An L-shaped relationship between dietary vitamin K and atherosclerotic cardiovascular disease

BACKGROUND AND AIMS

Few studies link vitamin K intake with incident atherosclerotic cardiovascular disease (ASCVD), and the specific mechanism remains uncertain. We aimed to evaluate the relationship between dietary vitamin K and ASCVD.

METHODS

This study used cross-sectional data from people over 20 years old who took part in the National Health and Nutrition Examination Survey (NHANES) between 2013 and 2018. Vitamin K intake was assessed using a 24-h dietary review. The Patient Medical Conditions Questionnaire was used to assess ASCVD. The stability of the outcomes was evaluated using cubic spline models with restricted parameters and logistic regression, while subgroup analyses were also performed.

RESULTS

There were 14,465 participants, with 9.78% (1415/14,465) who diagnosed with ASCVD. Compared with individuals with lower vitamin K intake Q1 (≤39.0 ug/day), the adjusted OR values for dietary vitamin K intake and ASCVD in Q2 (39.1-70.8 ug/day), Q3 (70.9-131.0 mg/day), and Q4 (≥131.1 ug/day) were 0.88 (95% CI: 0.74-1.04, p = 0.134), 0.77(95% CI: 0.65-0.93, p = 0.005), and 0.78 (95% CI: 0.65-0.95, p = 0.013), respectively. The association between dietary vitamin K intake and ASCVD showed an L-shaped curve (nonlinear, p = 0.006). The OR for ASCVD in participants with vitamin K intake <127.1ug/day was 0.996 (95% CI: 0.993-0.998, p = 0.002).

CONCLUSIONS

The relationship between dietary vitamin K intake and ASCVD was L-shaped curve in US adults, the inflection point was roughly 127.1 ug/day.

Mediterranean Diet Favors Vitamin K Intake: A Descriptive Study in a Mediterranean Population

The Mediterranean diet (MD) is associated with improved longevity and the prevention and management of chronic inflammatory diseases (CIDs). Vitamin K, which is present in MD core components such as leafy green vegetables, is also known as a protective factor for CIDs. Estimates of vitamin K intake in Mediterranean settings are still scarce, and the association between MD and vitamin K intake is yet to be established. This study analyzed vitamin K intake and MD adherence in the Algarve region, in Portugal. We conducted a cross-sectional study in a nonrandom sample of adults using an online questionnaire which included a validated food-frequency questionnaire and a screener for MD adherence. A total of 238 participants were recruited (68% women and 32% men). Adherence to the MD was low (11%). Only 10% of the participants had vitamin K intake below the adequate intake. Adherence to the MD was positively correlated with vitamin K intake (r = 0.463; p < 0.001) and age (r = 0.223; p < 0.001). Our findings underscore the importance of promoting adherence to the MD for optimal vitamin K intake, and future research should focus on developing effective interventions to promote this dietary pattern, particularly among younger individuals and men.

Biological Role of Vitamin K-With Particular Emphasis on Cardiovascular and Renal Aspects

Vitamin K (VK) plays many important functions in the body. The most important of them include the contribution in calcium homeostasis and anticoagulation. Vascular calcification (VC) is one of the most important mechanisms of renal pathology. The most potent inhibitor of this process-matrix Gla protein (MGP) is VK-dependent. Chronic kidney disease (CKD) patients, both non-dialysed and hemodialysed, often have VK deficiency. Elevated uncarboxylated matrix Gla protein (ucMGP) levels indirectly reflected VK deficiency and are associated with a higher risk of cardiovascular events in these patients. It has been suggested that VK intake may reduce the VC and related cardiovascular risk. Vitamin K intake has been suggested to reduce VC and the associated cardiovascular risk. The role and possibility of VK supplementation as well as the impact of anticoagulation therapy on VK deficiency in CKD patients is discussed.

Fetal intracranial hemorrhage and maternal vitamin K deficiency induced by total parenteral nutrition: A case report

RATIONALE

Fetal brain hemorrhage is rare. It is caused mainly by maternal trauma or fetal coagulation disorder, but in some cases, vitamin K deficiency may be the cause.

PATIENT CONCERNS

We describe the case of a pregnant woman with bowel obstruction who was susceptible to vitamin K deficiency due to oral diet restriction, decreased intestinal absorption, and limited intravenous vitamin K supplementation.

DIAGNOSIS

After 18 days of intermittent total parenteral nutrition, acute onset of severe fetal brain hemorrhage developed.

INTERVENTIONS

After acute onset of fetal brain hemorrhage, the patient underwent an emergency cesarean section at 25 + 3 weeks of gestation due to fetal non-reassuring fetal monitoring.

OUTCOMES

The Apgar score at birth was 0/0, and despite cardiopulmonary resuscitation, neonatal death was confirmed. After the baby was delivered, we checked the maternal upper abdominal cavity and found a massive adhesion in the small bowel to the abdominal wall near the liver and stomach with an adhesion band. The adhesion band, presumably a complication of previous hepatobiliary surgery, appeared to have caused small bowel obstruction. Adhesiolysis between the small bowel and abdominal wall was performed.

LESSONS

This case demonstrates that even relatively short-term total parenteral nutrition can cause severe fetal brain hemorrhage. Vitamin K supplementation is required for mothers who are expected to be vitamin K deficient, especially if they are on total parenteral nutrition for more than 3 weeks.

Belgian Consensus Recommendations to Prevent Vitamin K Deficiency Bleeding in the Term and Preterm Infant

Neonatal vitamin K prophylaxis is essential to prevent vitamin K deficiency bleeding (VKDB) with a clear benefit compared to placebo. Various routes (intramuscular (IM), oral, intravenous (IV)) and dosing regimens were explored. A literature review was conducted to compare vitamin K regimens on VKDB incidence. Simultaneously, information on practices was collected from Belgian pediatric and neonatal departments. Based on the review and these practices, a consensus was developed and voted on by all co-authors and heads of pediatric departments. Today, practices vary. In line with literature, the advised prophylactic regimen is 1 or 2 mg IM vitamin K once at birth. In the case of parental refusal, healthcare providers should inform parents of the slightly inferior alternative (2 mg oral vitamin K at birth, followed by 1 or 2 mg oral weekly for 3 months when breastfed). We recommend 1 mg IM in preterm <32 weeks, and the same alternative in the case of parental refusal. When IM is perceived impossible in preterm <32 weeks, 0.5 mg IV once is recommended, with a single additional IM 1 mg dose when IV lipids are discontinued. This recommendation is a step towards harmonizing vitamin K prophylaxis in all newborns.

Association between vitamin K1 intake and mortality in the Danish Diet, Cancer, and Health cohort

Reported associations between vitamin K₁ and both all-cause and cause-specific mortality are conflicting. The 56,048 participants from the Danish Diet, Cancer, and Health prospective cohort study, with a median [IQR] age of 56 [52–60] years at entry and of whom 47.6% male, were followed for 23 years, with 14,083 reported deaths. Of these, 5015 deaths were CVD-related, and 6342 deaths were cancer-related. Intake of vitamin K₁ (phylloquinone) was estimated from a food-frequency questionnaire (FFQ), and its relationship with mortality outcomes was investigated using Cox proportional hazards models. A moderate to high (87–192 µg/d) intake of vitamin K₁ was associated with a lower risk of all-cause [HR (95%CI) for quintile 5 vs quintile 1: 0.76 (0.72, 0.79)], cardiovascular disease (CVD)-related [quintile 5 vs quintile 1: 0.72 (0.66, 0.79)], and cancer-related mortality [quintile 5 vs quintile 1: 0.80 (0.75, 0.86)], after adjusting for demographic and lifestyle confounders. The association between vitamin K₁ intake and cardiovascular disease-related mortality was present in all subpopulations (categorised according to sex, smoking status, diabetes status, and hypertension status), while the association with cancer-related mortality was only present in current/former smokers (p for interaction = 0.002). These findings suggest that promoting adequate intakes of foods rich in vitamin K₁ may help to reduce all-cause, CVD-related, and cancer-related mortality at the population level.

Dual therapy with an oral non-vitamin K antagonist and a P2Y12 inhibitor vs triple therapy with aspirin, a P2Y12 inhibitor and a vitamin K antagonist for the treatment of diabetes mellitus patients with co-existing atrial fibrillation following percutaneous coronary intervention: A meta-analysis

BACKGROUND

In this analysis, we aimed to compare the efficacy and safety of dual therapy (DT) with a non-vitamin K oral anticoagulant (NOAC) and an adenosine diphosphate receptor antagonist (P2Y12 inhibitor) vs triple therapy (TT) with aspirin, a P2Y12 inhibitor and a vitamin K antagonist for the treatment of diabetes mellitus (DM) patients with co-existing atrial fibrillation (AF) following percutaneous coronary intervention (PCI).

METHODS

Medical Literature Analysis and Retrieval System Online (MEDLINE), http://www.ClinicalTrials.gov, Excerpta Medical data BASE (EMBASE), Web of Science, Cochrane Central and Google Scholar were the searched databases. Studies that were randomized trials or observational studies comparing DT vs TT for the treatment of DM patients with co-existing AF following PCI were included in this analysis. The adverse cardiovascular outcomes and bleeding events were the endpoints. This meta-analysis was carried out by the RevMan version 5.4 software. Risk ratios (RR) with 95% confidence intervals (CI) were used to represent data and interpret the analysis.

RESULTS

A total number of 4970 participants were included whereby 2456 participants were assigned to the DT group and 2514 participants were assigned to the TT group. The enrollment period varied from year 2006 to year 2018. Our current results showed that major adverse cardiac events (RR: 1.00, 95% CI: 0.84-1.20; P = .98), mortality (RR: 1.08, 95% CI: 0.78-1.48; P = .66), myocardial infarction (RR: 1.02, 95% CI: 0.74-1.42; P = .90), stroke (RR: 0.94, 95% CI: 0.53-1.67; P = .84) and stent thrombosis (RR: 1.09, 95% CI: 0.56-2.10; P = .80) were similar with DT versus TT in these patients. However, the risks for total major bleeding (RR: 0.66, 95% CI: 0.54-0.82; P = .0001), total minor bleeding (RR: 0.74, 95% CI: 0.64-0.85; P = .0001), Thrombolysis in Myocardial Infarction (TIMI) defined major bleeding (RR: 0.58, 95% CI: 0.35-0.95; P = .03), TIMI defined minor bleeding (RR: 0.62, 95% CI: 0.42-0.92; P = .02), intra-cranial bleeding (RR: 0.34, 95% CI: 0.13-0.95; P = .04) and major bleeding defined by the International Society on Thrombosis and Hemostasis (RR: 0.68, 95% CI: 0.51-0.90; P = .008) were significantly higher with TT.

CONCLUSIONS

DT with a NOAC and a P2Y12 inhibitor was associated with significantly less bleeding events without increasing the adverse cardiovascular outcomes when compared to TT with aspirin, a P2Y12 inhibitor and a Vitamin K antagonist for the treatment of DM patients with co-existing AF following PCI. Hence, DT is comparable in efficacy, but safer compared to TT. This interesting hypothesis will have to be confirmed in future studies.

Vitamin K and D Supplementation and Bone Health in Chronic Kidney Disease-Apart or Together?

Vitamin K (VK) and vitamin D (VD) deficiency/insufficiency is a common feature of chronic kidney disease (CKD), leading to impaired bone quality and a higher risk of fractures. CKD patients, with disturbances in VK and VD metabolism, do not have sufficient levels of these vitamins for maintaining normal bone formation and mineralization. So far, there has been no consensus on what serum VK and VD levels can be considered sufficient in this particular population. Moreover, there are no clear guidelines how supplementation of these vitamins should be carried out in the course of CKD. Based on the existing results of preclinical studies and clinical evidence, this review intends to discuss the effect of VK and VD on bone remodeling in CKD. Although the mechanisms of action and the effects of these vitamins on bone are distinct, we try to find evidence for synergy between them in relation to bone metabolism, to answer the question of whether combined supplementation of VK and VD will be more beneficial for bone health in the CKD population than administering each of these vitamins separately.

Health-related quality of life in nonvalvular atrial fibrillation patients with controlled or uncontrolled anticoagulation status

BACKGROUND

There is a dearth of evidence regarding Health-Related Quality of Life (HRQoL) in nonvalvular atrial fibrillation (NVAF) patients undergoing oral anticoagulation therapy. Our objective was to describe HRQoL in NVAF patients on oral anticoagulation, focusing on uncontrolled patients on vitamin K antagonists (VKAs) versus controlled patients on VKAs or non-vitamin K antagonist oral anticoagulants (NOACs), in a real-world setting. Additionally, we assessed the clinical characteristics of patients with uncontrolled anticoagulation.

METHODS

An observational, multicentre, and cross-sectional study, enrolling 38 Spanish Hospitals' Internal Medicine Departments. HRQoL was assessed using the validated Spanish version of the Sawicki questionnaire. High self-perceived HRQoL was indicated by high scores in the general treatment satisfaction and self-efficacy dimensions, and by low scores in the strained social network, daily hassles and distress dimensions.

RESULTS

Five hundred and one patients were included for assessment. Mean scores ± SD were closer to a high perceived HRQoL in controlled than uncontrolled patients for the five dimensions of the questionnaire: 4.9 ± 1.0 versus 3.6 ± 1.3 for general treatment satisfaction; 4.3 ± 1.0 versus 3.6 ± 1.0 for self-efficacy, 3.1 ± 0.9 versus 3.9 ± 1.1 for strained social network, 2.1 ± 0.8 versus 3.0 ± 1.0 for daily hassles and 1.8 ± 0.9 versus 2.6 ± 1.2 for distress.

CONCLUSIONS

HRQoL in patients with controlled anticoagulant status treated with NOACs or VKAs was better than in patients with uncontrolled anticoagulant status. This seems to indicate that anticoagulation control status influences perception of HRQoL, highlighting the importance of its evaluation when assessing HRQoL in NVAF patients.

Propensity score adjusted comparison of three-factor versus four-factor prothrombin complex concentrate for emergent warfarin reversal: a retrospective cohort study

BACKGROUND

Prothrombin Complex Concentrates (PCC) are prescribed for emergent warfarin reversal (EWR). The comparative effectiveness and safety among PCC products are not fully understood.

METHODS

Patients in an academic level one trauma center who received PCC3 or PCC4 for EWR were identified. Patient characteristics, PCC dose and time of dose, pre- and post-INR and time of measurement, fresh frozen plasma and vitamin K doses, and patient outcomes were collected. Patients whose pre-PCC International Normalized Ratio (INR) was > 6 h before PCC dose or the pre-post PCC INR was > 12 h were excluded. The primary outcome was achieving an INR ≤ 1.5 post PCC. Secondary outcomes were the change in INR over time, post PCC INR, thromboembolic events (TE), and death during hospital stay. Logistic regression modelled the primary outcome with and without a propensity score adjustment accounting for age, sex, actual body weight, dose, initial INR value, and time between INR measurements. Data are reported as median (IQR) or n (%) with p < 0.05 considered significant.

RESULTS

Eighty patients were included (PCC3 = 57, PCC4 = 23). More PCC4 patients achieved goal INR (87.0% vs. 31.6%, odds ratio (OR) = 14.4, 95% CI: 3.80-54.93, p < 0.001). This result remained true after adjusting for possible confounders (AOR = 10.7, 95% CI: 2.17-51.24, p < 0.001). The post-PCC INR was lower in the PCC4 group (1.3 (1.3-1.5) vs. 1.7 (1.5-2.0)). The INR change was greater for PCC4 (2.3 (1.3-3.3) vs. 1.1 (0.6-2.0), p = 0.003). Death during hospital stay (p = 0.52) and TE (p = 1.00) were not significantly different.

CONCLUSIONS

PCC4 was associated with a higher achievement of goal INR than PCC3. This relationship was observed in the unadjusted and propensity score adjusted results.

Cheung A. Vitamin K and Osteoporosis

Vitamin K acts as a coenzyme of carboxylase, catalyzing the carboxylation of several vitamin K dependent proteins. Beyond its well-known effects on blood coagulation, it also exerts relevant effects on bone and the vascular system. In this review, we point out the relevance of an adequate vitamin K intake to obtain sufficient levels of carboxylated (active form) vitamin K dependent proteins (such as Osteocalcin and matrix Gla protein) to prevent bone health. Another bone-related action of Vitamin K is being a ligand of the nuclear steroid and xenobiotic receptor (SXR). We also discuss the recommended intake, deficiency, and assessment of vitamin K. Furthermore, we review the few available studies that have as pre-specified outcome bone fractures, indicating that we need more clinical studies to confirm that vitamin K is a potential therapeutic agent for bone fractures.

Effect of Fat-Soluble Vitamins A, D, E and K on Vitamin Status and Metabolic Profile in Patients with Fat Malabsorption with and without Urolithiasis

Patients with intestinal fat malabsorption and urolithiasis are particularly at risk of acquiring fat-soluble vitamin deficiencies. The aim of the study was to evaluate the vitamin status and metabolic profile before and after the supplementation of fat-soluble vitamins A, D, E and K (ADEK) in 51 patients with fat malabsorption due to different intestinal diseases both with and without urolithiasis. Anthropometric, clinical, blood and 24-h urinary parameters and dietary intake were assessed at baseline and after ADEK supplementation for two weeks. At baseline, serum aspartate aminotransferase (AST) activity was higher in stone formers (SF; n = 10) than in non-stone formers (NSF; n = 41) but decreased significantly in SF patients after supplementation. Plasma vitamin D and E concentrations increased significantly and to a similar extent in both groups during intervention. While plasma vitamin D concentrations did not differ between the groups, vitamin E concentrations were significantly lower in the SF group than the NSF group before and after ADEK supplementation. Although vitamin D concentration increased significantly in both groups, urinary calcium excretion was not affected by ADEK supplementation. The decline in plasma AST activity in patients with urolithiasis might be attributed to the supplementation of ADEK. Patients with fat malabsorption may benefit from the supplementation of fat-soluble vitamins ADEK.

Causes of Vitamin K Deficiency in Patients on Haemodialysis

Background: A low vitamin K status is common in patients on haemodialysis, and this is considered one of the reasons for the accelerated atherosclerosis in these patients. The vitamin is essential in activation of the protein Matrix Gla Protein (MGP), and the inactive form, dp-ucMGP, is used to measure vitamin K status. The purpose of this study was to investigate possible underlying causes of low vitamin K status, which could potentially be low intake, washout during dialysis or inhibited absorption capacity. Moreover, the aim was to investigate whether the biomarker dp-ucMGP is affected in these patients. Method: Vitamin K intake was assessed by a Food Frequency Questionnaire (FFQ) and absorption capacity by means of D-xylose testing. dp-ucMGP was measured in plasma before and after dialysis, and phylloquinine (vitamin K1) and dp-ucMGP were measured in the dialysate. Changes in dp-ucMGP were measured after 14 days of protein supplementation. Results: All patients had plasma dp-ucMGP above 750 pmol/L, and a low intake of vitamin K. The absorption capacity was normal. The difference in dp-ucMGP before and after dialysis was -1022 pmol/L (p < 0.001). Vitamin K1 was not present in the dialysate but dp-ucMGP was at a high concentration. The change in dp-ucMGP before and after protein supplementation was -165 pmol/L (p = 0.06). Conclusion: All patients had vitamin K deficiency. The reason for the low vitamin K status is not due to removal of vitamin K during dialysis or decreased absorption but is plausibly due to a low intake of vitamin K in food. dp-ucMGP is washed out during dialysis, but not affected by protein intake to a clinically relevant degree.

Beneficial Effects of Vitamin K Status on Glycemic Regulation and Diabetes Mellitus: A Mini-Review

Type 2 diabetes mellitus is a chronic disease that is characterized by hyperglycemia, insulin resistance, and dysfunctional insulin secretion. Glycemic control remains a crucial contributor to the progression of type 2 diabetes mellitus as well as the prevention or delay in the onset of diabetes-related complications. Vitamin K is a fat-soluble vitamin that plays an important role in the regulation of the glycemic status. Supplementation of vitamin K may reduce the risk of diabetes mellitus and improve insulin sensitivity. This mini-review summarizes the recent insights into the beneficial effects of vitamin K and its possible mechanism of action on insulin sensitivity and glycemic status, thereby suppressing the progression of diabetes mellitus.

Educating Parents on Vitamin K Prophylaxis for Newborns

Vitamin K is important in the clotting cascade, and vitamin K prophylaxis is important in preventing vitamin K deficiency bleeding (VKDB) in newborns. Breastfed newborns have been found to be particularly vulnerable to VKDB. Although oral vitamin K is available, there is no version for newborns approved by the U.S. Food and Drug Administration (FDA), and if a dose is missed, the risk of VKDB may more than double. Therefore, an injection is recommended by the American Academy of Pediatrics to prevent VKDB in newborns. Nurses often administer the newborn vitamin K injection, and they play a key role in educating parents and helping them make informed decisions about vitamin K prophylaxis for their newborns.

Vitamin K for kidney transplant organ recipients: investigating vessel stiffness (ViKTORIES): study rationale and protocol of a randomised controlled trial

BACKGROUND

Renal transplant recipients (RTRs) exhibit increased vascular stiffness and calcification; these parameters are associated with increased cardiovascular risk. Activity of endogenous calcification inhibitors such as matrix gla protein (MGP) is dependent on vitamin K. RTRs commonly have subclinical vitamin K deficiency. The Vitamin K in kidney Transplant Organ Recipients: Investigating vEssel Stiffness (ViKTORIES) study assesses whether vitamin K supplementation reduces vascular stiffness and calcification in a diverse population of RTR.

METHODS AND ANALYSIS

ViKTORIES (ISRCTN22012044) is a single-centre, phase II, parallel-group, randomised, double-blind, placebo-controlled trial of the effect of vitamin K supplementation in 90 prevalent RTR. Participants are eligible if they have a functioning renal transplant for >1 year. Those on warfarin, with atrial fibrillation, estimated glomerular filtration rate <15 mL/min/1.73 m2 or contraindications to MRI are excluded. Treatment is with vitamin K (menadiol diphosphate) 5 mg three times per week for 1 year or matching placebo. All participants have primary and secondary endpoint measures at 0 and 12 months. The primary endpoint is ascending aortic distensibility on cardiac MR imaging. Secondary endpoints include vascular calcification (coronary artery calcium score by CT), cardiac structure and function on MR, carotid-femoral pulse wave velocity, serum uncarboxylated MGP, transplant function, proteinuria and quality of life. The study is powered to detect 1.0×10-3 mm Hg-1 improvement in ascending aortic distensibility in the vitamin K group relative to placebo at 12 months. Analyses will be conducted as between-group differences at 12 months by intention to treat.

DISCUSSION

This trial may identify a novel, inexpensive and low-risk treatment to improve surrogate markers of cardiovascular risk in RTR.

Vitamin K Status in Adherent and Non-Adherent Patients with Phenylketonuria: A Cross-Sectional Study

This is the first study to evaluate vitamin K status in relation to dietary intake and phenylalanine dietary compliance in patients with phenylketonuria (PKU). The dietary and PKU formula intake of vitamin K was calculated in 34 PKU patients, with vitamin K status determined by the measurement of prothrombin induced by vitamin K absence (PIVKA-II). Blood phenylalanine concentrations in the preceding 12 months were considered. There were significantly more phenylalanine results exceeding 6 mg/dL in patients with normal PIVKA-II concentrations than in those with abnormal PIVKA-II levels (p = 0.035). Similarly, a higher total intake of vitamin K and dietary vitamin intake expressed as μg/day (p = 0.033 for both) and %RDA (p = 0.0002 and p = 0.003, respectively) was observed in patients with normal PIVKA-II levels. Abnormal PIVKA-II concentrations were associated with a lower OR (0.1607; 95%CI: 0.0273–0.9445, p = 0.043) of having a median phenylalanine concentration higher than 6 mg/dL. In conclusion, vitamin K deficiency is not uncommon in phenylketonuria and may also occur in patients with adequate vitamin K intake. PKU patients with better dietary compliance have a higher risk of vitamin K deficiency. The present findings highlight the need for further studies to re-evaluate dietary recommendations regarding vitamin K intake, both concerning formula-based and dietary consumption of natural products.

Vitamin K supplementation for cystic fibrosis

BACKGROUND

Malabsorption and deficiency of fat-soluble vitamins K may occur in cystic fibrosis, a genetic disorder affecting multiple organs. Vitamin K is known to play an important role in both blood coagulation and bone formation, hence the role of supplementation of vitamin K in this category needs to be reviewed. This is an updated version of the review.

OBJECTIVES

To assess the effects of vitamin K supplementation in people with cystic fibrosis and to investigate the hypotheses that vitamin K will decrease deficiency-related coagulopathy, increase bone mineral density, decrease risk of fractures and improve quality of life in people with CF. Also to determine the optimal dose and route of administration of vitamin K for people with CF (for both routine and therapeutic use).

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Most recent search: 12 August 2019.

SELECTION CRITERIA

Randomised controlled trials of all preparations of vitamin K used as a supplement compared to either no supplementation (or placebo) at any dose or route and for any duration, in patients with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Two authors independently screened papers, extracted trial details and assessed their risk of bias. The quality of the evidence was assessed using the GRADE criteria.

MAIN RESULTS

Three trials (total 70 participants, aged 8 to 46 years) assessed as having a moderate risk of bias were included. One trial compared vitamin K to placebo, a second to no supplementation and the third compared two doses of vitamin K. No trial in either comparison reported our primary outcomes of coagulation and quality of life or the secondary outcomes of nutritional parameters and adverse events. Vitamin K versus control Two trials compared vitamin K to control, but data were not available for analysis. One 12-month trial (n = 38) compared 10 mg vitamin K daily or placebo in a parallel design and one trial (n = 18) was of cross-over design with no washout period and compared 5 mg vitamin K/week for four-weeks to no supplementation for four-weeks. Only the 12-month trial reported on the primary outcome of bone formation; we are very uncertain whether vitamin K supplementation has any effect on bone mineral density at the femoral hip or lumbar spine (very low-quality evidence). Both trials reported an increase in serum vitamin K levels and a decrease in undercarboxylated osteocalcin levels. The cross-over trial also reported that levels of proteins induced by vitamin K absence (PIVKA) showed a decrease and a return to normal following supplementation, but due to the very low-quality evidence we are not certain that this is due to the intervention. High-dose versus low-dose vitamin K One parallel trial (n = 14) compared 1 mg vitamin K/day to 5 mg vitamin K/day for four weeks. The trial did report that there did not appear to be any difference in serum undercarboxylated osteocalcin or vitamin K levels (very low-quality evidence). While the trial reported that serum vitamin K levels improved with supplementation, there was no difference between the high-dose and low-dose groups.

AUTHORS' CONCLUSIONS

There is very low-quality evidence of any effect of vitamin K in people with cystic fibrosis. While there is no evidence of harm, until better evidence is available the ongoing recommendations by national CF guidelines should be followed.

Time in Therapeutic Range for Dialysis Patients on Warfarin: Determination and the Effect of Dietary Intervention

This study aimed to identify the time in therapeutic range (TTR) for dialysis patients on warfarin, and improve TTR with dietary review and intervention of interacting foods. We identified 151 patients undergoing hemodialysis in two units who were being treated with warfarin from January 1, 2010, through February 1, 2018, who were included in the overall TTR study. Of these, 15 patients were available to undergo the dietary intervention. International normalized ratio values were collected retrospectively for all eligible hemodialysis patients, and TTR was calculated for each period in which the patient was on hemodialysis. Patients who were available and agreed to the intervention underwent targeted dietician review of interacting foods, and their TTR post-treatment was calculated. The median (interquartile range [IQR]) TTR was 44 (IQR, 29 to 53) % among the 151 patients. Among the 15 patients who underwent the intervention, median (IQR) TTR was 52 (IQR, 32 to 56) pre-intervention and 51 (IQR, 38 to 69) post-intervention (P=0.53). TTR for dialysis patients is low in this overall cohort despite patients being seen at an integrated health care system. Focused improvement projects such as dietary review of interacting foods may help increase a patient's TTR.

Effects of Upadacitinib Coadministration on the Pharmacokinetics of Sensitive Cytochrome P450 Probe Substrates: A Study With the Modified Cooperstown 5+1 Cocktail

The aim of this study was to characterize the effects of upadacitinib, a Janus kinase 1 inhibitor, on in vivo activity of different cytochrome P450 (CYP) enzymes using a cocktail approach. Healthy subjects (n = 20) received single oral doses of the modified Cooperstown 5+1 cocktail drugs (midazolam [CYP3A], caffeine [CYP1A2], warfarin + vitamin K [CYP2C9], omeprazole [CYP2C19], and dextromethorphan [CYP2D6]) without upadacitinib and on day 11 (midazolam) or 12 (all other probes) of a 15-day regimen of upadacitinib 30 mg once daily (extended-release formulation). Serial blood samples and 12-hour urine samples were collected for assays of the probe substrates and select metabolites. The ratio (90%CI) of area under the plasma concentration-time curve from time 0 to infinity (AUCinf ) central values when the cocktail drugs were administered with upadacitinib relative to when administered alone were 0.74 (0.68-0.80) for midazolam, 1.22 (1.15-1.29) for caffeine, 1.11 (1.07-1.15) for S-warfarin, 1.07 (0.95-1.22) for dextromethorphan, and 0.82 (0.72-0.94) for omeprazole. The ratio (90%CI) was 1.09 (1.00-1.19) for 5-hydroxy-omeprazole to omeprazole AUCinf ratio and 1.17 (0.97-1.41) for dextromethorphan to dextrorphan 12-hour molar urinary ratio. Upadacitinib 30 mg once daily (a dose that is twice the optimal dose in rheumatoid arthritis based on phase 3 results) has a limited effect on CYP3A activity (26% decrease in exposure of midazolam, a sensitive CYP3A substrate) and no relevant effects on CYP1A2, CYP2C9, CYP2C19, or CYP2D6 activity in vivo. No clinically relevant changes in plasma exposures are expected for drugs that are substrates for the evaluated CYP enzymes when coadministered with upadacitinib.

Vitamin K role in mineral and bone disorder of chronic kidney disease

Vitamin K is a key cofactor for the activation of proteins involved in blood coagulation, apoptosis, bone mineralization regulation, and vessel health. Scientific evidence shows an important role of activated osteocalcin and matrix-Gla protein in bone and vessels, markedly affected along the course of chronic kidney disease (CKD). In fact, CKD corresponds to an unique condition of vitamin K deficiency caused by dietary restriction, intestinal dysfunction, and impaired vitamin K recycling. Clinical data suggest that vitamin K status can be modulated and this prompts us to speculate whether patients with CKD might benefit from vitamin K supplementation. However, as important as whether the improvement in vitamin K status would be able to result in better bone quality, less vascular calcification, and lower mortality rates, several issues need to be clarified. These include better standardized methods for measuring vitamin K levels, and definition of the optimal concentration range for supplementation in different subgroups. Here, we review the literature data concerning the impact of vitamin K deficiency and supplementation on CKD-associated mineral and bone disorders (CKD-MBD). We present and discuss the available evidence from basic science and clinical studies, and highlight perspectives for further research.

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

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

The Relationship between Dietary Vitamin K and Depressive Symptoms in Late Adulthood: A Cross-Sectional Analysis from a Large Cohort Study

Few studies assessed the associations between dietary vitamin K and depressive symptoms. We aimed to investigate the association between dietary vitamin K and depressive symptoms in a large cohort of North American People. In this cross-sectional analysis, 4,375 participants that were aged 45⁻79 years from the Osteoarthritis Initiative were included. Dietary vitamin K intake was collected through a semi-quantitative food frequency questionnaire and categorized in quartiles. Depressive symptoms were diagnosed using the 20-item Center for Epidemiologic Studies-Depression (CES-D) ≥ 16. To investigate the associations between vitamin K intake and depressive symptoms, logistic regression analysis were run, which adjusted for potential confounders. Overall, 437 (=10%) subjects had depressive symptoms. After adjusting for 11 confounders, people with the highest dietary vitamin K intake had lower odds of having depressive symptoms (OR = 0.58; 95%CI: 0.43⁻0.80). This effect was only present in people not taking vitamin D supplementation. In conclusion, higher dietary vitamin K intake was significantly associated with a lower presence of depressive symptoms, also after accounting for potential confounders. Future longitudinal research is required to explore the directionality of the association.

A new LC-MS assay for the quantitative analysis of vitamin K metabolites in human urine

Vitamin K (VK), in both its phylloquinone and menaquinone forms, has been hypothesized to undergo ω- and β-oxidation on its hydrophobic side chain in order to generate the observed urinary metabolites, K acid I and K acid II, which are excreted primarily as glucuronide conjugates. Synthetic standards of K acid I, K acid II, and a putative intermediate metabolite, menaquinone (MK)1 ω-COOH, were used to develop and optimize a new atmospheric pressure negative chemical ionization LC-MS/MS assay for the quantitation of these compounds in urine from untreated individuals and subjects treated with a high dose VK supplement. VK catabolites were extracted from urine, deconjugated, and converted to their methyl ester derivatives using previously reported methodology. The assay showed a high degree of sensitivity, with limits of detection below 10-50 fmol of metabolite per milliliter of urine, as well as an inter-assay precision of 8-12%. Metabolite standards provided unambiguous evidence for MK1 ω-COOH as a new human urinary metabolite of VK. This assay provides a minimally invasive, highly sensitive, and specific alternative for monitoring VK status in humans.