A Negative Association between Plasma Phylloquinone and All-Cause Mortality in Chinese Adults with Hypertension: A Nested Case-Control Study

BACKGROUND

Previous studies have revealed that vitamin K is essential for preventing various chronic diseases. Phylloquinone is the primary dietary and circulating form of vitamin K. However, data concerning the association between plasma phylloquinone and all-cause mortality are limited.

OBJECTIVES

This study aimed to evaluate the association between plasma phylloquinone and risk of all-cause mortality and examine some potential confounders.

METHODS

This study is a post hoc analysis of the RCT and a nested, case-control design was used. Enrolled participants had to have hypertension at baseline. Study initiation was 19 May, 2008, and the median follow-up was 4.5 y. A total of 604 mortality cases and 604 controls matched for age, sex, treatment group, and study site were included in this study. Odds ratios (OR) and 95% confidence intervals (CIs) of all-cause mortality were calculated using conditional or unconditional logistic regression, without or with adjusting for pertinent covariates, respectively. The concentration of phylloquinone was measured by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS).

RESULTS

The mean and median phylloquinone levels were 1.62 nmol/L and 0.89 nmol/L, respectively. There was a significant negative association between log-transformed plasma phylloquinone and all-cause mortality after controlling for potential confounders (per 1 unit increase-OR: 0.79; 95% CI: 0.66, 0.95). Furthermore, the association of plasma phylloquinone with risk of all-cause mortality differed by body mass index (BMI) (<25 kg/m2 compared with ≥25 kg/m2, P-interaction = 0.004). A significant trend of decreasing risk with increasing concentration of phylloquinone was observed in participants with higher BMI (per 1 unit increase-OR: 0.71; 95% CI: 0.56, 0.90; P = 0.004). No significant correlation was found between phylloquinone and risk of all-cause mortality in those with BMI <25 kg/m2.

CONCLUSIONS

In Chinese patients with hypertension, there was a significant negative association between baseline plasma phylloquinone and all-cause mortality, especially among those with higher BMI.

Vitamin K - a scoping review for Nordic Nutrition Recommendations 2023

Vitamin K occurs in dietary supply in two major forms: phylloquinone (vitamin K1) and menaquinones (collectively referred as vitamin K2). Phylloquinone is derived from plants. There are at least 10 forms of menaquinones varying in chain length and they are produced by bacteria except menaquinone-4. Menaquinone-4 is formed from phylloquinone or other menaquinone forms. Phylloquinone is considered to be the major contributor and menaquinones are thought to contribute less to vitamin K intake in Western diets. However, less is known about the content of menaquinones than phylloquinones in foods. Vitamin K is known to function as an enzymatic cofactor in the gamma-carboxylation of vitamin K dependent proteins (VKDPs). Hepatic VKDPs are involved in coagulation. Extrahepatic VKDPs have a role e.g. in bone health and vascular calcification. However, the amount of vitamin K needed for optimal functioning of the different VKDPs is not known.

Vitamin K1 Intake and Incident Diabetes in the Danish Diet, Cancer, and Health Study

CONTEXT

Observational studies have reported lower risks of type 2 diabetes with higher vitamin K1 intake, but these studies overlook effect modification due to known diabetes risk factors.

OBJECTIVE

To identify subgroups that might benefit from vitamin K1 intake, we examined associations between vitamin K1 intake and incident diabetes overall and in subpopulations at risk of diabetes.

METHODS

Participants from the prospective cohort, the Danish Diet, Cancer, and Health Study, with no history of diabetes were followed up for diabetes incidence. The association between intake of vitamin K1, estimated from a food frequency questionnaire completed at baseline, and incident diabetes was determined using multivariable-adjusted Cox proportional-hazards models.

RESULTS

In 54 787 Danish residents with a median (interquartile range) age of 56 (52-60) years at baseline, 6700 individuals were diagnosed with diabetes during 20.8 (17.3-21.6) years of follow-up. Vitamin K1 intake was inversely and linearly associated with incident diabetes (P < .0001). Compared to participants with the lowest vitamin K1 intake (median:57 µg/d), participants with the highest intakes (median:191 µg/d) had a 31% lower risk of diabetes (HR; 95% CI, 0.69; 0.64-0.74) after multivariable adjustments. The inverse association between vitamin K1 intake and incident diabetes was present in all subgroups (namely, men and women, ever and never smokers, low and high physical activity groups, and in participants who were normal to overweight and obese), with differences in absolute risk between subgroups.

CONCLUSION

Higher intake of foods rich in vitamin K1 was associated with a lower risk of diabetes. If the associations observed are causal, our results indicate that more cases of diabetes would be prevented in subgroups at higher risk (men, smokers, participants with obesity, and those with low physical activity).

Lack of Consensus Between Measurements of Plasma Phylloquinone by Enzyme-Linked Immunosorbent assays and a Well-Validated High-Performance Liquid Chromatographic Method

Enzyme-linked i2mmunosorbent assays (ELISAs) that measure circulating phylloquinone have become commercially available, but their validity is uncertain. The objective of this study was to compare plasma phylloquinone concentrations measured using two commercially available ELISAs with concentrations measured using a validated high-performance liquid chromatography (HPLC) assay in 108 samples obtained from participants in a depletion (∼10 mcg phylloquinone/d)-supplementation (∼500 mcg phylloquinone/d) study. The geometric mean of plasma phylloquinone measured with ELISA A was 0.70 nmol/L, 37% lower than that measured with HPLC. The mean of the ELISA B measures was 12.4 nmol/L, >700% higher than the HPLC measures. Plasma phylloquinone measured using HPLC was significantly lower during phylloquinone depletion than supplementation (0.4 ± 0.1 compared with 1.2 ± 0.2 nmol/L; P < 0.001). Neither of the two ELISAs detected any significant difference in plasma phylloquinone concentrations between depletion and supplementation (ELISA A, P = 0.76; ELISA B, P = 0.29). These findings reinforce the need to validate plasma phylloquinone assays as they become available. Curr Dev Nutr 2023;x:xx.

Measurement of vitamin K and its derivatives in human plasma through enzyme-assisted liquid chromatography-tandem mass spectrometry assay

Vitamin K is an essential lipophilic vitamin that acts as a coenzyme in several metabolic pathways. Accurate measurement of apolar metabolites transported by lipoproteins in serum matrices requires high-recovery extractions of vitamin K and its derivatives following standardized protocols. Conventionally developed methods in this field have predominantly employed solid-phase extraction for the measurement of vitamin K and its derivatives. In this study, our objective was to develop an enzyme-assisted extraction method for the precise measurement of vitamin K and its derivatives. Our methodology involved mixing 450 µL of serum samples with 50 µL of an internal standard and 50 µL of a lipase enzyme solution. Following vortexing, the mixture was incubated at 37°C for 15 min to activate the enzymes. The enzyme reaction was subsequently quenched with a mixture of 250 µL of methanol and 1 mL of hexane, followed by centrifugation at 12,000 g for 5 min. The upper phase was collected, concentrated using a concentrator device, and dissolved in a 100 µL solution of methanol/acetone/isopropanol (7:1:1, v/v/v) for analysis. Spectrum analysis was performed using the open-source MZmine 3 software, and a reference interval was established using the Python programming language on the Google Colab platform. The developed method for measuring vitamin K and its derivatives exhibited limit of detection and limit of quantitation values of 0.005 and 0.01 ng/mL, respectively. In conclusion, our study presents a precise and reliable method for the measurement of vitamin K and its derivatives using enzyme-assisted extraction.

Effect of phylloquinone on indomethacin-induced gastric ulceration in rats: Role of SIRT-1

Gastric ulcer is the most common gastrointestinal disorder affecting people globally. Although many drugs are available to treat ulcers, the mortality rate is relatively high, and drugs lack selectivity to treat ulcers without causing side effects. In this study, the potential therapeutic effects of phylloquinone were tested against indomethacin-induced gastric ulcer in rats by giving rats a single oral dose of indomethacin (48 mg/kg), followed by phylloquinone (10 mg/kg) orally, once daily for six consecutive days. Phylloquinone significantly attenuated indomethacin-induced oxidative and inflammatory responses through hindering the inflammatory cascade by decreasing the levels of TNF-α, NF-κB, INOS and COX-2 which counteracts indomethacin effects. Also, it increased NAD⁺ which enhanced SIRT-1 level. Furthermore, phylloquinone was effective in increasing mucus secretion, decreasing acid secretion, reversing histological effects caused by indomethacin and minimizing ulcer and lesion indices All these findings indicate that phylloquinone may be used in protection and treatment of indomethacin-induced gastric ulcer.

COVID-19-associated Coagulopathy: Role of Vitamins D and K

Recent reports show coagulopathy as a potential complication and poorer outcome of coronavirus disease 2019 (COVID-19), especially in those with comorbid conditions such as diabetes and hypertension as thrombosis could result in stroke and heart attacks. Indeed, cardiovascular complications in COVID-19 account for 40% of mortality. Although there is no standard treatment protocol or guidelines for COVID-19, it is a common practice to use anti-inflammatory corticosteroids and anti-coagulants, especially for severe COVID-19 patients. It has also been confirmed that deficiencies of vitamin D and/or vitamin K can exacerbate premorbid cardiovascular and diabetes conditions associated with COVID-19, at least partially due to a higher incidence of coagulopathy. Here, we discuss the roles of vitamins D and K in general and in COVID-19-related coagulopathy. Moreover, the suggestion for proper supplementations of these vitamins in countering COVID-19 is provided.

Fish Microbiome Modulation and Convenient Storage of Aquafeeds When Supplemented with Vitamin K1

Vitamin K (VK) is a fat-soluble vitamin necessary for fish metabolism and health. VK stability as dietary component during aquafeed storage and its potential effect on intestinal microbiome in fish have not yet been completely elucidated. The convenient storage conditions of aquafeeds when supplemented with phylloquinone (VK1), as well as its potential effects on the gut microbiota of Senegalese sole (Solea senegalensis) juveniles, have been explored. Experimental feeds were formulated to contain 0, 250 and 1250 mg kg^-1 of VK1 and were stored at different temperatures (4, -20 or -80 °C). VK stability was superior at -20 °C for short-term (7 days) storage, while storing at -80 °C was best suited for long-term storage (up to 3 months). A comparison of bacterial communities from Senegalese sole fed diets containing 0 or 1250 mg kg^-1 of VK1 showed that VK1 supplementation decreased the abundance of the Vibrio, Pseudoalteromonas, and Rhodobacterace families. All these microorganisms were previously associated with poor health status in aquatic organisms. These results contribute not only to a greater understanding of the physiological effects of vitamin K, particularly through fish intestinal microbiome, but also establish practical guidelines in the industry for proper aquafeed storage when supplemented with VK1.

Treatment of Vitamin K Deficiency in Hemodialysis Patients - A Pilot Study Comparing Menaquinone-7 Tablets and a Vitamin K Rich Diet

Purpose

Vitamin K deficiency and hence a high level of plasma dephosphorylated undercarboxylated matrix Gla protein (dp-ucMGP) is frequent in patients on hemodialysis. This group is recommended to restrict their potassium intake which often leads to restriction of vitamin K rich foods. A menaquinone-7 (MK-7) supplement has been shown to decrease dp-ucMGP, but it has yet to be examined if a vitamin K rich diet could be equally effective.

Patients and Methods

A prospective randomized crossover intervention trial with two arms; 6 weeks of 360 μg MK-7 tablet/day and 6 weeks of a vitamin K rich diet with a 3-week washout period in between. Participants were 10 patients in hemodialysis and the primary outcome measures were changes in dp-ucMGP, total MGP (tMGP), and undercarboxylated osteocalcin (ucOC). Furthermore, the level of potassium and phylloquinone in broccoli was determined after different durations of boiling.

Results

During the MK-7 intervention the dp-ucMGP and ucOC decreased significantly compared to baseline (−0.42 [−0.93; −0.22] nmol/L (p=<0.01) and −1.85 [−2.91; −1.30] nmol/L (p<0.01)), while these were unchanged during the dietary intervention (0.03 [−0.64; 0.37] nmol/L (p=1.00) and 0.30 [−1.71; 1.41] nmol/L (p=0.77)). Between the two interventions there was a greater decrease in ucOC (p=0.02) during the MK-7 compared to the dietary period. No significant changes in the total MGP levels were found in any of the periods. The retention of potassium following boiling for 2 minutes and 8 minutes was 76% and 49%, respectively, while for phylloquinone the retention was 92%, and independent of duration of boiling.

Conclusion

A daily MK-7 supplement for 6 weeks lowered dp-ucMGP and ucOC significantly, while a vitamin K rich diet was not able to induce any significant effect. Boiled broccoli maintains a reasonable content of phylloquinone while potassium is extracted and is a reasonable source of phylloquinone for patients on hemodialysis.

New insights into vitamin K biology with relevance to cancer

Phylloquinone (vitamin K1) and menaquinones (vitamin K2 family) are essential for post-translational γ-carboxylation of a small number of proteins, including clotting factors. These modified proteins have now been implicated in diverse physiological and pathological processes including cancer. Vitamin K intake has been inversely associated with cancer incidence and mortality in observational studies. Newly discovered functions of vitamin K in cancer cells include activation of the steroid and xenobiotic receptor (SXR) and regulation of oxidative stress, apoptosis, and autophagy. We provide an update of vitamin K biology, non-canonical mechanisms of vitamin K actions, the potential functions of vitamin K-dependent proteins in cancer, and observational trials on vitamin K intake and cancer.

Carboxylative efficacy of trans and cis MK7 and comparison with other vitamin K isomers

Carboxylative enzymes are involved in many pathways and their regulation plays a crucial role in many of these pathways. In particular, γ-glutamylcarboxylase (GGCX) converts glutamate residues (Glu) into γ-carboxyglutamate (Gla) of the vitamin K-dependent proteins (VKDPs) activating them. VKDPs include at least 17 proteins involved in processes such as blood coagulation, blood vessels calcification, and bone mineralization. VKDPs are activated by the reduced form of vitamin K, naturally occurring as vitamin K1 (phylloquinone) and K2 (menaquinones, MKs). Among these, MK7 is the most efficient in terms of bioavailability and biological effect. Similarly to other trans isomers, it is produced by natural fermentation or chemically in both trans and cis. However, the efficacy of the biological effect of the different isomers and the impact on humans are unknown. Our study assessed carboxylative efficacy of trans and cis MK7 and compared it with other vitamin K isomers, evaluating both the expression of residues of carboxylated Gla-protein by western blot analysis and using a cell-free system to determine the GGCX activity by HPLC. Trans MK7H₂ showed a higher ability to carboxylate the 70 KDa GLA-protein, previously inhibited in vitro by warfarin treatment. However, cis MK7 also induced a carboxylation activity albeit of a small extent. The data were confirmed chromatographically, in which a slight carboxylative activity of cis MK7H₂ was demonstrated, comparable with both K1H₂ and oxidized trans MK7 but less than trans MK7H₂ . For the first time, a difference of biological activity between cis and trans configuration of menaquinone-7 has been reported.

Inverse Association between Plasma Phylloquinone and Risk of Ischemic Stroke in Chinese Adults with Hypertension and High BMI: A Nested Case-Control Study

BACKGROUND

Evidence on the association between phylloquinone status and cardiovascular diseases is scarce and conflicting. These inconsistencies may be due to differences in individual characteristics of the study populations, which may modify the association.

OBJECTIVE

This study aimed to evaluate the association between plasma phylloquinone and the risk of first total stroke and its subtypes, and to examine potential effect modifications by BMI in patients with hypertension.

METHODS

We performed a nested case-control study including 604 first stroke cases and 604 matched controls. The mean age was 62.2 y (range, 45 to 75). Lower BMI was defined as <25 kg/m2  and higher BMI was defined as ≥25 kg/m2. The risks of the first stroke were estimated by ORs and 95% CIs using conditional logistic regression. The primary outcome was total stroke or ischemic stroke.

RESULTS

The relation between log-transformed phylloquinone concentration and stroke or ischemic stroke was modified by BMI. Higher phylloquinone concentrations were associated with lower stroke risk in those with a higher BMI. When plasma phylloquinone was assessed as tertiles, the adjusted ORs of first stroke and ischemic stroke for participants with a high BMI in tertile 2-3 were 0.70 (95% CI: 0.46, 1.08) and 0.57 (95% CI: 0.35, 0.92) compared with those in tertile 1, respectively. However, there was no significant association between plasma phylloquinone and risk of first total stroke or ischemic stroke for those with a lower BMI. Patients with a higher BMI and lower phylloquinone concentrations had the highest risk of ischemic stroke and showed a statistically significant difference compared with the reference group with a lower BMI and higher phylloquinone (OR = 1.80, 95% CI: 1.06, 3.10; P-interaction: 0.017).

CONCLUSIONS

In Chinese patients with hypertension, there was an inverse association between baseline plasma phylloquinone and risk of first ischemic stroke among those with a higher BMI. This trial was registered at clinicaltrials.gov as NCT00794885.

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.

Role of Vitamin K in Chronic Kidney Disease: A Focus on Bone and Cardiovascular Health

Chronic kidney disease (CKD) is commonly associated with vitamin K deficiency. Some of the serious complications of CKD are represented by cardiovascular disease (CVD) and skeletal fragility with an increased risk of morbidity and mortality. A complex pathogenetic link between hormonal and ionic disturbances, bone tissue and metabolism alterations, and vascular calcification (VC) exists and has been defined as chronic kidney disease–mineral and bone disorder (CKD-MBD). Poor vitamin K status seems to have a key role in the progression of CKD, but also in the onset and advance of both bone and cardiovascular complications. Three forms of vitamin K are currently known: vitamin K1 (phylloquinone), vitamin K2 (menaquinone), and vitamin K3 (menadione). Vitamin K plays different roles, including in activating vitamin K-dependent proteins (VKDPs) and in modulating bone metabolism and contributing to the inhibition of VC. This review focuses on the biochemical and functional characteristics of vitamin K vitamers, suggesting this nutrient as a possible marker of kidney, CV, and bone damage in the CKD population and exploring its potential use for promoting health in this clinical setting. Treatment strategies for CKD-associated osteoporosis and CV disease should include vitamin K supplementation. However, further randomized clinical studies are needed to assess the safety and the adequate dosage to prevent these CKD complications.

Estimation of Vitamin K Content and Its Sources in the Diet of the Polish Participants of the PURE Study

The aim of the study was to estimate the content of K1, K2 (MK-n) as well as total K vitamins and their sources in the diets of 1985 PURE Poland study participants based on the FFQ questionnaire. Due to the pleiotropic effect of K vitamins, it is important to know their food sources depending on different eating habits. Total vitamin K in the diets amounted to 331.1 ± 151.5 µg/d and 358.6 ± 181.0 µg/d for men and women, respectively. Dietary patterns (DPs) were identified in the study group, and the relationship between them and vitamin K intake was assessed. The proportion of dominant products as sources of vitamin K in the fourth quartile of each of the three identified DPs did not change significantly compared to the proportion of these products as sources of vitamin K in all subjects. In the fourth quartile of individual DPs, vitamin K1 came mainly from vegetables (56.5-76.8%); K2 mainly from processed meat and high-fat cheese and cream (70.1-77.6%); and total K mainly from vegetables and processed meat (57.6-67.8%). Intakes of K vitamins were high and similar in terms of predominant vitamin K provider products, in groups of subjects whose diets were most consistent with the particular DP. In the absence of global findings on the most appropriate dietary content of MK-n vitamins other than phylloquinone, the estimated high content of these vitamins in the diets of the subjects compared with other nations suggests that their level in diets was satisfactory. Future studies should aim to determine the need for MK-n vitamins in terms of fulfilling all their functions in the body.

Multiple Dietary Vitamin K Forms Are Converted to Tissue Menaquinone-4 in Mice

BACKGROUND

Vitamin K is a term that comprises a family of structurally related quinones, phylloquinone (PK) and the menaquinones (MKn), that share a common naphthoquinone ring but vary in sidechain length (n) and saturation. Dietary PK is a biosynthetic precursor to tissue menaquinone-4 (MK4), but little is known about the absorption and metabolism of dietary MKn.

OBJECTIVE

To characterize the absorption and metabolism of dietary MKn relative to PK.

METHODS

In the 4-week diet study, 10-week-old male and female C57BL/6 mice were pair-fed a vitamin K deficient diet (control) or a diet supplemented with 5.0 μmol/kg total PK, MK4, and/or MK9 (separately and in combination). In the 1-week stable isotope study, 12-week-old mice were pair-fed diets containing 2.2 μmol/kg PK (unlabeled control), 2H7PK, 13C11MK4, 2H7MK7, or 2H7MK9. Vitamin K tissue content was quantified by HPLC and/or LC-MS, and concentrations were compared by sex and diet group using 2-factor ANOVA.

RESULTS

Regardless of the form(s) of vitamin K provided in the diet, tissue MK4 concentrations did not differ across equimolar supplemented groups in the kidney, adipose, reproductive organ, bone, or pancreas in either males or females in the diet study (all P values > 0.05). Isotopic labeling confirmed the naphthoquinone ring of MK4 in tissues originated from the administered dietary PK or MKn. Despite equimolar supplementation, accumulation of the administered dietary form differed across diet groups in small intestinal segments (all P values < 0.002) and the liver (P < 0.001). Female mice had greater total vitamin K than males in every tissue examined (P < 0.05).

CONCLUSIONS

Dietary PK, MK4, MK7, and MK9 all served as precursors to tissue MK4 in mice. This study expands our understanding of vitamin K metabolism and supports a common conversion mechanism of all dietary vitamin K forms to MK4. Further investigation of the metabolism and physiological roles of MK4 that may be independent of classical vitamin K function is warranted.

Feeding Practice and Delivery Mode Are Determinants of Vitamin K in the Infant Gut: An Exploratory Analysis

Background

Infants have low stores of vitamin K at birth. Dietary intake of phylloquinone (PK) differs dramatically by infant feeding practice, but the contribution of microbially produced vitamin K (menaquinones) to infant vitamin K status is not well understood.

Objectives

The objective of this study was to investigate determinants of infant fecal vitamin K profiles in mother-infant dyads at 6 wk postpartum.

Methods

Fecal and breast milk samples were collected from a subsample of breastfeeding (n = 23) or formula-feeding (n = 23) mother and infant dyads, delivered vaginally (n = 26) or by cesarean section (CS) (n = 20) in the Synergistic Theory and Research on Nutrition and Growth (STRONG) Kids 2 cohort. Vitamin K concentrations in breast milk and feces were analyzed by LC/MS and/or HPLC. Fecal bacterial metagenomes were analyzed to derive taxonomy and vitamin K biosynthetic genes. Multivariate linear modeling was used to assess effects of delivery and feeding modes on infant fecal vitamin K.

Results

Breast milk contained 1.3 ± 0.2 ng/mL PK, and formula was reported to contain 52 ng/mL PK. Fecal PK was 38-times higher (P < 0.001) in formula-fed than breastfed infants. Infant fecal menaquinones (MKn) MK6, MK7, MK12, and MK13 were higher (P < 0.001) in formula-fed than breastfed infants, whereas MK8 predominated in breastfed and was 5-times higher than formula-fed infants. Total MKn were greater (P < 0.001) in vaginally delivered than CS infants. Relative abundances of 33 bacterial species were affected by feeding mode, 2 by delivery mode, and 4 by both (P < 0.05). Bacterial gene content of 5/12 vitamin K biosynthetic genes were greater (P < 0.05) in breastfed compared with formula-fed infants, and 1 differed by delivery mode.

Conclusions

Feeding practice and delivery mode influence bacterial vitamin K production in the infant gut. High concentrations of unmetabolized PK in feces of formula-fed infants suggests formula PK content exceeds the absorptive capacity of the infant gut.

Successful treatment of calciphylaxis with vitamin K in a patient on haemodialysis

Calciphylaxis has high mortality. Vitamin K deficiency is common in haemodialysis patients and may be a trigger for calciphylaxis due to its role in activating a tissue inhibitor of calcification, matrix Gla protein. We report a second case of a female haemodialysis patient who developed calciphylaxis twice and was successfully treated with vitamin K supplementation on both occasions. She did not receive sodium thiosulphate or bisphosphonates nor was there a change made to her dialysis time or prescription. This case highlights how supplementation with vitamin K may improve the outcome of this condition.

Vitamin K Insufficiency in the Indian Population: Pilot Observational Epidemiology Study

Background

The fat-soluble K vitamins K1 and K2 play an essential role in the blood coagulation cascade and are made available predominantly through selective dietary intakes. They are less known for their nonessential roles in a family of vitamin K–dependent proteins that promote various functions of organs and systems in the body. A lack of vitamin K can characterize vitamin and nutritional element insufficiency, which is different from a clinically apparent vitamin deficiency.

Objective

This epidemiological study evaluated the nutritional status of vitamin K in a sample of the Indian population and vitamin K content in staple Indian foods.

Methods

Serum levels of vitamin K1 and vitamin K2 in the form of menaquinone-7 (MK-7) were assessed via high-performance liquid chromatography coupled with fluorescence detection in 209 patients with type 2 diabetes, 50 healthy volunteers, and common staple foods in India.

Results

After comparing populations with high and low serum vitamin K levels from various geographical regions, our results indicated that the sample of healthy Indian individuals and the sample of Indian patients with type 2 diabetes had low (insufficient) levels of vitamin K2 (MK-7; range 0.3-0.4 ng/mL). No significant differences existed in vitamin K1–related and MK-7–related values between healthy male and female subjects, between male and female subjects with diabetes, and between the healthy sample and the sample of patients with diabetes. The staple, commonly consumed Indian foods that were tested in this study had undetectable levels of vitamin K2, while levels of vitamin K1 varied widely (range 0-37 µg/100 g).

Conclusions

Based on our sample’s low serum levels of vitamin K2 (MK-7) as well as the low levels of vitamin K2 in their typical diet, we propose that the general Indian population could benefit from the consumption of vitamin K2 in the form of MK-7 supplements.

Trial Registration

Clinical Trials Registry - India CTRI/2019/05/014246; http://ctri.nic.in/Clinicaltrials/showallp.php?mid1=21660&EncHid=&userName=014246; Clinical Trials Registry - India CTRI/2019/03/018278; http://ctri.nic.in/Clinicaltrials/showallp.php?mid1=32349&EncHid=&userName=018278

Vitamin K dietary intake is associated with cognitive function in an older adult Mediterranean population

BACKGROUND

In the last years, evidence that dietary vitamin K could have a role in the cognitive domain has increased. However, data from large trials are limited. The objective of this study was to assess the association of 2 year changes in the dietary intake of vitamin K with cognitive function measured through neuropsychological performance tests.

METHODS

In 5,533 participants of the multicentre PREDIMED-Plus study (48.1% women, age 65.1 ± 4.9 years with overweight/obesity and metabolic syndrome), we assessed the adjusted odds ratios of cognitive function decline according to 2 year changes in vitamin K intake. Participants answered a battery of cognitive function tests and Food Frequency Questionnaires (FFQs) in order to estimate the vitamin K dietary intake.

RESULTS

After adjusting for potential cofounders, the highest tertile of change of dietary vitamin K intake (median [IQR]; 194.4 μg/d [120.9, 373.1]) was inversely associated with a Mini-Mental State Examination (MMSE) score ≤24 (OR [95% CI]; 0.53 [0.35, 0.79] P for trend = 0.002) compared with a decrease in the intake of vitamin K (median [IQR]; -97.8 μg/d [-292.8, -51.5]). A significant positive association between changes in dietary vitamin K intake and the semantic verbal fluency test scores (OR [95% CI]; 0.69 [0.51, 0.94] P for trend = 0.019) was found.

CONCLUSIONS

An increase of the intake of dietary vitamin K was associated with better cognitive function scores, independently of recognised risk factors for cognitive decline, in an older adult Mediterranean population with high cardiovascular risk.

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.

Development of a Vitamin K Database for Commercially Available Food in Australia

Vitamin K content of foods is known to vary substantially by geographical location. In Australia, no Vitamin K database of food exists, thereby creating ambiguity when trying to develop national dietary intake guidelines. This investigation aimed to develop a Vitamin K database for commonly consumed foods that are commercially available in Australian supermarkets. The Vitamin K1 (phylloquinone; PK) and K2 (menaquinone; MK4, MK7) content of 60 foods known to contain Vitamin K were assessed (e.g., vegetables fruits, oils, animal products, dairy and fermented foods). A liquid chromatography with tandem mass spectrometry (LCMS/MS) method was developed and used to measure PK and MKs in different foods with an improved chromatographic separation and detection of Vitamin K's and their analogs. The LOD and LOQ for PK and MK4 was 0.1, 0.5 ng/ml and 0.5, 1.0 ng/ml, respectively. The majority foods contained detectable PK (53/60), about half contained MK4 (31/60), and few contained MK7 (3/60). PK was highest in green leafy vegetables, with moderate amounts in oils. Highest MK4 content was in chicken eggs and meat products such as ham and chicken. This database enables nutritional epidemiologist to estimate dietary Vitamin K intake, especially in Australian cohorts, for a range of health outcomes.

How do holoparasitic plants exploit vitamin K1?

Phylloquinone (vitamin K1) is a thylakoid-embedded electron carrier essential for photosynthesis. Paradoxically, we found that phylloquinone biosynthesis is retained in the nonphotosynthetic holoparasite Phelipanche aegyptiaca (Egyptian broomrape). The phylloquinone pathway genes are preferentially expressed during development of the invasive organ, the haustorium, and exhibit strong coexpression with redox-active proteins known to be involved in parasitism. Unlike in photoautotrophic taxa, the late pathway genes of the holoparasite lack the chloroplast-targeting sequence and their proteins are targeted to the plasma membrane instead. Plasma membrane phylloquinone may enable Phelipanche to sense changes in the redox environment during host interactions. The N-truncated isoforms are conserved in several other Orobanchaceae root holoparasites, and interestingly, in a number of closely related photoautotrophic species as well. This suggests an ancient origin of distinct phylloquinone pathways predating the evolution of parasitic plants in the Orobanchaceae. These findings represent exciting opportunities to probe plasma membrane phylloquinone function and diversification in parasitic and nonparasitic plant responses to external redox chemistry in the rhizosphere.

Analysis of Lipophilic Antioxidants in the Leaves of Kaempferia parviflora Wall. Ex Baker Using LC-MRM-MS and GC-FID/MS

Lipophilic metabolites such as carotenoids, fatty acids, vitamin K1, phytosterols, and tocopherols are important antioxidants that are used in the cosmetics, foods, and nutraceutical industries. Recently, there has been a growing demand for the use of byproducts (wastes) as a potential source of industrially important compounds. The leaves of Kaempferia parviflora (black ginger) (KP-BG) are major byproducts of KP-BG cultivation and have been reported to contain several bioactive metabolites; however, the composition of lipophilic metabolites in KP-BG leaves has not been examined. In this study, the lipophilic antioxidant profile was analyzed in the leaves of KP-BG plants grown in vitro and ex vitro. Lipophilic compounds, namely carotenoids (80.40-93.84 µg/g fresh weight (FW)), tocopherols (42.23-46.22 µg/g FW), phytosterols (37.69-44.40 µg/g FW), and vitamin K1 (7.25-7.31 µg/g FW), were quantified using LC-MRM-MS. The fatty acid profile of the KP-BG leaves was identified using GC-FID/MS. The content of individual lipophilic compounds varied among the KP-BG leaves. Ex vitro KP-BG leaves had high levels of lutein (44.38 µg/g FW), α-carotene (14.79 µg/g FW), neoxanthin (12.30 µg/g FW), β-carotene (11.33 µg/g FW), violaxanthin (11.03 µg/g FW), α-tocopherol (39.70 µg/g FW), α-linolenic acid (43.12%), palmitic acid (23.78%), oleic acid (12.28%), palmitoleic acid (3.64%), total carotenoids (93.84 µg/g FW), and tocopherols (46.22 µg/g FW) compared with in vitro KP-BG leaves. These results indicate that ex-vitro-grown KP-BG leaves could be used as a valuable natural source for extracting important lipophilic antioxidants.

Dietary Vitamin K Intake and the Risk of Pancreatic Cancer: A Prospective Study of 101,695 American Adults

No epidemiologic studies have been conducted to assess the association of intake of dietary vitamin K with the risk of pancreatic cancer. We used prospective data from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial between 1993 and 2009 to fill this gap. A total of 101,695 subjects were identified. Dietary intakes of phylloquinone (vitamin K1), menaquinones (vitamin K2), and dihydrophylloquinone (dihydrovitamin K1) were assessed using a food frequency questionnaire. Cox regression was applied to calculate hazard ratios and 95% confidence intervals. During a mean follow-up of 8.86 years (900,744.57 person-years), 361 cases of pancreatic cancer were documented. In the fully adjusted model, dietary intakes of phylloquinone (for quartile 4 vs. quartile 1, hazard ratio (HR) = 0.57, 95% confidence interval (CI): 0.39, 0.83; P for trend = 0.002) and dihydrophylloquinone (for quartile 4 vs. quartile 1, HR = 0.59; 95% CI: 0.41, 0.85; P for trend = 0.006), but not menaquinones (for quartile 4 vs. quartile 1, HR = 0.93; 95% CI: 0.65, 1.33; P for trend = 0.816), were found to be inversely associated with the risk of pancreatic cancer in a nonlinear dose-response manner (all P values for nonlinearity < 0.05), and this was not modified by predefined stratification factors and remained in sensitivity analyses. In conclusion, dietary intakes of phylloquinone and dihydrophylloquinone, but not menaquinones, confer a lower risk of pancreatic cancer. Future studies should confirm our findings.

Vitamin K - sources, physiological role, kinetics, deficiency, detection, therapeutic use, and toxicity

Vitamin K is traditionally connected with blood coagulation, since it is needed for the posttranslational modification of 7 proteins involved in this cascade. However, it is also involved in the maturation of another 11 or 12 proteins that play different roles, encompassing in particular the modulation of the calcification of connective tissues. Since this process is physiologically needed in bones, but is pathological in arteries, a great deal of research has been devoted to finding a possible link between vitamin K and the prevention of osteoporosis and cardiovascular diseases. Unfortunately, the current knowledge does not allow us to make a decisive conclusion about such a link. One possible explanation for this is the diversity of the biological activity of vitamin K, which is not a single compound but a general term covering natural plant and animal forms of vitamin K (K₁ and K₂) as well as their synthetic congeners (K₃ and K₄). Vitamin K₁ (phylloquinone) is found in several vegetables. Menaquinones (MK₄–MK₁₃, a series of compounds known as vitamin K₂) are mostly of a bacterial origin and are introduced into the human diet mainly through fermented cheeses. Current knowledge about the kinetics of different forms of vitamin K, their detection, and their toxicity are discussed in this review.

Vitamin K Intake and Atherosclerotic Cardiovascular Disease in the Danish Diet Cancer and Health Study

Background

Dietary vitamin K (K₁ and K₂) may reduce atherosclerotic cardiovascular disease (ASCVD) risk via several mechanisms. However, studies linking vitamin K intake with incident ASCVD are limited. We aimed to determine the relationship between dietary vitamin K intake and ASCVD hospitalizations.

Methods and Results

In this prospective cohort study, participants from the Danish Diet, Cancer, and Health Study, with no prior ASCVD, completed a food‐frequency questionnaire at baseline and were followed up for hospital admissions of ASCVD; ischemic heart disease, ischemic stroke, or peripheral artery disease. Intakes of vitamin K₁ and vitamin K₂ were estimated from the food‐frequency questionnaire, and their relationship with ASCVD hospitalizations was determined using Cox proportional hazards models. Among 53 372 Danish citizens with a median (interquartile range) age of 56 (52–60) years, 8726 individuals were hospitalized for any ASCVD during 21 (17–22) years of follow‐up. Compared with participants with the lowest vitamin K₁ intakes, participants with the highest intakes had a 21% lower risk of an ASCVD‐related hospitalization (hazard ratio, 0.79; 95% CI: 0.74–0.84), after multivariable adjustments for relevant demographic covariates. Likewise for vitamin K₂, the risk of an ASCVD‐related hospitalization for participants with the highest intakes was 14% lower than participants with the lowest vitamin K₂ intake (hazard ratio, 0.86; 95% CI, 0.81–0.91).

Conclusions

Risk of ASCVD was inversely associated with diets high in vitamin K₁ or K₂. The similar inverse associations with both vitamin K₁ and K₂, despite very different dietary sources, highlight the potential importance of vitamin K for ASCVD prevention.

The Role of Vitamin K in Humans: Implication in Aging and Age-Associated Diseases

As human life expectancy is rising, the incidence of age-associated diseases will also increase. Scientific evidence has revealed that healthy diets, including good fats, vitamins, minerals, or polyphenolics, could have antioxidant and anti-inflammatory activities, with antiaging effects. Recent studies demonstrated that vitamin K is a vital cofactor in activating several proteins, which act against age-related syndromes. Thus, vitamin K can carboxylate osteocalcin (a protein capable of transporting and fixing calcium in bone), activate matrix Gla protein (an inhibitor of vascular calcification and cardiovascular events) and carboxylate Gas6 protein (involved in brain physiology and a cognitive decline and neurodegenerative disease inhibitor). By improving insulin sensitivity, vitamin K lowers diabetes risk. It also exerts antiproliferative, proapoptotic, autophagic effects and has been associated with a reduced risk of cancer. Recent research shows that protein S, another vitamin K-dependent protein, can prevent the cytokine storm observed in COVID-19 cases. The reduced activation of protein S due to the pneumonia-induced vitamin K depletion was correlated with higher thrombogenicity and possibly fatal outcomes in COVID-19 patients. Our review aimed to present the latest scientific evidence about vitamin K and its role in preventing age-associated diseases and/or improving the effectiveness of medical treatments in mature adults ˃50 years old.

Safety and efficacy of an additive consisting of synthetic vitamin K1 (phytomenadione) for horses (JARAZ Enterprises GmbH & Co. KG)

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of a feed additive consisting of vitamin K1 (phytomenadione) produced by chemical synthesis when used as a nutritional additive in complementary feed of horses at a maximum supplemental level of 14 mg vitamin K1/horse per day. The use of vitamin K1 is safe when used as a feed additive for horses under the proposed conditions of use. The use of vitamin K1 in nutrition of horses under the proposed conditions of use is considered safe for the consumer and the environment. No exposure of users by inhalation is expected. The Panel cannot conclude on the potential of the additive to be a skin and eye irritant. Vitamin K1 is considered a moderate dermal sensitiser. Vitamin K1 is an effective source of vitamin K in horse nutrition. The Panel recommends that the specifications of the additive refer to the substance-related impurities listed in the most updated monograph of the European Pharmacopoeia.

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

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

[Diseases Due to the Deficiency in Vitamin K Conversion System and Its Prevention]

Vitamin K is a fat-soluble vitamin that plays an important role in blood coagulation and bone formation. Vitamin K has homologues due to differences in the side chain structure, phylloquinone (abbreviated as vitamin K1, PK) having a phytyl side chain and menaquinones (MK-n, n=1 to 14) having an isoprenoid side chain structure. The main vitamin K that we take from our daily diet is PK, and a fermented food, natto, contains MK-7 produced by Bacillus subtilis natto. However, the majority of vitamin K present in the tissues of mammals, including humans, is menaquinone-4 (abbreviated as vitamin K2, MK-4) having a geranylgeranyl side chain. This reason is that PK or MK-n obtained in the diet is converted into MK-4 in the body. We identified that the UbiA prenyltransferase domain containing protein 1 (UBIAD1) is the conversion enzyme of PK and MK-n to MK-4. The physiological roles of MK-4 in all tissues of the whole body and the physiological significance of MK-4 converted from PK and MK-n by UBIAD1 have not been sufficiently elucidated yet. To investigate the function of UBIAD1 in vivo, we generated UBIAD1 systemic knockout mice and tissue-specific UBIAD1 knockout mice. In this paper, we introduce the usefulness of vitamin K for diseases that may involve vitamin K and UBIAD1.

The Cryptic Plastid of Euglena longa Defines a New Type of Nonphotosynthetic Plastid Organelle

Most secondary nonphotosynthetic eukaryotes have retained residual plastids whose physiological role is often still unknown. One such example is Euglena longa, a close nonphotosynthetic relative of Euglena gracilis harboring a plastid organelle of enigmatic function. By mining transcriptome data from E. longa, we finally provide an overview of metabolic processes localized to its elusive plastid. The organelle plays no role in the biosynthesis of isoprenoid precursors and fatty acids and has a very limited repertoire of pathways concerning nitrogen-containing metabolites. In contrast, the synthesis of phospholipids and glycolipids has been preserved, curiously with the last step of sulfoquinovosyldiacylglycerol synthesis being catalyzed by the SqdX form of an enzyme so far known only from bacteria. Notably, we show that the E. longa plastid synthesizes tocopherols and a phylloquinone derivative, the first such report for nonphotosynthetic plastids studied so far. The most striking attribute of the organelle could be the presence of a linearized Calvin-Benson (CB) pathway, including RuBisCO yet lacking the gluconeogenetic part of the standard cycle, together with ferredoxin-NADP⁺ reductase (FNR) and the ferredoxin/thioredoxin system. We hypothesize that the ferredoxin/thioredoxin system activates the linear CB pathway in response to the redox status of the E. longa cell and speculate on the role of the pathway in keeping the redox balance of the cell. Altogether, the E. longa plastid defines a new class of relic plastids that is drastically different from the best-studied organelle of this category, the apicoplast.IMPORTANCE Colorless plastids incapable of photosynthesis evolved in many plant and algal groups, but what functions they perform is still unknown in many cases. Here, we study the elusive plastid of Euglena longa, a nonphotosynthetic cousin of the familiar green flagellate Euglena gracilis We document an unprecedented combination of metabolic functions that the E. longa plastid exhibits in comparison with previously characterized nonphotosynthetic plastids. For example, and truly surprisingly, it has retained the synthesis of tocopherols (vitamin E) and a phylloquinone (vitamin K) derivative. In addition, we offer a possible solution of the long-standing conundrum of the presence of the CO₂-fixing enzyme RuBisCO in E. longa Our work provides a detailed account on a unique variant of relic plastids, the first among nonphotosynthetic plastids that evolved by secondary endosymbiosis from a green algal ancestor, and suggests that it has persisted for reasons not previously considered in relation to nonphotosynthetic plastids.

Vitamin K and Kidney Transplantation

The assessment of the vitamin K status and its effects on clinical outcomes in kidney transplantation (KT) patients has sparked interest, but it is still largely unfulfilled. In part, this is due to difficulties in laboratory measurements of vitamin K, especially K2 vitamers. Vitamin K status is currently best assessed by measuring undercarboxylated vitamin-K-dependent proteins. The relative contribution of vitamin K1 and K2 to the health status of the general population and CKD (chronic kidney disease) patients, including KT patients, is also poorly studied. Through a complete and first review of the existing literature, we summarize the current knowledge of vitamin K pathophysiology and its potential role in preventing KT complications and improving organ survival. A specific focus is placed on cardiovascular complications, bone fractures, and the relationship between vitamin K and cancer. Vitamin K deficiency could determine adverse outcomes, and KT patients should be better studied for vitamin K assessment and modalities of effective therapeutic approaches.

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.

Correlations among vitamin K intake, body fat, lipid profile and glucose homeostasis in adults and the elderly

Objective Recent research has investigated the possible inverse relationship between vitamin K intake and body fat. In addition, an increasing number of studies are supporting a key role for this vitamin in improving lipid profile and insulin sensitivity and reducing the risk of type 2 diabetes mellitus, but little is known about what mechanisms would be involved. Thus, the objective of this study was to investigate the relationship between vitamin K intake (in the form of phylloquinone - PK), body fat, lipid profile and markers of glucose homeostasis in adults and the elderly. Subjects and methods A cross-sectional study with 298 participants (46% men) in the São Paulo Health Survey 2014-2015. Spearman correlations were performed to evaluate the associations between vitamin K intake and the biochemical and body composition measures. Results Among normal-weight male adults (n = 15), PK intake presented a positive correlation with the quantitative insulin sensitivity check index (QUICKI) (r = 0.525; p = 0.045). Among men with high fat mass index (FMI) (n = 101), PK intake had a negative correlation with homeostasis model assessment estimate for β-cell function (HOMA-β) (r = -0.227; p = 0.022). In women with high FMI (n = 122), PK intake had a negative correlation with HOMA-β (r = -0.199, p = 0.032) and insulin (r = -0.207, p = 0.026). No correlations were found between PK intake and lipid profile. Conclusions Our findings support a potential relationship among PK intake, body fat and markers of glucose homeostasis in adults and the elderly.

Associations between Circulating Lipids and Fat-Soluble Vitamins and Carotenoids in Healthy Overweight and Obese Men

Inconsistent associations between lipids and circulating markers of fat-soluble vitamin and carotenoid status have been reported. The aim of this hypothesis-generating study was to examine the contribution of the LC-MS-based lipidome, characterized by lipid class, carbon count, and the number of unsaturated bonds, to the interindividual variability in circulating concentrations of retinol, carotenoids, 25-hydroxyvitamin D3, α-tocopherol, γ-tocopherol, and phylloquinone in 35 overweight and obese, but healthy men. A sparse partial least-squares method was used to accomplish this aim. Highly abundant phospholipids and triglycerides (TGs) contributed to the interindividual variability in phylloquinone, α-tocopherol, and γ-tocopherol. Interindividual variability in lycopene concentrations was driven by concentrations of low-abundant TG. 25-Hydroxyvitamin D3, retinol, and the other carotenoids were not influenced by lipids. Except for lycopene, evaluation of lipids beyond class does not appear to further explain the interindividual variability in circulating concentrations of fat-soluble vitamins and carotenoids.

Vitamin K status, cardiovascular disease, and all-cause mortality: a participant-level meta-analysis of 3 US cohorts

BACKGROUND

Vitamin K-dependent proteins in vascular tissue affect vascular stiffness and calcification, which is associated with cardiovascular disease (CVD) and all-cause mortality.

OBJECTIVE

To determine the association of circulating vitamin K concentrations with CVD and all-cause mortality by conducting a participant-level meta-analysis.

METHODS

We obtained individual participant-level data from the Health, Aging, and Body Composition Study, the Multi-Ethnic Study of Atherosclerosis, and the Framingham Offspring Study, known cohorts with available measures of fasting circulating phylloquinone (vitamin K-1) and confirmed CVD events and mortality. Circulating phylloquinone was measured in a central laboratory from fasting blood samples and categorized as ≤0.5 nmol/L, >0.5-1.0 nmol/L, and >1.0 nmol/L. Multivariable Cox proportional hazard regression with multiple imputations was used to evaluate the association of circulating phylloquinone with incident CVD and all-cause mortality risk.

RESULTS

Among 3891 participants (mean age 65 ± 11 y; 55% women; 35% nonwhite), there were 858 incident CVD events and 1209 deaths over a median of 13.0 y. The risk of CVD did not significantly differ according to circulating phylloquinone [fully adjusted HR (95% CI) relative to >1.0 nmol/L: ≤0.5 nmol/L, 1.12 (0.94, 1.33); >0.5-1.0 nmol/L, 1.02 (0.86, 1.20)]. Participants with ≤0.5 nmol/L circulating phylloquinone had an adjusted 19% higher risk of all-cause mortality compared with those with >1.0 nmol/L [fully adjusted HR (95% CI): 1.19 (1.03, 1.38)]. Mortality risk was similar in participants with >0.5-1.0 nmol/L compared with >1.0 nmol/L [fully adjusted HR (95% CI): 1.04 (0.92, 1.17)].

CONCLUSIONS

Low circulating phylloquinone concentrations were associated with an increased risk of all-cause mortality, but not of CVD. Additional studies are needed to clarify the mechanism underlying this association and evaluate the impact of increased phylloquinone intake on cardiovascular and other health outcomes in individuals with low vitamin K status.

Development, Optimization, and Comparison of Different Sample Pre-Treatments for Simultaneous Determination of Vitamin E and Vitamin K in Vegetables

The absence of vitamin E from the diet can lead to cardiovascular disease, cancer, cataracts, and premature aging. Vitamin K deficiency can lead to bleeding disorders. These fat-soluble vitamins are important nutritional factors that can be determined in different methods in vegetables. In this work, the simultaneous determination of α-tocopherol, α-tocopheryl acetate, phylloquinone, and menaquinone-4 by gas chromatography–mass spectrometry (GC–MS) has been optimized using both direct injection and solid phase microextraction (SPME). Three different sample pre-treatment approaches based on: (A) solid–liquid–liquid–liquid extraction (SLE–LLE), (B) SLE, and (C) SPME were then applied to extract the target analytes from vegetables samples using menaquinone as internal standard. All the procedures allowed the determination of the target analytes in onion, carrot, celery, and curly kale samples. Similar results were obtained with the three different approaches, even if the one based on SPME offers the best performance, together with a reduced use of solvent, time consumption, and experimental complexity, which makes it the preferable option for industrial applications.

The Relationship between Vitamin K and Osteoarthritis: A Review of Current Evidence

Vitamin K is a cofactor of γ-glutamyl carboxylase, which plays an important role in the activation of γ-carboxyglutamate (gla)-containing proteins that negatively regulate calcification. Thus, vitamin K status might be associated with osteoarthritis (OA), in which cartilage calcification plays a role in the pathogenesis of the disease. This review collates the evidence on the relationship between vitamin K status (circulating or dietary intake level of vitamin K, or circulating uncarboxylated gla proteins) and OA from human observational studies and clinical trial, to examine its potential as an agent in preventing OA. The current literature generally agrees that a sufficient level of vitamin K is associated with a lower risk of OA and pathological joint features. However, evidence from clinical trials is limited. Mechanistic study shows that vitamin K activates matrix gla proteins that inhibit bone morphogenetic protein-mediated cartilage calcification. Gla-rich proteins also inhibit inflammatory cascade in monocytic cell lines, but this function might be independent of vitamin K-carboxylation. Although the current data are insufficient to establish the optimal dose of vitamin K to prevent OA, ensuring sufficient dietary intake seems to protect the elderly from OA.

Prevalence of vitamin K deficiency in older people with hip fracture

Introduction: Vitamin K plays an important role in blood coagulation. Diet is the main source of vitamin K and body stores are depleted in days, hence deficiency is common in malnourished older people. A high proportion of people who sustain a hip fracture are already malnourished, compounded by fasting for surgery which might further increase deficiency. We wanted to explore the prevalence of vitamin K deficiency in hip fracture patients and the impact of a short period of fasting.Methods: In consecutive patients hospitalised with a hip fracture, we measured vitamin K and PIVKA-II (undercarboxylated factor II - a marker of subclinical vitamin K status) on admission and on first post-operative day. We excluded those on anticoagulants.Results: N = 62 participated; 4 had missing pre-op vitamin K samples and n = 3 had no surgery leaving n = 55 with paired samples. Mean age was 80.0 ± 9.6 years, 33% males. Prevalence of subclinical vitamin K deficiency on admission was 36% (20/55) based on reference range of > 0.15µg/L. The proportion with subclinical K deficiency after surgery rose to 64% (35/55), p < 0.05. 13% had detectable PIVKA-II concentrations pre-operatively, 15% did post-operatively. None had abnormal prothrombin time. Vitamin K status was not associated with post-operative haemoglobin drop or transfusion requirements.Conclusion: Prevalence of vitamin K deficiency in hip fracture patients is high and increases further following a short period of fasting. Though no significant impact was noted on peri-operative blood loss, larger studies are warranted to explore this, and the potential role of vitamin K supplements peri-operatively.

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.

Concentrations of Circulating Phylloquinone, but Not Cerebral Menaquinone-4, Are Positively Correlated with a Wide Range of Cognitive Measures: Exploratory Findings in Centenarians

BACKGROUND

Vitamin K (VK) exists in the form of phylloquinone (PK) and menaquinones (MKs). Roles of VK on cognitive health in the elderly are emerging, but there is limited evidence on VK uptake and metabolism in human brain.

OBJECTIVES

The primary objective of this study was to characterize VK distribution in brains of an elderly population with varied cognitive function. In addition, associations among circulating (a biomarker of VK intake) and cerebral VK concentrations and cognition were investigated.

METHODS

Serum or plasma (n = 27) and brain samples from the frontal cortex (FC; n = 46) and the temporal cortex (TC; n = 33) were acquired from 48 decedents (aged 98-107 y; 25 demented and 23 nondemented) enrolled in the Georgia Centenarian Study. Both circulating and brain VK concentrations were measured using HPLC with fluorescence detection. Cognitive assessment was performed within 1 y prior to mortality. Partial correlations between serum/plasma or cerebral VK concentrations and cognitive function were performed, adjusting for covariates and separating by dementia and antithrombotic use.

RESULTS

MK-4 was the predominant vitamer in both FC (mean ± SD = 4.92 ± 2.31 pmol/g, ≥89.15% ± 5.09% of total VK) and TC (4.60 ± 2.11 pmol/g, ≥89.71% ± 4.43% of total VK) regardless of cognitive status. Antithrombotic users had 34.0% and 53.9% lower MK-4 concentrations in FC (P < 0.05) and TC (P < 0.001), respectively. Circulating PK was not correlated with cerebral MK-4 or total VK concentrations. Circulating PK concentrations were significantly associated with a wide range of cognitive measures in nondemented centenarians (P < 0.05). In contrast, cerebral MK-4 concentrations were not associated with cognitive performance, either before or after exclusion of antithrombotic users.

CONCLUSIONS

Circulating VK concentrations are not related to cerebral MK-4 concentrations in centenarians. Cerebral MK-4 concentrations are tightly regulated over a range of VK intakes and cognitive function. Circulating PK may reflect intake of VK-rich foods containing other dietary components beneficial to cognitive health. Further investigation of VK uptake and metabolism in the brain is warranted.

Effects of MK-7 Supplementation on Glycemic Status, Anthropometric Indices and Lipid Profile in Patients with Type 2 Diabetes: A Randomized Controlled Trial

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a prevalent disorder which accounts for 90-95% of diabetic patients. The aim of this study was to assess the effects of menaquinone (MK-7) supplementation on glycemic indices, anthropometric indices and lipid profile, among patients with T2DM.

METHODS

In this double-blind placebo-controlled randomized clinical trial, 60 men and women with T2DM were allocated equally into either the MK-7 (200 µg/day) or the placebo group. Physical activity level and dietary intake were assessed using the international physical activity questionnaire-short form (IPAQ-SF) and a 3-day food record, pre- and post-intervention. Anthropometric measures, blood pressure, glycemic indices and lipid profile including fasting blood sugar (FBS), hemoglobin A1c (HBA1C), fasting insulin (FI), homeostatic model assessment insulin resistance index (HOMA-IR), triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL-C) and low-density lipoprotein (LDL-C) were measured at baseline and after twelve weeks.

RESULTS

Forty-five patients completed the trial. There were no significant between-group differences for calorie intake, macronutrient intake, physical activity level or anthropometric measures at baseline and at the end of the study. Dietary vitamin K intake increased significantly at the end of the study in the MK-7 (p: 0.02) and placebo (p: 0.001) groups, but intergroup differences were not significant (p: 0.86). FBS (p: 0.01), HbA1c (p: 0.002), fasting insulin (p: 0.01) and HOMA-IR (p: 0.007) decreased significantly in the MK-7 group. Furthermore, after adjustment for the baseline values and changes of vitamin K intake at the end of study, FBS and HbA1C showed significant intergroup changes, and they were significantly lower in the MK-7 group compared to the placebo group. Lipid profile (TG, TC, LDL-C, HDL-C and LDL-C/HDL-C) did not change significantly within or between groups.

CONCLUSION

MK-7 supplementation seems to be effective in the improvement of glycemic indices, but not the lipid profile of patients with T2DM.

CLINICAL TRIAL REGISTRATION

The present study was prospectively registered at the Iranian Registry of Clinical Trials on May 2019 (ID: IRCT20100123003140N22).

Minimizing an Electron Flow to Molecular Oxygen in Photosynthetic Electron Transfer Chain: An Evolutionary View

Recruitment of H₂O as the final donor of electrons for light-governed reactions in photosynthesis has been an utmost breakthrough, bursting the evolution of life and leading to the accumulation of O₂ molecules in the atmosphere. O₂ molecule has a great potential to accept electrons from the components of the photosynthetic electron transfer chain (PETC) (so-called the Mehler reaction). Here we overview the Mehler reaction mechanisms, specifying the changes in the structure of the PETC of oxygenic phototrophs that probably had occurred as the result of evolutionary pressure to minimize the electron flow to O₂. These changes are warranted by the fact that the efficient electron flow to O₂ would decrease the quantum yield of photosynthesis. Moreover, the reduction of O₂ leads to the formation of reactive oxygen species (ROS), namely, the superoxide anion radical and hydrogen peroxide, which cause oxidative stress to plant cells if they are accumulated at a significant amount. From another side, hydrogen peroxide acts as a signaling molecule. We particularly zoom in into the role of photosystem I (PSI) and the plastoquinone (PQ) pool in the Mehler reaction.

The Contribution of Lipids to the Interindividual Response of Vitamin K Biomarkers to Vitamin K Supplementation

SCOPE

A better understanding of factors contributing to interindividual variability in biomarkers of vitamin K can enhance the understanding of the equivocal role of vitamin K in cardiovascular disease. Based on the known biology of phylloquinone, the major form of vitamin K, it is hypothesized that plasma lipids contribute to the variable response of biomarkers of vitamin K metabolism to phylloquinone supplementation.

METHODS AND RESULTS

The association of plasma lipids and 27 lipid-related genetic variants with the response of biomarkers of vitamin K metabolism is examined in a secondary analysis of data from a 3-year phylloquinone supplementation trial in men (n = 66) and women (n = 85). Year 3 plasma triglycerides (TG), but not total cholesterol, LDL-cholesterol, or HDL-cholesterol, are associated with the plasma phylloquinone response (men: β = 1.01, p < 0.001, R2  = 0.34; women: β = 0.61, p = 0.008, R2  = 0.11; sex interaction p = 0.077). Four variants and the TG-weighted genetic risk score are associated with the plasma phylloquinone response in men only. Plasma lipids are not associated with changes in biomarkers of vitamin K function (undercarboxylated osteocalcin and matrix gla protein) in either sex.

CONCLUSION

Plasma TG are an important determinant of the interindividual response of plasma phylloquinone to phylloquinone supplementation, but changes in biomarkers of vitamin K carboxylation are not influenced by lipids.

Barley isochorismate synthase mutant is phylloquinone-deficient, but has normal basal salicylic acid level

Salicylic acid (SA) is an important signaling hormone in plant immunity. It can be synthesized by either the phenylpropanoid pathway or the isochorismate pathway, but mutant studies of this have been scarce in other species than Arabidopsis. Here we identified a mutation that introduced a stop-codon early in the barley gene for isochorismate synthase (ICS). We found that homozygous ics plants wilted if not sprayed with 1,4-dihydroxy-2-naphthoic acid, a precursor of phylloquinone, also synthesized via the isochorismate pathway. Interestingly, ics had unchanged SA, suggesting that the basal level of SA is synthesized via the phenylpropanoid pathway. Previous studies have failed seeing increased SA levels in barley after attack by the powdery mildew fungus, Blumeria graminis f.sp. hordei (Bgh), and indeed, we saw no changes in the interaction of ics with this fungus. Overall, we hope this mutant will be useful for other studies of SA in barley.

Vitamin K, Vascular Calcification, and Chronic Kidney Disease: Current Evidence and Unanswered Questions

More than 15% of the US population is currently >65 y old. As populations age there is a concomitant increase in age-related chronic diseases. One such disease is chronic kidney disease (CKD), which becomes more prevalent with age, especially over age 70 y. Individuals with CKD are at increased risk of cardiovascular disease, in part because arterial calcification increases as kidney function declines. Vitamin K is a shortfall nutrient among older adults that has been implicated in arterial calcification. Evidence suggests CKD patients have low vitamin K status, but data are equivocal because the biomarkers of vitamin K status can be influenced by CKD. Animal studies provide more compelling data on the underlying role of vitamin K in arterial calcification associated with CKD. The purpose of this review is to evaluate the strengths and limitations of the available evidence regarding the role of vitamin K in CKD.

Trends of INR and Fecal Excretion of Vitamin K During Cholestasis Reversal: Implications in the Treatment of Neonates With Intestinal Failure-Associated Liver Disease

BACKGROUND

Vitamin K is a fat-soluble compound that plays important roles in coagulation. In children with intestinal failure-associated liver disease (IFALD), the disrupted enterohepatic circulation can lead to intestinal loss of vitamin K. Fish oil-based lipid emulsion (FOLE) has proven effective in treating IFALD. As biliary excretion is restored during cholestasis reversal, the accelerated vitamin K loss can pose a risk for deficiency.

METHODS

Ten neonates with IFALD and receiving FOLE monotherapy were prospectively enrolled in the study from 2016 to 2018. In addition to weekly measurements of international normalized ratio (INR) and direct bilirubin (DB), ostomy output was collected for determination of fecal concentrations of phylloquinone (PK). Trends of DB, INR, and fecal PK concentrations were summarized with locally estimated scatterplot smoothing.

RESULTS

The median time (interquartile range) from FOLE initiation to cholestasis reversal was 59 (19-78) days. During cholestasis reversal, INR remained relatively unchanged, whereas the mean (95% confidence interval) daily fecal excretion of PK increased from 25.1 (5.0-158.5) ng at the time of FOLE initiation to 158.5 (31.6-1000.0) ng at complete reversal. Examination of individual trends in fecal PK excretion and INR revealed little correlation between the 2 measurements (r = -0.10; P = 0.50).

CONCLUSION

Children with IFALD are at risk for vitamin K deficiency during cholestasis reversal. Close monitoring and quantified supplementation of vitamin K may be warranted during this period. However, this should not be guided by INR alone, as it is a poor indicator of vitamin K status.

Kinetics and Energetics of Phylloquinone Reduction in Photosystem I: Insight From Modeling of the Site Directed Mutants

Two phylloquinone molecules (A ₁), one being predominantly coordinated by PsaA subunit residues (A _1A) the other by those of PsaB (A _1B), act as intermediates in the two parallel electron transfer chains of Photosystem I. The oxidation kinetics of the two phyllosemiquinones by the iron-sulfur cluster F_X differ by approximately one order of magnitude, with A 1 A - being oxidized in about 200 ns and A 1 B - in about 20 ns. These differences are generally explained in terms of asymmetries in the driving force for F_X reduction on the two electron transfer chains. Site directed mutations of conserved amino acids composing the A ₁ binding site have been engineered on both reaction center subunits, and proved to affect selectively the oxidation lifetime of either A 1 A - , for PsaA mutants, or A 1 B - , for PsaB mutants. The mutation effects are here critically reviewed, also by novel modeling simulations employing the tunneling formalism to estimate the electron transfer rates. Three main classes of mutation effects are in particular addressed: (i) those leading to an acceleration, (ii) those leading to a moderated slowing (~5-folds), and (iii) those leading to a severe slowing (>20-folds) of the kinetics. The effect of specific amino acid perturbations contributing to the poising of the phylloquinones redox potential and, in turn, to PSI functionality, is discussed.

Microwave Assisted Cloud Point Extraction for the Determination of Vitamin K Homologues in Vegetables by Liquid Chromatography with Tandem Mass Spectrometry

Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) with a triple quadrupole (QqQ) is proposed for determining the vitamin K homologues, phylloquinone (PK), menaquinone-4 (MK) and menadione (MD), in vegetables. The analytes were isolated from the samples (1-1.5 g) by ultrasound assisted extraction using acetonitrile (2 mL), and the liquids were submitted to microwave assisted cloud point extraction with Triton X-45. The enrichment factors were between 20 and 50, depending on the vitamin homologue in question. The analytes were determined by LC-ESI-QqQ-MS/MS in the multiple reaction monitoring (MRM) mode, providing unequivocal identification and quantification, with limits of detection of 0.8, 1.0, and 16 ng/g for MK, PK, and MD, respectively. Recovery assays for samples spiked at two concentration levels, between 40 and 600 ng/g depending on the compound, provided recoveries in the 90-114% range. Only PK was detected in the samples analyzed, at concentrations in the 90-2350 ng/g range.