Roles for vitamin K beyond coagulation

Phylloquinone improves endothelial function, inhibits cellular senescence, and vascular inflammation

Phylloquinon (PK) and menaquinones (MK) are both naturally occurring compounds belonging to vitamin K group. Present study aimed to comprehensively analyze the influence of PK in several models of vascular dysfunction to determine whether PK has vasoprotective properties, similar to those previously described for MK. Effects of PK and MK on endothelial dysfunction were studied in ApoE/LDLR-/- mice in vivo, in the isolated aorta incubated with TNF, and in vascular cells as regard inflammation and cell senescence (including replicative and stress-induced models of senescence). Moreover, the vascular conversion of exogenous vitamins to endogenous MK-4 was analyzed. PK, as well as MK, given for 8 weeks in diet (10 mg/kg) resulted in comparable improvement in endothelial function in the ApoE/LDLR-/- mice. Similarly, PK and MK prevented TNF-induced impairment of endothelium-dependent vasorelaxation in the isolated aorta. In in vitro studies in endothelial and vascular smooth muscle cells, we identified that both PK and MK displayed anti-senescence effects via decreasing DNA damage while in endothelial cells anti-inflammatory activity was ascribed to the modulation of NFκB activation. The activity of PK and MK was comparable in terms of their effect on senescence and inflammation. Presence of endogenous synthesis of MK-4 from PK in aorta and endothelial and smooth muscle cells suggests a possible involvement of MK in vascular effects of PK. In conclusion, PK and MK display comparable vasoprotective effects, which may be ascribed, at least in part, to the inhibition of cell senescence and inflammation. The vasoprotective effect of PK in the vessel wall can be related to the direct effects of PK, as well as to the action of MK formed from PK in the vascular wall.

Vitamin K1 intake is associated with lower risk for all-cause and cardiovascular disease mortality in community-dwelling older Australian women

BACKGROUND AND AIMS

Assessing the relationship between vitamin K1 intakes, using region-specific food databases, with both all-cause, and cardiovascular disease (CVD) mortality warrants further investigation to inform future preventative strategies. Consequently, we examined the aforementioned associations in the Perth Longitudinal Study of Ageing Women (PLSAW).

METHODS AND RESULTS

1436 community-dwelling older Australian women (mean ± SD age 75.2 ± 2.7 years) completed a validated food frequency questionnaire at baseline (1998). Vitamin K1 intake was calculated based on an Australian vitamin K food database, supplemented with published data. All-cause and CVD mortality data was obtained from linked health records. Associations were examined using restricted cubic splines within Cox-proportional hazard models, adjusted for a range of cardiovascular and lifestyle related risk factors. Over 15 years of follow-up, 601 (41.9%) women died, with 236 deaths (16.4%) due to CVD. Compared to women with the lowest vitamin K1 intakes (Quartile 1, median 49.1 μg/day), those with the highest intakes (Quartile 4, median 119.3 μg/day) had lower relative hazards for all-cause mortality (HR 0.66 95%CI 0.51-0.86) and CVD mortality (HR 0.61 95%CI 0.41-0.92). A plateau in the inverse association was observed from vitamin K1 intakes of approximately ≥80 μg/day.

CONCLUSION

Higher vitamin K1 intakes were associated with lower risk for both all-cause and CVD mortality in community-dwelling older women, independent of CVD related risk factors. A higher intake of vitamin K1 rich foods, such as leafy green vegetables, may support cardiovascular health.

Menadione Contribution to the In Vitro Radical Scavenging Potential of Phytochemicals Naringenin and Lignin

Vitamin K3 (menadione), classified as a pro-vitamin, is a synthetic form of the fat-soluble family of vitamin K compounds. The combination of the vitamin with other molecules sharing structural and/or functional similarities, such as naturally occurring polyphenols, vitamins, or biopolymers, could potentiate mutual improvement of their antioxidant activity. The aim of the present study was to evaluate the role and contribution of vitamin K3 to the in vitro radical scavenging capacity of double and triple combinations with the phytochemicals naringenin and lignin, as well as assess possible intermolecular interactions between the bioactive compounds. Comparative analyses of the DPPH and ABTS radical scavenging activity of the pure substances vitamin K3, naringenin, and lignin; the two-component systems lignin/vitamin K3 and vitamin K3/naringenin; and the triple combination vitamin K3/flavonoid/lignin were carried out. The experimental results demonstrated increased DPPH and ABTS activities of the vitamin in combination with lignin compared to those of the two pure substances, i.e., a synergistic effect was observed. The registered significant increases in the radical scavenging activity of the triple combination determined via both methods are indicative of a remarkable potentiation effect, i.e., higher antioxidant potential exceeding the additive activity of the three pure substances.

Effects of dietary vitamin K3 supplementation on production performance, egg quality, vitamin K-dependent proteins, and antioxidant properties in breeding geese during the laying period

The aim of this work was to investigate the effects of dietary vitamin K3 (VK3) supplementation on production performance, egg quality, vitamin K-dependent proteins, and antioxidant properties in breeding geese during the laying period. A total of one hundred twenty 82-wk-old Wulong geese with similar body weights were randomly divided into 6 groups with 4 replicates and 5 geese each (1 male and 4 female). The geese in the control group were fed a basal diet, and the geese in the treatment groups were fed diets supplemented with different levels of VK3 (2.5, 5.0, 7.5, 10.0, and 12.5 mg/kg) for 11 wk. Dietary VK3 supplementation linearly and quadratically increased feed intake, egg mass, egg weight, and egg production (P < 0.05). Increasing VK3 levels linearly and quadratically increased albumen height, shell thickness and Haugh unit of eggs (P < 0.05). VK3 reduced osteocalcin (OC) and uncarboxylated osteocalcin (ucOC) levels in the serum. Dietary VK3 addition linearly decreased serum malondialdehyde (MDA) levels (P < 0.01). There was linear and quadratic effect in the activity of serum total superoxide dismutase (T-SOD) (P < 0.01), and linear effect in serum total antioxidant capacity (T-AOC) (P < 0.01). In conclusion, dietary VK3 supplementation enhanced the production performance, egg quality, vitamin K-dependent proteins, and antioxidant properties in breeding geese during the laying period. The optimal dose of dietary VK3 supplementation was 10.0 mg/kg.

Links between Vitamin K, Ferroptosis and SARS-CoV-2 Infection

Ferroptosis is a recently discovered form of programmed cell death. It is characterized by the accumulation of iron and lipid hydroperoxides in cells. Vitamin K is known to have antioxidant properties and plays a role in reducing oxidative stress, particularly in lipid cell membranes. Vitamin K reduces the level of reactive oxygen species by modulating the expression of antioxidant enzymes. Additionally, vitamin K decreases inflammation and potentially prevents ferroptosis. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leading to coronavirus disease 2019 (COVID-19) is associated with oxidant–antioxidant imbalance. Studies have shown that intensified ferroptosis occurs in various tissues and cells affected by COVID-19. Vitamin K supplementation during SARS-CoV-2 infection may have a positive effect on reducing the severity of the disease. Preliminary research suggests that vitamin K may reduce lipid peroxidation and inhibit ferroptosis, potentially contributing to its therapeutic effects in COVID-19 patients. The links between ferroptosis, vitamin K, and SARS-CoV-2 infection require further investigation, particularly in the context of developing potential treatment strategies for COVID-19.

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.

New Insights into Vitamin K-From Its Natural Sources through Biological Properties and Chemical Methods of Quantitative Determination

Vitamin K is one of the many health-promoting substances whose impact on the human body has been underestimated until recently. However, recently published research results have changed this situation, prompting some researchers to consider it a new panacea for diseases of old age. The result is a significant increase in interest in the accurate analysis of vitamin K in various types of samples, ranging from food, through dietary supplements, to biological matrices and clinical trials, both observational and interventional. This review summarizes the current state of knowledge about the proven and speculated biological activity of vitamin K and its importance for the world's aging societies, including the methods used for its isolation and analysis in various matrices types. Of all the analytical methods, the currently preferred methods of choice for the direct analysis of vitamin K are chromatographic methods, in particular liquid chromatography-tandem mass spectrometry. This technique, despite its sensitivity and selectivity, requires an appropriate stage of sample preparation. As there is still room for improvement in the efficiency of these methods, especially at the sample preparation stage, this review shows the directions that need to be taken to make these methods faster, more efficient and more environmentally friendly.

Dietary Vitamin K Intake and HPV-Infection Status Among American Women: A Secondary Analysis From National Health and Nutrition Examination Survey Data From 2003 to 2016

Objective: Cervical cancer is a serious potential risk to women’s health, and is closely related to persistent HPV infection. Vitamin K mainly existed in green vegetables, fruit, and dairy products. This research aims to observe the association between vitamin K and HPV-infection.

Methods: 13,447 participants from the NHANES were selected. Dietary vitamin K intake was used as the objective independent variable and continuous variable, HPV-infection status was used as the outcome variable, and characteristics of selected participants were used as the covariates.

Results: There was a nonlinearity between vitamin K intake and HPV-infection, and the inflection point is 3.81 of log2 vitamin K intake. In a range of 0–3.81, Each one-unit increase in log2 vitamin K intake was associated with a 43% reduction in the risk of HPV infection. When log2 vitamin K intake excess of 3.81, the risk of HPV infection did not continue to decline. The HPV-subtype was not associated with vitamin K intake.

Conclusion: There is a nonlinearity between vitamin K intake and HPV-infection status. But HPV-subtype was not associated with vitamin K intake.

Efficacy of vitamin K2 in the prevention and treatment of postmenopausal osteoporosis: A systematic review and meta-analysis of randomized controlled trials

Introduction

Vitamin K (VK) as a nutrient, is a cofactor in the carboxylation of osteocalcin (OC), which can bind with hydroxyapatite to promote bone mineralization and increase bone strength. However, some studies have been inconsistent on whether vitamin K2 (VK2) can maintain or improve bone mineral density (BMD) and reduce the incidence of fractures in postmenopausal women. Therefore, the main objective of this meta-analysis was to determine the effect of VK2 as a nutritional supplement on BMD and fracture incidence in postmenopausal women.

Methods

We searched PubMed, EMBASE, and Cochrane Library databases (published before March 17, 2022) and then extracted and pooled data from all randomized controlled trials (RCTs) that met the inclusion criteria.

Results

Sixteen RCTs with a total of 6,425 subjects were included in this meta-analysis. The overall effect test of 10 studies showed a significant improvement in lumbar spine BMD (BMD LS) (P = 0.006) with VK2. The subgroup analysis of VK2 combination therapy showed that BMD LS was significantly maintained and improved with the administration of VK2 (P = 0.03). The overall effect test of the six RCTs showed no significant difference in fracture incidence between the two groups (RR=0.96, P=0.65). However, after excluding one heterogeneous study, the overall effect test showed a significant reduction in fracture incidence with VK2 (RR = 0.43, P = 0.01). In addition, this meta-analysis showed that VK2 reduced serum undercarboxylated osteocalcin (uc-OC) levels and the ratio of uc-OC to cOC in both subgroups of VK2 combined intervention and alone. However, for carboxylated osteocalcin (cOC), both subgroup analysis and overall effect test showed no significant effect of VK2 on it. And the pooled analysis of adverse reactions showed no significant difference between the VK2 and control groups (RR = 1.03, 95%CI 0.87 to 1.21, P = 0.76).

Conclusions

The results of this meta-analysis seem to indicate that VK2 supplementation has a positive effect on the maintenance and improvement of BMD LS in postmenopausal women, and it can also reduce the fracture incidence, serum uc-OC levels and the ratio of uc-OC to cOC. In conclusion, VK2 can indirectly promote bone mineralization and increase bone strength.

Associations Between Dietary Intake of Vitamin K and Changes in Symptomatic and Structural Changes in Patients With Knee Osteoarthritis

OBJECTIVE

To investigate associations of dietary vitamin K intake with changes in knee symptoms and structures in patients with knee osteoarthritis (OA).

METHODS

Participants with symptomatic knee OA were enrolled (n = 259) and followed up for 2 years (n = 212). Baseline dietary vitamin K intake was calculated from a validated food frequency questionnaire. Knee symptoms were assessed by using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. Knee cartilage defects, bone marrow lesions, and effusion-synovitis volume were measured from magnetic resonance imaging (MRI) scans. Univariable and multivariable linear regressions were used for analyses.

RESULTS

A higher vitamin K intake quartile was significantly associated with a greater decrease in the total WOMAC score and dysfunction score over 24 months. The subgroup analyses showed in patients with severe baseline visual analog scale (VAS) pain that a higher vitamin K intake quartile was associated with more improvement in all WOMAC scores. There were no overall significant associations between vitamin K intake and changes in MRI features. In subgroup analysis, vitamin K intake was negatively associated with changes in tibiofemoral, patellar, and total cartilage defects in participants with a severe baseline radiographic grade and was negatively associated with change in total and patellar cartilage defects in participants with severe baseline VAS pain and in female patients.

CONCLUSION

The association of higher vitamin K intake with decreased knee symptoms over 24 months in patients with knee OA suggests that clinical trials examining the effect of vitamin K supplementation for knee OA symptoms are warranted. Whether there is an effect on knee structure is unclear.

Dietary vitamin K3 activates mitophagy, improves antioxidant capacity, immunity and affects glucose metabolism in Litopenaeus vannamei

An 8-week feeding experiment was conducted to appraise the influence of dietary vitamin K₃ on the growth performance, antioxidant capacities, immune responses, mitophagy and glucose metabolism in Litopenaeus vannamei. Six diets containing graded dietary vitamin K₃ (0.40(control), 9.97, 20.29, 39.06, 79.81 and 156.02 mg kg^-1 of vitamin K₃, respectively) levels were formulated. A total of 900 shrimp with 0.90 g initial weight were randomly assigned to six diets with three replications. Our results revealed that diets supplemented with 9.97-156.02 mg kg^-1 vitamin K₃ didn't affect the growth performance in L. vannamei. In general, compared with the control group, 39.06 mg kg^-1 vitamin K₃ group significantly increased (P < 0.05) the total antioxidative capacity, and the activities of catalase, glutathione, nitric oxide synthase, alkaline phosphatase and acid phosphatase in serum and hepatopancreas. 39.06 mg kg^-1 vitamin K₃ group significantly decreased (P < 0.05) the malondialdehyde in serum and hepatopancreas. The mRNA levels of antioxidant and immune related genes were increased synchronously (P < 0.05). In addition, 39.06 mg kg^-1 vitamin K₃ group increased glycogen content and levels of mitophagy (pink1, ampkα, parkin, lc3, atg13, atg12) genes. Expression levels of glucose transport related gene (glut1), glycolysis related genes (hk, pfk), glycogen synthesis related genes (gsk-3β, gys), insulin-like peptides (ILPs)/AKT/PI3K pathway related genes (insr, irsl, akt, pi3k, pdpk1) were increased in the hepatopancreas of 39.06 mg kg^-1 vitamin K₃ group. In conclusion, the present results indicated that although dietary supplementing vitamin K₃ had no influence on the growth performance, 39.06 mg kg^-1 vitamin K₃ could activate ampkα/pink1/parkin mediated mitophagy, improve antioxidant capacity and immune response. Moreover, vitamin K₃ could trigger ILPs/AKT/PI3K signaling pathways and influence glucose metabolism in L. vannamei. This finding would help to advance the field of vitamin K₃ nutrition and guide the development of future crustacean feeds.

Inhibit progression of coronary artery calcification with vitamin K in hemodialysis patients (the iPACK-HD study): a randomized, placebo-controlled multi-center, pilot trial

BACKGROUND

Vitamin K activates matrix Gla protein (MGP), a key inhibitor of vascular calcification. There is a high prevalence of sub-clinical vitamin K deficiency in patients with end-stage kidney disease.

METHODS

A parallel randomized placebo-controlled pilot trial was designed to determine whether 10 mg of phylloquinone thrice weekly versus placebo modifies coronary artery calcification progression over 12 months in patients requiring hemodialysis with a coronary artery calcium score (CAC) ≥30 Agatston Units (ClinicalTrials.gov identifier NCT01528800). The primary outcome was feasibility (recruitment rate, compliance with study medication, study completion and adherence overall to study protocol). CAC score was used to assess calcification at baseline and 12 months. Secondary objectives were to explore the impact of phylloquinone on vitamin K-related biomarkers (phylloquinone, dephospho-uncarboxylated MGP and the Gla-osteocalcin to Glu-osteocalcin ratio) and events of clinical interest.

RESULTS

A total of 86 patients with a CAC score ≥30 Agatston Units were randomized to either 10 mg of phylloquinone or a matching placebo three times per week. In all, 69 participants (80%) completed the trial. Recruitment rate (4.4 participants/month) and medication compliance (96%) met pre-defined feasibility criteria of ≥4.17 and ≥90%, respectively. Patients randomized to phylloquinone for 12 months had significantly reduced levels of dephospho-uncarboxylated MGP (86% reduction) and increased levels of phylloquinone and Gla-osteocalcin to Glu-osteocalcin ratio compared with placebo. There was no difference in the absolute or relative progression of coronary artery calcification between groups.

CONCLUSION

We demonstrated that phylloquinone treatment improves vitamin K status and that a fully powered randomized trial may be feasible.

Probiotics Enhance Bone Growth and Rescue BMP Inhibition: New Transgenic Zebrafish Lines to Study Bone Health

Zebrafish larvae, especially gene-specific mutants and transgenic lines, are increasingly used to study vertebrate skeletal development and human pathologies such as osteoporosis, osteopetrosis and osteoarthritis. Probiotics have been recognized in recent years as a prophylactic treatment for various bone health issues in humans. Here, we present two new zebrafish transgenic lines containing the coding sequences for fluorescent proteins inserted into the endogenous genes for sp7 and col10a1a with larvae displaying fluorescence in developing osteoblasts and the bone extracellular matrix (mineralized or non-mineralized), respectively. Furthermore, we use these transgenic lines to show that exposure to two different probiotics, Bacillus subtilis and Lactococcus lactis, leads to an increase in osteoblast formation and bone matrix growth and mineralization. Gene expression analysis revealed the effect of the probiotics, particularly Bacillus subtilis, in modulating several skeletal development genes, such as runx2, sp7, spp1 and col10a1a, further supporting their ability to improve bone health. Bacillus subtilis was the more potent probiotic able to significantly reverse the inhibition of bone matrix formation when larvae were exposed to a BMP inhibitor (LDN212854).

The Relationship Among Intestinal Bacteria, Vitamin K and Response of Vitamin K Antagonist: A Review of Evidence and Potential Mechanism

The vitamin K antagonist is a commonly prescribed effective oral anticoagulant with a narrow therapeutic range, and the dose requirements for different patients varied greatly. In recent years, studies on human intestinal microbiome have provided many valuable insights into disease development and drug reactions. A lot of studies indicated the potential relationship between microbiome and the vitamin K antagonist. Vitamin K is absorbed by the gut, and the intestinal bacteria are a major source of vitamin K in human body. A combined use of the vitamin K antagonist and antibiotics may result in an increase in INR, thus elevating the risk of bleeding, while vitamin K supplementation can improve stability of anticoagulation for oral vitamin K antagonist treatment. Recently, how intestinal bacteria affect the response of the vitamin K antagonist remains unclear. In this review, we reviewed the research, focusing on the physiology of vitamin K in the anticoagulation treatment, and investigated the potential pathways of intestinal bacteria affecting the reaction of the vitamin K antagonist.

Antioxidant, anti-inflammatory and immunomodulatory roles of vitamins in COVID-19 therapy

oxidative stress is caused by an abundant generation of reactive oxygen species, associated to a diminished capacity of the endogenous systems of the organism to counteract them. Activation of pro-oxidative pathways and boosting of inflammatory cytokines are always encountered in viral infections, including SARS-CoV-2. So, the importance of counteracting cytokine storm in COVID-19 pathology is highly important, to hamper the immunogenic damage of the endothelium and alveolar membranes. Antioxidants prevent oxidative processes, by impeding radical species generation. It has been proved that vitamin intake lowers oxidative stress markers, alleviates cytokine storm and has a potential role in reducing disease severity, by lowering pro-inflammatory cytokines, hampering hyperinflammation and organ failure. For the approached compounds, direct antiviral roles are also discussed in this review, as these activities encompass secretion of antiviral peptides, modulation of angiotensin-converting enzyme 2 receptor expression and interaction with spike protein, inactivation of furin protease, or inhibition of pathogen replication by nucleic acid impairment induction. Vitamin administration results in beneficial effects. Nevertheless, timing, dosage and mutual influences of these micronutrients should be carefullly regarded.

Role of Vitamin K in Intestinal Health

Intestinal diseases, such as inflammatory bowel diseases (IBDs) and colorectal cancer (CRC) generally characterized by clinical symptoms, including malabsorption, intestinal dysfunction, injury, and microbiome imbalance, as well as certain secondary intestinal disease complications, continue to be serious public health problems worldwide. The role of vitamin K (VK) on intestinal health has drawn growing interest in recent years. In addition to its role in blood coagulation and bone health, several investigations continue to explore the role of VK as an emerging novel biological compound with the potential function of improving intestinal health. This study aims to present a thorough review on the bacterial sources, intestinal absorption, uptake of VK, and VK deficiency in patients with intestinal diseases, with emphasis on the effect of VK supplementation on immunity, anti-inflammation, intestinal microbes and its metabolites, antioxidation, and coagulation, and promoting epithelial development. Besides, VK-dependent proteins (VKDPs) are another crucial mechanism for VK to exert a gastroprotection role for their functions of anti-inflammation, immunomodulation, and anti-tumorigenesis. In summary, published studies preliminarily show that VK presents a beneficial effect on intestinal health and may be used as a therapeutic drug to prevent/treat intestinal diseases, but the specific mechanism of VK in intestinal health has yet to be elucidated.

Relationship between Structure and Biological Activity of Various Vitamin K Forms

Vitamin K is involved many biological processes, such as the regulation of blood coagulation, prevention of vascular calcification, bone metabolism and modulation of cell proliferation. Menaquinones (MK) and phylloquinone vary in biological activity, showing different bioavailability, half-life and transport mechanisms. Vitamin K1 and MK-4 remain present in the plasma for 8–24 h, whereas long-chain menaquinones can be detected up to 96 h after administration. Geometric structure is also an important factor that conditions their properties. Cis-phylloquinone shows nearly no biological activity. An equivalent study for menaquinone is not available. The effective dose to decrease uncarboxylated osteocalcin was six times lower for MK-7 than for MK-4. Similarly, MK-7 affected blood coagulation system at dose three to four times lower than vitamin K1. Both vitamin K1 and MK-7 inhibited the decline in bone mineral density, however benefits for the occurrence of cardiovascular diseases have been observed only for long-chain menaquinones. There are currently no guidelines for the recommended doses and forms of vitamin K in the prevention of osteoporosis, atherosclerosis and other cardiovascular disorders. Due to the presence of isomers with unknown biological properties in some dietary supplements, quality and safety of that products may be questioned.

Exogenous Vitamins K Exert Anti-Inflammatory Effects Dissociated from Their Role as Substrates for Synthesis of Endogenous MK-4 in Murine Macrophages Cell Line

Vitamins K exert a range of activities that extend far beyond coagulation and include anti-inflammatory effects, but the mechanisms involved in anti-inflammatory action remain unclear. In the present study, we showed that various forms of exogenous vitamins-K1, K3, K2 (MK-4, MK-5, MK-6 and MK-7)-regulated a wide scope of inflammatory pathways in murine macrophages in vitro, including NOS-2, COX-2, cytokines and MMPs. Moreover, we demonstrated for the first time that macrophages are able to synthesise endogenous MK-4 on their own. Vitamins with shorter isoprenoid chains-K1, K3 and MK-5-exhibited stronger anti-inflammatory potential than vitamins with longer isoprenoid chains (MK-6 and MK-7) and simultaneously were preferably used as a substrate for MK-4 endogenous production. Most interesting, atorvastatin pretreatment inhibited endogenous MK-4 production but had no impact on the anti-inflammatory activity of vitamins K. In summary, our results demonstrate that macrophages are able to synthesise endogenous MK-4 using exogenous vitamins K, and statin inhibits this process. However, the anti-inflammatory effect of exogenous vitamins K was independent of endogenous MK-4 synthesis.

Posttranslational Regulation of HMG CoA Reductase, the Rate-Limiting Enzyme in Synthesis of Cholesterol

The polytopic, endoplasmic reticulum (ER) membrane protein 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase produces mevalonate, the key intermediate in the synthesis of cholesterol and many nonsterol isoprenoids including geranylgeranyl pyrophosphate (GGpp). Transcriptional, translational, and posttranslational feedback mechanisms converge on this reductase to ensure cells maintain a sufficient supply of essential nonsterol isoprenoids but avoid overaccumulation of cholesterol and other sterols. The focus of this review is mechanisms for the posttranslational regulation of HMG CoA reductase, which include sterol-accelerated ubiquitination and ER-associated degradation (ERAD) that is augmented by GGpp. We discuss how GGpp-induced ER-to-Golgi trafficking of the vitamin K₂ synthetic enzyme UbiA prenyltransferase domain-containing protein-1 (UBIAD1) modulates HMG CoA reductase ERAD to balance the synthesis of sterol and nonsterol isoprenoids. We also summarize the characterization of genetically manipulated mice, which established that sterol-accelerated, UBIAD1-modulated ERAD plays a major role in regulation of HMG CoA reductase and cholesterol metabolism in vivo.

Menaquinone Biosynthesis: The Mechanism of 5,8-Dihydroxy-2-naphthoate Synthase (MqnD)

MqnD catalyzes the conversion of cyclic dehypoxanthine futalosine (6) to 5,8-dihydroxy-2-naphthoic acid (7) and an uncharacterized product. This study describes a chemoenzymatic synthesis of 6. This synthesis achieved a 2-fold yield enhancement by using titanium(III) citrate as the reducing agent and another 5-fold yield enhancement using a fluorinated analogue of dehypoxanthine futalosine (5) that was converted to 6 by an ipso substitution mechanism. This synthetic route enabled the synthesis of 6 in sufficient quantity to identify the second reaction product and to determine that the MqnD-catalyzed reaction proceeds by a hemiacetal ring opening-tautomerization-retroaldol sequence.

Vitamin K2 (Menaquinone-7) supplementation does not affect vitamin K-dependent coagulation factors activity in healthy individuals

BACKGROUND

Vitamin K has long been regarded as a procoagulant drug by physicians, and concerns have been raised with regard to its effects on hemostasis. Although many studies have shown that vitamin K supplementation is safe for thrombotic events, the effect of vitamin K supplementation on the activities of vitamin K dependent procoagulation factors in healthy individuals is not available.

OBJECTIVES

This study aimed to investigate whether vitamin K2 supplementation at recommended doses affects the activity of vitamin K dependent procoagulation factors in healthy individuals without any anticoagulation treatment.

DESIGN

Forty healthy volunteers between 25 and 40 years of age were recruited. Menaquinone-7 (MK-7) was administrated at 90 μg for 30 days. Prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), and blood coagulation factors II, VII, IX, and X activities and Protein induced by vitamin K absence or antagonist-II (PIVKA-II) were measured on days 0 and 30 after MK-7 administration.

RESULTS

PT, APTT, and TT showed no significant differences on day 30 when compared with baseline. The activities of coagulation factors II, VII, IX, and X on day 30 showed no significant differences with those at baseline. PIVKA-II levels were unchanged after 30 days of MK-7 supplementation.

CONCLUSIONS

MK-7 supplementation at recommended dosage does not affect vitamin K-dependent coagulation factors' coagulation activity, and does not enhance the carboxylation of prothrombin in healthy individuals. This indicated that MK-7 administration does not alter hemostatic balance in healthy populations without anticoagulation treatment.

Fat-Soluble Vitamins and the Current Global Pandemic of COVID-19: Evidence-Based Efficacy from Literature Review

The outbreak of pneumonia caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), later named COVID-19 by the World Health Organization (WHO), was initiated at Wuhan, Hubei, China, and there was a rapid spread of novel SARS-CoV-2 and the disease COVID-19 in late 2019. The entire world is now experiencing the challenge of COVID-19 infection. However, still very few evidence-based treatment options are available for the prevention and treatment of COVID-19 disease. The present review aims to summarize the publicly available information to give a comprehensive yet balanced scientific overview of all the fat-soluble vitamins concerning their role in SARS-CoV-2 virus infection. The roles of different fat-soluble vitamins and micronutrients in combating SARS-CoV-2 infection have been recently explored in several studies. There are various hypotheses to suggest their use to minimize the severity of COVID-19 infection. These vitamins are pivotal in the maintenance and modulation of innate and cell-mediated, and antibody-mediated immune responses. The data reported in recent literature demonstrate that deficiency in one or more of these vitamins compromises the patients' immune response and makes them more vulnerable to viral infections and perhaps worse disease prognosis. Vitamins A, D, E, and K boost the body's defense mechanism against COVID-19 infection and specifically prevent its complications such as cytokine storm and other inflammatory processes, leading to increased morbidity and mortality overemphasis. However, more detailed randomized double-blind clinical pieces of evidence are required to define the use of these supplements in preventing or reducing the severity of the COVID-19 infection.

Effect of vitamin K2 and vitamin D3 on bone mineral density in children with acute lymphoblastic leukemia: a prospective cohort study

OBJECTIVES

Current treatment protocols in acute lymphoblastic leukemia (ALL) are associated with high remission rates and long life expectancy, enhancing the importance of quality of life and prevention of treatment-related complications in patient care. As osteoporosis is a frequent complication in patients under chemotherapy, we investigated the effect of vitamin K2 (100 mcg menaquinone-7) and vitamin D3 (10 mcg calcitriol) on bone metabolism in children with ALL.

METHODS

Twenty-nine consecutive patients recently diagnosed with B precursor ALL (B-ALL) and treated according to the Turkish Acute Lymphoblastic Leukemia Berlin Frankfurt Münster 2000 protocol were randomly assigned into study and control groups. The study group (n=15, M/F: 8/7, age 1-14.5 years, mean 6.5 years) received vitamin K2 and vitamin D3 with their chemotherapy, while the control group (n=14, M/F 9/5, age 2-17 years, mean 7.1 years) received chemotherapy only. Serum calcium, phosphorus, magnesium, alkaline phosphatase, bone-specific alkaline phosphatase, uncarboxylated osteocalcin (ucOC), tartrate resistant acid phosphatase 5b, carboxyl terminal procollagen propeptide (PICP), osteoprotegerin (OPG), and receptor activator nuclear kappa B ligand (RANKL) were measured and bone mineral density (BMD) was determined at baseline and first, second, third and sixth months.

RESULTS

The study group had higher serum OPG/RANKL ratio and lower ucOC levels compared to the control group at the first month; PICP levels were higher in the study group at second and third months.

CONCLUSIONS

These results suggest an early beneficial effect of the combination of vitamin K2 and vitamin D3 on BMD in ALL patients especially during the period of intensive steroid therapy in the first months.

The effect of vitamin MK-7 on bone mineral density and microarchitecture in postmenopausal women with osteopenia, a 3-year randomized, placebo-controlled clinical trial

We conducted a randomized placebo-controlled double-blinded clinical trial of MK-7 or placebo daily for 3 years in postmenopausal women with osteopenia. BMD decreased at all sites without differences between the MK-7 and placebo-treated women. Changes in bone turnover markers and microstructure were similar between the two groups.

INTRODUCTION

Vitamin K is a cofactor in the carboxylation of osteocalcin (OC) and carboxylated OC promotes mineralization of bone. Clinical studies suggest that vitamin K2 prevents bone loss. The aim of the study was to investigate the effect of vitamin K2 as an add-on to calcium and vitamin D supplementation on osteocalcin, bone mass, and microarchitecture in postmenopausal women.

METHODS

We conducted a randomized placebo-controlled double-blinded clinical trial, including 142 postmenopausal women with osteopenia who received vitamin K2 (375 μg MK-7) or placebo daily for 3 years. Both groups received vitamin D3 (38 μg/day) and calcium (800 mg/day). We measured bone turnover markers in serum and bone mineral density and microarchitecture by DXA and HRpQCT.

RESULTS

Undercarboxylated osteocalcin decreased in the MK-7-group (- 65.2 ± 23.5%) (mean ± SD) compared with the placebo group (- 0.03 ± 38.5%), p < 0.01 after 1 year. After 3 years, aBMD decreased at all sites without differences between the MK-7 and placebo-treated women (p > 0.09). aBMD decreased at the total hip by 1.5 ± 2.5% and 2.4 ± 2.7% in the MK-7 and the placebo groups, respectively, at the femoral neck by 1.5 ± 3.5% and 1.0 ± 5.0% in the MK-7 and the placebo groups, respectively, and at the lumbar spine by 1.8 ± 3.9% and 1.1 ± 3.1% in the MK-7 and the placebo groups, respectively. Changes in bone turnover markers were also similar between the two groups.We have previously reported improved microarchitecture with MK-7 after 1 year. However, changes in microstructure over 3 years were similar between the two groups, as assessed by both HRpQCT and DXA trabecular bone score.

CONCLUSION

Treatment with MK-7 375 μg daily as an add-on to calcium and vitamin D increased carboxylation of osteocalcin. However, treatment of postmenopausal women with osteopenia for 3 years did not affect biochemical markers of bone turnover, bone mineral density, or bone microarchitecture.

TRIAL REGISTRATION

The study was registered at Clinicaltrial.gov : NCT01922804 .

Disruption of Abcc6 Transporter in Zebrafish Causes Ocular Calcification and Cardiac Fibrosis

Pseudoxanthoma elasticum (PXE), caused by ABCC6/MRP6 mutation, is a heritable multisystem disorder in humans. The progressive clinical manifestations of PXE are accompanied by ectopic mineralization in various connective tissues. However, the pathomechanisms underlying the PXE multisystem disorder remains obscure, and effective treatment is currently available. In this study, we generated zebrafish abcc6a mutants using the transcription activator-like effector nuclease (TALEN) technique. In young adult zebrafish, abcc6a is expressed in the eyes, heart, intestine, and other tissues. abcc6a mutants exhibit extensive calcification in the ocular sclera and Bruch's membrane, recapitulating part of the PXE manifestations. Mutations in abcc6a upregulate extracellular matrix (ECM) genes, leading to fibrotic heart with reduced cardiomyocyte number. We found that abcc6a mutation reduced levels of both vitamin K and pyrophosphate (PPi) in the serum and diverse tissues. Vitamin K administration increased the gamma-glutamyl carboxylated form of matrix gla protein (cMGP), alleviating ectopic calcification and fibrosis in vertebrae, eyes, and hearts. Our findings contribute to a comprehensive understanding of PXE pathophysiology from zebrafish models.

Effects of Vitamin Forms and Levels on Vitamin Bioavailability and Growth Performance in Piglets

The objective of this study was to quantify the relative bioavailability of microencapsulated vitamins A and E in nursery pigs and compare the effects of vitamin forms and vitamin levels on the plasma vitamin content and growth performance of weaned piglets. In experiment (Exp.) 1, 12 nursery pigs (fitted with jugular catheters) were supplied at 0 h with non-microencapsulated or microencapsulated vitamin A and E. Blood samples were collected at 1, 3, 6, 9, 12, 16, 18, 21, 24, 27, 30, 36, 48, and 72 h after feeding to compare the bioavailability of oral vitamins A and E. In Exp. 2, a total of 216 crossbred weaned piglets were assigned to six treatments. This experiment was a 2 × 3 factorial arrangement, with two factors for vitamin forms (non-microencapsulated and microencapsulated) and three factors for vitamin levels (the National Research Council level of vitamins, 75% commercial recommendations of vitamins (CRV) level, and a 100% CVR level). In Exp. 1, the relative bioavailability of microencapsulated vitamin E was significantly greater than that of non-microencapsulated vitamin E. In Exp. 2, the pigs fed diets containing 75% or 100% CRV levels of vitamins increased their growth performance and plasma vitamin concentrations compared to the control group. In conclusion, microencapsulation can improve the bioavailability of vitamins, and supplementation with high levels of vitamins was able to improve the growth performance of the piglets.

Quantification of fat-soluble vitamins and their metabolites in biological matrices: an updated review

Fat-soluble vitamins (FSVs) are micronutrients essential in maintaining normal physiological function, metabolism and human growth. Ongoing increased awareness regarding FSV concentrations and their impact on human growth along with disease progression warrant the need of developing selective and sensitive analytical methods. LC–MS/MS is currently the method of choice for accurate quantitation of FSVs. However, there are multiple approaches for extraction, separation and calibration of FSVs in biological matrices. This review discusses recent LC–MS/MS methods for the simultaneous quantification of FSVs in biological matrices and summarizes sample pretreatment procedures, chromatographic conditions and calibration approaches. Current challenges and clinical applications in various disease states are also highlighted.

Effect of Low-Dose Vitamin K2 Supplementation on Bone Mineral Density in Middle-Aged and Elderly Chinese: A Randomized Controlled Study

Previous studies indicated a positive effect of vitamin K2 (VK2) supplementation on bone turnover biomarkers and bone mineral density (BMD), but the doses varied, and few studies have focused on the difference between VK2 supplementation alone and in combination with calcium and vitamin D₃. The aim of this study was to explore a low and effective dose of VK2 for improving BMD, and to examine whether the co-supplementation of VK2, calcium and vitamin D₃ would bring greater effects. In this trial, a total of 311 community-dwelling men and postmenopausal women aged 50 and 75 years were randomly assigned to four groups, receiving placebo, 50 µg/day, 90 µg/day or co-supplementation with calcium (500 mg/day) and vitamin D₃ (10 µg/day) for 1 year. At the endpoint, the bone loss of femoral neck was significantly lower in postmenopausal women in the two 90 µg groups (treatment × time, p = 0.006) compared with placebo, but no effects in men. Serum biomarkers cOC/ucOC ratio increased in the intervention groups (treatment × time, p < 0.001). VK2 supplementation in dose of 90 µg/day performed a significant effect on reducing bone loss in postmenopausal women, but in combination with calcium and vitamin D₃ brought no additional effects.Trial registration This trial was registered at http://www.chictr.org.cn as chiCTR1800019240.

The effects of vitamin K-rich green leafy vegetables on bone metabolism: A 4-week randomised controlled trial in middle-aged and older individuals

Background

High vegetable intake is associated with beneficial effects on bone. However, the mechanisms remain uncertain. Green leafy vegetables are a rich source of vitamin K1, which is known to have large effects on osteoblasts and osteocalcin (OC) metabolism.

Objective

To examine the effects of consumption of two to three extra serves of green leafy vegetables daily on bone metabolism.

Methods

Thirty individuals (mean age 61.8 ± 9.9 years, 67% male) completed three experimental phases in a randomised controlled crossover design, each lasting four weeks, with a washout period of four weeks between phases (clinical trial registration: ACTRN12615000194561). The three experimental phases were: (i) increased dietary vitamin K1 by consuming green leafy vegetables (H-K; ~200 g/d containing 164.3 [99.5-384.7] μg/d of vitamin K1); (ii) low vitamin K1 by consuming vitamin K1-poor vegetables (L-K; ~200 g/d containing 9.4 [7.7-11.6] μg/d of vitamin K1); and (iii) control (CON) where participants consumed an energy-matched non-vegetable control. OC forms, total OC (tOC), carboxylated OC (cOC) and undercarboxylated OC (ucOC), were measured in serum pre- and post-intervention for each experimental phase using a sandwich-electrochemiluminescence immunoassay.

Results

Pre-intervention tOC, ucOC and ucOC:tOC levels were similar between phases (P > .05). Following H-K, but not L-K, tOC, ucOC and ucOC:tOC levels were significantly lower compared to pre-intervention levels (P ≤ .001) and compared to CON (~14%, 31% and 19%, respectively, all P < .05), while cOC remained unchanged.

Conclusions

In middle-aged healthy men and women, an easily achieved increase in dietary intake of vitamin K1-rich green leafy vegetables substantially reduces serum tOC and ucOC suggesting increased entry of OC into bone matrix, where it may improve the material property of bone. In conjunction with previous epidemiological and randomised controlled trial data, these findings suggest that interventions to increase vegetable intake over extended periods should include bone end points including fracture risk.

Epigenome-wide association study reveals a molecular signature of response to phylloquinone (vitamin K1) supplementation

Evidence suggests there are roles for vitamin K in various chronic disease outcomes, but population-level diet and supplement recommendations are difficult to determine due to high levels of variability in measures of status and response to intake compared to other nutrients. In this preliminary investigation, a blood-based epigenome-wide association study (EWAS) comparing responders and non-responders to phylloquinone (vitamin K1) supplementation (NCT00183001) was undertaken in order to better understand the molecular underpinnings of this observed variability. Responders (n = 24) and non-responders (n = 24) were identified in a prior 3-year phylloquinone supplementation trial based on their changes in plasma phylloquinone concentrations. Differential DNA methylation was identified in multiple regions with previously unknown relationships to phylloquinone absorption and metabolism, such as at the TMEM263 locus. A hypothesis-driven analysis of lipid-related genes highlighted a site in the NPC1L1 gene, supplementing existing evidence for its role in phylloquinone absorption. Furthermore, an EWAS for baseline plasma phylloquinone concentrations revealed a strong correlation between the epigenomic signatures of phylloquinone baseline status and response to supplementation. This work can guide future epigenomic research on vitamin K and contributes to the development of more personalized dietary recommendations for vitamin K.

Enhanced ER-associated degradation of HMG CoA reductase causes embryonic lethality associated with Ubiad1 deficiency

UbiA prenyltransferase domain-containing protein-1 (UBIAD1) synthesizes the vitamin K subtype menaquinone-4 (MK-4). Previous studies in cultured cells (Schumacher et al., 2015) revealed that UBIAD1 also inhibits endoplasmic reticulum (ER)-associated degradation (ERAD) of ubiquitinated HMG CoA reductase (HMGCR), the rate-limiting enzyme of the mevalonate pathway that produces cholesterol and essential nonsterol isoprenoids. Gene knockout studies were previously attempted to explore the function of UBIAD1 in mice; however, homozygous germ-line elimination of the Ubiad1 gene caused embryonic lethality. We now report that homozygous deletion of Ubiad1 is produced in knockin mice expressing ubiquitination/ERAD-resistant HMGCR. Thus, embryonic lethality of Ubiad1 deficiency results from depletion of mevalonate-derived products owing to enhanced ERAD of HMGCR rather than from reduced synthesis of MK-4. These findings provide genetic evidence for the significance of UBIAD1 in regulation of cholesterol synthesis and offer the opportunity in future studies for the discovery of new physiological roles of MK-4.

Serum vitamin K1 associated to microangiopathy and/or macroangiopathy in individuals with and without diabetes

OBJECTIVE

Vitamin K has proposed beneficial effects on cardiovascular health. We investigated whether serum vitamin K₁ was associated with prevalence of microangiopathy and/or macroangiopathy.

RESEARCH DESIGN AND METHODS

Serum vitamin K was quantified in 3239 individuals with and 3808 without diabetes enrolled in Vejle Diabetes Biobank (2007-2010). Each individual was assessed for microangiography and macroangiopathy at enrollment based on registered diagnoses in the Danish National Patient Registry according to the International Classification of Disease 8 (1977-1993) and 10 (since 1994). Using multinomial logistic regression, relative risk ratios (RRRs) were calculated within each group of individuals with and without diabetes. RRRs were estimated for microangiopathic/macroangiopathic status compared with individuals without complications as a function of 1 nmol/L increments in K₁. Adjustment for potential confounders was also performed.

RESULTS

Vitamin K₁ (median) varied 0.86-0.95 nmol/L depending on diabetes, microangiopathic and macroangiopathic status. In individuals with diabetes, the crude RRR for only having microangiopathy was 1.05 (95% CI 0.98 to 1.12) and was found significant when adjusting 1.10 (95% CI 1.01 to 1.19). RRR for having only macroangiopathy was 0.89 (95% CI 0.77 to 1.03) and was again significant when adjusting 0.79 (95% CI 0.66 to 0.96). In individuals without diabetes, adjustments again led to similar estimates that was not significant. The adjusted RRR for having only macroangiopathy was 1.08 (95% CI 0.98 to 1.19).

CONCLUSIONS

Serum vitamin K₁ levels were associated with microangiopathic and macroangiopathic status in individuals with diabetes, but considered of no clinical relevance. The clinical value of other candidate markers for vitamin K status needs to be evaluated in future studies.

A comprehensive mechanistic review insight into the effects of micronutrients on toll-like receptors functions

Toll-like receptors (TLRs) are the special proteins receptors for recognition of molecules related to the pathogens. In this way, TLRs and secreted cytokines as a result of TLRs activation are involved in the inflammation pathways. So far, in vivo and in vitro studies have demonstrated that micronutrients (vitamins & minerals) with a broad range of effects on body health, can regulate TLRs signaling pathways. Current review aimed at determining the possible mechanisms of micronutrient effects on TLRs functions. In the aspect of gene expression, micronutrients have inconsistent effects on mRNA level of TLRs which are dependent on time, dose and type of studied TLR. Also, some micronutrients affect gene expression of TLRs signaling mediators namely TLRs adaptors like Myeloid differentiation primary response 88 (MyD88). In the aspect of TLRs signaling pathways, nuclear factor-κB (NF-κB) is an important mediator which is regulated by micronutrients. Also, the regulatory effects of micronutrients on phosphorylation reactions may be effective in the activation/inactivation of TLRs signaling mediators. In addition, zinc can regulate TLRs signaling indirectly via the zinc finger proteins which have contradictory effects on TLRs cascade. In conclusion, the relationship between micronutrients and TLRs signaling is complicated and depends on some known internal, external and genetic factors like form of studied micronutrient, cell type, TLR agonist, dose and time of exposure, inflammation, apoptosis, cell cycle, and environmental factors. Some unknown factors may be effective in TLRs response and as a result additional mechanistic studies are needed to elucidate exact effect of micronutrients on TLRs signaling.

Vitamin K2-MK-7 improves nitric oxide-dependent endothelial function in ApoE/LDLR-/- mice

Although, vitamin K₂ displays vasoprotective effects, it is still not known whether K₂ treatment improves endothelial function. In ApoE/LDLR^-/- mice at the stage prior to atherosclerosis development, four-week treatment with K₂-MK-7, given at a low dose (0.05 mg/kg), improved acetylcholine- and flow-induced, endothelium-dependent vasodilation in aorta or in femoral artery, as assessed by MRI in vivo. This effect was associated with an increased NO production, as evidenced by EPR measurements in ex vivo aorta. Treatment with higher doses of K₂-MK-7 (0.5; 5 mg/kg) resulted in a dose-dependent increase in plasma K₂-MK-7 and K₂-MK-4 concentration, without further improvement in endothelial function. In ApoE/LDLR^-/- mice with developed atherosclerotic plaques, treatment with a low (0.03 mg/kg) or high (10 mg/kg) dose of K₂-MK-7 resulted in a similar degree of endothelium-dependent vasodilation improvement and increase in plasma nitrate concentration, what was not associated with changes in thrombin generation as measured by CAT. Both doses of K₂-MK-7 also reduced media thickness in the brachiocephalic artery, but did not modify atherosclerotic plaque size. In conclusion, K₂-MK-7 improves NO-dependent endothelial function in ApoE/LDLR^-/- mice. This study, identifies the endothelial profile of the pharmacological activity of vitamin K₂, which has not been previously described.

Effect of vitamin K on bone mineral density and fractures in adults: an updated systematic review and meta-analysis of randomised controlled trials

Vitamin K may affect bone mineral density and fracture incidence. Since publication of a previous systematic review the integrity of some of the previous evidence has been questioned and further trials have been published. Therefore an update to the systematic review was required.

INTRODUCTION

This systematic review was designed to assess the effectiveness of oral vitamin K supplementation for increasing bone mineral density and reducing fractures in adults.

METHODS

MEDLINE, EMBASE, CENTRAL, CINAHL, clinicaltrials.gov, and WHO-ICTRP were searched for eligible trials. Randomised controlled trials assessing oral vitamin K supplementation that assessed bone mineral density or fractures in adult populations were included. A total of 36 studies were identified. Two independent reviewers extracted data using a piloted extraction form.

RESULTS

For post-menopausal or osteoporotic patients, meta-analysis showed that the odds of any clinical fracture were lower for vitamin K compared to controls (OR, 0.72, 95%CI 0.55 to 0.95). Restricting the analysis to low risk of bias trials reduced the OR to 0.76 (95%CI, 0.58 to 1.01). There was no difference in vertebral fractures between the groups (OR 0.96, 95%CI 0.83 to 1.11). In the bone mineral density meta-analysis, percentage change from baseline at the lumbar spine was higher at 1 year (MD 0.93, 95%, CI - 0.02 to 1.89) and 2 years (MD 1.63%, 95%CI 0.10 to 3.16) for vitamin K compared to controls; however, removing trials at high risk of bias tended to result in smaller differences that were not statistically significant. At 6 months, it was higher in the hip (MD 0.42%, 95%CI 0.01 to 0.83) and femur (MD 0.29%, 95%CI 0.17 to 0.42). There was no significant difference at other anatomical sites.

CONCLUSIONS

For post-menopausal or osteoporotic patients, there is no evidence that vitamin K affects bone mineral density or vertebral fractures; it may reduce clinical fractures; however, the evidence is insufficient to confirm this. There are too few trials to draw conclusions for other patient groups.

Quantitation of vitamin K1 in serum using online SPE-LC-MS/MS and the challenges of working with vitamin K

Vitamin K1 (phylloquinone) is one of the vitamin Ks. Several studies have previously investigated the role of vitamin K1 status in respect to disease, but without consistent results. Since vitamin K deficiency has been associated with different disease states it is important to develop a biochemical analysis with sufficient sensitivity and a low limit of quantitation (LOQ). The vitamin Ks are very fat-soluble. This non-polar nature has given rise to several challenges during the method development, because vitamin K1 sticks to materials used during the process and is lost during evaporation. We found that reducing the sample preparation as much as possible offline, instead using online SPE-LC-MS/MS improves recovery and gives satisfactory chromatograms. An Protein BEH C4 column, 300 Å (50 × 2.1 mm, 1.7 μm particle size) was used as trap column and a Phenyl-Hexyl-LC-column, 100 Å (100 × 2.1 mm, 2.6 μm particle size) was used as analytical column. The mobile phases consisted of 30 μmol/L NH₄F in water and 30 μmol/L NH₄F in MeOH. A triple quadrupole tandem mass spectrometer with atmospheric pressure chemical ionization (APCI) ion source, positive ion mode, was used to perform the mass spectrometric measurements. The method is simple, highly sensitive and fast. The method was validated for vitamin K1 with good analytical performance. With a LOQ of 0.05 nmol/L it is to our knowledge the vitamin K1 method with lowest LOQ reported to date in the literature. It can easily be automated and applied in a routine diagnostic laboratory. Blood collection tubes with different additives were tested and showed no difference. Stability of vitamin K1 in serum was tested at different temperatures (-20 °C, 4 °C and in light and dark at 20 °C over a period of 30 days) and showed that vitamin K1 is light sensitive in serum even after only one day.

A concise review of quantification methods for determination of vitamin K in various biological matrices

Vitamin K is an essential nutrient in the body and involved in numerous physiological and pathophysiological functions. Both the lack and surplus of vitamin K can put human health at risk. Therefore, it becomes necessary to monitor vitamin K concentrations in different biomatrices through establishing sensitive and specific analytical methods. This review collectively describes an updated overview of the sample pretreatment methodologies and methods for quantitative determination of vitamin K that have been used in last two decades. High Performance Liquid Chromatography (HPLC) is commonly utilized as a standard for separation of vitamin K in combination with different detection including spectroscopic, spectrometric, fluorometric and mass spectroscopy. Recent progress in sample pretreatment technologies and quantitation methodologies have enhanced the ability to identify and quantitate vitamin K in biomatrices to further advance our understanding of the role of this vitamin in human health and disease.

Vitamin K intake and prostate cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial

Background

Vitamin K inhibits prostate cancer cells, and an altered expression of vitamin K-dependent proteins in prostate tumors has been linked to their aggressiveness and progression. However, little is known about the effect of vitamin K intake on prostate cancer in human populations.

Objectives

We evaluated the associations of dietary intake of phylloquinone (vitamin K-1), menaquinones (vitamin K-2), and total vitamin K with the development of prostate cancer among participants in the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial.

Design

Dietary intake of vitamin K was assessed with the Dietary Questionnaire (DQX) at baseline and the Dietary History Questionnaire (DHQ) at the third anniversary of randomization by using high-performance liquid chromatography-based food-composition data obtained from the USDA and published studies. During a median follow-up of 11.8 y, 2978 cases of prostate cancer (including 490 advanced cases) were identified from the 28,356 men who completed DQX. Similarly, 2973 cases of prostate cancer (including 647 advanced cases) were documented from the 48,090 men who completed DHQ. Cox proportional hazards regression was used to estimate prostate cancer risk in relation to the dietary intake of vitamin K.

Results

After adjustment for confounders, dietary intakes of phylloquinone, menaquinones, and total vitamin K, assessed with either the DQX or DHQ, were not significantly associated with the risk of advanced, nonadvanced, and total prostate cancer. These results remained virtually the same when vitamin K intake was modeled as a categorical (divided into quintiles) or continuous (per IQR increase) variable or after outliers of total vitamin K intake (defined as a value that falls above the sum of third quartile and twice the IQR) were excluded.

Conclusions

The present study does not suggest that vitamin K intake influences the occurrence of total and advanced prostate cancer in the general US population.

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.

Reuniting overnutrition and undernutrition, macronutrients, and micronutrients

Over-nutrition and its late consequences are a dominant theme in medicine today. In addition to the health hazards brought on by over-nutrition, the medical community has recently accumulated a roster of health benefits with obesity, grouped under "obesity paradox." Throughout the world and throughout history until the 20^th century, under-nutrition was a dominant evolutionary force. Under-nutrition brings with it a mix of benefits and detriments that are opposite to and continuous with those of over-nutrition. This continuum yields J-shaped or U-shaped curves relating body mass index to mortality. The overweight have an elevated risk of dying in middle age of degenerative diseases while the underweight are at increased risk of premature death from infectious conditions. Micronutrient deficiencies, major concerns of nutritional science in the 20^th century, are being neglected. This "hidden hunger" is now surprisingly prevalent in all weight groups, even among the overweight. Because micronutrient replacement is safe, inexpensive, and predictably effective, it is now an exceptionally attractive target for therapy across the spectrum of weight and age. Nutrition-related conditions worthy of special attention from caregivers include excess vitamin A, excess vitamin D, and deficiency of magnesium.

In silico model-guided identification of transcriptional regulator targets for efficient strain design

BACKGROUND

Cellular metabolism is tightly regulated by hard-wired multiple layers of biological processes to achieve robust and homeostatic states given the limited resources. As a result, even the most intuitive enzyme-centric metabolic engineering endeavours through the up-/down-regulation of multiple genes in biochemical pathways often deliver insignificant improvements in the product yield. In this regard, targeted engineering of transcriptional regulators (TRs) that control several metabolic functions in modular patterns is an interesting strategy. However, only a handful of in silico model-added techniques are available for identifying the TR manipulation candidates, thus limiting its strain design application.

RESULTS

We developed hierarchical-Beneficial Regulatory Targeting (h-BeReTa) which employs a genome-scale metabolic model and transcriptional regulatory network (TRN) to identify the relevant TR targets suitable for strain improvement. We then applied this method to industrially relevant metabolites and cell factory hosts, Escherichia coli and Corynebacterium glutamicum. h-BeReTa suggested several promising TR targets, many of which have been validated through literature evidences. h-BeReTa considers the hierarchy of TRs in the TRN and also accounts for alternative metabolic pathways which may divert flux away from the product while identifying suitable metabolic fluxes, thereby performing superior in terms of global TR target identification.

CONCLUSIONS

In silico model-guided strain design framework, h-BeReTa, was presented for identifying transcriptional regulator targets. Its efficacy and applicability to microbial cell factories were successfully demonstrated via case studies involving two cell factory hosts, as such suggesting several intuitive targets for overproducing various value-added compounds.

A simple, sensitive, and high-throughput LC-APCI-MS/MS method for simultaneous determination of vitamin K1, vitamin K1 2,3-epoxide in human plasma and its application to a clinical pharmacodynamic study of warfarin

Warfarin exerts its anticoagulation activity by blocking the vitamin K-epoxide cycle. A quantitative understanding of how warfarin and related genes interact with the vitamin K-epoxide cycle and the associated change of coagulation activity in the human body may help study the pharmacodynamics of warfarin. The plasma concentration of vitamin K₁ (VK₁) and vitamin K₁ 2,3-epoxide (VK₁O) could reflect the status of vitamin K-epoxide cycle. However, their determination is a challenging task due to their extremely low concentrations in human plasma and the severe interferences caused by co-extracted lipids. In this study, we developed an LC-APCI-MS/MS method for the simultaneous determination of VK₁ and VK₁O in human plasma using stable deuterium-labeled vitamin K₁ (vitamin K₁-d7) as the internal standard (IS). Plasma samples were prepared through protein denaturation followed by one-step liquid extraction with cyclohexane. Chromatographic separation of analytes from isobaric interferences and endogenous ion suppressor was performed on a Synergi Hydro-RP column (150 mm × 4.6 mm, 4 μm) under the reversed-phase condition with isocratic elution. The selective reaction monitoring (SRM) transitions were chosen as m/z = 451.5→187.3 for VK₁, m/z = 467.5→161.2 for VK₁O, and m/z = 458.6→194.3 for IS in APCI positive mode. The assay was linear in the range of 100-10,000 pg/mL for the two analytes and achieved considerable extraction recoveries (87.8-93.3%, 91.0-96.9%, and 92.0% for VK₁, VK₁O, and IS, respectively), negligible matrix effects (93.6-96.0%, 96.3-100.1%, and 95.5%), and high selectivity with a small sample volume requirement (0.2 mL) and short run time (15 min). The validated method was successfully applied in a clinical pharmacodynamic study of warfarin, and the clotting activity was found to be negatively correlated with the plasma concentration ratio of VK₁O to VK₁.