Vitamin K2 (menaquinone-7) prevents age-related deterioration of trabecular bone microarchitecture at the tibia in postmenopausal women

Investigating the Effects and Mechanisms of Combined Vitamin D and K Supplementation in Postmenopausal Women: An Up-to-Date Comprehensive Review of Clinical Studies

Aging is a complex process and a significant risk factor for chronic diseases. Menopause, a component of aging in women, is associated with several important cardiometabolic conditions including metabolic syndrome, osteoporosis, and cardiovascular diseases. Menopausal women could benefit from preventative strategies that may decrease morbidity and mortality and improve their quality of life. Vitamins D and K are essential nutrients required for bone health, immune function, and reducing cardiovascular risks, yet their synergistic effect is less understood in aging women. This is the first comprehensive review to summarize the evidence found in randomized clinical trials of the beneficial effects of vitamin D and K co-treatment in postmenopausal women. In our literature search across key electronic databases such as Cochrane, PubMed, and Ovid, we identified 31 pertinent studies. Overall, significant findings indicate that the combined intake of vitamins D and K may positively affect cardiovascular and bone health in postmenopausal women, emphasizing the importance of maintaining a healthy diet rich in vegetables and fermented dairy products. Given the challenges in obtaining all necessary nutrients solely through the diet, vitamin D and K supplements are recommended for postmenopausal women to promote healthy aging and well-being.

Vitamin K Status Based on K1, MK-4, MK-7, and Undercarboxylated Prothrombin Levels in Adolescent and Adult Patients with Cystic Fibrosis: A Cross-Sectional Study

The available evidence on vitamin K status in cystic fibrosis (CF) is scarce, lacking data on vitamin K2 (menaquinones-MK). Therefore, we assessed vitamin K1, MK-4 and MK-7 concentrations (LC-MS/MS) in 63 pancreatic insufficient and modulator naïve CF patients, and compared to 61 healthy subjects (HS). Vitamin K1 levels did not differ between studied groups. MK-4 concentrations were higher (median <1st-3rd quartile>: 0.778 <0.589-1.086> vs. 0.349 <0.256-0.469>, p < 0.0001) and MK-7 levels lower (0.150 <0.094-0.259> vs. 0.231 <0.191-0.315>, p = 0.0007) in CF patients than in HS. MK-7 concentrations were higher in CF patients receiving K1 and MK-7 supplementation than in those receiving vitamin K1 alone or no supplementation. Moreover, vitamin K1 concentrations depended on the supplementation regime. Based on multivariate logistic regression analysis, we have found that MK-7 supplementation dose has been the only predictive factor for MK-7 levels. In conclusion, vitamin K1 levels in CF are low if not currently supplemented. MK-4 concentrations in CF patients supplemented with large doses of vitamin K1 are higher than in HS. MK-7 levels in CF subjects not receiving MK-7 supplementation, with no regard to vitamin K1 supplementation, are low. There do not seem to be any good clinical predictive factors for vitamin K status.

Association of serum osteocalcin with bone microarchitecture and muscle mass in Beijing community-dwelling postmenopausal women

BACKGROUND

Osteoporosis is a systemic skeletal disease with increasing bone fragility and prone to fracture. Osteocalcin (OC), as the most abundant non collagen in bone matrix, has been extensively used in clinic as a biochemical marker of osteogenesis. Two forms of OC were stated on circulation, including carboxylated osteocalcin (cOC) and undercarboxylated osteocalcin (ucOC). OC was not only involved in bone mineralization, but also in the regulation of muscle function.

OBJECTIVE

This study explored the relationship between serum OC, cOC, ucOC levels and bone mineral density (BMD), bone microarchitecture, muscle mass and physical activity in Chinese postmenopausal women.

METHOD

216 community-dwelling postmenopausal women were randomized enrolled. All subjects completed biochemical measurements, including serum β-isomer of C-terminal telopeptides of type I collagen (β-CTX), N-terminal propeptide of type 1 procollagen (P1NP), alkaline phosphatase (ALP), OC, cOC and ucOC. They completed X-ray absorptiometry (DXA) scan to measure BMD, appendicular lean mass (ALM) and trabecular bone score (TBS). They completed high resolution peripheral quantitative CT (HR-pQCT) to assess peripheral bone microarchitectures.

RESULTS

Serum OC, cOC and ucOC were elevated in osteoporosis postmenopausal women. In bone geometry, serum ucOC was positively related with total bone area (Tt.Ar) and trabecular area(Tb.Ar). In bone volumetric density, serum OC and ucOC were negatively associated with total volume bone mineral density (Tt.vBMD) and trabecular volume bone mineral density (Tb.vBMD). In bone microarchitecture, serum OC and ucOC were negatively correlative with Tb.N and Tb.BV/TV, and were positively correlated with Tb.Sp. Serum OC and ucOC were positively associated with Tb.1/N.SD. Serum OC was negatively related with Tb.Th. Serum ucOC was positively associated with ALM. The high level of serum OC was the risk factor of osteoporosis. ALM was the protective factor for osteoporosis.

CONCLUSION

All forms of serum OC were negatively associated with BMD. Serum OC and ucOC mainly influenced microstructure of trabecular bone in peripheral skeletons. Serum ucOC participated in modulating both bone microstructure and muscle mass.

Vitamin K: Infection, Inflammation, and Auto-Immunity

Vitamin K (VK) comprises a group of substances with chlorophyll quinone bioactivity and exists in nature in the form of VK1 and VK2. As its initial recognition originated from the ability to promote blood coagulation, it is known as the coagulation vitamin. However, based on extensive research, VK has shown potential for the prevention and treatment of various diseases. Studies demonstrating the beneficial effects of VK on immunity, antioxidant capacity, intestinal microbiota regulation, epithelial development, and bone protection have drawn growing interest in recent years. This review article focuses on the mechanism of action of VK and its potential preventive and therapeutic effects on infections (eg, asthma, COVID-19), inflammation (eg, in type 2 diabetes mellitus, Alzheimer's disease, Parkinson's disease, cancer, aging, atherosclerosis) and autoimmune disorders (eg, inflammatory bowel disease, type 1 diabetes mellitus, multiple sclerosis, rheumatoid arthritis). In addition, VK-dependent proteins (VKDPs) are another crucial mechanism by which VK exerts anti-inflammatory and immunomodulatory effects. This review explores the potential role of VK in preventing aging, combating neurological abnormalities, and treating diseases such as cancer and diabetes. Although current research appoints VK as a therapeutic tool for practical clinical applications in infections, inflammation, and autoimmune diseases, future research is necessary to elucidate the mechanism of action in more detail and overcome current limitations.

The Potential of Vitamin K as a Regulatory Factor of Bone Metabolism-A Review

Vitamin K (VK), a fat-soluble vitamin, is essential for the clotting of blood because of its role in the production of clotting factors in the liver. Moreover, researchers continue to explore the role of VK as an emerging novel bioactive molecule with the potential function of improving bone health. This review focuses on the effects of VK on bone health and related mechanisms, covering VK research history, homologous analogs, dietary sources, bioavailability, recommended intake, and deficiency. The information summarized here could contribute to the basic and clinical research on VK as a natural dietary additive and drug candidate for bone health. Future research is needed to extend the dietary VK database and explore the pharmacological safety of VK and factors affecting VK bioavailability to provide more support for the bone health benefits of VK through more clinical trials.

Vitamin K supplementation and bone mineral density in dialysis: results of the double-blind, randomized, placebo-controlled RenaKvit trial

BACKGROUND

Vitamin K deficiency is highly prevalent in patients on dialysis and may contribute to their low bone mineral density (BMD) and increased risk of fracture. This study investigated the effect of menaquinone-7 (MK-7) supplementation on BMD in patients on chronic dialysis.

METHODS

In a multicentre, double-blind, placebo-controlled intervention trial, 123 patients on chronic dialysis were randomised to a daily oral supplement of either MK-7 360 µg or placebo for 2 years. BMD of the distal radius (1/3, mid, ultradistal and total), femoral neck, lumbar spine (L1-L4) and whole body was assessed by dual-energy X-ray absorptiometry. Serum levels of vitamin K1 and MK-7 and plasma levels of total osteocalcin, dephosphorylated-uncarboxylated matrix Gla protein and protein induced by vitamin K absence II were measured to assess vitamin K status.

RESULTS

After 2 years, an accelerated BMD loss of the 1/3 distal radius was found with MK-7 supplementation {mean difference of changes relative to placebo -0.023 g/cm2 [95% confidence interval (CI) -0.039 to -0.008]}, whereas the decrease in lumbar spine BMD seen in the placebo group was prevented [mean difference of changes between groups 0.050 g/cm2 (95% CI 0.015-0.085)]. No significant effects were observed at the remaining skeletal sites. Vitamin K status strongly improved in MK-7-supplemented participants.

CONCLUSION

Compared with placebo, an accelerated BMD loss of the 1/3 distal radius was found after 2 years of MK-7 supplementation, whereas a decline in lumbar spine BMD was prevented. As such, MK-7 supplementation might modify BMD site-specifically in patients on dialysis. In aggregate, our findings do not support MK-7 supplementation to preserve bone in patients on dialysis.

The additive effect of vitamin K supplementation and bisphosphonate on fracture risk in post-menopausal osteoporosis: a randomised placebo controlled trial

This study assessed whether vitamin K, given with oral bisphosphonate, calcium and/or vitamin D has an additive effect on fracture risk in post-menopausal women with osteoporosis. No difference in bone density or bone turnover was observed although vitamin K1 supplementation led to a modest effect on parameters of hip geometry.

PURPOSE

Some clinical studies have suggested that vitamin K prevents bone loss and may improve fracture risk. The aim was to assess whether vitamin K supplementation has an additive effect on bone mineral density (BMD), hip geometry and bone turnover markers (BTMs) in post-menopausal women with osteoporosis (PMO) and sub-optimum vitamin K status receiving bisphosphonate, calcium and/or vitamin D treatment.

METHODS

We conducted a trial in 105 women aged 68.7[12.3] years with PMO and serum vitamin K1 ≤ 0.4 µg/L. They were randomised to 3 treatment arms; vitamin K1 (1 mg/day) arm, vitamin K2 arm (MK-4; 45 mg/day) or placebo for 18 months. They were on oral bisphosphonate and calcium and/or vitamin D. We measured BMD by DXA, hip geometry parameters using hip structural analysis (HSA) software and BTMs. Vitamin K1 or MK-4 supplementation was each compared to placebo. Intention to treat (ITT) and per protocol (PP) analyses were performed.

RESULTS

Changes in BMD at the total hip, femoral neck and lumbar spine and BTMs; CTX and P1NP did not differ significantly following either K1 or MK-4 supplementation compared to placebo. Following PP analysis and correction for covariates, there were significant differences in some of the HSA parameters at the intertrochanter (IT) and femoral shaft (FS): IT endocortical diameter (ED) (% change placebo:1.5 [4.1], K1 arm: -1.02 [5.07], p = 0.04), FS subperiosteal/outer diameter (OD) (placebo: 1.78 [5.3], K1 arm: 0.46 [2.23] p = 0.04), FS cross sectional area (CSA) (placebo:1.47 [4.09],K1 arm: -1.02[5.07], p = 0.03).

CONCLUSION

The addition of vitamin K1 to oral bisphosphonate with calcium and/or vitamin D treatment in PMO has a modest effect on parameters of hip geometry. Further confirmatory studies are needed.

TRIAL REGISTRATION

The study was registered at Clinicaltrial.gov:NCT01232647.

Role of Vitamin K in Bone and Muscle Metabolism

Vitamin K, a cofactor for the γ-glutamyl carboxylase enzyme, is required for the post-translational activation of osteocalcin and matrix Gla protein, which play a key role in bone and muscle homeostasis. In vivo and in vitro models for osteoporosis and sarcopenia suggest the vitamin K could exert a positive effect in both conditions. In bone, it increases osteoblastogenesis, whilst decreases osteoclast formation and function. In muscle, it is associated with increased satellite cell proliferation and migration and might play a role in energy metabolism. Observational trials suggest that high levels of vitamin K are associated with increased bone mineral density and reduced fracture risk. However, interventional studies for vitamin K supplementation yielded conflicting results. Clinical trials in sarcopenia suggest that vitamin K supplementation could improve muscle mass and function. One of the main limitations on the vitamin K studies are the technical challenges to measure its levels in serum. Thus, they are obtained from indirect sources like food questionnaires, or levels of undercarboxylated proteins, which can be affected by other environmental or biological processes. Although current research appoints to a beneficial effect of vitamin K in bone and muscle, further studies overcoming the current limitations are required in order to incorporate this supplementation in the clinical management of patients with osteosarcopenia.

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.

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

Introduction

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

Methods

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

Results

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

Conclusions

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

Dietary Supplements and Natural Products: An Update on Their Clinical Effectiveness and Molecular Mechanisms of Action During Accelerated Biological Aging

Accelerated biological aging, which involves the gradual decline of organ or tissue functions and the distortion of physiological processes, underlies several human diseases. Away from the earlier free radical concept, telomere attrition, cellular senescence, proteostasis loss, mitochondrial dysfunction, stem cell exhaustion, and epigenetic and genomic alterations have emerged as biological hallmarks of aging. Moreover, nutrient-sensing metabolic pathways are critical to an organism’s ability to sense and respond to nutrient levels. Pharmaceutical, genetic, and nutritional interventions reverting physiological declines by targeting nutrient-sensing metabolic pathways can promote healthy aging and increase lifespan. On this basis, biological aging hallmarks and nutrient-sensing dependent and independent pathways represent evolving drug targets for many age-linked diseases. Here, we discuss and update the scientific community on contemporary advances in how dietary supplements and natural products beneficially revert accelerated biological aging processes to retrograde human aging and age-dependent human diseases, both from the clinical and preclinical studies point-of-view. Overall, our review suggests that dietary/natural products increase healthspan—rather than lifespan—effectively minimizing the period of frailty at the end of life. However, real-world setting clinical trials and basic studies on dietary supplements and natural products are further required to decisively demonstrate whether dietary/natural products could promote human lifespan.

Fat-Soluble Vitamins in Standard vs. Liposomal Form Enriched with Vitamin K2 in Cystic Fibrosis: A Randomized Multi-Center Trial

Background: We aimed to assess a liposomal fat-soluble vitamin formulation containing vitamin K2 with standard treatment in cystic fibrosis (CF). Methods: A multi-center randomized controlled trial was carried out in 100 pancreatic-insufficient patients with CF. The liposomal formulation contained vitamin A as retinyl palmitate (2667 IU daily) and beta-carotene (1333 IU), D3 (4000 IU), E (150 IU), K1 (2 mg), and K2 as menaquinone-7 (400 µg). It was compared with the standard vitamin preparations in the closest possible doses (2500 IU, 1428 IU, 4000 IU, 150 IU, 2.14 mg, respectively; no vitamin K2) over 3 months. Results: Forty-two patients finished the trial in the liposomal and 49 in the control group (overall 91 pts: 22.6 ± 7.6 years, 62.6% female, BMI 19.9 ± 2.8 kg/m², FEV1% 70% ± 30%). The main outcome was the change of vitamin status in the serum during the study (liposomal vs. standard): all-trans-retinol (+1.48 ± 95.9 vs. −43.1 ± 121.4 ng/mL, p = 0.054), 25-hydroxyvitamin D3 (+9.7 ± 13.4 vs. +2.0 ± 9.8 ng/mL, p = 0.004), α-tocopherol (+1.5 ± 2.5 vs. −0.2 ± 1.6 µg/mL, p < 0.001), %undercarboxylated osteocalcin (−17.2 ± 24.8% vs. −8.3 ± 18.5%, p = 0.061). The secondary outcome was the vitamin status at the trial end: all-trans-retinol (370.0 ± 116.5 vs. 323.1 ± 100.6 ng/mL, p = 0.045), 25-hydroxyvitamin D3 (43.2 ± 16.6 vs. 32.7 ± 11.5 ng/mL, p < 0.001), α-tocopherol (9.0 ± 3.1 vs. 7.7 ± 3.0 µg/mL, p = 0.037), %undercarboxylated osteocalcin (13.0 ± 11.2% vs. 22.7 ± 22.0%, p = 0.008). Conclusion: The liposomal fat-soluble vitamin supplement containing vitamin K2 was superior to the standard form in delivering vitamin D3 and E in pancreatic-insufficient patients with CF. The supplement was also more effective in strengthening vitamin K-dependent carboxylation, and could improve vitamin A status.

Nutrition, Physical Activity, and Dietary Supplementation to Prevent Bone Mineral Density Loss: A Food Pyramid

Bone is a nutritionally modulated tissue. Given this background, aim of this review is to evaluate the latest data regarding ideal dietary approach in order to reduce bone mineral density loss and to construct a food pyramid that allows osteopenia/osteoporosis patients to easily figure out what to eat. The pyramid shows that carbohydrates should be consumed every day (3 portions of whole grains), together with fruits and vegetables (5 portions; orange-colored fruits and vegetables and green leafy vegetables are to be preferred), light yogurt (125 mL), skim milk (200 mL,) extra virgin olive oil (almost 20 mg/day), and calcium water (almost 1 l/day); weekly portions should include fish (4 portions), white meat (3 portions), legumes (2 portions), eggs (2 portions), cheeses (2 portions), and red or processed meats (once/week). At the top of the pyramid, there are two pennants: one green means that osteopenia/osteoporosis subjects need some personalized supplementation (if daily requirements cannot be satisfied through diet, calcium, vitamin D, boron, omega 3, and isoflavones supplementation could be an effective strategy with a great benefit/cost ratio), and one red means that there are some foods that are banned (salt, sugar, inorganic phosphate additives). Finally, three to four times per week of 30-40 min of aerobic and resistance exercises must be performed.

Fat-Soluble Vitamin Supplementation Using Liposomes, Cyclodextrins, or Medium-Chain Triglycerides in Cystic Fibrosis: A Randomized Controlled Trial

Fat-soluble vitamin deficiency remains a challenge in cystic fibrosis (CF), chronic pancreatitis, and biliary atresia. Liposomes and cyclodextrins can enhance their bioavailability, thus this multi-center randomized placebo-controlled trial compared three-month supplementation of fat-soluble vitamins in the form of liposomes or cyclodextrins to medium-chain triglycerides (MCT) in pancreatic-insufficient CF patients. The daily doses were as follows: 2000 IU of retinyl palmitate, 4000 IU of vitamin D3, 200 IU of RRR-α-tocopherol, and 200 µg of vitamin K2 as menaquinone-7, with vitamin E given in soybean oil instead of liposomes. All participants received 4 mg of β-carotene and 1.07 mg of vitamin K1 to ensure compliance with the guidelines. The primary outcome was the change from the baseline of all-trans-retinol and 25-hydroxyvitamin D3 concentrations and the percentage of undercarboxylated osteocalcin. Out of 75 randomized patients (n = 28 liposomes, n = 22 cyclodextrins, and n = 25 MCT), 67 completed the trial (89%; n = 26 liposomes, n = 18 cyclodextrins, and n = 23 MCT) and had a median age of 22 years (IQR 19–28), body mass index of 20.6 kg/m² [18.4–22.0], and forced expiratory volume in 1 s of 65% (44–84%). The liposomal formulation of vitamin A was associated with the improved evolution of serum all-trans-retinol compared to the control (median +1.7 ng/mL (IQR −44.3–86.1) vs. −38.8 ng/mL (−71.2–6.8), p = 0.028). Cyclodextrins enhanced the bioavailability of vitamin D3 (+9.0 ng/mL (1.0–17.0) vs. +3.0 ng/mL (−4.0–7.0), p = 0.012) and vitamin E (+4.34 µg/mL (0.33–6.52) vs. −0.34 µg/mL (−1.71–2.15), p = 0.010). Liposomes may augment the bioavailability of vitamin A and cyclodextrins may strengthen the supplementation of vitamins D3 and E relative to MCT in pancreatic-insufficient CF but further studies are required to assess liposomal vitamin E (German Clinical Trial Register number DRKS00014295, funded from EU and Norsa Pharma).

Nutrients with anabolic/anticatabolic, antioxidant, and anti-inflammatory properties: Targeting the biological mechanisms of aging to support musculoskeletal health

Old age is associated with declines in bone density and muscle mass and function, which predisposes to mobility disability, falls, and fractures. Poor nutritional status, a risk factor for several age-related pathologies, becomes prevalent in old age and contributes to the structural and functional changes of the musculoskeletal system that increases the risk of osteoporosis, sarcopenia, osteosarcopenia, and physical frailty. The biological mechanisms underpinning these pathologies often overlap and include loss of proteostasis, impaired redox functioning, and chronic low-grade inflammation. Thus, provision of nutrients with anabolic/anticatabolic, antioxidant, and anti-inflammatory properties may be an effective strategy to offset these age-related pathologies. We searched PUBMED for pre-clinical and clinical work examining the effects of nutrients with a combined effect on muscle and bone. This review summarizes recent evidence on the mechanisms of action and potential clinical use of nutrients that concomitantly improve muscle and bone health in older persons.

Vitamin K2 Holds Promise for Alzheimer's Prevention and Treatment

Recent studies have highlighted the importance of vitamin K2 (VK2) in human health. However, there have been no clinical studies investigating the role of VK2 in the prevention or treatment of Alzheimer's disease (AD), a debilitating disease for which currently there is no cure. In reviewing basic science research and clinical studies that have connected VK2 to factors involved in AD pathogenesis, we have found a growing body of evidence demonstrating that VK2 has the potential to slow the progression of AD and contribute to its prevention. In our review, we consider the antiapoptotic and antioxidant effects of VK2 and its impact on neuroinflammation, mitochondrial dysfunction, cognition, cardiovascular health, and comorbidities in AD. We also examine the link between dysbiosis and VK2 in the context of the microbiome's role in AD pathogenesis. Our review is the first to consider the physiological roles of VK2 in the context of AD, and, given the recent shift in AD research toward nonpharmacological interventions, our findings emphasize the timeliness and need for clinical studies involving VK2.

Beyond Nutrient Deficiency-Opportunities to Improve Nutritional Status and Promote Health Modernizing DRIs and Supplementation Recommendations

The US Dietary Guidelines for Americans (DGA) provide dietary recommendations to meet nutrient needs, promote health, and prevent disease. Despite 40 years of DGA, the prevalence of under-consumed nutrients continues in the US and globally, although dietary supplement use can help to fill shortfalls. Nutrient recommendations are based on Dietary Reference Intakes (DRIs) to meet the nutrient requirements for nearly all (97 to 98 percent) healthy individuals in a particular life stage and gender group and many need to be updated using current evidence. There is an opportunity to modernize vitamin and mineral intake recommendations based on biomarker or surrogate endpoint levels needed to 'prevent deficiency' with DRIs based on ranges of biomarker or surrogate endpoints levels that support normal cell/organ/tissue function in healthy individuals, and to establish DRIs for bioactive compounds. We recommend vitamin K and Mg DRIs be updated and DRIs be established for lutein and eicosapentaenoic and docosahexaenoic acid (EPA + DHA). With increasing interest in personalized (or precision) nutrition, we propose greater research investment in validating biomarkers and metabolic health measures and the development and use of inexpensive diagnostic devices. Data generated from such approaches will help elucidate optimal nutrient status, provide objective evaluations of an individual's nutritional status, and serve to provide personalized nutrition guidance.

Microstructural and mechanical recovery of bone in ovariectomized rats: The effects of menaquinone-7

The loss of bone quantity and quality in postmenopausal female patients can be a problem for dental treatment. A sufficient intake of nutrients such as calcium, magnesium, and vitamins D and K is likely correlated with the mechanical properties of bone. In particular, vitamin K2, also called menaquinone (MK), inhibits bone loss in postmenopausal women. Here we demonstrate the microstructural and mechanical properties of bone recovery in ovariectomized (OVX) rats during MK-7 administration. Bilateral ovariectomy and a sham operation were performed on 14-week-old female SPF Wistar rats. MK-4 and -7 were orally administered at 30 mg/kg daily for 12 weeks. The femur was used for the 3-point bending test and microstructural analysis of the cancellous bone by micro-CT, and the mandibular cortical bone for the evaluation of mechanical properties on a nanoscale. Micro-computed tomography revealed irregular trabecular architecture, hollow marrow cavities, and sparse trabecular bone in the femurs of the OVX group. Trabecular bone structure analysis showed that the MK-7 group had greater bone volume per tissue volume (BV/TV) and a higher trabecular number than the OVX group. The bulk-scale 3-point bending test did not allow the mechanical properties between OVX and OVX/MK7 groups to be discerned, yet at the smallest level, the elastic-plastic transition point of the nanoindentation stress-strain curve of the mandibular cortical bone was higher in the MK-7 group than in the OVX group. These findings suggest that MK-7 enables bone microstructural and mechanical recovery in the OVX model.

The anti-osteoporosis effects of Vitamin K in postmenopausal women

As a common systemically muscular-skeleton disorder in aging, osteoporosis is characterized by the uninterrupted deconstruction in osseous microarchitecture. Osteoporosis can consequently lead to a significantly high risk of osteoporotic fractures, such as osteoporotic vertebral compressive fractures [OVCF] in the spine and osteoporotic femoral neck fractures, which can significantly increase the numbers of mortality and morbidity in aging people, especially in postmenopausal women. In addition, vitamin K has been demonstrated to play a key role in inhibiting osteoporotic fractures among postmenopausal women, but its long-term benefits, potential harms, and effects of the combination between vitamin K and other anti-osteoporosis medicines such as bisphosphonates or teriparatide were just extensively studied. Therefore, the present review aimed to systematically reviewed published literature on the role of vitamin K in the treatment of osteoporosis. We currently, via multiple queries strategy, searched the relevant literature in Cochrane and PubMed from January 2010 to December 2019. Subsequently, we conducteda systematic review according to the standard guideline of Preferred Reporting Item for Systematic Reviews and Meta-Analyses [PRISMA]. Finally, ten relevant works of literature met our current criteria for inclusion, and then we followed the PRISMA guideline and systematically reviewed each study by the categorized data sources and analytical approaches in each study, meanwhile set up variables and defined each study outcomes.

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.

Vitamin K2 (menaquinone-7) increases plasma adiponectin but does not affect insulin sensitivity in postmenopausal women: a randomized controlled trial

BACKGROUND/OBJECTIVES

Vitamin K is a co-factor in the carboxylation of the bone matrix protein osteocalcin (OC), and thus decreases the concentration of undercarboxylated osteocalcin (ucOC). Animal and in vitro studies suggest that ucOC increases insulin sensitivity. However, epidemiological studies find positive associations between vitamin K intake and insulin sensitivity. We aimed to investigate the effect of vitamin K2 in the form of menaquinone-7 (MK-7) on serum ucOC, bone mass, and insulin sensitivity in postmenopausal women.

SUBJECTS/METHODS

This was a randomized placebo-controlled trial. One hundred forty-eight postmenopausal women received MK-7 375 µg daily or placebo, as an add-on to calcium (800 mg) and vitamin D (38 µg) for 12 months. We measured serum ucOC, insulin sensitivity by HOMA-IR, and plasma adiponectin and leptin at baseline and after 12 months.

RESULTS

S-ucOC decreased in the MK-7 group (-70.3 (-75.6; -63.8) %) compared to the placebo group (-7.2 (-15.9; 2.0) %) after 12 months (p < 0.01). P-adiponectin increased in the MK-7 group (6.1 ± 20.1%) (mean ± SD) compared to the placebo group (-0.7 ± 15.5%) after 12 months (p = 0.03). HOMA-IR and p-leptin did not change in the two groups.

CONCLUSION

Treatment with MK-7 for 12 months decreased p-ucOC, increased p-adiponectin, but did not change insulin sensitivity suggesting that ucOC does not affect insulin sensitivity in healthy postmenopausal women.

Effect of Vitamin K2 Alone or in Combination on Various Bone Turnover Markers Amongst Postmenopausal Females

Background

Osteoporosis is common in postmenopausal women. Some studies have demonstrated the usefulness of vitamin K through the action of bone-specific proteins and osteoblast and osteoclast activities. However, no systematic review had explored this aspect in postmenopausal women. Hence, this systematic review aimed to explore the effect of vitamin K₂ alone or in combination with other agents (vitamin D₃ or calcium) on various bone turnover markers (BTMs) and bone mineral density (BMD) in postmenopausal women.

Methods

MEDLINE, ScienceDirect, PubMed, and Google Scholar were searched to identify relevant studies using specific inclusion criteria. Data extraction and quality assessment were carried out using standardized tests, and the results were narratively synthesized and presented in the form of tables.

Results

Vitamin K₂ was beneficial in inducing an improvement or preventing deterioration, as evidenced by the BMD and osteocalcin (OC), undercarboxylated OC (ucOC), carboxylated OC (cOC), and γ-carboxylated OC levels. However, its effect was not conclusive when procollagen type 1 N-terminal propeptide, carboxyterminal propeptide of type I procollagen, C-terminal telopeptide of type I collagen, bone alkaline phosphatase, deoxypyridinoline, and N-terminal telopeptide levels (NTX) and ucOC:cOC or cOC:ucOC, and NTX:creatinine ratios were examined.

Conclusions

Vitamin K₂ supplementation combined with vitamin D and calcium was found to be advantageous. However, vitamin K₂ supplementation cannot replace the existing treatment options. In addition, vitamin K₂ should be used with caution, considering its interactions with food and other drugs.

Randomised Controlled Trial of Nutritional Supplement on Bone Turnover Markers in Indian Premenopausal Women

Young Indian women may be at risk of poor bone health due to malnutrition. The aim of this study was to examine the effects on bone metabolism of a nutritional supplement in women aged 25 to 44. The nutritional supplement was a protein-rich beverage powder fortified with multi-micronutrients including calcium (600 mg), vitamin D (400 IU), and vitamin K (55 mcg) per daily serving, while a placebo supplement was low-protein non-fortified isocaloric beverage powder. This 6-month randomised, controlled trial showed favorable changes in bone turnover markers (decreased) and calcium homeostasis; such changes in older adults have been associated with slowing of bone loss and reduced fracture risk. For example, serum CTX decreased by about 30% and PINP by about 20% as a result of the increase in calcium intake. There were also changes in the ratio of carboxylated to undercarboxylated osteocalcin and such changes have been linked to a slowing of bone loss in older subjects. For example, the ratio increased by about 60% after 3 months as a result in the improvement in vitamin K status. Finally, there were improvements in the status of B vitamins, and such changes have been associated with reductions in homocysteine, but it is uncertain whether this would affect fracture risk. The product was generally well tolerated. This study shows the nutritional supplement holds promise for improved bone health among young Indian women.

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

TRIAL REGISTRATION

The study was registered at Clinicaltrial.gov : NCT01922804 .

The Gut Microbiome and Bone Strength

PURPOSE OF REVIEW

Osteoporosis is commonly diagnosed through the clinical assessment of bone quantity using bone mineral density; however, the primary clinical concern is bone fragility. Bone fragility is determined by both bone quantity and bone quality. Over the past decade, the gut microbiome has emerged as a factor that can regulate diseases throughout the body. This review discusses how microbial organisms and their genetic products that inhabit the gastrointestinal tract influence bone quantity, bone quality, and bone strength.

RECENT FINDINGS

Recent studies have shown that the gut microbiome regulates bone loss during estrogen depletion and glucocorticoid treatment. A series of studies has also shown that the gut microbiome influences whole bone strength by modifying bone tissue quality. The possible links between the gut microbiome and bone tissue quality are discussed focusing on the effects of microbiome-derived vitamin K. We provide a brief introduction to the gut microbiome and how modifications to the gut microbiome may lead to changes in bone. The gut microbiome is a promising target for new therapeutic approaches that address bone quality in ways not possible with current interventions.

Evaluation of vitamin K status and rationale for vitamin K supplementation in dialysis patients

The cardinal biological role of vitamin K is to act as cofactor for the carboxylation of a number of vitamin K-dependent proteins, some of which are essential for coagulation, bone formation and prevention of vascular calcification. Functional vitamin K deficiency is common and severe among dialysis patients and has garnered attention as a modifiable risk factor in this population. However, no single biochemical parameter can adequately assess vitamin K status. For each biological function of vitamin K, the degree of carboxylation of the relevant vitamin K-dependent protein most accurately reflects vitamin K status. Dephosphorylated uncarboxylated matrix Gla protein (dp-ucMGP) is the best biomarker for vascular vitamin K status when cardiovascular endpoints are studied. Dp-ucMGP levels are severely elevated in haemodialysis patients and correlate with markers of vascular calcification and mortality in some but not all studies. The aetiology of vitamin K deficiency in haemodialysis is multifactorial, including deficient intake, uraemic inhibition of the vitamin K cycle and possibly interference of vitamin K absorption by phosphate binders. The optimal vitamin K species, dose and duration of supplementation to correct vitamin K status in dialysis patients are unknown. Dp-ucMGP levels dose-proportionally decrease with supraphysiological vitamin K2 supplementation, but do not normalize even with the highest doses. In the general population, long-term vitamin K1 or K2 supplementation has beneficial effects on cardiovascular disease, bone density and fracture risk, and insulin resistance, although some studies reported negative results. In haemodialysis patients, several trials on the effects of vitamin K on surrogate markers of vascular calcification are currently ongoing.

Association of aortic valve calcification and vitamin K antagonist treatment

Aims 

Vitamin K antagonists (VKAs) are suspected of causing aortic valve calcification (AVC). The objective of this study was to clarify whether patients undergoing VKA treatment have increased AVC scores compared to patients treated with new oral anticoagulants (NOACs) and patients who never have been treated with VKA/NOAC.

Methods and results 

We included participants from the population-based DANCAVAS trial (n = 15 048). Information on confounders was collected, and the AVC scores were measured on non-contrast computed tomography scans. The participants’ medication data, including VKA and NOAC data, were collected from the Danish National Health Service Prescription Database. The final population consisted of 14 604 participants (67.4 years, 95% men) of whom 873 had been treated with VKA and 602 with NOAC. The association between AVC score and duration of anticoagulant use was investigated in an adjusted zero-inflated negative binomial regression model. For every year treated with VKA, the AVC score increased, on average, by 6% [ratio of expected counts (RECs) = 1.06; 95% confidence interval (CI) 1.02–1.10] compared to non-use. The results were consistent in sensitivity analyses excluding patients with known cardiovascular disease and statin users (REC = 1.07; 95% CI 1.02–1.11 and REC = 1.10; 95% CI 1.03–1.17, respectively). NOAC treatment was not significantly associated with AVC score in any of the corresponding models (REC = 1.03, 1.02, and 0.96).

Conclusion 

Compared to no treatment with anticoagulants, VKA use was associated with increased AVC score, while a similar association could not be established for NOAC.

A chemical screening method for menaquinone-producing strains based on HPLC-UV technology

Despite menaquinones (MKs)-4 and - 7 being known to have extensive biological activities and applications, less attention has been paid to the other MKs. Thus, to obtain a range of MKs to further explore their pharmacological activities, structure-activity relationships, and applications, a chemical screening method for MK-producing strains was established based on high-performance liquid chromatography-ultraviolet (HPLC-UV) technology. Considering that Bacillus strains have proven to be an important MK-producing bioresource, twenty-nine putative Bacillus isolates previously sought from a fermented soybean sample were used for the validation of the chemical screening method, which ultimately led to the discovery of sixteen MK-producing strains. Among them, Bacillus subtilis DC-1 presented excellent ability to produce MKs. Another, a purchased strain of B. amyloliquefaciens was discovered to be an MK-producing strain. These results indicated this screening method was simple and highly efficient for the discovery of MK-producing strains, especially those producing a range of MK structures.

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

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

Natto Intake is Inversely Associated with Osteoporotic Fracture Risk in Postmenopausal Japanese Women

BACKGROUND

The direct association between intake of Japanese fermented soybeans, namely natto, and bone mineral density (BMD) is known. However, the association with osteoporotic fractures has not been studied.

OBJECTIVE

This study aimed to investigate whether habitual natto intake is associated with a risk of osteoporotic fractures.

METHODS

This prospective cohort study included 1417 postmenopausal Japanese women who were enrolled in the Japanese Population-Based Osteoporosis cohort study in 1996, 1999, 2002, and 2006 and were aged ≥45 y at baseline. The intake of natto, tofu, and other soybean products was surveyed with use of a FFQ at baseline. Fractures were ascertained in follow-up surveys conducted in 1999, 2002, 2006, and 2011/2012. Osteoporotic fracture was the primary outcome and was defined as a clinical fracture occurring without strong external force, diagnosed with radiographs by a medical doctor. HRs with 95% CIs were estimated with Cox proportional hazard models.

RESULTS

During the 17,699 person-years of follow-up (median, 15.2 y), 172 women experienced osteoporotic fractures. After adjustment for age and BMD at the total hip, the HRs compared with those of < 1 pack (approximately 40 g)/wk natto intake were 0.72 (95% CI: 0.52, 0.98) and 0.51 (95% CI: 0.30, 0.87) for 1-6 and ≥7 packs/wk, respectively. After further adjustment for BMI, history of osteoporotic fractures, history of myocardial infarction or stroke, diabetes mellitus, current smoking, alcohol intake, frequency of tofu and other soybean product intakes, and dietary calcium intake, the HRs were 0.79 (95% CI: 0.56, 1.10) and 0.56 (95% CI: 0.32, 0.99) for 1-6 and ≥7 packs/wk, respectively. Frequency of tofu or other soybean product intakes had no association with the risk of osteoporotic fractures.

CONCLUSIONS

Habitual natto intake may be associated with a reduced risk of osteoporotic fractures independent of confounding factors, including BMD, in Japanese postmenopausal women. This trial was registered at umin.ac.jp as UMIN 000032869.

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A comparatively study of menaquinone-7 isolated from Cheonggukjang with vitamin K1 and menaquinone-4 on osteoblastic cells differentiation and mineralization

The effect of menaquinone-7 isolated from cheonggukjang was comparatively investigated with vitamin K₁ and menaquinone-4 on cell differentiation and mineralization of the osteoblastic cell line MC3T3-E1. Results indicated that all vitamin K species significantly increased MC3T3-E1 cell proliferation, cellular alkaline phosphatase activity, osteocalcin synthesis, and calcium deposition in a dose-dependent manner. Menaquinone-4 and menaquinone-7 had more potent effects on calcium deposition than vitamin K₁, and their effects were only partly reduced by warfarin (γ-carboxylation inhibitor) treatment, while warfarin abolished the induction activity of vitamin K₁ on calcification. This suggests that vitamin K₁ and K₂ (menaquinone-4 & menaquinone-7) may have different mechanisms in stimulating osteoblast mineralization. In addition, the mRNA expression ratio of osteoprotegerin and the receptor activator of nuclear factor-kB ligand was also dramatically increased by treatment with vitamin K₁ (62%), menaquinone-4 (247%), and menaquinone-7 (329%), suggesting that vitamin K may suppress the formation of osteoclast by up-regulating the ratio of osteoprotegerin/receptor activator of nuclear factor-kB ligand in osteoblasts. These results provide compelling evidence that vitamin K₁, menaquinone-4, and menaquinone-7 all can promote bone health, which might be associated with elevations in the osteoprotegerin/receptor activator of nuclear factor-kB ligand ratio.

Tissue Distribution of Menaquinone-7 and the Effect of α-Tocopherol Intake on Menaquinone-7 Concentration in Rats

We have reported that vitamin E intake lowers phylloquinone (PK) concentration in extrahepatic tissues of rats. In this study, we aimed to clarify the characteristic of the distribution of menaquinone-7 (MK-7), a vitamin K contained in fermented foods, by comparison with other vitamin K distributions and to clarify the effect of vitamin E intake on MK-7 concentration in rats. Rats were fed a vitamin K-free diet (Free group), a diet containing 0.75 mg PK/kg (PK group), a 0.74 mg menaquinone-4 (MK-4)/kg diet (MK-4 group), a 1.08 mg MK-7/kg diet (MK-7 group), or a 0.29 mg menadione (MD)/kg diet (MD group) for 16 wk. MK-7 mainly accumulated in the liver, spleen, and adrenal gland of the MK-7 group, although PK accumulated in the serum and all tissues of the PK group. Conversely, MK-4 was present in all tissues of the PK, MK-4, MK-7, and MD groups. MK-4 concentration in the serum, liver, adipose tissue, and spleen was higher in the MK-4 group than in the other groups; however, MK-4 concentration in the kidney, testis, tibia, and brain was lower in the MK-4 group than in the PK, MK-7, and MD groups. Next, vitamin E- and K-deficient rats were orally administered MK-7 with or without α-tocopherol. α-Tocopherol did not affect MK-7 or MK-4 concentration in the serum and various tissues. These results suggested that MK-7 is particularly liable to accumulate in the liver, and MK-7 concentration is not affected by vitamin E intake.

Menaquinone 7 Stability of Formulations and Its Relationship with Purity Profile

Menaquinone-7 (MK7) is a member of the vitamin K family in which interest has considerably increased over the last decade, mainly due to its beneficial role in human health. MK7 can be produced by synthesis or fermentation, and its purity profile can differ depending on methodologies and extraction procedures. Finished formulations show a high heterogeneity of purity profiles, as well as frequent discrepancies in the nominal content, compared to the actual title. The present study compared purity profiles of different raw material and related them to their stability in normal (12 months/25 °C/60%RH) and accelerated conditions (6 months/40 °C/75% RH) in order to test their performance in the presence of different common excipients. Results showed higher purity profile results in enhanced stability, and this could explain title discrepancies found in finished products, which are present on the market worldwide.

Bone Microstructure in Response to Vitamin D3 Supplementation: A Randomized Placebo-Controlled Trial

Vitamin D supplementation is often used in the prevention and treatment of osteoporosis, but the role of vitamin D has lately been questioned. We aimed to investigate the effect of 3 months of daily vitamin D3 supplementation (70 µg [2800 IU] vs. placebo) initiated in winter months on bone health. This study is a double-blinded placebo-controlled randomized trial. Bone health was assessed by bone turnover markers, DXA, HRpQCT, and QCT scans. The participants were 81 healthy postmenopausal women with low 25(OH)D (< 50 nmol/l) and high PTH levels (> 6.9 pmol/l) at screening. Vitamin D3 supplementation significantly increased levels of 25(OH)D and 1,25(OH)₂D by 59 nmol/l and 19 pmol/l, respectively, whereas PTH was reduced by 0.7 pmol/l (all p < 0.0001). Compared with placebo, vitamin D3 did not affect bone turnover markers, aBMD by DXA or trabecular bone score. Vitamin D3 increased trabecular vBMD (QCT scans) in the trochanter region (0.4 vs. - 0.7 g/cm³) and the femoral neck (2.1 vs. - 1.8 g/cm³) p_all < 0.05. HRpQCT scans of the distal tibia showed reduced trabecular number (- 0.03 vs. 0.05 mm^-1) and increased trabecular thickness (0.001 vs. - 0.005 mm), as well as an improved estimated bone strength as assessed by failure load (0.1 vs. - 0.1 kN), and stiffness (2.3 vs. - 3.1 kN/mm p_all ≤ 0.01). Changes in 25(OH)D correlated significantly with changes in trabecular thickness, stiffness, and failure load. Three months of vitamin D3 supplementation improved bone strength and trabecular thickness in tibia, vBMD in the trochanter and femoral neck, but did not affect aBMD.

Effects of menaquinone-7 supplementation in patients with aortic valve calcification: study protocol for a randomised controlled trial

INTRODUCTION

Aortic stenosis is a common heart valve disease, and due to the growing elderly population, the prevalence is increasing. The disease is progressive with increasing calcification of the valve cusps. A few attempts with medical preventive treatment have failed; thus, presently, the only effective treatment of aortic stenosis is surgery. This study will examine the effect of menaquinone-7 (MK-7) supplementation on progression of aortic valve calcification (AVC). We hypothesise that MK-7 supplementation will slow down the calcification process.

METHODS AND ANALYSIS

In this multicenter and double-blinded, placebo-controlled study, 400 men aged 65-74 years with substantial AVC are randomised (1:1) to treatment with MK-7 (720 µg/day) supplemented by the recommended daily dose of vitamin D (25 µg/day) or placebo treatment (no active treatment) for 2 years. Exclusion criteria are treatment with vitamin K antagonist or coagulation disorders. To evaluate AVC score, a non-contrast CT scan is performed at baseline and repeated after 12 and 24 months of follow-up. Primary outcome is difference in AVC score from baseline to follow-up at 2 years. Intention-to-treat principle is used for all analyses.

ETHICS AND DISSEMINATION

There are no reported adverse effects associated with the use of MK-7. The protocol is approved by the Regional Scientific Ethical Committee for Southern Denmark (S-20170059) and the Data Protection Agency (17/19010). It is conducted in accordance with the Declaration of Helsinki. Positive as well as negative findings will be reported.

TRIAL REGISTRATION NUMBER

NCT03243890.

Bone Mineral Density is Lower in Patients with Severe Knee Osteoarthritis and Attrition

Bone quality is probably important for the survival of knee arthroplasty (KA), but little is known about systemic bone mineral density and bone turnover in patients prior to KA surgery. The aim of this study was to explore the prevalence of osteoporosis and bone turnover in relation to knee osteoarthritis (OA) grade in patients scheduled for KA surgery. Prospective preoperative evaluation of 450 patients (259 females) prior to KA between 2014 and 2016 with standing knee radiography, Dual-energy X-ray absorptiometry (DXA), biomarkers for bone turnover (CTX, P1NP), and vitamin D. Grading of knee OA was done with the Altman Atlas and Kellgren Lawrence (KL). Adjustments for age and BMI were made. The mean age was 67.9 years (range 39-94), and mean BMI was 28.8 (SD 4.8). The prevalence of osteoporosis was 9.6% (CI 95% 7.2; 12.7), while the proportion of patients with osteopenia was 36.0%. T score was similar between KL OA grade 3 and 4 (p = 0.06); however, T score was lower (p = 0.02) with the worst knee OA grade (attrition). The median serum Vitamin D level was 78.5 nmol/L (range 10-196), and there was no association between serum vitamin D and the grade of OA (p > 0.88). P1NP was significantly higher in KL grade 4 compared to KL grade 3 (p = 0.03), but there was no association between KL grade and CTX (p = 0.21). 10% had osteoporosis, which is similar to the age-matched background population. Bone mineral density was lower with severe knee osteoarthritis (attrition), and P1NP was higher with worse osteoarthritis grading.

Menaquinone-4 enhances osteogenic potential of human amniotic fluid mesenchymal stem cells cultured in 2D and 3D dynamic culture systems

Menaquinones, also known as Vitamin K2 family, regulate calcium homeostasis in a 'bone-vascular cross-talk' and recently received particular attention for their positive effect on bone formation. Given that the correlation between menaquinones and bone metabolism to date is still unclear, the objective of our study was to investigate the possible role of menaquinone-4 (MK-4), an isoform of the menaquinones family, in the modulation of osteogenesis. For this reason, we used a model of human amniotic fluid mesenchymal stem cells (hAFMSCs) cultured both in two-dimensional (2D) and three-dimensional (3D; RCCS™bioreactor) in vitro culture systems. Furthermore, to mimic the 'bone remodelling unit' in vitro, hAFMSCs were co-cultured in the 3D system with human monocyte cells (hMCs) as osteoclast precursors. The results showed that in a conventional 2D culture system, hAFMSCs were responsive to the MK-4, which significantly improved the osteogenic process through γ-glutamyl carboxylase-dependent pathway. The same results were obtained in the 3D dynamic system where MK-4 treatment supported the osteoblast-like formation promoting the extracellular bone matrix deposition and the expression of the osteogenic-related proteins (alkaline phosphatase, osteopontin, collagen type-1 and osteocalcin). Notably, when the hAFMSCs were co-cultured in a 3D dynamic system with the hMCs, the presence of MK-4 supported the cellular aggregate formation as well as the osteogenic function of hAFMSCs, but negatively affected the osteoclastogenic process. Taken together, our results demonstrate that MK-4 supported the aggregate formation of hAFMSCs and increased the osteogenic functions. Specifically, our data could help to optimize bone regenerative medicine combining cell-based approaches with MK-4 treatment.

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.