Vitamin K Abstracts 8

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The effect of low-dose oral vitamin K supplementation on INR stability in patients receiving warfarin. A randomised trial.
            (Boonyawat et al., 2016)  Download
The anticoagulant effect of warfarin is influenced by variations in vitamin K intake. Concomitant use of daily low-dose oral vitamin K (LDVK) and warfarin may improve INR stability. We hypothesise that administration of LDVK improves INR control. To test this hypothesis we performed a multi-centre, placebo-controlled, randomised trial conducted at four university-affiliated hospitals in Canada. Patients on chronic warfarin therapy received oral vitamin K 150 mcg daily or a matching placebo for a total of six months after a one-month run in period. The primary outcome was a comparison of mean time in therapeutic range (TTR) in LDVK and placebo group during a six-month-period. The secondary outcome was number of INR excursions <1.5 or >4.5. There was no significant difference in the final TTR between the two groups (65.1 % vs 66 %, p =0.8). Mean TTR in both LDVK and placebo groups were statistically increased compared with prior to the study. The number of INR excursions were significantly decreased in the LDVK group (9.4 % and 5.4 %, absolute difference [pre- minus post-] = 4 %, 95 % CI, 2 to 6 %, p-value <0.001). We conclude that LDVK administration did not increase mean TTR, but did decrease the number of INR excursions. The observed improvement in mean TTR in both groups suggests that more attentive monitoring of warfarin therapy, rather than LDVK, was responsible for the improvement in TTR observed. The reduced excursions suggest that LDVK did reduce extreme INR variation. The study is registered at www.ClinicalTrial.gov# NCT00990158.

Vitamin K2 supplementation in haemodialysis patients: a randomized dose-finding study.
            (Caluwé et al., 2014)  Download
BACKGROUND:  Haemodialysis patients suffer from accelerated vascular calcification. The vitamin K-dependent matrix Gla protein (MGP) is one of the most powerful inhibitors of vascular calcification. Haemodialysis patients have high levels of the inactive form of MGP (desphosphorylated-uncarboxylated-MGP, dp-uc-MGP) and may benefit from pharmacological doses of vitamin K2 (menaquinone) to improve the calcification inhibitory activity of MGP. METHODS:  To determine the optimal dose of menaquinone-7 (MK-7) for MGP activation, 200 chronic haemodialysis patients were recruited to randomly receive 360, 720 or 1080 µg of MK-7 thrice weekly for 8 weeks. Dp-uc-MGP was measured at baseline and after 8 weeks. Dietary intake of vitamin K1 (phylloquinone) and menaquinone was estimated based on a detailed questionnaire. RESULTS:  At baseline, dp-uc-MGP was not associated with phylloquinone intake (P = 0.92), but correlated inversely with menaquinone intake (P = 0.023). MK-7 supplementation dose dependently reduced dp-uc-MGP. The levels decreased by 17, 33 and 46% in the respective groups. Drop-outs were mainly due to gastrointestinal side-effects related to the unpleasant smell of the tablets. CONCLUSIONS:  Chronic haemodialysis patients have high levels of inactive MGP, possibly related to a low dietary vitamin K intake. Pharmacological doses of MK-7 dose-dependently reduce dp-uc-MGP. Menaquinone supplementation may be a novel approach to prevent vascular calcifications in chronic haemodialysis patients.

Association of Dietary Vitamin K1 Intake With the Incidence of Cataract Surgery in an Adult Mediterranean Population: A Secondary Analysis of a Randomized Clinical Trial.
            (Camacho-Barcia et al., 2017)  Download
Importance:  Cataract, one of the most frequent causes of blindness in developed countries, is strongly associated with aging. The exact mechanisms underlying cataract formation are still unclear, but growing evidence suggests a potential role of inflammatory and oxidative processes. Therefore, antioxidant and anti-inflammatory factors of the diet, such as vitamin K1, could play a protective role. Objective:  To examine the association between dietary vitamin K1 intake and the risk of incident cataracts in an elderly Mediterranean population. Design, Setting, and Participants:  A prospective analysis was conducted in 5860 participants from the Prevención con Dieta Mediterránea Study, a randomized clinical trial executed between 2003 and 2011. Participants were community-dwelling men (44.2%) and women (55.8%), and the mean (SD) age was 66.3 (6.1) years. Main Outcomes and Measures:  Dietary vitamin K1 intake was evaluated using a validated food frequency questionnaire. The time to the cataract event was calculated as the time between recruitment and the date of the occurrence to cataract surgery, the time to the last visit of the follow-up, date of death, or the end of the study. Hazard ratios and 95% CIs for cataract incidence were estimated with a multivariable Cox proportional hazards model. Results:  Participants were community-dwelling men (44.2%; n = 868) and women (55.8%; n = 1086), and the mean (SD) age was 66.3 (6.1) years. After a median of 5.6 years follow-up, we documented a total of 768 new cataracts. Participants in the highest tertile of dietary vitamin K1 intake had a lower risk of cataracts than those in the lowest tertile (hazard ratio, 0.71; 95% CI, 0.58-0.88; P = .002), after adjusting for potential confounders. Conclusions and Relevance:  High intake of dietary vitamin K1 was associated with a reduced risk of cataracts in an elderly Mediterranean population even after adjusting by other potential confounders. Trial Registration:  isrctn.org: ISRCTN35739639.


 

Vitamin K3 suppressed inflammatory and immune responses in a redox-dependent manner.
            (Checker et al., 2011) Download
Recent investigations suggest that cellular redox status may play a key role in the regulation of several immune functions. Treatment of lymphocytes with vitamin K3 (menadione) resulted in a significant decrease in cellular GSH/GSSG ratio and concomitant increase in the ROS levels. It also suppressed Concanavalin A (Con A)-induced proliferation and cytokine production in lymphocytes and CD4 + T cells in vitro. Immunosuppressive effects of menadione were abrogated only by thiol containing antioxidants. Mass spectrometric analysis showed that menadione directly interacted with thiol antioxidant GSH. Menadione completely suppressed Con A-induced activation of ERK, JNK and NF-κB in lymphocytes. It also significantly decreased the homeostasis driven proliferation of syngeneic CD4 + T cells. Further, menadione significantly delayed graft-vs-host disease morbidity and mortality in mice. Menadione suppressed phytohemagglutinin-induced cytokine production in human peripheral blood mononuclear cells. These results reveal that cellular redox perturbation by menadione is responsible for significant suppression of lymphocyte responses.

Effect of Vitamin K on Vascular Health and Physical Function in Older People with Vascular Disease--A Randomised Controlled Trial.
            (Fulton et al., 2016)  Download
BACKGROUND AND AIMS:  Vitamin K insufficiency is common and linked to an increased risk of cardiovascular disease and osteoporotic fractures. The aim of this study was to examine whether daily supplementation with oral vitamin K could improve vascular health and physical function in older people with established vascular disease. METHODS AND RESULTS:  A double blind, randomised, placebo-controlled trial. Participants aged ≤ 70 years with a history of vascular disease were randomised to receive 6 months of daily oral 100mcg vitamin K2 (MK7 subtype) or matching placebo with outcomes measured at 0, 3 and 6 months. The primary outcome was between-group difference in endothelial function assessed using flow-mediated dilatation of the brachial artery at 6 months. Secondary outcomes included carotid-radial pulse wave velocity, augmentation index, blood pressure, carotid intima-media thickness, C-reactive protein, B-type natriuretic peptide, cholesterol and desphospho-uncarboxylated matrix Gla protein levels. Handgrip strength and the Short Physical Performance Battery assessed physical function, while postural sway was measured using a 3-dimensional force platform. RESULTS:  80 participants were randomised, mean age 77 (SD 5) years; 44/80 were male. Vitamin K levels rose in the intervention arm compared to placebo (+48 pg/ml vs -6 pg/ml, p=0.03) at 6 months. Desphospho-uncarboxylated Matrix Gla protein levels fell in the intervention group compared to placebo at 6 months (-130 [SD 117] pmol/L vs +13 [SD 180] pmol/L, p<0.001). No change was seen in endothelial function (between group difference -0.3% [95%CI -1.3 to 0.8], p=0.62). A modest, non-significant improvement in pulse wave velocity was seen in the vitamin K group (-0.8m/s [95%CI -1.8 to 0.3], p=0.15) while all other vascular and physical function outcomes unchanged. CONCLUSIONS:  Six months of vitamin K2 supplementation did not improve markers of vascular health or physical function in older patients with vascular disease.

Low-Dose Daily Intake of Vitamin K(2) (Menaquinone-7) Improves Osteocalcin γ-Carboxylation: A Double-Blind, Randomized Controlled Trials.
            (Inaba et al., 2015)  Download
Vitamin K is essential for bone health, but the effects of low-dose vitamin K intake in Japanese subjects remain unclear. We investigated the effective minimum daily menaquinone-7 dose for improving osteocalcin γ-carboxylation. Study 1 was a double-blind, randomized controlled dose-finding trial; 60 postmenopausal women aged 50-69 y were allocated to one of four dosage group and consumed 0, 50, 100, or 200 μg menaquinone-7 daily for 4 wk, respectively, with a controlled diet in accordance with recommended daily intakes for 2010 in Japan. Study 2 was a double-blind, randomized placebo-controlled trial based on the results of Study 1; 120 subjects aged 20-69 y were allocated to the placebo or MK-7 group and consumed 0 or 100 μg menaquinone-7 daily for 12 wk, respectively. In both studies, circulating carboxylated osteocalcin and undercarboxylated osteocalcin were measured. The carboxylated osteocalcin/undercarboxylated osteocalcin ratio decreased significantly from baseline in the 0 μg menaquinone-7 group, in which subjects consumed the recommended daily intake of vitamin K with vitamin K1 and menaquinone-4 (Study 1). Menaquinone-7 increased the carboxylated osteocalcin/undercarboxylated osteocalcin ratio dose dependently, and significant effects were observed in both the 100 and 200 μg groups compared with the 0 μg group. Undercarboxylated osteocalcin concentrations decreased significantly, and the carboxylated osteocalcin/undercarboxylated osteocalcin ratio increased significantly in the 100 μg menaquinone-7 group compared with the placebo group (Study 2). Daily menaquinone-7 intake ≥100 μg was suggested to improve osteocalcin γ-carboxylation.


 

Impact of supplemental vitamin K1 administration on postoperative blood component requirements after craniosynostosis repair: a prospective, placebo-controlled, randomized, blinded study.
            (Kicker et al., 2014)  Download
Total cranial vault craniosynostosis repairs often require additional blood transfusions in the intensive care unit. Vitamin K1 participates in hepatic production of procoagulant proteins, and body stores of vitamin K1 are limited and dietary dependent. Surgical stress and diet interference may place infants at risk for vitamin K deficiency. Through design of a surgically stratified, randomized, placebo-controlled, blinded pilot study, we evaluated impact of vitamin K1 supplementation on coagulation parameters in infants after craniosynostosis repair. Patients received intramuscular vitamin K1 or placebo coincident with surgical incision. Serum vitamin K1 levels, protein induced in vitamin K absence-prothrombin, and factor VII were obtained at predetermined intervals after surgery. Patients received blood products in the intensive care unit in accordance with transfusion thresholds. Fifteen patients (vitamin K1 = 6, placebo = 9) completed the study procedures. Despite group assignment, patients received an average of 3 postoperative transfusions. Variations were observed with respect to intraoperative resuscitation of patients between comparably trained pediatric anesthesiologists. Thirty-three percent of patients were vitamin K1 deficient on 1 or more laboratory specimens. All breast-fed patients became deficient. Compared with placebo, elevated serum vitamin K1 levels at 6, 12, and 24 hours in the active drug group (P < 0.0001) were not associated with increased factor VII levels or reduced need for postoperative blood products. However, lack of a standardized intraoperative resuscitation plan may contribute to postoperative coagulopathy and is a major study limitation.

Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women. A double-blind randomised clinical trial.
            (Knapen et al., 2015) Download
Observational data suggest a link between menaquinone (MK, vitamin K2) intake and cardiovascular (CV) health. However, MK intervention trials with vascular endpoints are lacking. We investigated long-term effects of MK-7 (180 µg MenaQ7/day) supplementation on arterial stiffness in a double-blind, placebo-controlled trial. Healthy postmenopausal women (n=244) received either placebo (n=124) or MK-7 (n=120) for three years. Indices of local carotid stiffness (intima-media thickness IMT, Diameter end-diastole and Distension) were measured by echotracking. Regional aortic stiffness (carotid-femoral and carotid-radial Pulse Wave Velocity, cfPWV and crPWV, respectively) was measured using mechanotransducers. Circulating desphospho-uncarboxylated matrix Gla-protein (dp-ucMGP) as well as acute phase markers Interleukin-6 (IL-6), high-sensitive C-reactive protein (hsCRP), tumour necrosis factor-α (TNF-α) and markers for endothelial dysfunction Vascular Cell Adhesion Molecule (VCAM), E-selectin, and Advanced Glycation Endproducts (AGEs) were measured. At baseline dp-ucMGP was associated with IMT, Diameter, cfPWV and with the mean z-scores of acute phase markers (APMscore) and of markers for endothelial dysfunction (EDFscore). After three year MK-7 supplementation cfPWV and the Stiffness Index βsignificantly decreased in the total group, whereas distension, compliance, distensibility, Young's Modulus, and the local carotid PWV (cPWV) improved in women having a baseline Stiffness Index β above the median of 10.8. MK-7 decreased dp-ucMGP by 50 % compared to placebo, but did not influence the markers for acute phase and endothelial dysfunction. In conclusion, long-term use of MK-7 supplements improves arterial stiffness in healthy postmenopausal women, especially in women having a high arterial stiffness.

Beneficial role of vitamin K supplementation on insulin sensitivity, glucose metabolism, and the reduced risk of type 2 diabetes: A review.
            (Manna and Kalita, 2016) Download
Micronutrients are gaining acceptance as an important nutritional therapy for the prevention and/or management of diabetes and its associated health risks. Although a very small quantity of micronutrients are required for specific functions in our bodies, moderate deficiencies can lead to serious health issues. Impaired insulin sensitivity and glucose intolerance play a major role in the development of diabetic pathophysiology. Vitamin K is well known for its function in blood coagulation. Moreover, several human studies reported the beneficial role of vitamin K supplementation in improving insulin sensitivity and glucose tolerance, preventing insulin resistance, and reducing the risk of type 2 diabetes (T2 D). Both animal and human studies have suggested that vitamin K-dependent protein (osteocalcin [OC]), regulation of adipokine levels, antiinflammatory properties, and lipid-lowering effects may mediate the beneficial function of vitamin K in insulin sensitivity and glucose tolerance. This review for the first time provides an overview of the currently available preclinical and clinical evidences on the effect of vitamin K supplementation in the management of insulin sensitivity and glucose tolerance. The outcome of this review will increase understanding for the development of a novel adjuvant therapy to achieve better control of glycemia and improve the lives of diabetic patients.

Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women.
            (Sato et al., 2012) Download
BACKGROUND:  Vitamin K₂ contributes to bone and cardiovascular health. Therefore, two vitamin K₂ homologues, menaquinone-4 (MK-4) and menaquinone-7 (MK-7), have been used as nutrients by the food industry and as nutritional supplements to support bone and cardiovascular health. However, little is known about the bioavailability of nutritional MK-4. To investigate MK-4 and MK-7 bioavailability, nutritional doses were administered to healthy Japanese women. FINDINGS:  Single dose administration of MK-4 (420 μg; 945 nmol) or MK-7 (420 μg; 647 nmol) was given in the morning together with standardized breakfast. MK-7 was well absorbed and reached maximal serum level at 6 h after intake and was detected up to 48 h after intake. MK-4 was not detectable in the serum of all subjects at any time point. Consecutive administration of MK-4 (60 μg; 135 nmol) or MK-7 (60 μg; 92 nmol) for 7 days demonstrated that MK-4 supplementation did not increase serum MK-4 levels. However, consecutive administration of MK-7 increased serum MK-7 levels significantly in all subjects. CONCLUSIONS:  We conclude that MK-4 present in food does not contribute to the vitamin K status as measured by serum vitamin K levels. MK-7, however significantly increases serum MK-7 levels and therefore may be of particular importance for extrahepatic tissues.

Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7.
            (Schurgers et al., 2007) Download
Vitamin K is a cofactor in the production of blood coagulation factors (in the liver), osteocalcin (in bone), and matrix Gla protein (cartilage and vessel wall). Accumulating evidence suggests that for optimal bone and vascular health, relatively high intakes of vitamin K are required. The synthetic short-chain vitamin K(1) is commonly used in food supplements, but recently the natural long-chain menaquinone-7 (MK-7) has also become available as an over-the-counter (OTC) supplement. The purpose of this paper was to compare in healthy volunteers the absorption and efficacy of K(1) and MK-7. Serum vitamin K species were used as a marker for absorption and osteocalcin carboxylation as a marker for activity. Both K(1) and MK-7 were absorbed well, with peak serum concentrations at 4 hours after intake. A major difference between the 2 vitamin K species is the very long half-life time of MK-7, resulting in much more stable serum levels, and accumulation of MK-7 to higher levels (7- to 8-fold) during prolonged intake. MK-7 induced more complete carboxylation of osteocalcin, and hematologists should be aware that preparations supplying 50 mug/d or more of MK-7 may interfere with oral anticoagulant treatment in a clinically relevant way.

Vitamin K supplementation and progression of coronary artery calcium in older men and women.
            (Shea et al., 2009) Download
BACKGROUND:  Coronary artery calcification (CAC) is an independent predictor of cardiovascular disease. A preventive role for vitamin K in CAC progression has been proposed on the basis of the properties of matrix Gla protein (MGP) as a vitamin K-dependent calcification inhibitor. OBJECTIVE:  The objective was to determine the effect of phylloquinone (vitamin K1) supplementation on CAC progression in older men and women. DESIGN:  CAC was measured at baseline and after 3 y of follow-up in 388 healthy men and postmenopausal women; 200 received a multivitamin with 500 microg phylloquinone/d (treatment), and 188 received a multivitamin alone (control). RESULTS:  In an intention-to-treat analysis, there was no difference in CAC progression between the phylloquinone group and the control group; the mean (+/-SEM) changes in Agatston scores were 27 +/- 6 and 37 +/- 7, respectively. In a subgroup analysis of participants who were > or =85% adherent to supplementation (n = 367), there was less CAC progression in the phylloquinone group than in the control group (P = 0.03). Of those with preexisting CAC (Agatston score > 10), those who received phylloquinone supplements had 6% less progression than did those who received the multivitamin alone (P = 0.04). Phylloquinone-associated decreases in CAC progression were independent of changes in serum MGP. MGP carboxylation status was not determined. CONCLUSIONS:  Phylloquinone supplementation slows the progression of CAC in healthy older adults with preexisting CAC, independent of its effect on total MGP concentrations. Because our data are hypothesis-generating, further studies are warranted to clarify this mechanism. This trial was registered at clinicaltrials.gov as NCT00183001.

Effect of vitamin K supplementation on insulin sensitivity: a meta-analysis.
            (Suksomboon et al., 2017) Download
OBJECTIVE:  To perform a systematic review and meta-analysis of randomized, placebo-controlled trials to assess the effect of vitamin K supplementation on insulin sensitivity. DATA SOURCES:  MEDLINE, the Cochrane Library, CINAHL, Web of Science, Scopus, clinicaltrials.gov, and clinicaltrialresults.org were searched up to January 2017. Reference lists of related papers were also scanned. STUDY SELECTION:  Randomized controlled trials were selected if they compared vitamin K supplementation with placebo or no treatment and reported homeostasis model assessment of insulin resistance, fasting plasma glucose, fasting plasma insulin, C-reactive protein, adiponectin, leptin, or interleukin-6 levels. DATA EXTRACTION:  Data extraction and study quality assessment were performed independently by two investigators using a standardized data extraction form. Any inconsistencies were resolved by a third reviewer. Effect estimates were pooled using inverse-variance weighted method. Heterogeneity was assessed by the  RESULTS:  A total of eight trials involving 1,077 participants met the inclusion criteria. A wide variety of participants were enrolled, including older men, postmenopausal women, prediabetic premenopausal women, and participants with a history of diabetes, hypertension, or vascular disease. Vitamin K1 and vitamin K2 (MK-4 and MK-7 subtypes) were assessed. Supplementation period ranged from 4 weeks to 3 years. Vitamin K supplementation did not affect insulin sensitivity as measured by homeostasis model assessment of insulin resistance, fasting plasma glucose, fasting plasma insulin, C-reactive protein, adiponectin, leptin, and interleukin-6 levels. CONCLUSION:  Our analysis suggests no effect of vitamin K supplementation on insulin sensitivity.

 


References

Boonyawat, K, et al. (2016), ‘The effect of low-dose oral vitamin K supplementation on INR stability in patients receiving warfarin. A randomised trial.’, Thromb Haemost, 116 (3), 480-85. PubMed: 27346552
Caluwé, R, et al. (2014), ‘Vitamin K2 supplementation in haemodialysis patients: a randomized dose-finding study.’, Nephrol Dial Transplant, 29 (7), 1385-90. PubMed: 24285428
Camacho-Barcia, ML, et al. (2017), ‘Association of Dietary Vitamin K1 Intake With the Incidence of Cataract Surgery in an Adult Mediterranean Population: A Secondary Analysis of a Randomized Clinical Trial.’, JAMA Ophthalmol, 135 (6), 657-61. PubMed: 28494067
Checker, R, et al. (2011), ‘Vitamin K3 suppressed inflammatory and immune responses in a redox-dependent manner.’, Free Radic Res, 45 (8), 975-85. PubMed: 21651451
Fulton, RL, et al. (2016), ‘Effect of Vitamin K on Vascular Health and Physical Function in Older People with Vascular Disease--A Randomised Controlled Trial.’, J Nutr Health Aging, 20 (3), 325-33. PubMed: 26892582
Inaba, N, T Sato, and T Yamashita (2015), ‘Low-Dose Daily Intake of Vitamin K(2) (Menaquinone-7) Improves Osteocalcin γ-Carboxylation: A Double-Blind, Randomized Controlled Trials.’, J Nutr Sci Vitaminol (Tokyo), 61 (6), 471-80. PubMed: 26875489
Kicker, JS, et al. (2014), ‘Impact of supplemental vitamin K1 administration on postoperative blood component requirements after craniosynostosis repair: a prospective, placebo-controlled, randomized, blinded study.’, J Craniofac Surg, 25 (1), 154-59. PubMed: 24406570
Knapen, MH, et al. (2015), ‘Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women. A double-blind randomised clinical trial.’, Thromb Haemost, 113 (5), 1135-44. PubMed: 25694037
Manna, P and J Kalita (2016), ‘Beneficial role of vitamin K supplementation on insulin sensitivity, glucose metabolism, and the reduced risk of type 2 diabetes: A review.’, Nutrition, 32 (7-8), 732-39. PubMed: 27133809
Sato, T, LJ Schurgers, and K Uenishi (2012), ‘Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women.’, Nutr J, 11 93. PubMed: 23140417
Schurgers, L. J., et al. (2007), ‘Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7’, Blood, 109 (8), 3279-83. PubMed: 17158229
Shea, M. K., et al. (2009), ‘Vitamin K supplementation and progression of coronary artery calcium in older men and women’, Am J Clin Nutr, 89 (6), 1799-807. PubMed: 19386744
Suksomboon, N, N Poolsup, and H Darli Ko Ko (2017), ‘Effect of vitamin K supplementation on insulin sensitivity: a meta-analysis.’, Diabetes Metab Syndr Obes, 10 169-77. PubMed: 28496349