circulating phylloquinone would be adequate. The primary purpose of the present study was to validate the use of a single measurement of serum phylloquinone as a surrogate for long-term phylloquinone exposure in healthy older adults. Using data from the Québec Longitudinal Study on Nutrition and Successful Aging, the objectives were to: 1) determine the reproducibility of circulating phylloquinone over 2 y (n = 234); 2) calculate how a single measurement would rank or classify individuals and attenuate the regression coefficient between circulating phylloquinone and a health outcome; and 3) investigate the association of a single measurement of serum phylloquinone with long-term phylloquinone intakes assessed over the year prior to the blood draw (n = 228). The variance analysis based on 2 blood samples showed a fair to good reproducibility for serum phylloquinone (intra-class correlation = 0.49). The correlation coefficient between the ranking of individuals based on a single measurement of circulating phylloquinone and the "true" ranking would be 0.70. The multiple regression analysis showed that long-term phylloquinone intake was the strongest predictor of serum phylloquinone (t = 4.94; P < 0.001). The partial correlation coefficient (r = 0.32) was comparable with those reported in studies where blood sampling and diet recording were juxtaposed and/or multiple blood samples were used. The present study provides evidence that the use of a single measurement of circulating phylloquinone is adequate for assessing long-term phylloquinone exposure in healthy older adults.

Age group and sex do not influence responses of vitamin K biomarkers to changes in dietary vitamin K

Inadequate vitamin K intake has been associated with abnormal soft tissue calcification. Older adults may have insufficient intakes of vitamin K and respond less to vitamin K supplementation compared with younger adults. However, little is known about the determinants that influence the response to vitamin K supplementation. Our primary objective was to assess dietary and nondietary determinants of vitamin K status in healthy younger and older adults. In a nonrandomized, nonmasked study, 21 younger (18-40 y) and 21 older (55-80 y) men and women consumed a baseline diet (200 μg phylloquinone/d) for 5 d, a phylloquinone-restricted diet (10 μg phylloquinone/d) for 28 d, and a phylloquinone-supplemented diet (500 μg phylloquinone/d) for 28 d. Changes in vitamin K status markers in response to vitamin K depletion and repletion were studied and the influences of BMI, body fat, and circulating TG were assessed by including them as covariates in the model. Despite baseline differences in measures of vitamin K status, plasma phylloquinone tended to increase (P = 0.07) and the percentage of uncarboxylated osteocalcin and uncarboxylated prothrombin both improved with phylloquinone supplementation (P < 0.007), regardless of age group or sex. Only the excretion of urinary menadione, a vitamin K metabolite, was greater among younger adults in response to depletion than in older adults (P = 0.012), regardless of sex. Adiposity measures and circulating TG did not predict response of any measures. In conclusion, poor vitamin K status can be similarly improved with vitamin K supplementation, regardless of age group or sex.

Warfarin and vitamin K intake in the era of pharmacogenetics

The considerable variability in the warfarin dose-response relationship between individuals, is explained mainly by genetic variation in its major metabolic (CYP2C9) and target (VKORC1) enzymes. Despite the predominance of pharmacogenetics, environmental factors also affect the pharmacokinetics and pharmacodynamics of warfarin, and are often overlooked. Among these factors, dietary and supplemental vitamin K consumption is a controllable contributor to within-, and between-patient variability of warfarin sensitivity. In this commentary we review the current role of vitamin K in warfarin anticoagulation therapy, with emphasis on the following: 1 The effect of dietary and supplemental vitamin K on warfarin anticoagulation, beyond the impact of genetic variability in CYP2C9 and VKORC1. We deal separately with the effects of vitamin K on warfarin dose requirements during the induction of therapy, as opposed to its effect on stability of anticoagulation control during maintenance therapy. 2 The role of vitamin K supplementation in warfarin treated patients with vitamin K deficiency as well as in patients with unstable warfarin anticoagulation, and 3 The role of therapeutic vitamin K in cases of warfarin over-anticoagulation.

Optimizing nutritional management in children with chronic liver disease

Malnutrition is common in infants and children with chronic liver disease (CLD) and may easily be underestimated by clinical appearance alone. The cause of malnutrition in CLD is multifactorial, although insufficient dietary intake is probably the most important factor and is correctable. Fat malabsorption occurs in cholestatic disorders, and one must also consider any accompanying fat-soluble vitamin and essential fatty acid deficiencies. The clinician should proactively evaluate, treat, and re-evaluate response to treatment of nutritional deficiencies. Because a better nutritional state is associated with better survival before and after liver transplantation, aggressive nutritional management is an important part of the care of these children.

Unique secretion mode of human protein Z: its Gla domain is responsible for inefficient, vitamin K–dependent and warfarin-sensitive secretion

Protein Z is a vitamin K–dependent plasma glycoprotein that is involved in the regulation of blood coagulation. Plasma concentrations of protein Z vary widely between subjects and are greatly reduced during warfarin therapy. We developed a sensitive and quantitative assay for protein secretion using a secretory luciferase to explore the mode of secretion of protein Z compared with that of factor X. Protein Z secretion was much less efficient than factor X and was totally dependent upon added vitamin K, while factor X secretion was not. Protein Z secretion was highly sensitive to warfarin treatment of the synthesizing cells. In contrast, although factor X secretion was not precluded by warfarin, its γ-carboxylation was completely blocked. An exchange of the propeptide and/or γ-carboxyglutamic acid domain between protein Z and factor X reproduced the inefficient and warfarin-sensitive secretion pattern of protein Z, and vice versa. Joining of the propeptide and γ-carboxyglutamic acid domain to luciferase also demonstrated that the γ-carboxyglutamic acid domain of protein Z was responsible for its warfarin-sensitive secretion. Thus, it was concluded that the difference observed in secretion patterns of protein Z and factor X was mainly based on the structure of their γ-carboxyglutamic acid domains.

Prevalence of low bone mass and deficiencies of vitamins D and K in pediatric patients with cystic fibrosis from 3 Canadian centers

OBJECTIVE

In this cross-sectional observational study, we assessed both vitamins D and K status and bone health in pancreatic insufficient pediatric patients with cystic fibrosis from 3 Canadian cystic fibrosis centers.

METHODS

Eighty-one patients who had cystic fibrosis and were clinically stable for at least 3 months were enrolled. At the time of the clinic visit, anthropometric variables, lung function, pubertal status, intake of calcium and vitamins D and K, and physical activity were assessed. Blood was taken for analysis of biochemical biomarkers of bone turnover and status of vitamins D and K, and a urine sample was obtained for calcium, creatinine, sodium, and deoxypyridoline analyses. Whole-body bone mineral content and lumbar spine (L1-L4) bone mineral density were measured.

RESULTS

The children were relatively well nourished and had moderate to mild lung disease. Low bone mineral mass defined as a z score between -1.0 and -2.0, for gender and age was detected in 38% of the children for whole body and in 28% for lumbar spine. z score less than -2.0 was observed in 7 children for both bone measures. Suboptimal vitamin D status occurred in 95% of patients; suboptimal vitamin K status occurred in 82% of patients. Measures of plasma osteocalcin and carboxy-terminal propeptide type 1 procollagen and urinary deoxypyridoline compared with reference values for age, gender, and pubertal status reflected a state of suppressed bone formation and elevated bone resorption in a large proportion of the patients.

CONCLUSIONS

Bone mass of the whole body and spine was lower than expected for chronological age in approximately one third of pediatric patients with cystic fibrosis irrespective of gender or age. This may be explained by the observation of low bone turnover for developmental stage as indicated by bone biomarkers. Suboptimal status of vitamins D and K may be key causative factors of the low bone status for age.

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.

Relationship between diet and anticoagulant response to warfarin: a factor analysis

BACKGROUND

Diet composition is one of the factors that may contribute to intraindividual variability in the anticoagulant response to warfarin.

AIM OF THE STUDY

To determine the associations between food pattern and anticoagulant response to warfarin in a group of Brazilian patients with vascular disease.

METHODS

Recent and usual food intakes were assessed in 115 patients receiving warfarin; and corresponding plasma phylloquinone (vitamin K(1)), serum triglyceride concentrations, prothrombin time (PT), and International Normalized Ratio (INR) were determined. A factor analysis was used to examine the association of specific foods and biochemical variables with anticoagulant data.

RESULTS

Mean age was 59 +/- 15 years. Inadequate anticoagulation, defined as values of INR 2 or 3, was found in 48% of the patients. Soybean oil and kidney beans were the primary food sources of phylloquinone intake. Factor analysis yielded four separate factors, explaining 56.4% of the total variance in the data set. The factor analysis revealed that intakes of kidney beans and soybean oil, 24-h recall of phylloquinone intake, PT and INR loaded significantly on factor 1. Triglycerides, PT, INR, plasma phylloquinone, and duration of anticoagulation therapy loaded on factor 3.

CONCLUSIONS

Fluctuations in phylloquinone intake, particularly from kidney beans, and plasma phylloquinone concentrations were associated with variation in measures of anticoagulation (PT and INR) in a Brazilian group of patients with vascular disease.

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

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 55·5×104MBq/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 curvet1/2was 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 exponentialt1/2was 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 of3H-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.

Plasma phylloquinone (vitamin K1) concentration and its relationship to intake in a national sample of British elderly people

Plasma phylloquinone (vitamin K1) concentration was examined according to season, socio-demographic and lifestyle factors and phylloquinone intake in a nationally representative sample of British people aged 65 years and over from the 1994–5 National Diet and Nutrition Survey. Values for both plasma phylloquinone concentration and phylloquinone intake were available from 1076 participants (561 men, 515 women). Eight hundred and thirty-four were living in private households, 242 in residential or nursing homes. Weighted geometric mean plasma phylloquinone concentrations were 0·36 (95 % CI 0·06, 2·01) and 0·24 (95 % CI 0·06, 0·96) nmol/l in free-living and institution samples respectively. Plasma phylloquinone concentrations did not generally differ between men and women, although values in free-living people were significantly lower during autumn and winter (October to March). Plasma phylloquinone concentration was not significantly associated with age. Plasma phylloquinone concentrations were positively correlated with phylloquinone intake in free-living men and women (r0·18 and 0·30 respectively, bothP<0·001). Stepwise multiple regression analysis found that 11 % of the variation in plasma phylloquinone concentration was explained by phylloquinone intake, season and plasma triacylglycerol concentration. After adjustment for age and corresponding nutrient intakes, plasma phylloquinone concentration was significantly associated (eachP<0·01) with plasma concentrations of triacylglycerol, cholesterol, retinol and 25-hydroxyvitamin D in free-living women but not men, and with plasma concentrations of carotenes, α- and γ-tocopherols and lutein in free-living men and women. The possibility of concurrent low fat-soluble vitamin status in elderly populations may be a cause for concern.

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.

Dietary phylloquinone depletion and repletion in postmenopausal women: effects on bone and mineral metabolism

INTRODUCTION

Vitamin K has been implicated in increased bone fracture risk. Despite a potential role of vitamin K in bone, little is known about the effects of altered dietary phylloquinone intake on the underlying components of bone and mineral metabolism.

METHODS

A 84-day in-house dietary phylloquinone (vitamin K) depletion-repletion study was undertaken in 21 postmenopausal women (mean age: 70 years) to assess the effects of altered vitamin K status on intestinal calcium (Ca) absorption, urinary and serum Ca and phosphorus (P), serum calcemic hormones, and serum biomarkers of bone turnover [osteocalcin and N-telopeptide type 1 collagen cross-links (NTx)] and the response to 1,25-dihydroxyvitamin D treatment (1 microg/dayx7 d).

RESULTS

The group receiving calcitriol treatment (n=11) had higher Ca absorption, urinary Ca, urinary and serum P and serum osteocalcin and lower serum parathyroid hormone (PTH). There were no significant effects of acute (4-week) phylloquinone depletion on response to 1,25-dihydroxyvitamin D treatment or on measures of bone formation or mineral metabolism. However, phylloquinone treatment had a significant effect (p<0.04) on serum NTx. Phylloquinone repletion, up to five times (450 microg phylloquinone per day) the currently recommended adequate intake level of dietary phylloquinone for women, significantly reduced serum NTx (16.8+/-0.9 nmol bone collagen equivalents (BCE) per liter following repletion vs 18.4+/-1.1 nmol BCE per liter following depletion; p<0.01).

CONCLUSIONS

These findings suggest that altering vitamin K status in postmenopausal women by manipulating phylloquinone intake does not have an acute affect on intestinal Ca absorption, renal mineral excretion, or bone formation, but high phylloquinone intake may modestly reduce bone resorption. The impact of high phylloquinone intake on bone mineral density and fracture risk needs to be ascertained in randomized clinical trials.

Antibody Microarray Profiling Reveals Individual and Combined Serum Proteins Associated with Pancreatic Cancer

We used antibody microarrays to probe the associations of multiple serum proteins with pancreatic cancer and to explore the use of combined measurements for sample classification. Serum samples from pancreatic cancer patients (n = 61), patients with benign pancreatic disease (n = 31), and healthy control subjects (n = 50) were probed in replicate experiment sets by two-color, rolling circle amplification on microarrays containing 92 antibodies and control proteins. The antibodies that had reproducibly different binding levels between the patient classes revealed different types of alterations, reflecting inflammation (high C-reactive protein, alpha-1-antitrypsin, and serum amyloid A), immune response (high IgA), leakage of cell breakdown products (low plasma gelsolin), and possibly altered vitamin K usage or glucose regulation (high protein-induced vitamin K antagonist-II). The accuracy of the most significant antibody microarray measurements was confirmed through immunoblot and antigen dilution experiments. A logistic-regression algorithm distinguished the cancer samples from the healthy control samples with a 90% and 93% sensitivity and a 90% and 94% specificity in duplicate experiment sets. The cancer samples were distinguished from the benign disease samples with a 95% and 92% sensitivity and an 88% and 74% specificity in duplicate experiment sets. The classification accuracies were significantly improved over those achieved using individual antibodies. This study furthered the development of antibody microarrays for molecular profiling, provided insights into the nature of serum-protein alterations in pancreatic cancer patients, and showed the potential of combined measurements to improve sample classification accuracy.

Ethnic differences in osteocalcin gamma-carboxylation, plasma phylloquinone (vitamin K1) and apolipoprotein E genotype

OBJECTIVE

To investigate plasma osteocalcin gamma-carboxylation and its relationship to plasma phylloquinone concentration and apolipoprotein E (apoE) genotype in women from three ethnic groups with differing osteoporotic fracture risk.

DESIGN AND SUBJECTS

Fasted blood samples were collected from postmenopausal Gambian (n=50), British (n=31) and Chinese women (n=23), and 11 premenopausal women in each group from three cross-sectional studies.

RESULTS

After adjustment for total osteocalcin, plasma undercarboxylated osteocalcin (adjusted ucOC) was lowest in Chinese and highest in British women postmenopause (British vs Chinese 103% higher, P<0.0001; Gambian vs Chinese 66% higher, P<0.01). No differences were observed premenopause. Within each ethnic group, adjusted ucOC was similar pre- and postmenopause. Postmenopause, plasma phylloquinone was higher in Chinese women (1.0 ng/ml) than in British (0.31 ng/ml) and Gambian women (0.36 ng/ml) (P<0.0001). Premenopause, plasma phylloquinone was higher in Gambian and Chinese women (0.6 ng/ml) than in British women (0.3 ng/ml; P=0.01). Plasma phylloquinone and adjusted ucOC were inversely related in postmenopausal British women (R2=32.4%; P=0.0008). ApoE4 frequency was Gambian 32.6%, British 13.8% and Chinese 6%. A lower adjusted ucOC was associated with apoE2 genotype in British and Chinese women. Ethnic differences in adjusted ucOC persisted after adjustment for phylloquinone and apoE genotype.

CONCLUSION

These preliminary data indicate suboptimal vitamin K status in postmenopausal British compared to Chinese and Gambian women. Ethnic differences in apoE genotype may also influence osteocalcin gamma-carboxylation status. The study highlights the need for larger epidemiological investigations of ethnic differences in vitamin K status and the possible implications to bone health.

The physiology of vitamin K nutriture and vitamin K-dependent protein function in atherosclerosis

Recent advances in the discovery of new functions for vitamin K-dependent (VKD) proteins and in defining vitamin K nutriture have led to a substantial revision in our understanding of vitamin K physiology. The only unequivocal function for vitamin K is as a cofactor for the carboxylation of VKD proteins which renders them active. While vitamin K was originally associated only with hepatic VKD proteins that participate in hemostasis, VKD proteins are now known to be present in virtually every tissue and to be important to bone mineralization, arterial calcification, apoptosis, phagocytosis, growth control, chemotaxis, and signal transduction. The development of improved methods for analyzing vitamin K has shed considerable insight into the relative importance of different vitamin K forms in the diet and their contribution to hepatic vs. non-hepatic tissue. New assays that measure the extent of carboxylation in VKD proteins have revealed that while the current recommended daily allowance for vitamin K is sufficient for maintaining functional hemostasis, the undercarboxylation of at least one non-hemostatic protein is frequently observed in the general population. The advances in defining VKD protein function and vitamin K nutriture are described, as is the potential impact of VKD proteins on atherosclerosis. Many of the VKD proteins contribute to atherogenesis. Recent studies suggest involvement in arterial calcification, which may be influenced by dietary levels of vitamin K and by anticoagulant drugs such as warfarin that antagonize vitamin K action.

Effect of vitamin E supplementation on vitamin K status in adults with normal coagulation status

BACKGROUND

Cases of enhanced anticoagulant effect in response to high-dose vitamin E supplementation have been reported among patients taking oral anticoagulants. Although a vitamin E-vitamin K interaction was proposed to underlie this effect, it has not been systematically investigated in adults with normal baseline coagulation status.

OBJECTIVE

The objective was to study the effect of 12 wk of supplementation with 1000 IU RRR-alpha-tocopherol/d on biochemical measures of vitamin K status in men and women not taking oral anticoagulants.

DESIGN

Vitamin K status, which was assessed with the use of plasma phylloquinone concentrations, the degree of under-gamma-carboxylation of prothrombin (proteins induced by vitamin K absence-factor II, PIVKA-II), and the percentage of undercarboxylated osteocalcin (ucOC), was determined in 38 men and women with rheumatoid arthritis (study A) and in 32 healthy men (study B) participating in 2 independent, 12-wk randomized clinical trials of vitamin E supplementation (1000 IU/d).

RESULTS

Mean (+/- SD) PIVKA-II increased from 1.7 +/- 1.7 to 11.9 +/- 16.1 ng/mL (P < 0.001) in study A and from 1.8 +/- 0.6 to 5.3 +/- 3.9 ng/mL (P < 0.001) in study B in response to 12 wk of vitamin E supplementation. An increase in PIVKA-II is indicative of poor vitamin K status. In contrast, the other measures of vitamin K status (ie, plasma phylloquinone concentration and percentage of ucOC) did not change significantly in response to the supplementation.

CONCLUSIONS

High-dose vitamin E supplementation increased PIVKA-II in adults not receiving oral anticoagulant therapy. The clinical significance of these changes warrants further investigation, but high doses of vitamin E may antagonize vitamin K. Whether such an interaction is potentially beneficial or harmful remains to be determined.

Dietary vitamin K influences intra-individual variability in anticoagulant response to warfarin

The 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 microg in the daily dietary intake of vitamin K averaged over 4 d, the INR was reduced by 0.2. 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 = 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.