Vitamin K intake and osteocalcin levels in women with and without aortic atherosclerosis: a population-based study

Modic Changes in the Lumbar Spine: Exploring Their Association with Abdominal Aortic Calcification as a Potential Indicator of Systemic Atherosclerosis

BACKGROUND

This was a cross-sectional study on the correlation between abdominal aortic calcification (AAC) and Modic changes (MC). Little is known regarding the etiology of MC in the lumbar spine. Currently, insufficient vascularization of the endplate has been proposed to contribute to the appearance of MC. Our objective was to investigate whether AAC, a marker for a poor vascular status, is associated with MC in patients suffering from degenerative disc disease.

METHODS

Radiologic images of patients (n = 130) suffering from degenerative lumbar disc disease were reviewed. Type and severity of MC were assessed using magnetic resonance images, and severity of AAC was evaluated using computed tomography images or fluoroscopy. Both items were dichotomized into minimal and relevant grades. The correlation between them was studied using Spearman's correlation test, with age as a covariate.

RESULTS

Of the patients, 113 (87%) demonstrated MC (31% type I, 63% type II, and 6% type III) (55% relevant grade), and 68% had AAC (44% relevant grade). Spearman statistical analysis revealed that AAC was correlated with age (P < 0.001), whereas MC were not (P = 0.142). AAC severity was significantly correlated with MC, remaining so after age adjustment (P < 0.05). While MC type I lacked correlation with AAC, MC type II were significantly correlated with AAC (0.288, P = 0.015); however, this association lost significance after adjusting for age (P = 0.057).

CONCLUSIONS

AAC and MC (mainly MC type II) are associated, indicating that reduced blood supply or even a poor systemic vascularization status due to atherosclerotic disease may play a role in the formation of MC. Future studies focusing on the etiology of MC should pay more attention to patients' vascular status and determinants of abdominal aorta calcification.

Identification of dietary components in association with abdominal aortic calcification

The precise impact of dietary components on vascular health remains incompletely understood. To identify the dietary components and their associations with abdominal aortic calcification (AAC), the data from NHANES was employed in this cross-sectional study. The LASSO method and logistic regression were utilized to identify dietary components that exhibited the strongest association with AAC. Grouped WQS regression analysis was employed to evaluate the combined effects of dietary components on AAC. Furthermore, principal component analysis was employed to identify the primary dietary patterns in the study population. The present analysis included 1862 participants, from whom information on 35 dietary macro- and micronutrient components was obtained through 24-hour dietary recall interviews. The assessment of AAC was performed utilizing dual-energy X-ray absorptiometry. The LASSO method identified 10 dietary components that were associated with AAC. Total protein, total fiber, vitamin A, and β-cryptoxanthin exhibited a negative association with AAC. Compared to the first quartile, the adjusted odds ratios (95% CIs) for the highest quartile were 0.59 (0.38, 0.93), 0.63 (0.42, 0.93), 0.59 (0.41, 0.84), and 0.68 (0.48, 0.94), respectively. Grouped WQS regression demonstrated a positive association between the lipid group and AAC (aOR: 1.29; 95% CI: 1.12, 1.50), while the proteins and phytochemical group exhibited a negative association with AAC (aOR: 0.69; 95% CI: 0.58, 0.82). For the dietary pattern analysis, high adherence to the plant-based pattern (aOR: 0.62; 95% CI: 0.44, 0.88) was associated with a lower risk of AAC, whereas the caffeine and theobromine pattern (aOR: 1.73; 95% CI: 1.25, 2.41) was associated with a higher risk of AAC. The findings of this study indicate that adopting a dietary pattern characterized by high levels of protein and plant-based foods, as well as reduced levels of fat, may offers potential advantages for the prevention of AAC.

Tomatoes: An Extensive Review of the Associated Health Impacts of Tomatoes and Factors That Can Affect Their Cultivation

Simple Summary

The research outlined in this review paper discusses potential health benefits associated with a diet enriched with tomatoes and tomato products. This includes details of previous studies investigating the anticancer properties of tomatoes, protection against cardiovascular and neurodegenerative diseases and diabetes, maintenance of a healthy gut microbiome, and improved skin health, fertility, immune response, and exercise recovery. The specific parts of a tomato fruit that contribute these health benefits are also outlined. The potential disadvantages to a tomato-rich diet are detailed, especially the consumption of supplements that contain compounds found in tomatoes, such as lycopene. This review also discusses how the cultivation of tomato plants can affect the nutritional value of the fruit harvested. Different environmental growing conditions such as light intensity, growing media, and temperature are explained in terms of the impact they have on the quality of fruit, its nutrient content, and hence the potential health benefits acquired from eating the fruit.

Abstract

This review outlines the health benefits associated with the regular consumption of tomatoes and tomato products. The first section provides a detailed account of the horticultural techniques that can impact the quality of the fruit and its nutritional properties, including water availability, light intensity, temperature, and growing media. The next section provides information on the components of tomato that are likely to contribute to its health effects. The review then details some of the health benefits associated with tomato consumption, including anticancer properties, cardiovascular and neurodegenerative diseases and skin health. This review also discusses the impact tomatoes can have on the gut microbiome and associated health benefits, including reducing the risk of inflammatory bowel diseases. Other health benefits of eating tomatoes are also discussed in relation to effects on diabetes, the immune response, exercise recovery, and fertility. Finally, this review also addresses the negative effects that can occur as a result of overconsumption of tomato products and lycopene supplements.

Emerging Role of Vitamins D and K in Modulating Uremic Vascular Calcification: The Aspect of Passive Calcification

Vascular calcification is a critical complication in patients with chronic kidney disease (CKD) because it is predictive of cardiovascular events and mortality. In addition to the traditional mechanisms associated with endothelial dysfunction and the osteoblastic transformation of vascular smooth muscle cells (VSMCs), the regulation of calcification inhibitors, such as calciprotein particles (CPPs) and matrix vesicles plays a vital role in uremic vascular calcification in CKD patients because of the high prevalence of vitamin K deficiency. Vitamin K governs the gamma-carboxylation of matrix Gla protein (MGP) for inhibiting vascular calcification, and the vitamin D binding protein receptor is related to vitamin K gene expression. For patients with chronic kidney disease, adequate use of vitamin D supplements may play a role in vascular calcification through modulation of the calciprotein particles and matrix vesicles (MVs).

Effect of vitamin K in bone metabolism and vascular calcification: A review of mechanisms of action and evidences

Osteoporosis is a public health concern associated with an increased risk of bone fractures and vascular calcification. Vitamin K presents unique benefits on these issues, although understudied. The two main forms of vitamin K are phylloquinone (vitamin K₁) and menaquinone (vitamin K₂). In this study, it was especially investigated the action of vitamin K₂ in bones and vessels. Vitamin K₂ has shown to stimulate bone formation by promoting osteoblast differentiation and carboxylation of osteocalcin, and increasing alkaline phosphatase, insulin-like growth factor-1, growth differentiation factor-15, and stanniocalcin 2 levels. Furthermore, vitamin K₂ reduces the pro-apoptotic proteins Fas and Bax in osteoblasts, and decreases osteoclast differentiation by increasing osteoprotegerin and reducing the receptor activator of nuclear factor kappa-B ligand. In blood vessels, vitamin K₂ reduces the formation of hydroxyapatite, through the carboxylation of matrix Gla protein and Gla rich protein, inhibits the apoptosis of vascular smooth muscle cells, by increasing growth arrest-specific gene 6, and reduces the transdifferentiation of vascular smooth muscle cells to osteoblasts. The commonly used dosage of vitamin K₂ in human studies is 45 mg/day and its application can be an interesting strategy in benefitting bone and vascular health, especially to osteoporotic post-menopausal women.

Phylloquinone Intake Is Associated with Cardiac Structure and Function in Adolescents

BACKGROUND

Associations between childhood vitamin K consumption and cardiac structure and function have not been investigated.

OBJECTIVE

We determined associations between phylloquinone (vitamin K-1) intake and left ventricular (LV) structure and function in adolescents.

METHODS

We assessed diet with three to seven 24-h recalls and physical activity (PA) by accelerometry in 766 adolescents (aged 14-18 y, 50% female, 49% black). Fat-free soft tissue (FFST) mass and fat mass were measured by dual-energy X-ray absorptiometry. LV structure [LV mass (g)/height (m)2.7 (LV mass index) and relative wall thickness] and function [midwall fractional shortening (MFS) and ejection fraction] were assessed by echocardiography. Associations were evaluated by comparing the LV structure and function variables across tertiles of phylloquinone intake. Prevalence and OR of LV hypertrophy (LV mass index >95th percentile for age and sex) were also assessed by phylloquinone tertiles.

RESULTS

The prevalence of LV hypertrophy progressively decreased across tertiles of phylloquinone intake (P-trend < 0.01). Multinomial logistic regression-adjusting for age, sex, race, Tanner stage, systolic blood pressure, FFST mass, fat mass, socioeconomic status, PA, and intakes of energy, fiber, calcium, vitamin C, vitamin D, and sodium-revealed that compared with the highest phylloquinone intake tertile (reference group), the adjusted OR for LV hypertrophy was 3.3 (95% CI: 1.2, 7.4) for those in the lowest phylloquinone intake tertile. When LV structure variables were compared across phylloquinone intake tertiles adjusting for the same covariates, there were significant linear downward trends for LV mass index (6.5% difference, tertile 1 compared with tertile 3) and relative wall thickness (9.2% difference, tertile 1 compared with tertile 3; both P-trend ≤ 0.02). Conversely, significant linear upward trends across phylloquinone intake tertiles were observed for MFS (3.4% difference, tertile 1 compared with tertile 3) and ejection fraction (2.6% difference, tertile 1 compared with tertile 3; both P-trend < 0.04).

CONCLUSION

Our adolescent data suggest that subclinical cardiac structure and function variables are most favorable at higher phylloquinone intakes.

Synergistic effect of low K and D vitamin status on arterial stiffness in a general population

Both vitamins K and D are nutrients with pleiotropic functions in human tissues. The metabolic role of these vitamins overlaps considerably in calcium homeostasis. We analyzed their potential synergetic effect on arterial stiffness. In a cross-sectional study, we analyzed aortic pulse wave velocity (aPWV) in 1023 subjects from the Czech post-MONICA study. Desphospho-uncarboxylated matrix γ-carboxyglutamate protein (dp-ucMGP), a biomarker of vitamin K status, was measured by sandwich ELISA and 25-hydroxyvitamin D3 (25-OH-D3) by a commercial immunochemical assay. In a subsample of 431 subjects without chronic disease or pharmacotherapy, we detected rs2228570 polymorphism for the vitamin D receptor. After adjustment for confounders, aPWV was independently associated with both factors: dp-ucMGP [β-coefficient(S.E.M.)=13.91(4.87); P=.004] and 25-OH-D3 [0.624(0.28); P=.027]. In a further analysis, we divided subjects according to dp-ucMGP and 25-OH-D3 quartiles, resulting in 16 subgroups. The highest aPWV had subjects in the top quartile of dp-ucMGP plus bottom quartile of 25-OH-D3 (i.e., in those with insufficient status of both vitamin K and vitamin D), while the lowest aPVW had subjects in the bottom quartile of dp-ucMGP plus top quartile of 25-OH-D3 [9.8 (SD2.6) versus 6.6 (SD1.6) m/s; P<.0001]. When we compared these extreme groups of vitamin K and D status, the adjusted odds ratio for aPWV≥9.3 m/s was 6.83 (95% CI:1.95-20.9). The aPWV was also significantly higher among subjects bearing the GG genotype of rs2228570, but only in those with a concomitantly poor vitamin K status. In conclusion, we confirmed substantial interaction of insufficient K and D vitamin status in terms of increased aortic stiffness.

Dietary reference values for vitamin K

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

Observations on Possible Effects of Daily Vitamin K Replacement, Especially Upon Warfarin Therapy

Daily parenteral vitamin K supplement is now recommended by the U.S. Food and Drug Administration (FDA) for patients receiving IV hyperalimentation. This is considered as preferable to the previous recommendations of weekly parenteral or oral supplement, or as in some cases no supplement at all. Supplemental vitamin K1 will ensure adequate supplies for hepatic saturation and thus the production of clotting factors II, VII, IX, and X, plus the anticoagulants protein C, protein S, and protein Z. But this is not the entire story. This recommended supplement will affect other physiologic systems that also use vitamin K-dependent gamma-carboxylation. Vitamin K is not 1 molecule but rather 2 natural substances, vitamin K1 and K2, and the synthetic K3's. It is not understood, what, if any, effect may occur because of the saturation or competition from the vitamin K1 upon the functioning of vitamins K2 and the derivatives of K3 in vivo upon bone mineralization, cell growth, and blood vessel health, all known to be influenced by the vitamins K. There are probably other physiologic systems yet to be studied relative to vitamins K and gamma-carboxylation. This review also considers the available research upon warfarin when given to patients receiving hyperalimentation and what effects the vitamin K supplements may have. Because studies to date have not controlled for vitamin K intake, consideration is given to whether one should expect any change in previously reported outcomes when using low-dose warfarin for prophylaxis against central vein thrombosis. Also considered are possible positive or negative effects that chronic warfarin therapy may have upon the other vitamin K-dependent systems under discussion. This review offers a platform for further discussion and derived clinical research provoked by this new FDA recommendation.

Osteocalcin, Vascular Calcification, and Atherosclerosis: A Systematic Review and Meta-analysis

BACKGROUND

Osteocalcin (OC) is an intriguing hormone, concomitantly being the most abundant non-collagenous peptide found in the mineralized matrix of bone, and expanding the endocrine function of the skeleton with far-reaching extra-osseous effects. A new line of enquiry between OC and vascular calcification has emerged in response to observations that the mechanism of vascular calcification resembles that of bone mineralisation. To date, studies have reported mixed results. This systematic review and meta-analysis aimed to identify any association between OC and vascular calcification and atherosclerosis.

METHODS AND RESULTS

Databases were searched for original, peer reviewed human studies. A total of 1,453 articles were retrieved, of which 46 met the eligibility criteria. Overall 26 positive, 17 negative, and 29 neutral relationships were reported for assessments between OC (either concentration in blood, presence of OC-positive cells, or histological staining for OC) and extent of calcification or atherosclerosis. Studies that measured OC-positive cells or histological staining for OC reported positive relationships (11 studies). A higher percentage of Asian studies found a negative relationship (36%) in contrast to European studies (6%). Studies examining carboxylated and undercarboxylated forms of OC in the blood failed to report consistent results. The meta-analysis found no significant difference between OC concentration in the blood between patients with "atherosclerosis" and control (p = 0.13, n = 1,197).

CONCLUSION

No definitive association was determined between OC and vascular calcification or atherosclerosis; however, the presence of OC-positive cells and histological staining had a consistent positive correlation with calcification or atherosclerosis. The review highlighted several themes, which may influence OC within differing populations leading to inconclusive results. Large, longitudinal studies are required to further current understanding of the clinical relevance of OC in vascular calcification and atherosclerosis.

Desphospho-uncarboxylated matrix Gla protein is associated with increased aortic stiffness in a general population

Matrix Gla protein (MGP), a natural inhibitor of calcification, strongly correlates with the extent of coronary calcification. Vitamin K is the essential cofactor for the activation of MGP. The nonphosphorylated-uncarboxylated isoform of MGP (dp-ucMGP) reflects the status of this vitamin. We investigated whether there is an association between dp-ucMGP and stiffness of elastic and muscular-type large arteries in a random sample from the general population. In a cross-sectional design, we analyzed 1087 subjects from the Czech post-MONICA study. Aortic and femoro-popliteal pulse wave velocities (PWVs) were measured using a Sphygmocor device. Dp-ucMGP concentrations were assessed in freshly frozen samples by enzyme-linked immunosorbent assay methods using the InaKtif MGP iSYS pre-commercial kit developed by IDS and VitaK. Aortic PWV significantly (P<0.0001) increased across the dp-ucMGP quartiles. After adjustment for all potential confounders, aortic PWV independently correlated with dp-ucMGP (with beta coefficient (s.d.) 11.61 (5.38) and P-value=0.031). In a categorized manner, subjects in the top quartile of dp-ucMGP (⩾ 671 pmol l(-1)) had a higher risk of elevated aortic PWV, with corresponding adjusted odds ratio (95% confidence interval) 1.73 (1.17-2.5). In contrast, no relation between dp-ucMGP and femoro-popliteal PWV was found. In conclusion, increased dp-ucMGP, which is a circulating biomarker of vitamin K status and vascular calcification, is independently associated with aortic stiffness, but not with stiffness of distal muscular-type arteries.

Vitamin K for the primary prevention of cardiovascular disease

BACKGROUND

A deficiency in vitamin K has been associated with increased calcium deposition and coronary artery calcification, which may lead to cardiovascular disease.

OBJECTIVES

To determine the effectiveness of vitamin K supplementation as a single nutrient supplement for the primary prevention of cardiovascular disease.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL, Issue 8 of 12, 2014); MEDLINE (Ovid, 1946 to September week 2 2014); EMBASE Classic + EMBASE (Ovid, 1947 to September 18 2014); Science Citation Index Expanded (SCI-EXPANDED) and Conference Proceedings Citation Index, Science (CPCI-S) (both 1990 to 17 September 2014) on Web of Science (Thomson Reuters); Database of Abstracts of Reviews of Effects (DARE); Health Technology Assessment Database and Health Economics Evaluations Database (Issue 3 of 4, 2014). We searched trial registers and reference lists of reviews for further studies. We applied no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials of vitamin K supplementation as a single nutrient supplement, lasting at least three months, and involving healthy adults or adults at high risk of cardiovascular disease. The comparison group was no intervention or placebo. The outcomes of interest were cardiovascular disease clinical events and cardiovascular disease risk factors.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, abstracted the data and assessed the risk of bias.

MAIN RESULTS

We included only one small trial (60 participants randomised) which overall was judged to be at low risk of bias. The study examined two doses of menaquinone (vitamin K2) over 3 months in healthy participants aged 40 to 65 years. The primary focus of the trial was to examine the effects of menaquinone (subtype MK7) on different matrix Gla proteins (MGP - vitamin K dependent proteins in the vessel wall) at different doses, but the authors also reported blood pressure and lipid levels. The trial did not report on our primary outcomes (cardiovascular disease clinical events) as it was small, short term and conducted in healthy participants.In terms of cardiovascular disease risk factors, no effects were seen for vitamin K2 on blood pressure or lipid levels, although the trial was small and findings are limited. The trial did not report any of our other secondary outcomes.

AUTHORS' CONCLUSIONS

The very limited results of this review highlight the lack of evidence currently available to determine the effectiveness of vitamin K supplementation for the primary prevention of cardiovascular disease, and demonstrate the need for further high quality trials in this area.

Coronary artery calcification is associated with high serum concentration of undercarboxylated osteocalcin in asymptomatic Korean men

CONTEXT

Osteocalcin is associated with energy metabolism and atherosclerosis, besides bone metabolism. However, the association between osteocalcin or its undercarboxylated form (ucOC) and coronary artery calcification is controversial.

OBJECTIVE

To evaluate the relationship between coronary artery calcium score (CACS) and the concentration of serum osteocalcin and ucOC.

DESIGN

Cross-sectional.

PATIENTS

A total of 162 subjects (114 men and 48 women) with no angina symptom.

MEASUREMENTS

Serum analyses included glucose, insulin and lipid profiles as well as osteocalcin and ucOC. Bone mineral density (BMD) was measured by dual X-ray absorptiometry. CACS was measured using multidetector computed tomography and categorized into CACS = 0 and CACS > 0.

RESULTS

The mean osteocalcin concentration in men was 15·6 ± 4·2 for CACS = 0 group and 14·1 ± 4·0 for CACS > 0 group, respectively (P = 0·050). In women, the osteocalcin concentration, ucOC concentration and ucOC to osteocalcin ratio (OCR) were not different between the CACS groups. However, the concentrations of osteocalcin and ucOC were significantly lower in women with hypertension or diabetes than those without, respectively. In the multivariate logistic regression models adjusted for medical history, body mass index, lipid profiles, insulin resistance and BMD in men, the higher concentration of ucOC and higher OCR showed significant association with coronary calcification (CACS > 0).

CONCLUSION

Higher ucOC concentration was associated with coronary artery calcification independent of conventional cardiovascular risk factors and BMD in men.

[The matrix-gla protein awakening may lead to the demise of vascular calcification]

Matrix-gla-protein (MGP) is mainly secreted by chondrocytes and smooth vascular muscle cells. This potent inhibitor of vascular calcification need to undergo 2 post-transcriptional steps to be fully active: one phosphorylation of 3 serine residues (on 5) and a carboxylation of 5 glutamate residues (on 9). Like other "Gla" proteins, this carboxylation is vitamin K dependant. Several forms of MGP thus circulate in the plasma, some of them being totally inactive (the unphosphorylated and uncarboxylated MGP), some others being partially or fully active, according to the number of phosphorylated or carboxylated sites. A theoretical link exists between MGP, vitamin K, vascular calcifications and cardiovascular diseases. This link is even more evident in patients suffering from chronic kidney diseases (CKD), and notably hemodialysis patients. If this link has been demonstrated in different experimental studies, clinical studies are mainly observational and their results must be interpreted accordingly. MGP concentrations are definitely not yet a surrogate to estimate the levels of vascular calcification, but could allow the monitoring of vitamin K treatment. Modulation of MGP concentrations may reduce vascular calcification in hemodialyzed patients, if the large ongoing trials show an efficiency of this treatment. In this review, we will summarize the role of MGP in the vascular calcifications process, describe the problems linked to the analytical determination of MGP in plasma and finally describe the different clinical studies on MGP and vascular calcifications in the general population and in CKD patients.

Safety assessment of menaquinone-7 for use in human nutrition

Vitamin K occurs widely in foods and has been shown to have a beneficial effect on the cardiovascular system, as well as anticancer, anti-inflammatory, and antiosteoporosis properties. A previous study indicates that long-chain menaquinone-7 may be more bioavailable than vitamin K and short-chain menaquinones. In the present study, acute, subacute toxicity and genotoxicity assays were carried out to evaluate the safety of oral menaquinone-7 in albino Wistar rats. Oral administration of menaquinone-7, at a concentration of 2000 mg/kg, did not cause toxic symptoms in either male or female rats. A subacute toxicity study also proved the safety and tolerance of prolonged treatment (for 90 days) with menaquinone-7 in rats, as evidenced by biochemical, hematological, and urine parameters as well as by histopathological analysis. Genotoxicity and mutagenicity studies were performed by comet, micronucleus, and Ames tests on Salmonella typhimurium strains, which showed cellular safety and nonmutagenicity of menaquinone-7. The results indicate the safety of menaquinone-7 for human consumption.

Dietary intake of vitamin K is inversely associated with mortality risk

Vitamin K has been related to cardiovascular disease and cancer risk. However, data on total mortality are scarce. The aim of the present study was to assess the association between the dietary intake of different types of vitamin K and mortality in a Mediterranean population at high cardiovascular disease risk. A prospective cohort analysis was conducted in 7216 participants from the PREDIMED (Prevención con Dieta Mediterránea) study (median follow-up of 4.8 y). Energy and nutrient intakes were evaluated using a validated 137-item food frequency questionnaire. Dietary vitamin K intake was calculated annually using the USDA food composition database and other published sources. Deaths were ascertained by an end-point adjudication committee unaware of the dietary habits of participants after they had reviewed medical records and linked up to the National Death Index. Cox proportional hazard models were fitted to assess the RR of mortality. Energy-adjusted baseline dietary phylloquinone intake was inversely associated with a significantly reduced risk of cancer and all-cause mortality after controlling for potential confounders (HR: 0.54; 95% CI: 0.30, 0.96; and HR: 0.64; 95% CI: 0.45, 0.90, respectively). In longitudinal assessments, individuals who increased their intake of phylloquinone or menaquinone during follow-up had a lower risk of cancer (HR: 0.64; 95% CI: 0.43, 0.95; and HR: 0.41; 95% CI: 0.26, 0.64, respectively) and all-cause mortality (HR: 0.57; 95% CI: 0.44, 0.73; and HR: 0.55; 95% CI: 0.42, 0.73, respectively) than individuals who decreased or did not change their intake. Also, individuals who increased their intake of dietary phylloquinone had a lower risk of cardiovascular mortality risk (HR: 0.52; 95% CI: 0.31, 0.86). However, no association between changes in menaquinone intake and cardiovascular mortality was observed (HR: 0.76; 95% CI: 0.44, 1.29). An increase in dietary intake of vitamin K is associated with a reduced risk of cardiovascular, cancer, or all-cause mortality in a Mediterranean population at high cardiovascular disease risk. This trial was registered at http://www.controlled-trials.com as ISRCTN35739639.

Vitamin K status and vascular calcification: evidence from observational and clinical studies

Vascular calcification occurs when calcium accumulates in the intima (associated with atherosclerosis) and/or media layers of the vessel wall. Coronary artery calcification (CAC) reflects the calcium burden within the intima and media of the coronary arteries. In population-based studies, CAC independently predicts cardiovascular disease (CVD) and mortality. A preventive role for vitamin K in vascular calcification has been proposed based on its role in activating matrix Gla protein (MGP), a calcification inhibitor that is expressed in vascular tissue. Although animal and in vitro data support this role of vitamin K, overall data from human studies are inconsistent. The majority of population-based studies have relied on vitamin K intake to measure status. Phylloquinone is the primary dietary form of vitamin K and available supplementation trials, albeit limited, suggest phylloquinone supplementation is relevant to CAC. Yet observational studies have found higher dietary menaquinone, but not phylloquinone, to be associated with less calcification. Vascular calcification is highly prevalent in certain patient populations, especially in those with chronic kidney disease (CKD), and it is plausible vitamin K may contribute to reducing vascular calcification in patients at higher risk. Subclinical vitamin K deficiency has been reported in CKD patients, but studies linking vitamin K status to calcification outcomes in CKD are needed to clarify whether or not improving vitamin K status is associated with improved vascular health in CKD. This review summarizes the available evidence of vitamin K and vascular calcification in population-based studies and clinic-based studies, with a specific focus on CKD patients.

Vitamin K: fracture prevention and beyond

Morbidity and decreased function related to osteoporosis, fracture, cardiovascular disease, stroke, and peripheral vascular disease are encountered by clinicians daily. Although we have seen vast advancement in treatment and management of these conditions, preventative practice has unfortunately served a lesser role in patient care. Increasing the dietary intake of vitamin K may have substantial utility in the prevention of these disease states. Since the discovery of vitamin K in 1935, its primary role was thought to be involved in the synthesis of clotting factors II, VII, IX, and X. Recently, its function in other metabolic pathways has emerged, leading to exploration of its significance beyond coagulation. Vitamin K is essential to bone physiology and prevention of atherosclerosis. It is involved in bone remodeling, cell signaling, apoptosis, arterial calcification, and chemotaxis, and it has anti-inflammatory effects. Conversely, warfarin, a potent vitamin K inhibitor, has demonstrated adverse effects on bone remodeling and atherosclerosis. Natural forms of vitamin K are available in multiple dietary sources, and some structural forms are more readily available for use in metabolic pathways than are others. With regard to supplementation, the specific form of vitamin K is often not disclosed, and the recommended daily value is potentially less than what is physiologically required. On the basis of a review of the literature, it appears advantageous to encourage patients to eat a diet rich in vitamin K; however, the benefit of vitamin K supplementation alone is yet to be thoroughly conveyed.

A minimum of six days of diet recording is needed to assess usual vitamin K intake among older adults

There is a growing interest in the role of vitamin K in health, especially in aging populations. Knowledge of inter- and intra-individual variability of dietary vitamin K intake could be useful to accurately assess usual intake and rank participants in epidemiological studies. Our objectives were to: 1) estimate the variance components of vitamin K intake; 2) investigate whether day of the week, season, and energy intake are factors related to intra-individual variance; and 3) calculate the requisite number of days to achieve desired degrees of accuracy for estimating individual vitamin K intake, ranking individuals and estimating regression coefficient. Vitamin K intake was assessed in 939 older adults (67-84 y) enrolled in the Québec Longitudinal Study on Nutrition and Successful Aging study using 2 sets of 3 nonconsecutive multiple-pass 24-h dietary recalls (24HR) collected 6 mo apart. Each set included 2 weekdays and one weekend day. Intra- to inter-individual variance ratios for vitamin K intake were 3.2 (95% CI = 2.6-3.9) overall, 2.6 (95% CI = 2.1-3.5) for men, and 3.7 (95% CI = 2.9-5.0) for women. Day of the week (weekdays) and season (May to October) were positively and significantly associated with vitamin K intake but explained a negligible part of intra-individual variation (<1%). Adjusting for energy intake explained <7% of variance and did not affect the variance ratio. Six to 13 24HR are required to properly rank individuals according to their usual vitamin K intake and limit attenuation of the regression coefficient. These results should be considered in studies planning to assess vitamin K intakes in older adults.

Vitamin K and vascular calcifications

The role of vitamin K in the synthesis of some coagulation factors is well known. The implication of vitamin K in vascular health was demonstrated in many surveys and studies conducted over the past years on the vitamin K-dependent proteins non-involved in coagulation processes. The vitamin K-dependent matrix Gla protein is a potent inhibitor of the arterial calcification, and may become a non-invasive biochemical marker for vascular calcification. Vitamin K(2) is considered to be more important for vascular system, if compared to vitamin K(1). This paper is reviewing the data from recent literature on the involvement of vitamin K and vitamin K-dependent proteins in cardiovascular health.

Relation of infra-renal abdominal aortic calcific deposits and cardiovascular events in patients with peripheral artery disease

In patients with peripheral artery disease, aortic calcific deposits are a common finding. The aim of this study was to assess the association of infrarenal abdominal aortic calcific deposits with prospective cardiovascular events in patients with peripheral artery disease. A consecutive series of 213 patients who presented for investigation of abdominal aortic aneurysm or intermittent claudication were assessed using computed tomographic angiography. Infrarenal abdominal aortic calcific deposits were estimated using a previously defined highly reproducible semiautomated program. Patients were followed prospectively for a median of 2.8 years (interquartile range 1.7 to 3.6), and cardiovascular events were recorded. Kaplan-Meier and Cox proportional-hazards analysis were used to examine the association of calcific deposits with cardiovascular events. A total of 45 cardiovascular events occurred during follow-up, including nonfatal myocardial infarction (n = 23), coronary revascularization (n = 6), stroke (n = 3), below-knee amputation (n = 2), and cardiovascular death (n = 11). The incidence of cardiovascular events was 21.7%, 33.0%, and 36.9% for patients with mild (<400 mm(3)), intermediate (400 to 1,700 mm(3)), and severe (>1,700 mm(3)) abdominal aortic calcific deposits, respectively (p = 0.039). Calcific deposit volume >400 mm(3) (relative risk 2.8, 95% confidence interval 1.2 to 6.6) and coronary artery disease (relative risk 2.8, 95% confidence interval 1.4 to 5.6) were independently associated with increased cardiovascular events during follow-up. In conclusion, abdominal aortic calcific deposits are prognostic for cardiovascular events in patients with peripheral artery disease.

Association of osteocalcin and abdominal aortic calcification in older women: the study of osteoporotic fractures

Osteocalcin (OC) is produced by osteoblasts and vascular smooth muscle cells. In animal models, serum OC levels are strongly correlated with vascular calcium content, however, the association of OC with vascular calcification in humans is uncertain. The Study of Osteoporotic Fractures (SOF) enrolled community-living women, age > or =65 years. The present study included a subsample of 363 randomly selected SOF participants. Serum total OC was measured by ELISA, and abdominal aortic calcification (AAC) was evaluated on lateral lumbar radiographs. We examined the cross-sectional association between serum OC and AAC. The mean serum OC level was 24 +/- 11 ng/ml and AAC was present in 188 subjects (52%). We observed no association of OC and AAC in either unadjusted or adjusted analyses. For example, each standard deviation higher OC level was associated with an odds ratio (OR) for AAC prevalence (AAC score >0) near unity (OR = 1.06; 95% CI, 0.82-1.36) in models adjusted for CVD risk factors. Further adjustment for intact parathyroid hormone, bone-specific alkaline phosphatase, 25-hydroxyvitamin D, and hip and spine bone mineral density did not materially change the results (OR = 1.22; 95% CI, 0.86-1.75). Similarly, higher OC levels were not associated with severity of AAC (P = 0.87). In conclusion, among community-living older women, serum OC is not associated with AAC. These findings suggest that serum OC levels may more closely reflect bone formation than vascular calcification in humans.

Vitamin K, an example of triage theory: is micronutrient inadequacy linked to diseases of aging?

The triage theory posits that some functions of micronutrients (the approximately 40 essential vitamins, minerals, fatty acids, and amino acids) are restricted during shortage and that functions required for short-term survival take precedence over those that are less essential. Insidious changes accumulate as a consequence of restriction, which increases the risk of diseases of aging. For 16 known vitamin K-dependent (VKD) proteins, we evaluated the relative lethality of 11 known mouse knockout mutants to categorize essentiality. Results indicate that 5 VKD proteins that are required for coagulation had critical functions (knockouts were embryonic lethal), whereas the knockouts of 5 less critical VKD proteins [osteocalcin, matrix Gla protein (Mgp), growth arrest specific protein 6, transforming growth factor beta-inducible protein (Tgfbi or betaig-h3), and periostin] survived at least through weaning. The VKD gamma-carboxylation of the 5 essential VKD proteins in the liver and the 5 nonessential proteins in nonhepatic tissues sets up a dichotomy that takes advantage of the preferential distribution of dietary vitamin K1 to the liver to preserve coagulation function when vitamin K1 is limiting. Genetic loss of less critical VKD proteins, dietary vitamin K inadequacy, human polymorphisms or mutations, and vitamin K deficiency induced by chronic anticoagulant (warfarin/coumadin) therapy are all linked to age-associated conditions: bone fragility after estrogen loss (osteocalcin) and arterial calcification linked to cardiovascular disease (Mgp). There is increased spontaneous cancer in Tgfbi mouse knockouts, and knockdown of Tgfbi causes mitotic spindle abnormalities. A triage perspective reinforces recommendations of some experts that much of the population and warfarin/coumadin patients may not receive sufficient vitamin K for optimal function of VKD proteins that are important to maintain long-term health.

Roles for vitamin K beyond coagulation

Recent interest in vitamin K has been motivated by evidence of physiological roles beyond that of coagulation. Vitamin K and vitamin K-dependent (VKD) proteins may be involved in regulation of calcification, energy metabolism, and inflammation. However, the evidence for many of these proposed roles in the maintenance of health is equivocal. There is also an emerging viewpoint that the biochemical function of vitamin K may extend beyond that of a cofactor for the VKD carboxylation of glutamyl residues (Glus) to carboxylated Glus in VKD proteins.

A high menaquinone intake reduces the incidence of coronary heart disease

BACKGROUND AND AIM

Vitamin K dependent proteins have been demonstrated to inhibit vascular calcification. Data on the effect of vitamin K intake on coronary heart disease (CHD) risk, however, are scarce. To examine the relationship between dietary vitamins K(1) and K(2) intake, and its subtypes, and the incidence of CHD.

METHODS AND RESULTS

We used data from the Prospect-EPIC cohort consisting of 16,057 women, enrolled between 1993 and 1997 and aged 49-70 years, who were free of cardiovascular diseases at baseline. Intake of vitamin K and other nutrients was estimated with a food frequency questionnaire. Multivariate Cox proportional hazards models were used to analyse the data. After a mean+/-SD follow-up of 8.1+/-1.6 years, we identified 480 incident cases of CHD. Mean vitamin K(1) intake was 211.7+/-100.3 microg/d and vitamin K(2) intake was 29.1+/-12.8 microg/d. After adjustment for traditional risk factors and dietary factors, we observed an inverse association between vitamin K(2) and risk of CHD with a Hazard Ratio (HR) of 0.91 [95% CI 0.85-1.00] per 10 microg/d vitamin K(2) intake. This association was mainly due to vitamin K(2) subtypes MK-7, MK-8 and MK-9. Vitamin K(1) intake was not significantly related to CHD.

CONCLUSIONS

A high intake of menoquinones, especially MK-7, MK-8 and MK-9, could protect against CHD. However, more research is necessary to define optimal intake levels of vitamin K intake for the prevention of CHD.

Validation of a semi-quantitative food frequency questionnaire measuring dietary vitamin K intake in elderly people

The study objective was to validate a semi-quantitative food frequency questionnaire (FFQ) specifically designed to measure dietary vitamin K intake. A 50-item FFQ was interviewer-administered and compared with data previously obtained from 5-day food records. Thirty-nine community-dwelling healthy men and women aged 65 to 85 years were recruited from the Montréal metropolitan area. Absolute and relative agreements between methods were assessed. Vitamin K intake measured by the vitamin K FFQ (mean+/-standard deviation; 222+/-186 microg/day) was significantly higher than that obtained by food records (135+/-153 microg/day; P<0.001). Bland-Altman analysis on log(10)-transformed data indicated that vitamin K intake from vitamin K FFQ was 2.26 times (95% confidence interval: 1.90 to 2.67) higher than food records, limits of agreement ranging from 0.80 to 6.35. However, correlation between methods was strong and highly significant (r=0.83; P<0.001). Cross-classification also showed that 72% of participants were correctly classified into thirds and only 8% were grossly miscategorized. Weighted kappa value (kappa=0.60) also indicated a good relative agreement. In light of these results, the vitamin K FFQ is a valid tool for ranking individuals according to their vitamin K intake. The poor absolute agreement likely results from the inability for food records to adequately measure the usual intake of episodically consumed foods, particularly those high in vitamin K. The vitamin K FFQ will be useful in large-scale, population-based research on vitamin K and disease as well as in clinical practice, especially that focusing on anticoagulant therapy.

Vitamin K intake and atherosclerosis

PURPOSE OF REVIEW

It has been hypothesized that insufficient intake of vitamin K may increase soft-tissue calcification owing to impaired gamma-carboxylation of the vitamin K-dependent protein matrix gamma-carboxyglutamic acid. The evidence to support this putative role of vitamin K intake in atherosclerosis is reviewed.

RECENT FINDINGS

In animal models, multiple forms of vitamin K have been shown to reverse the arterial calcification created by vitamin K antagonists. The human data, however, are less consistent. Phylloquinone, the primary dietary form, has not been associated consistently with the risk of cardiovascular diseases. High menaquinone intake may be associated with lower risk of coronary heart disease mortality, but this needs to be confirmed.

SUMMARY

The role of vitamin K in calcification remains controversial. Although biologically plausible, results from the human studies have not consistently supported this hypothesis.

Vascular calcification inhibitors in relation to cardiovascular disease with special emphasis on fetuin-A in chronic kidney disease

The mortality rate is extremely high in chronic kidney disease (CKD), primarily due to the high prevalence of cardiovascular disease (CVD) in this patient group. Apart from traditional Framingham risk factors, evidences suggest that nontraditional risk factors, such as inflammation, oxidative stress, endothelial dysfunction, and vascular calcification also contribute to this extremely high risk of CVD. Disturbance in the mineral metabolism, especially in the ions of Ca and PO4, are linked to enhanced calcification of blood vessels. Although the mechanism(s) of this enhanced calcification process are not fully understood, current knowledge suggests that a large number (and an imbalance between them) of circulating promoters and inhibitors of the calcification process, that is, fetuin-A (or alpha 2-Heremans-Schmid glycoprotein, AHSG), matrix-Gla protein (MGP), osteoprotegerin (OPG), osteopontin (OPN), bone morphogenetic proteins (BMPs), and inorganic pyrophosphate (PPi), are involved in the deterioration of vascular tissue. Thus, an imbalance in these factors may contribute to the high prevalence of vascular complications in CKD patients. Among these mediators, studies on fetuin-A deserve further attention as clinical studies consistently show that fetuin-A deficiency is associated with vascular calcification, all-cause and cardiovascular mortality in CKD patients. Both chronic inflammation and the uremic milieu per se may contribute to fetuin-A depletion, as well as specific mutations in the AHSG gene. Recent experimental and clinical studies also suggest an intriguing link between fetuin-A, insulin resistance, and the metabolic syndrome.

A stable isotope method for the simultaneous measurement of vitamin K1 (phylloquinone) kinetics and absorption

OBJECTIVES

To measure uptake and disposal kinetics and absolute absorption of vitamin K(1) using two stable isotope-labelled forms of vitamin K(1).

SUBJECTS

Ten subjects (nine women and one man) aged between 22 and 31 years, with a mean (+/-standard deviation) body mass index of 22.5+/-2.4 kg/m(2). Subjects took capsules containing 3 microg of methyl-(13)C vitamin K(1), three times a day for six days to reach a steady state for plasma vitamin K(1) isotopic enrichment. On day seven, subjects were given an intravenous dose of Konakion MM to measure disposal kinetics and at the same time, a capsule containing 4 microg of ring-D(4) vitamin K(1) to measure absorption. Plasma vitamin K(1) concentration was measured by high-performance liquid chromatography and isotopic composition by gas chromatography mass spectrometry.

RESULTS

The disposal kinetics of the intravenous dose of vitamin K(1) were resolved into two exponentials with half-times of 0.22 (+/-0.14) and 2.66 (+/-1.69) h. Absorption of oral, deuterated vitamin K(1) was 13 (+/-9)%.

CONCLUSIONS

Two-compartmental kinetic parameters observed in this study are similar to those obtained previously using radioactive tracers, but there may be additional slow-turnover body pools acting as stores of vitamin K(1). The kinetic parameters determined from the intravenous dose allowed determination of the absolute absorption of vitamin K(1) from a bolus oral dose.

Menaquinone-4 in breast milk is derived from dietary phylloquinone

The effect of maternal phylloquinone supplementation on vitamin K in breast milk was studied to establish: (1) if phylloquinone is the source of menaquinone-4 in breast milk; (2) the dose–effect relationship between intake and obtainable levels. Four groups of lactating mothers with a full-term healthy infant participated and took oral phylloquinone supplements of 0·0 (n8), 0·8 (n8), 2·0 (n8), and 4·0 (n7) mg/d for 12 d, starting at day 4 post-partum. Milk samples were collected on days 4, 8, 16, and 19. Blood samples were collected on days 4 and 16. Vitamin K and vitamin E concentrations, the latter for reason of comparison, were assayed. Phylloquinone and menaquinone-4 were present in all milk samples: 5·84 (SD 2·31) AND 2·98 (sd 1·51) nmol/l (n31) respectively, in colostrum (day 4 sample). A strong correlation between the vitamers was found (r0·78,P<0·001). Breast-milk phylloquinone levels were raised in a dose-dependent manner: 4-, 12-, and 30-fold on day 16 for the 0·8, 2·0, and 4·0 mg group respectively. In addition, menaquinone-4 levels were higher: 2·5- (P<0·05) and 7-fold (P<0·001) in the 2·0 and 4·0 mg groups respectively. Plasma of supplemented subjects contained 3-, 5-, and 10-fold higher phylloquinone levels on day 16. Detectable menaquinone-4 was found in ten of thirty-one day 4 plasma samples. All day 16 plasma samples of the 4 mg supplemented group contained the vitamin. There was no correlation between the K-vitamers in plasma. Vitamin E and phylloquinone appear to differ in their distribution in breast milk, milk:plasma concentration ratios were ≤1 and 3–5 for vitamin E and phylloquinone respectively. The milk:plasma concentration ratio of menaquinone-4 was >10. In conclusion, dietary phylloquinone is a source of menaquinone-4 in breast milk. Phylloquinone supplementation to lactating mothers may be of benefit to the newborn infant, since both phylloquinone and menaquinone-4 are raised by supplementation.

Intake and sources of phylloquinone (vitamin K1): variation with socio-demographic and lifestyle factors in a national sample of British elderly people

Intake and sources of phylloquinone (vitamin K1) were examined according to socio-demographic and lifestyle factors in free-living British people aged 65 years and over, from the 1994–5 National Diet and Nutrition Survey. Complete 4-d weighed dietary records were obtained from 1152 participants living in private households. Using newly-available, mainly UK-specific food content data, the weighted geometric mean intake of phylloquinone was estimated at 65 (95 % CI 62, 67) μg/d for all participants, with higher intakes in men than in women (70 v. 61 μg/d respectively, P<0·01). The mean nutrient densities of phylloquinone intake were 9·3 and 10·5 μg/MJ for men and women respectively (P<0·01), after adjusting for age group, region and smoking status. Of all the participants, 59 % had phylloquinone intakes below the current guideline for adequacy of 1 μg/kg body weight per d. Participants aged 85 years and over, formerly in manual occupations, or living in Scotland or in northern England reported lower phylloquinone intakes than their comparative groups. Overall, vegetables contributed 60 % of total phylloquinone intake, with cooked green vegetables providing around 28 % of the total. Dietary supplements contributed less than 0·5 % of phylloquinone intake. Participants living in northern England or in Scotland, in particular, derived less phylloquinone from vegetables than those living in southern England.

Phylloquinone (vitamin K1) intakes and serum undercarboxylated osteocalcin levels in Irish postmenopausal women

Low phylloquinone (vitamin K1) intakes have been associated with low bone mineral density in older adults. Phylloquinone intakes and serum undercarboxylated osteocalcin (ucOC) levels were assessed in ninety-seven apparently healthy, free-living Irish women aged 50–75 years. Phylloquinone intakes were estimated using a detailed dietary history, which measured habitual food intakes from a typical 14 d period, and recently published food composition data for phylloquinone. Fasting serum ucOC was measured using an enzyme immunoassay. The median daily intake of phylloquinone in the group from all sources was 108·8 mg and from food sources only was 106·6 mg, indicating that approximately 99% of the phylloquinone came from food. Vegetables and vegetable dishes contributed 67% of the total phylloquinone intake, but further analysis showed that broccoli, cabbage and lettuce were the primary sources, making a total contribution of 44 %. Twenty per cent of the women had a phylloquinone intake below the UK recommendation of 1μg/kg body weight per day and 34% failed to meet the US Adequate Intake value of 90mg/day. Mean serum ucOC levels in the women were 6·2 (SD 1·7) ng/ml and were predicted by phylloquinone intake (β— 22·20, generated from log-transformed phylloquinone intake data; P=4 0·04). On the basis of comparisons with both UK recommendations and US A equate Intakes for phylloquinone, the habitual intakes of phylloquinone in a high proportion of Irish postmenopausal women may not be adequate.

Comparative dietary intake and sources of phylloquinone (vitamin K1) among British adults in 1986-7 and 2000-1

Using data from 7 d weighed dietary records, dietary intake and sources of phylloquinone (vitamin K1) were examined by socio-demographic and lifestyle factors in 1916 participants aged 16-64 years from the 1986-7 Dietary and Nutritional Survey of British Adults, and 1423 participants aged 19-64 years from the 2000-1 National Diet and Nutrition Survey. Using UK-specific food content data, geometric mean phylloquinone intakes were estimated as 72 (95% CI 70, 74) and 67 (95% CI 65, 69) microg/d in 1986-7 and 2000-1 respectively (P<0.001). In 1986-7, 47% of participants had phylloquinone intakes below the UK guideline for adequacy (> or =1 microg/kg body weight per d), compared with 59% in 2000-1 (P<0.001). In both surveys, daily phylloquinone intake was higher among men than women and increased significantly with age. Participants of manual occupational social class, or who were smokers, had lower phylloquinone intake than their counterparts. Participants living in Scotland and northern England had lower phylloquinone intake than those living elsewhere in mainland Britain, particularly in 1986-7 when the contribution from vegetables was also lower than elsewhere. However, by 2000-1 this regional difference was no longer significant. Overall, vegetables contributed 63% of phylloquinone intake in 1986-7 and 60% in 2000-1, with cooked leafy green vegetables (LGV) providing 23 and 19% respectively. In both surveys, the contribution of vegetables (cooked LGV in particular) was directly associated with age. These data show a decrease in phylloquinone intake from 1986-7 to 2000-1, mainly owing to lower consumption of cooked LGV.

Phylloquinone intake and risk of cardiovascular diseases in men

BACKGROUND AND AIMS

Dietary patterns high in fruits and vegetables have been associated with lower risk of cardiovascular diseases. It is difficult to assess whether individuals are following a dietary pattern recommended for cardiovascular disease prevention in large population based studies. Therefore, the association between phylloquinone (vitamin K(1)) intake, derived mainly from green vegetables, and risk of cardiovascular diseases [total and fatal coronary heart disease (CHD), non-fatal myocardial infarction, total and ischemic stroke] was prospectively assessed.

METHODS AND RESULTS

The study was conducted in 40,087 men who participated in the Health Professionals' Follow-up Study during 1986-2000. There were 1857 CHD events and 617 strokes. After adjustment for lifestyle factors, the relative risks of total CHD events in increasing quintile categories of phylloquinone intake were 1 (reference), 0.84, 0.87, 0.82 and 0.84, respectively (P for trend 0.05). However, the risk of CHD events and strokes did not remain significantly associated with phylloquinone intake after adjustment for lifestyle and other dietary factors.

CONCLUSION

These results suggest that although not an independent risk factor, high phylloquinone intake may be a marker of dietary patterns associated with lower CHD risk and useful when used within that context.

Vitamin K intake and calcifications in breast arteries

OBJECTIVES

Vitamin K is an important co-factor in the production of proteins that inhibit vascular calcification. A low dietary Vitamin K intake has been associated with aortic and coronary calcifications and an elevated cardiovascular risk. Calcifications in the arteries of the breasts have also been associated with cardiovascular risk, but whether there is a relation with a low Vitamin K intake has not yet been studied.

METHODS

We conducted a cross-sectional study among 1689 women, aged 49-70 years. Dietary Vitamins K1 and K2 intake was calculated from a validated food frequency questionnaire. Breast arterial calcifications (BAC) were assessed on standard screening mammograms by two independent radiologists. With a general linear model mean Vitamins K1, K2 and Vitamin K2 subtypes were calculated for women with BAC and without, adjusted for age, smoking, diabetes, intake of saturated fat, mono-unsaturated fat, poly-unsaturated fat and protein- and calcium-intake.

RESULTS

BAC was less common in the highest (9%) quartile of Vitamin K2 intake, compared to the lowest (13%) (OR 0.7, 95% CI 0.5-1.1) and not different across quartiles of Vitamin K1 intake. Mean Vitamin K2 levels and mean levels of Vitamin K2 subtypes MK-5 through MK-10 were lower in the participants with BAC (p=0.01) compared to participants without BAC. However, after adjustment for aging, smoking, diabetes and dietary factors the association of mean Vitamin K2 intake with BAC was no longer significant.

CONCLUSION

Calcifications in breast arteries are not associated with a lower dietary intake of Vitamin K.

VKORC1 haplotypes are associated with arterial vascular diseases (stroke, coronary heart disease, and aortic dissection)

BACKGROUND

The haplotypes in the gene vitamin K epoxide reductase complex subunit 1 (VKORC1) have been found to affect warfarin dose response through effects on the formation of reduced-form vitamin K, a cofactor for gamma-carboxylation of vitamin K-dependent proteins, which is involved in the coagulation cascade and has a potential impact on atherosclerosis. We hypothesized that VKORC1-dependent effects on the coagulation cascade and atherosclerosis would contribute to susceptibility for vascular diseases.

METHODS AND RESULTS

To test the hypothesis, we studied the association of polymorphisms of VKORC1 with stroke (1811 patients), coronary heart disease (740 patients), and aortic dissection (253 patients) compared with matched controls (n=1811, 740, and 416, respectively). Five common noncoding single-nucleotide polymorphisms of VKORC1 were identified in a natural haplotype block with strong linkage disequilibrium (D'>0.9, r2>0.9), then single-nucleotide polymorphism (SNP) +2255 in the block was selected for the association study. We found that the presence of the C allele of the +2255 locus conferred almost twice the risk of vascular disease (odds ratio [OR] 1.95, 95% confidence interval [CI] .58 to 2.41, P<0.001 for stroke; OR 1.72, 95% CI 1.24 to 2.38, P<0.01 for coronary heart disease; and OR 1.90, 95% CI 1.04 to 3.48, P<0.05 for aortic dissection). We also observed that subjects with the CC and CT genotypes had lower levels of undercarboxylated osteocalcin (a regulator for the bone), probably vascular calcification, and lower levels of protein induced in vitamin K absence or antagonism II (PIVKA-II, a des-gamma-carboxy prothrombin) than those with TT genotypes.

CONCLUSIONS

The haplotype of VKORC1 may serve as a novel genetic marker for the risk of stroke, coronary heart disease, and aortic dissection.

Vitamin K in the treatment and prevention of osteoporosis and arterial calcification

PURPOSE

The role of vitamin K in the prevention and treatment of osteoporosis and arterial calcification is examined.

SUMMARY

Vitamin K is essential for the activation of vitamin K-dependent proteins, which are involved not only in blood coagulation but in bone metabolism and the inhibition of arterial calcification. In humans, vitamin K is primarily a cofactor in the enzymatic reaction that converts glutamate residues into gamma-carboxyglutamate residues in vitamin K-dependent proteins. Numerous studies have demonstrated the importance of vitamin K in bone health. The results of recent studies have suggested that concurrent use of menaquinone and vitamin D may substantially reduce bone loss. Menaquinone was also found to have a synergistic effect when administered with hormone therapy. Several epidemiologic and intervention studies have found that vitamin K deficiency causes reductions in bone mineral density and increases the risk of fractures. Arterial calcification is an active, cell-controlled process that shares many similarities with bone metabolism. Concurrent arterial calcification and osteoporosis have been called the "calcification paradox" and occur frequently in postmenopausal women. The results of two dose-response studies have indicated that the amount of vitamin K needed for optimal gamma-carboxylation of osteocalcin is significantly higher than what is provided through diet alone and that current dosage recommendations should be increased to optimize bone mineralization. Few adverse effects have been reported from oral vitamin K.

CONCLUSION

Phytonadione and menaquinone may be effective for the prevention and treatment of osteoporosis and arterial calcification.

Vitamin K1 intake and coronary calcification

OBJECTIVES

The activity of matrix Gla-protein (MGP), a potent inhibitor of vascular calcification, is dependent on carboxylation using vitamin K as a co-factor. In animals, low intake of total vitamin K has been shown to accelerate vascular calcification via the MGP mechanism. This has led to the hypothesis that low levels of dietary vitamin K intake may be a risk factor for accelerated vascular calcification in humans due to decreased MGP activity. Additionally, some authors have suggested that current recommended daily intake values for vitamin K might be insufficient to fully inhibit vascular calcification via the MGP mechanism. The aim of this study was to examine the relationship between dietary vitamin K1 (the most prevalent dietary form of vitamin K) intake and premature coronary artery calcification (CAC) in an asymptomatic screening population.

METHODS

We conducted a prospective study of 807 consecutive active-duty US Army personnel, 39-45 years of age, without known coronary heart disease. Vitamin K1 intake was measured with the Block Dietary Questionnaire and CAC was identified using electron-beam computed tomography (EBCT).

RESULTS

We found no significant correlation between CAC score and vitamin K1 intake (r = 0.132, P = 0.106). Multivariate analysis with adjustment for cardiac risk factors showed no association between dietary vitamin K1 intake and CAC.

CONCLUSIONS

Dietary vitamin K1 (phylloquinone) intake appears to be unrelated to premature coronary calcification in a screening population. Further investigation into the relationship of vascular calcification and other forms of vitamin K1 (menaquinones) is indicated.

Vitamin K status of older individuals in northern China is superior to that of older individuals in the UK

To explore whether differences in vitamin K nutrition might, at least in part, underlie differences in fracture incidence between Asian and European populations, the vitamin K status of older individuals in Shenyang, China (eighty-six men, ninety-two women) and in Cambridge, UK (sixty-seven men, sixty-seven women) was compared. Dietary information was collected by food questionnaire in Shenyang and food diary in Cambridge and used to estimate the intake and sources of phylloquinone. Fasting blood was analysed for phylloquinone, triacylglycerol, total osteocalcin (tOC) and undercarboxylated osteocalcin (expressed as percentage of tOC; %ucOC). The mean intakes of green leafy vegetables were 127 (SD 90) g/d in Shenyang and 39 (SD 48) g/d in Cambridge. The estimated phylloquinone intakes (geometric means) were 247 (95% CI 226, 270) microg/d in Shenyang and 103 (95% CI 94, 112) microg/d in Cambridge. Plasma phylloquinone concentrations (geometric means) were significantly higher in the Shenyang subjects (2.17 (95% CI 1.95, 2.42) nmol/l) than in the Cambridge subjects (0.69 (95% CI 0.63, 0.76) nmol/l; P<0.001). Plasma phylloquinone concentration was positively related to phylloquinone intake in both the Shenyang (coefficient 0.17 (SE 0.08); P=0.03) and Cambridge subjects (coefficient 0.29 (SE 0.10); P=0.005). tOC concentration and %ucOC (after adjusting for tOC) were significantly lower in the Shenyang than in the Cambridge subjects (tOC 25.2 (SE 4.2)% and %ucOC 68.5 (SE 10.0)% lower respectively; P<0.001). After adjusting for tOC and triacylglycerol, %ucOC was negatively related to plasma phylloquinone concentration in both the Shenyang (coefficient -0.41 (se 0.11); P=0.0003) and Cambridge subjects (coefficient -0.17 (SE 0.07); P=0.02). The present study demonstrates that older individuals in northern China have a better vitamin K status compared with their British counterparts in Cambridge, UK.

Characteristics and performance of an immunosorbent assay for human matrix Gla-protein

BACKGROUND

Matrix gammacarboxyglutamate (Gla)-protein (MGP) is a strong inhibitor of soft tissue calcification and is mainly produced by chondrocytes and vascular smooth muscle cells (VSMCs). MGP-deficient mice have extensive calcifications of cartilage and arteries leading to osteopenia, fractures and blood vessel ruptures. Promotor polymorphisms resulting in decreased expression levels were found to be associated with an increased risk for cardiovascular disease in humans.

METHODS

Recently, an ELISA-based assay has become available with which MGP may be detected in the circulation. The principle of the test kit is that of a competitive immunoassay using a monoclonal antibody against MGP bound to the microtiter plate.

RESULTS

Here, we report on a critical evaluation of this assay and its potential diagnostic utility in diseases associated with the degeneration of the arterial vessel wall and cartilage. The biochemical performance of the kit is satisfactory, and significant differences were found between a number of patient cohorts and the reference population. Serum MGP concentrations were significantly decreased in patients with angina pectoris and in various cartilage diseases.

CONCLUSIONS

The assay allows comparison of groups and may become a suitable marker for risk assessment or diagnosis in cardiovascular disease and osteoarthritis.

Phylloquinone intake as a marker for coronary heart disease risk but not stroke in women

OBJECTIVE

To examine the feasibility of using phylloquinone intake as a marker for coronary heart disease (CHD) and stroke risk in women.

DESIGN AND SETTING

Nurses' Health Study, a prospective cohort study during 1984-2000. Dietary data were collected in 1984, 1986, 1990, and 1994 using a validated semiquantitative food frequency questionnaire.

SUBJECTS

A total of 72 874 female nurses, aged 38-65 y, without previously diagnosed angina, myocardial infarction (MI), stroke, or cancer at baseline.

MAIN OUTCOME MEASURES

Incidence of nonfatal MI, CHD deaths, total CHD events, ischemic, and total strokes.

RESULTS

There were 1679 CHD events (1201 nonfatal) and 1009 strokes (567 ischemic). After adjustment for age and lifestyle factors associated with cardiovascular disease risk, the multivariate relative risks (RR) (95% CI) of total CHD from the lowest to the highest quintile category of phylloquinone intake were 1 (reference), 0.80 (0.69-0.94), 0.86 (0.74-1.00), 0.77 (0.66-0.99), and 0.79 (0.68-0.92), P for trend=0.01. Further adjustment for dietary intakes of saturated fat, polyunsaturated fat, trans fatty acids, eicosapentaenoic, and docosahexaenoic acids, cereal fiber, and folate attenuated the association (RR comparing extreme quintiles 0.84 [0.71-1.00], P for trend=0.12). Incidence rates of total or ischemic strokes were not associated with phylloquinone intake.

CONCLUSION

The data suggest that high phylloquinone intake may be a marker for low CHD risk. Dietary and lifestyle patterns associated with phylloquinone intakes, rather than intake of the nutrient itself, might account for all or part of the weak association. .