Vitamin K intake and bone mineral density in women and men

Association of vitamins with bone mineral density and osteoporosis measured by dual-energy x-ray absorptiometry: a cross-sectional study

BACKGROUND

We aimed to assess the associations of vitamins intake with osteoporosis based on a national sample from US adults.

METHODS

A total of 1536 participants were included in this cross-sectional study to investigate the relationship between vitamins intake and osteoporosis from National Health and Nutrition Examination Survey, including vitamin A, C, D. Logistic regression models were used to assess the associations between dietary vitamin intake and osteoporosis.

RESULTS

We found that vitamins intake were negatively associated with osteoporosis. For vitamin A, compared with the first tertile, the odds ratios (ORs) and 95% confidential intervals (CIs) were 0.93 (0.81-1.04) for the second tertile and 0.85 (0.78-0.96) for the third tertile (P < 0.01). For vitamin C, compared with the first tertile, the ORs and 95% CIs were 0.89 (0.78-1.05) for the second tertile and 0.79 (0.67-0.93) for the third tertile (P < 0.01). For vitamin D, compared with the first tertile, the odds ratios (ORs) and 95% confidential intervals (CIs) were 0.94 (0.82-1.07) for the second tertile and 0.88 (0.75-0.98) for the third tertile (P < 0.01). And the negative association between vitamins intake and osteoporosis were more evident for female, aged ≥ 60, and BMI > 30, including vitamin A, C and D.

CONCLUSIONS

Our findings provide evidence that vitamins intake is linked with decreased prevalence of osteoporosis, including vitamin A, C, D. Further large-scale prospective cohort studies are needed to verify our findings.

The mediation effect of vitamin A and vitamin D supplement in the association between serum vitamin K levels and musculoskeletal disorders in preschool children

Introduction

Vitamin K deficiency may elevate the incidence of musculoskeletal disorders (MSD), whereas it lacks validation for pediatric populations and has uncertain dose recommendations. In this context, we hypothesized that serum vitamin K levels are associated with MSD in preschool children, and the widely used vitamin A and vitamin D supplements may mediate these associations based on potential mechanisms, which expects to provide guidance for future practice.

Methods

A cross-sectional study was conducted in Sichuan province in southwestern China, from January 2021 to May 2022. Serum levels of vitamin K1/K2 and 25(OH)D were determined using the high-performance liquid chromatography method, and the diagnosis of MSD was executed by clinicians. Overall and stratified logistic regression analysis based on categorized 25(OH)D levels were conducted to assess association between serum vitamin K levels and MSD prevalence after adjusting for confounders. Mediation analysis was further performed and vitamin A and D supplementation was regressed as the mediator.

Results

A total of 6,368 children aged 0-6 years old were enrolled. MSD was identified in 1179 (18.51%) of the children, while 5,189 (81.49%) of them did not present such disorder. After adjusting confounders, a significant difference was found in serum vitamin K1 level between children in MSD and Non-MSD group (OR = 0.802, 95%CI 0.745-0.864). No significant difference was found in serum vitamin K2 level between the two groups (OR = 0.975, 95%CI 0.753-1.261). The association between vitamin K1 level and MSD prevalence was partly (36.8%) mediated by vitamin A and D supplementation.

Conclusions

A low serum vitamin K1 level is connected with an increased risk of MSD among children, highlighting that vitamin A and D supplementation is a helpful intervention to prevent MSD in children with vitamin K deficiency.

Effect of a Hop Extract Standardized in 8-Prenylnaringenin on Bone Health and Gut Microbiome in Postmenopausal Women with Osteopenia: A One-Year Randomized, Double-Blind, Placebo-Controlled Trial

Estrogen deficiency increases the risk of osteoporosis and fracture. The aim of this study was to investigate whether a hop extract standardized in 8-prenylnaringenin (8-PN), a potent phytoestrogen, could improve bone status of osteopenic women and to explore the gut microbiome roles in this effect. In this double-blind, placebo-controlled, randomized trial, 100 postmenopausal, osteopenic women were supplemented with calcium and vitamin D3 (CaD) tablets and either a hop extract (HE) standardized in 8-PN (n = 50) or a placebo (n = 50) for 48 weeks. Bone mineral density (BMD) and bone metabolism were assessed by DXA measurements and plasma bone biomarkers, respectively. Participant's quality of life (SF-36), gut microbiome composition, and short-chain fatty acid (SCFA) levels were also investigated. In addition to the CaD supplements, 48 weeks of HE supplementation increased total body BMD (1.8 ± 0.4% vs. baseline, p < 0.0001; 1.0 ± 0.6% vs. placebo, p = 0.08), with a higher proportion of women experiencing an increase ≥1% compared to placebo (odds ratio: 2.41 ± 1.07, p < 0.05). An increase in the SF-36 physical functioning score was observed with HE versus placebo (p = 0.05). Gut microbiome α-diversity and SCFA levels did not differ between groups. However, a higher abundance of genera Turicibacter and Shigella was observed in the HE group; both genera have been previously identified as associated with total body BMD. These results suggest that an 8-PN standardized hop extract could beneficially impact bone health of postmenopausal women with osteopenia.

The Pleiotropic Role of Vitamin K in Multimorbidity of Chronic Obstructive Pulmonary Disease

Although defined by the presence of airflow obstruction and respiratory symptoms, patients with chronic obstructive pulmonary disease (COPD) are characterized by multimorbidity. Numerous co-occurring conditions and systemic manifestations contribute to the clinical presentation and progression of COPD; however, underlying mechanisms for multimorbidity are currently not fully elucidated. Vitamin A and vitamin D have been related to COPD pathogenesis. Another fat-soluble vitamin, vitamin K, has been put forward to exert protective roles in COPD. Vitamin K is an unequivocal cofactor for the carboxylation of coagulation factors, but also for extra-hepatic proteins including the soft tissue calcification inhibitor matrix Gla-protein and the bone protein osteocalcin. Additionally, vitamin K has been shown to have anti-oxidant and anti-ferroptosis properties. In this review, we discuss the potential role of vitamin K in the systemic manifestations of COPD. We will elaborate on the effect of vitamin K on prevalent co-occurring chronic conditions in COPD including cardiovascular disorders, chronic kidney disease, osteoporosis, and sarcopenia. Finally, we link these conditions to COPD with vitamin K as a connecting factor and provide recommendations for future clinical studies.

Association of Vitamin K Status with Arterial Calcification and Stiffness in Chronic Kidney Disease: The Chronic Renal Insufficiency Cohort

Background

Arterial calcification and stiffness are common in people with chronic kidney disease (CKD). Higher vitamin K status has been associated with less arterial calcification and stiffness in CKD in cross-sectional studies.

Objectives

To determine the association of vitamin K status with coronary artery calcium (CAC) and arterial stiffness [pulse wave velocity (PWV)] at baseline and over 2-4 follow-up years in adults with mild-to-moderate CKD.

Methods

Participants (n = 2722) were drawn from the well-characterized Chronic Renal Insufficiency Cohort. Two vitamin K status biomarkers, plasma phylloquinone and plasma dephospho-uncarboxylated matrix gla protein [(dp)ucMGP], were measured at baseline. CAC and PWV were measured at baseline and over 2-4 y of follow-up. Differences across vitamin K status categories in CAC prevalence, incidence, and progression (defined as ≥100 Agatston units/y increase) and PWV at baseline and over follow-up were evaluated using multivariable-adjusted generalized linear models.

Results

CAC prevalence, incidence, and progression did not differ across plasma phylloquinone categories. Moreover, CAC prevalence and incidence did not differ according to plasma (dp)ucMGP concentration. Compared with participants with the highest (dp)ucMGP (≥450 pmol/L), those in the middle category (300-449 pmol/L) had a 49% lower rate of CAC progression (incidence rate ratio: 0.51; 95% CI: 0.33, 0.78). However, CAC progression did not differ between those with the lowest (<300 pmol/L) and those with the highest plasma (dp)ucMGP concentration (incidence rate ratio: 0.82; 95% CI: 0.56, 1.19). Neither vitamin K status biomarker was associated with PWV at baseline or longitudinally.

Conclusions

Vitamin K status was not consistently associated with CAC or PWV in adults with mild-to-moderate CKD.

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

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

Nutritional recommendations for patients undergoing prolonged glucocorticoid therapy

Glucocorticoid (GC) therapy is a common treatment used in rheumatic and autoimmune diseases, owing to its anti-inflammatory and immunosuppressive effects. However, GC therapy can also induce a number of adverse effects, including muscle and bone loss, hypertension, metabolic perturbations and increased visceral adiposity. We review available evidence in this area and provide nutritional recommendations that might ameliorate these adverse effects. Briefly, optimizing calcium, vitamin D, sodium and protein intake and increasing consumption of unprocessed and minimally processed foods, while decreasing the consumption of ultra-processed foods, might counteract some of the specific challenges faced by these patients. Importantly, we identify a dearth of empirical data on how nutritional intervention might impact health-related outcomes in this population. Further research is required to investigate the clinical and therapeutic efficacy of these theory-based recommendations.

Development of a synbiotic that protects against ovariectomy-induced trabecular bone loss

The gut microbiome has the capacity to regulate bone mass. The aim of this study was to develop a nutritional synbiotic dietary assemblage at an optimal dose to maintain bone mass in ovariectomized (Ovx) mice. We performed genomic analyses and in vitro experiments in a large collection of bacterial and fungal strains (>4,000) derived from fresh fruit and vegetables to identify candidates with the synergistic capacity to produce bone-protective short-chain fatty acids (SCFA) and vitamin K2. The candidate SBD111-A, composed of Lactiplantibacillus plantarum, Levilactobacillus brevis, Leuconostoc mesenteroides, Pseudomonas fluorescens, and Pichia kudriavzevii together with prebiotic dietary fibers, produced high levels of SCFA in vitro and protected against Ovx-induced trabecular bone loss in a dose-dependent manner in mice. Metagenomic sequencing revealed that SBD111-A changed the taxonomic composition and enriched specific pathways for synthesis of bone-protective SCFA, vitamin K2, and branched-chain amino acids in the gut microbiome.NEW & NOTEWORTHY We performed genomic analyses and in vitro experiments in a collection of bacterial and fungal strains. We identified a combination (SBD111-A) that produced high levels of SCFA in vitro and protected against ovariectomy-induced bone loss in a dose-dependent manner in mice. Metagenomic sequencing revealed that SBD111-A changed the taxonomic composition and function of the gut microbiome and enriched pathways for synthesis of bone-protective SCFA, vitamin K2, and branched-chain amino acids.

Vitamin K-Dependent Proteins in Skeletal Development and Disease

Vitamin K and Vitamin K-dependent proteins (VKDPs) are best known for their pivotal role in blood coagulation. Of the 14 VKPDs identified in humans to date, 6 play also important roles in skeletal biology and disease. Thus, osteocalcin, also termed bone Gla-protein, is the most abundant non-collagenous protein in bone. Matrix Gla protein and Ucma/GRP on the other hand are highly abundant in cartilage. Furthermore, periostin, protein S, and growth arrest specific 6 protein (GAS 6) are expressed in skeletal tissues. The roles for these VKDPs are diverse but include the control of calcification and turnover of bone and cartilage. Vitamin K plays an important role in osteoporosis and serum osteocalcin levels are recognized as a promising marker for osteoporosis. On the other hand, matrix Gla protein and Ucma/GRP are associated with osteoarthritis. This review focuses on the roles of these three VKDPs, osteocalcin, matrix Gla protein and Ucma/GRP, in skeletal development and disease but will also summarize the roles the other skeletal VKDPs (periostin, protein S and GAS6) in skeletal biology.

Osteoporosis and the effect of dysregulation of the transsulfuration pathway via taurine on intracellular calcium homeostasis, vitamin D absorption and vitamin K absorption

BACKGROUND & AIMS

In this article we connect the dysregulation of the transsulfuration pathway to bone dysregulations and propose a novel treatment for osteoporosis. Current treatments for osteoporosis are very frequently inadequate. In osteoporosis, the risk of fractures increases with increased homocysteine (Hcy).

METHODS

Here, we conduct a review on the relationship between osteoporosis and the dysregulation of the transsulfuration pathway.

RESULTS

we show that the transsulfuration pathway metabolizes Hcy to L-cysteine. Increased Hcy levels point to the transsulfuration pathway being dysregulated. With the transsulfuration pathway dysregulated, there will be decreased levels of L-cysteine and decreased levels of taurine, which is synthesized from L-cysteine. Taurine levels are decreased in patients with osteoporosis. Taurine regulates intracellular calcium homeostasis. Taurine, also, when conjugated with bile acids assists with absorption of fats and fat-soluble vitamins such as vitamin D and vitamin K. Dysregulated calcium homeostasis, decreased calcium absorption and decreased absorption of vitamin D and vitamin K due to low levels of taurine negatively affect bone mineral density (BMD) leading to osteoporosis and fractures.

CONCLUSIONS

In this article, we propose that a combination of taurine, calcium, vitamin D and vitamin K, could increase BMD reducing number of years spent in disability and reducing deaths due to fractures in patients with osteoporosis.

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.

Serum vitamin K1 (phylloquinone) is associated with fracture risk and hip strength in post-menopausal osteoporosis: A cross-sectional study

PURPOSE

Vitamin K may play a potential role in bone metabolism, although further evidence is needed. The mechanisms behind its skeletal effects and optimum intake for maintaining bone health remain poorly defined. To elucidate these two issues, we investigated the association between circulating vitamin K₁ (phylloquinone) concentrations with fracture risk, bone mineral density (BMD), hip geometry and plasma dephospho-uncarboxylated-Matrix Gla Protein (dp-ucMGP), an extra-hepatic vitamin K dependent protein (VKDP), in post-menopausal osteoporosis (PMO).

METHODS

We studied 374 women aged (mean [SD]) 68.7[12.3] years with PMO. Information including demographics, lifestyle habits and previous fractures was captured through a questionnaire. Serum was analysed for vitamin K₁. BMD at the lumbar spine (LS), total hip (TH) and femoral neck (FN) (n = 277) and hip structural analysis (HSA) parameters (n = 263) were derived from DXA scans. VKDPs including undercarboxylated prothrombin (PIVKA-II) and dp-ucMGP were measured in a sub-group (n = 130).

RESULTS

Serum vitamin K₁ was significantly lower in the group with fractures (prevalent fractures: 0.53 [0.41], no fractures; 0.65 [0.66] μg/L, p = 0.04) and independently associated with fracture risk. The adjusted odds ratio (95% CI) per μg/L increase in vitamin K₁ was 0.550 (0.310-0.978, p = 0.042). Among the HSA parameters, serum vitamin K₁ was positively associated with cross-sectional area (CSA) (p = 0.02), cross sectional moment of inertia (CSMI) (p = 0.028) and section modulus (Z) (p = 0.02) at the narrow neck (NN) of femur. Dp-ucMGP was detectable in 97 (75%) participants with serum vitamin K₁ of 0.26 [0.15] μg/L, whilst PIVKA-II was above the clinical threshold in only 3.8%.

CONCLUSIONS

Our data suggest that the positive effect of vitamin K on fracture risk may be related to its effects on bone strength. Higher concentrations of serum vitamin K₁ may be required for vitamin K's skeletal effects compared to coagulation. Further prospective or interventional studies are needed for confirmation and should include measures of bone quality.

British Obesity and Metabolic Surgery Society Guidelines on perioperative and postoperative biochemical monitoring and micronutrient replacement for patients undergoing bariatric surgery-2020 update

Bariatric surgery is recognized as the most clinically and cost-effective treatment for people with severe and complex obesity. Many people presenting for surgery have pre-existing low vitamin and mineral concentrations. The incidence of these may increase after bariatric surgery as all procedures potentially cause clinically significant micronutrient deficiencies. Therefore, preparation for surgery and long-term nutritional monitoring and follow-up are essential components of bariatric surgical care. These guidelines update the 2014 British Obesity and Metabolic Surgery Society nutritional guidelines. Since the 2014 guidelines, the working group has been expanded to include healthcare professionals working in specialist and non-specialist care as well as patient representatives. In addition, in these updated guidelines, the current evidence has been systematically reviewed for adults and adolescents undergoing the following procedures: adjustable gastric band, sleeve gastrectomy, Roux-en-Y gastric bypass and biliopancreatic diversion/duodenal switch. Using methods based on Scottish Intercollegiate Guidelines Network methodology, the levels of evidence and recommendations have been graded. These guidelines are comprehensive, encompassing preoperative and postoperative biochemical monitoring, vitamin and mineral supplementation and correction of nutrition deficiencies before, and following bariatric surgery, and make recommendations for safe clinical practice in the U.K. setting.

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.

Nutrition and physical activity level of adolescents with idiopathic scoliosis: a narrative review

Some studies have shown that patients with adolescent idiopathic scoliosis (AIS) have different anthropometric features compared with their peers such as taller stature, lower body mass index, and bone mineral density. Yet the causes explaining these differences remain uncertain. Nutritional intake and status, combined with physical activity, could explain these discrepancies. We aimed to review the current literature on energy and nutrient intake, on nutritional status and physical activity in relation to AIS and to discuss study methodologies and propose avenues for future studies. Studies describing energy or nutrient intake in AIS mostly focused on total energy and calcium and found no difference between AIS and control cohorts. Regarding nutritional status, it was found that AIS patients have lower vitamin D levels than controls and that most patients have insufficient or deficient vitamin D serum levels. Lower concentration of parathyroid hormones and calcitonin were also found in AIS compared to controls as well as anomalies in trace elements. In the studies that have assessed physical activity, three found that AIS girls were less active than controls, but four did not observe differences between groups. In this review, we highlight that nutrition and physical activity are important topics in AIS that require further research as they could help understand anthropometric discrepancies and disease etiology.

Vitamin K deficiency, evaluated with higher serum ucOC, was correlated with poor bone status in women

BACKGROUND

An increase in serum undercarboxylated osteocalcin concentrations suggests vitamin K deficiency. Clinical intervention studies suggested that the vitamin K supplementation might contribute to preventing bone loss in postmenopausal women. Evidence on the relationship between serum undercarboxylated osteocalcin (ucOC) levels and bone parameters of quantitative ultrasound (QUS) is limited. We examined the correlation between serum ucOC concentrations and bone status as measured by QUS among middle-aged and older Japanese men and women.

METHODS

The subjects were community-dwelling men (n = 358) and women (n = 503) aged ≥ 40 years in Japan. Heel QUS parameters, including the stiffness index, speed of sound, and broadband ultrasound attenuation, were measured. Serum ucOC concentrations were measured by electrochemiluminescence immunoassay. Grip strength was measured in the dominant hand. Information on alcohol drinking, current smoking, exercise, and menopause in women was collected.

RESULTS

Serum ucOC concentrations were significantly associated with age in both sexes. Serum ucOC concentrations in men were higher at ≥ 80 years than those in the age groups of 40-49, 50-59, and 60-69 years. Serum ucOC concentrations in women were higher in the age groups of 50-59 and 60-69 years than those at 40-49 years. Partial correlation analysis adjusting for covariates (age, body mass index, grip strength, alcohol drinking, current smoking, and exercise in men; age, body mass index, grip strength, alcohol drinking, current smoking, exercise, and menopause in women) showed that serum ucOC concentrations were negatively significantly correlated with all QUS parameters in women. Serum ucOC concentrations were not correlated with them in men.

CONCLUSIONS

Vitamin K deficiency, evaluated with higher serum ucOC, was correlated with poor bone status in women.

Vitamin K and Bone Health: A Review on the Effects of Vitamin K Deficiency and Supplementation and the Effect of Non-Vitamin K Antagonist Oral Anticoagulants on Different Bone Parameters

Although known for its importance in the coagulation cascade, vitamin K has other functions. It is an essential vitamin for bone health, taking part in the carboxylation of many bone-related proteins, regulating genetic transcription of osteoblastic markers, and regulating bone reabsorption. Vitamin K deficiency is not uncommon, as deposits are scarce and dependent upon dietary supplementation and absorption. Vitamin K antagonist oral anticoagulants, which are prescribed to many patients, also induce vitamin K deficiency. Most studies find that low serum K1 concentrations, high levels of undercarboxylated osteocalcin (ucOC), and low dietary intake of both K1 and K2 are associated with a higher risk of fracture and lower BMD. Studies exploring the relationship between vitamin K supplementation and fracture risk also find that the risk of fracture is reduced with supplements, but high quality studies designed to evaluate fracture as its primary endpoint are needed. The reduction in risk of fracture with the use of non-vitamin K antagonist oral anticoagulants instead of warfarin is also of interest although once again, the available evidence offers disparate results. The scarce and limited evidence, including low quality studies reaching disparate conclusions, makes it impossible to extract solid conclusions on this topic, especially concerning the use of vitamin K supplements.

Bone Mineral Density in Premenopausal Women Is Associated with the Dietary Intake of α-Tocopherol: A Cross-Sectional Study

This study aimed to investigate the relationship between the consumption of various nutrients and bone mineral density (BMD) in middle-aged women. This cross-sectional survey was conducted based on the clinical records of 157 women aged 38–76. Their lumbar spine BMD was measured with dual-energy X-ray absorptiometry and dietary habits were assessed with the brief-type self-administered diet history questionnaire. Participants were divided into premenopausal (n = 46) and postmenopausal (n = 111) groups and the correlation between the BMD Z-score (Z-score) and the intakes of 43 nutrients was investigated separately for each group. In premenopausal women, the daily intake of ash, calcium, and α-tocopherol was positively correlated with the Z-score (Pearson’s correlation coefficient, R = 0.31, 0.34, 0.33, p = 0.037, 0.020, 0.027, respectively). When dividing the consumption of ash, calcium, and α-tocopherol into low, middle, and high tertiles, the Z-score significantly differed only between the α-tocopherol tertiles. After adjustment for age, body mass index, and lifestyle factors, daily intake of α-tocopherol remained significantly associated with the Z-score (regression coefficient = 0.452, p = 0.022). No nutrient was found to be significantly correlated with the Z-score in postmenopausal women. Increase in the intake of α-tocopherol could help maintain bone mass in premenopausal women.

Long-chain vitamin K2 production in Lactococcus lactis is influenced by temperature, carbon source, aeration and mode of energy metabolism

Background

Vitamin K2 (menaquinone, MK-n) is a lipid-soluble vitamin that functions as a carboxylase co-factor for maturation of proteins involved in many vital physiological processes in humans. Notably, long-chain vitamin K2 is produced by bacteria, including some species and strains belonging to the group of lactic acid bacteria (LAB) that play important roles in food fermentation processes. This study was performed to gain insights into the natural long-chain vitamin K2 production capacity of LAB and the factors influencing vitamin K2 production during cultivation, providing a basis for biotechnological production of vitamin K2 and in situ fortification of this vitamin in food products.

Results

We observed that six selected Lactococcus lactis strains produced MK-5 to MK-10, with MK-8 and MK-9 as the major MK variant. Significant diversities between strains were observed in terms of specific concentrations and titres of vitamin K2. L. lactis ssp. cremoris MG1363 was selected for more detailed studies of the impact of selected carbon sources tested under different growth conditions [i.e. static fermentation (oxygen absent, heme absent); aerobic fermentation (oxygen present, heme absent) and aerobic respiration (oxygen present, heme present)] on vitamin K2 production in M17 media. Aerobic fermentation with fructose as a carbon source resulted in the highest specific concentration of vitamin K2: 3.7-fold increase compared to static fermentation with glucose, whereas aerobic respiration with trehalose resulted in the highest titre: 5.2-fold increase compared to static fermentation with glucose. When the same strain was applied to quark fermentation, we consistently observed that altered carbon source (fructose) and aerobic cultivation of the pre-culture resulted in efficient vitamin K2 fortification in the quark product.

Conclusions

With this study we demonstrate that certain LAB strains can be employed for efficient production of long-chain vitamin K2. Strain selection and optimisation of growth conditions offer a viable strategy towards natural vitamin K2 enrichment of fermented foods, and to improved biotechnological vitamin K2 production processes.

Electronic supplementary material

The online version of this article (10.1186/s12934-019-1179-9) contains supplementary material, which is available to authorized users.

VKORC1L1, An Enzyme Mediating the Effect of Vitamin K in Liver and Extrahepatic Tissues

Vitamin K is an essential nutrient involved in the regulation of blood clotting and tissue mineralization. Vitamin K oxidoreductase (VKORC1) converts vitamin K epoxide into reduced vitamin K, which acts as the co-factor for the γ-carboxylation of several proteins, including coagulation factors produced by the liver. VKORC1 is also the pharmacological target of warfarin, a widely used anticoagulant. Vertebrates possess a VKORC1 paralog, VKORC1-like 1 (VKORC1L1), but until very recently, the importance of VKORC1L1 for protein γ-carboxylation and hemostasis in vivo was not clear. Here, we first review the current knowledge on the structure, function and expression pattern of VKORC1L1, including recent data establishing that, in the absence of VKORC1, VKORC1L1 can support vitamin K-dependent carboxylation in the liver during the pre- and perinatal periods in vivo. We then provide original data showing that the partial redundancy between VKORC1 and VKORC1L1 also exists in bone around birth. Recent studies indicate that, in vitro and in cell culture models, VKORC1L1 is less sensitive to warfarin than VKORC1. Genetic evidence is presented here, which supports the notion that VKORC1L1 is not the warfarin-resistant vitamin K quinone reductase present in the liver. In summary, although the exact physiological function of VKORC1L1 remains elusive, the latest findings clearly established that this enzyme is a vitamin K oxidoreductase, which can support γ-carboxylation in vivo.

Dried Plum Polyphenolic Extract Combined with Vitamin K and Potassium Restores Trabecular and Cortical Bone in Osteopenic Model of Postmenopausal Bone Loss

Dried plum has unique anabolic effects on bone, but the responsible bioactive components have remained unclear. This study investigated components of dried plum with potential osteoprotective activity utilizing aged, osteopenic Sprague Dawley rats fed diets supplemented with a crude polyphenol extract, potassium, vitamin K or their combination. Whole body and femoral bone mineral density were restored with the polyphenol and combination treatments to a similar extent as the dried fruit. The combination treatment reversed trabecular bone loss in the spine and cortical bone in the femur mid-diaphysis in a similar manner. Biomarkers of bone resorption were reduced by the polyphenol and combination treatments. The polyphenol extract accounted for most of the anabolic effect of dried plum on bone. This study is the first to show the bioactive components in dried plum responsible for restoring bone in vivo.

Prevalence and Effects of Functional Vitamin K Insufficiency: The PREVEND Study

Matrix Gla Protein (MGP) is a strong vitamin K-dependent inhibitor of soft tissue calcification. We assessed the prevalence of functional vitamin K insufficiency, as derived from plasma desphospho-uncarboxylated MGP (dp-ucMGP), and investigated whether plasma dp-ucMGP is associated with all-cause and cardiovascular mortality in a large general population-based cohort. We included 4275 subjects (aged 53 ± 12 years, 46.0% male) participating in the prospective general population-based Prevention of Renal and Vascular End-Stage Disease (PREVEND) study. The prevalence of functional vitamin K insufficiency (i.e., dp-ucMGP > 500 pmol/L) was 31% in the total study population. This prevalence was significantly higher among elderly and subjects with comorbidities like hypertension, type 2 diabetes, chronic kidney disease, and cardiovascular disease (~50%). After 10 years of follow-up, 279 subjects had died, with 74 deaths attributable to cardiovascular causes. We found significant J-shaped associations of plasma dp-ucMGP with all-cause (linear term: hazard ratio (HR) (95% confidence interval (CI)) = 0.20 (0.12-0.33), p < 0.001; squared term: 1.14 (1.10-1.17), p < 0.001) and cardiovascular mortality (linear term: 0.12 (0.05-0.27), p < 0.001; squared term: 1.17 (1.11-1.23), p < 0.001). These associations remained significant after adjustment for potential confounders. Whether the correction of vitamin K insufficiency improves health outcomes needs to be addressed in future prospective intervention studies.

Vitamin K and osteoporosis: Myth or reality?

Vitamin K is a liposoluble vitamin. The predominant dietary form, phylloquinone or vitamin K1, is found in plants and green vegetables; whereas menaquinone, or vitamin K2, is endogenously synthesized by intestinal bacteria and includes several subtypes that differ in side chain length. Aside from its established role in blood clotting, several studies now support a critical function of vitamin K in improving bone health. Vitamin K is in fact required for osteocalcin carboxylation that in turn regulates bone mineral accretion; it seems to promote the transition of osteoblasts to osteocytes and also limits the process of osteoclastogenesis. Several observational and interventional studies have examined the relationship between vitamin K and bone metabolism, but findings are conflicting and unclear. This systematic review aims to investigate the impact of vitamin K (plasma levels, dietary intake, and oral supplementation) on bone health with a particular interest in bone remodeling, mineral density and fragility fractures.

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.

Bone Health and Osteoporosis: The Role of Vitamin K and Potential Antagonism by Anticoagulants

BACKGROUND

Vitamin K's effects extend beyond blood clotting to include a role in bone metabolism and potential protection against osteoporosis. Vitamin K is required for the gamma-carboxylation of osteocalcin. Likewise, this gamma-carboxylation also occurs in the liver for several coagulation proteins. This mechanism is interrupted by coumarin-based anticoagulants in both the liver and bone.

METHODS

A thorough review of the literature on vitamin K, osteocalcin and their role in bone metabolism and osteoporosis, as well as the potential bone effects of anticoagulant therapy was conducted.

CONCLUSIONS

Epidemiological studies and clinical trials consistently indicate that vitamin K has a positive effect on bone mineral density and decreases fracture risk. Typical dietary intakes of vitamin K are below the levels associated with better BMD and reduced fracture risk; thus issues of increasing dietary intakes, supplementation, and/or fortification arise. To effectively address these issues, large-scale, intervention trials of vitamin K are needed. The effects of coumarin-based anticoagulants on bone health are more ambiguous, with retrospective studies suggesting that long-term therapy adversely affects vertebral BMD and fracture risk. Anticoagulants that do not affect vitamin K metabolism are now available and make clinical trials feasible to answer the question of whether coumarins adversely affect bone. The research suggests that at a minimum, clinicians should carefully assess anticoagulated patients for osteoporosis risk, monitor BMD, and refer them to dietitians for dietary and supplement advice on bone health. Further research is needed to make more efficacious decisions about vitamin K intake, anticoagulant therapy, and bone health.

Vitamin D Status and Bone Mineral Density is Influenced by Vitamin D Supplementation and Vitamin K1 Intake in Adults with Diabetes and Chronic Kidney Disease

PURPOSE

Patients with diabetes (DM) and chronic kidney disease (CKD) are at increased risk for suboptimal bone health. The study objective was to investigate the relationships between vitamin D (vitD), vitamin K1 (vitK₁), and calcium intake with bone mineral density (BMD) and vitamin D status in an ambulatory population with DM and CKD.

METHODS

Adults (age 18-80 years; n = 62) with DM and CKD (stages 1-4) were recruited from the Northern Alberta Renal Program. Primary outcome variables included vitD, vitK₁, and calcium intake; serum 25(OH)D, 1,25(OH)₂D; and BMD as measured by dual X-ray absorptiometry. Statistical significance was determined at P < 0.05.

RESULTS

Participants met the estimated average requirement or adequate intake for vitD, vitK₁, and calcium intake in 73% (n = 45), 66% (n = 39), and 52% (n = 31), respectively, with a combined intake of micronutrient supplementation and diet. Participants had serum 25(OH)D concentrations ≥75 nmol/L (n = 41), normal BMDs (n = 48), and 66% (n = 41/62) were taking vitD supplements (>1000 IU/D). BMD was positively influenced by serum 25(OH)D. However, serum 25(OH) ≥100 nmol/L was associated with lower BMD (absolute and T-scores) for whole-body and spine (P ≤ 0.05). VitK₁ intake (≥200 μg/day) was associated with higher whole-body and femoral-neck BMDs (absoluteand T-scores; P ≤ 0.05).

CONCLUSION

VitD status and BMD in adults with DM and CKD was influenced by vitD supplementation and vitK₁ intake.

Combination of micellar casein with calcium and vitamins D2 and K2 improves bone status of ovariectomized mice

Nutritional approaches may help to preserve bone quality. The purpose of our study was to demonstrate the efficiency of an innovative bone health product (BHP) including micellar casein rich in calcium, vitamin D2 and vitamin K2, to improve bone mineral density.

INTRODUCTION

The aim of postmenopausal osteoporosis treatment is to decrease bone resorption and/or increase bone formation. Because of the slow bone turnover, osteoporosis prevention and therapies are long-lasting, implying great costs and poor compliance. Even if the effects of nutrition on bone are not as marked as that of pharmaceutical agents, it can be of great help. The purpose of our study was to demonstrate the efficiency of an innovative bone health product (BHP) containing micellar casein rich in calcium, vitamin D2 and vitamin K2, for the improvement of bone mineral density (BMD).

METHODS

An ovariectomized mice model was used to study the effect of different concentrations of the ingredient on BMD and microarchitectural parameters. Blood concentrations of C-terminal telopeptide of type I collagen (CTX), N-terminal propeptide of type 1 procollagene (PINP), alkaline phosphatase (ALP), osteocalcin (OC) and RANKL were also measured to evaluate bone remodelling, To evaluate the efficiency of the product to modulate osteoblast and osteoclast growth and differentiation, primary murine bone cells were used.

RESULTS

In vivo studies showed that BMD and microarchitectural parameters were dose-dependently improved after ingestion of the supplement for 3 months. We also report increased osteoblast activity as shown by increased OC activity and decreased osteoclastogenesis as shown by reduced CTX activity. In vitro studies support that BHPs stimulate osteoblast differentiation and mineralization and inhibit osteoclast resorption activity.

CONCLUSION

Our results show that, when chronically ingested, BHPs improve BMD of ovariectomized mice. This work supports that providing an ingredient including micellar casein rich in calcium, vitamin D2 and vitamin K2 is more efficient than the control diet to maintain bone quality.

Concepts and Controversies in Evaluating Vitamin K Status in Population-Based Studies

A better understanding of vitamin K's role in health and disease requires the assessment of vitamin K nutritional status in population and clinical studies. This is primarily accomplished using dietary questionnaires and/or biomarkers. Because food composition databases in the US are most complete for phylloquinone (vitamin K1, the primary form in Western diets), emphasis has been on phylloquinone intakes and associations with chronic diseases. There is growing interest in menaquinone (vitamin K2) intakes for which the food composition databases need to be expanded. Phylloquinone is commonly measured in circulation, has robust quality control schemes and changes in response to phylloquinone intake. Conversely, menaquinones are generally not detected in circulation unless large quantities are consumed. The undercarboxylated fractions of three vitamin K-dependent proteins are measurable in circulation, change in response to vitamin K supplementation and are modestly correlated. Since different vitamin K dependent proteins are implicated in different diseases the appropriate vitamin K-dependent protein biomarker depends on the outcome under study. In contrast to other nutrients, there is no single biomarker that is considered a gold-standard measure of vitamin K status. Most studies have limited volume of specimens. Strategic decisions, guided by the research question, need to be made when deciding on choice of biomarkers.

Dietary intake of vitamin K in relation to bone mineral density in Korea adults: The Korea National Health and Nutrition Examination Survey (2010-2011)

Low vitamin K nutritional status has been associated with increased risk of fracture, however inconsistent results exist to support the role of vitamin K on bone mineral density depending on ethnic difference and gender. Our objective was to determine vitamin K intake in Korean adults, examine correlation between vitamin K intake and bone mineral density. This study analyzed raw data from the fifth Korea National Health and Nutrition Examination Survey for adults (2,785 men, 4,307 women) aged over 19 years. Cross-sectional analyses showed only positive association between vitamin K intake and femur bone mineral density in men after adjusting bone-related factors. However, women in high tertiles of vitamin K intake had a significantly higher bone mineral density both in femur and lumber as compared to women in lowest tertiles (p<0.05). The risk for osteoporosis was decreased as vitamin K intake increased in women, but this effect was not persisted after adjusting factors. The findings of this study indicate that low dietary vitamin K intake was associated with low bone mineral density in subjects. From these results we may suggest an increase in dietary vitamin K intakes for maintaining bone mineral density. (2010-02CON-21-C, 2011-02CON-06-C).

Dietary Approaches for Bone Health: Lessons from the Framingham Osteoporosis Study

Osteoporosis is characterized by systemic impairment of bone mass, strength, and microarchitecture, resulting in increased risk for fragility fracture, disability, loss of independence, and even death. Adequate nutrition is important in achieving and maintaining optimal bone mass, as well as preventing this debilitating disease. It is widely accepted that adequate calcium and vitamin D intake are necessary for good bone health; however, nutritional benefits to bone go beyond these two nutrients. This review article will provide updated information on all nutrients and foods now understood to alter bone health. Specifically, this paper will focus on related research from the Framingham Osteoporosis Study, an ancillary study of the Framingham Heart Study, with data on more than 5000 adult men and women.

Multivitamin and mineral supplementation is associated with the reduction of fracture risk and hospitalization rate in Chinese adult males: a randomized controlled study

Controversy exists in the literature regarding the efficacy of bone health-related nutrients, especially calcium and vitamin D, in preventing fractures. The aim of our present study was to determine the effect of multivitamin and mineral supplementation on fracture incidence among 3,318 participants from a nutritional intervention trial in Linxian, China. A total of 1,461 men and 1,857 women were enrolled and randomized to daily supplementation with 26 vitamins and minerals tablet or placebo pills for 6 years, followed by a 16-year post-interventional follow-up. The dates, sites, and causes of the fractures were collected retrospectively via a standardized questionnaire. Cox proportional hazard model was used to estimate hazard ratios and 95% confidence intervals of fracture incidence in the intervention versus the placebo group. A total of 221 fractures (57 in men and 164 in women) occurred during the entire study period of 21 years and 9 months. In men, the supplement reduced the risk of fracture by 63% during the trial period, and this protective effect was sustained and statistically significant when analysis included both the trial period and 5- or 10-year post-intervention follow-up (years 0-11, P = 0.04; years 0-16, P = 0.02, respectively). The protection against fracture was not apparent >10 years after cessation of the intervention. In women, no significant effect of supplementation on fracture incidence was seen in any of the study periods. These results demonstrate that a 6-year multivitamin and mineral intervention was associated with significant reduction of fracture risk and fracture-related hospitalization in men, but not in women.

A four-season molecule: osteocalcin. Updates in its physiological roles

Osteocalcin (OC) is the main non-collagenous hydroxyapatite-binding protein synthesized by osteoblasts, odontoblasts, and hypertrophic chondrocytes. It has a regulatory role in mineralization and it is considered a marker of bone cell metabolism. Recent findings evidenced new extra-skeletal roles for OC, depicting it as a real hormone. OC shares many functional features with the common hormones, such as tissue-specific expression, circadian rhythm, and synthesis as a pre-pro-molecule. However, it has some peculiar features making it a unique molecule: OC exists in different forms based on the degree of carboxylation. Indeed, OC has three glutamic acid residues, in position 17, 21, and 24, which are subject to γ-carboxylation, through the action of a vitamin K-dependent γ-glutamyl carboxytransferase. The degree of carboxylation, and thus the negative charge density, determines the affinity for the calcium ions deposited in the extracellular matrix of the bone. The modulation of the carboxylation could, thus, represent the mechanism by which the body controls the circulating levels, and hence the hormonal function, of OC. There are evidences linking OC, and the bone metabolism, with a series of endocrine (glucose metabolism, energy metabolism, fertility) physiological (muscle activity) and pathological functions (ectopic calcification). Aim of this review is to give a full overview of the physiological roles of OC by collecting the newest experimental findings on this intriguing molecule.

Meta-analysis of genome-wide association studies for circulating phylloquinone concentrations

BACKGROUND

Poor vitamin K status is linked to greater risk of several chronic diseases. Age, sex, and diet are determinants of circulating vitamin K; however, there is still large unexplained interindividual variability in vitamin K status. Although a strong genetic component has been hypothesized, this has yet to be examined by a genome-wide association (GWA) study.

OBJECTIVE

The objective was to identify common genetic variants associated with concentrations of circulating phylloquinone, the primary circulating form of vitamin K.

DESIGN

We conducted a 2-stage GWA meta-analysis of circulating phylloquinone in 2 populations of European descent from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium Nutrition Working Group. Circulating phylloquinone was measured by using reversed-phase high-performance liquid chromatography. Results from adjusted cohort-specific discovery GWA analyses were meta-analyzed with inverse variance weights (n = 2138). Associations with circulating phylloquinone at P < 1 × 10(-6) were then evaluated in a second-stage analysis consisting of one independent cohort (n = 265).

RESULTS

No significant association was observed for circulating phylloquinone at the genome-wide significance level of 5 × 10(-8). However, from the discovery GWA, there were 11 single-nucleotide polymorphism (SNP) associations with circulating phylloquinone at P < 1 × 10(-6), including a functional variant previously associated with warfarin dose and altered phylloquinone metabolism. These SNPs are on 5 independent loci on 11q23.3, 8q24.3, 5q22.3, 2p12, and 19p13.12, and they fall within or near the candidate genes APOA1/C3/A4/A5 cluster (involved in lipoprotein metabolism), COL22A1, CDO1, CTNAA2, and CYP4F2 (a phylloquinone oxidase), respectively. Second-stage analysis in an independent cohort further suggests the association of the 5q22.3 locus with circulating phylloquinone (P < 0.05).

CONCLUSIONS

Multiple candidate genes related to lipoprotein and vitamin K metabolism were identified as potential determinants of circulating phylloquinone. Further investigation with a larger sample is warranted to verify our initial findings and identify other loci contributing to circulating phylloquinone. Trials related to this study were registered at clinicaltrials.gov as NCT00005121 (Framingham Offspring Study) and NCT00005487 (Multi-Ethnic Study of Atherosclerosis).

Incident long-term warfarin use and risk of osteoporotic fractures: propensity-score matched cohort of elders with new onset atrial fibrillation

Association between warfarin use and fracture risk is unclear. We examined the association between long-term warfarin use and fracture risk at the hip, spine, and wrist in elders. No significant association was found between long-term warfarin use and fracture risk, despite biological plausibility.

INTRODUCTION

Prior studies examining the association of warfarin use and osteoporotic fractures have been conflicting, potentially related to methodological limitations. Thus, we examined the association of long-term warfarin use with risk of hip, spine, and wrist fractures among older adults with atrial fibrillation, attempting to address prior methodologic challenges.

METHODS

We included men and women ≥ 65 years of age with incident atrial fibrillation and without prior history of fractures from The Health Improvement Network followed between 2000 and 2010. Long-term warfarin use was defined in two ways: (1) warfarin use ≥ 1 year; (2) warfarin use ≥ 3 years. Propensity-score matched cohorts of warfarin users and nonusers were created to evaluate the association between long-term warfarin use and risk of hip, spine, and wrist fractures separately as well as combined, using Cox-proportional hazards regression models.

RESULTS

Among >20,000 participants with incident atrial fibrillation, the hazard ratios (HR) for hip fracture with warfarin use ≥ 1 and ≥ 3 years, respectively, were 1.08 (95%CI 0.87, 1.35) and 1.13 (95% CI 0.84, 1.50). Similarly, no significant associations were observed between long-term warfarin use and risk of spine or wrist fracture. When risk of any fracture was assessed with warfarin use, no association was found [HR for warfarin use ≥ 1 year 0.92 (95%CI 0.77, 1.10); HR for warfarin use ≥ 3 years 1.12 (95%CI 0.88, 1.43)].

CONCLUSIONS

Long-term warfarin use among elders with atrial fibrillation was not associated with increased risk of osteoporotic fractures and therefore does not appear to necessitate additional surveillance or prophylaxis.

Vitamin K and bone health in older adults

Vitamin K is one of several nutrients that have been linked with bone health. In particular, there is an emerging literature regarding the questionable efficacy of vitamin K supplementation in reducing age-related bone loss. This review aims to summarize the role of vitamin K in bone health in older adults and discuss the clinical implications from a select few human studies. The evidence for vitamin K supplementation in older adults is mixed. Although the observational studies have shown linkages between vitamin K intake and lower risk of fractures in this population, the current evidence from randomized controlled trials is not strongly supportive of vitamin K supplementation in older adults for the intent of improving bone health.

Vitamin K1 (phylloquinone) and K2 (menaquinone-4) supplementation improves bone formation in a high-fat diet-induced obese mice

Several reports suggest that obesity is a risk factor for osteoporosis. Vitamin K plays an important role in improving bone metabolism. This study examined the effects of vitamin K1 and vitamin K2 supplementation on the biochemical markers of bone turnover and morphological microstructure of the bones by using an obese mouse model. Four-week-old C57BL/6J male mice were fed a 10% fat normal diet group or a 45% kcal high-fat diet group, with or without 200 mg/1000 g vitamin K1 (Normal diet + K1, high-fat diet + K1) and 200 mg/1000 g vitamin K2 (Normal diet + K2, high-fat diet + K2) for 12 weeks.

Serum levels of osteocalcin were higher in the high-fat diet + K2 group than in the high-fat diet group. Serum OPG level of the high-fat diet group, high-fat diet + K1 group, and high-fat diet + K2 group was 2.31 ± 0.31 ng/ml, 2.35 ± 0.12 ng/ml, and 2.90 ± 0.11 ng/ml, respectively. Serum level of RANKL in the high-fat diet group was significantly higher than that in the high-fat diet + K1 group and high-fat diet + K2 group (p<0.05). Vitamin K supplementation seems to tend to prevent bone loss in high-fat diet induced obese state. These findings suggest that vitamin K supplementation reversed the high fat diet induced bone deterioration by modulating osteoblast and osteoclast activities and prevent bone loss in a high-fat diet-induced obese mice.

Skeletal effects of nutrients and nutraceuticals, beyond calcium and vitamin D

There is a need to understand the role of nutrition, beyond calcium and vitamin D, in the treatment and prevention of osteoporosis in adults. Results regarding soy compounds on bone density and bone turnover are inconclusive perhaps due to differences in dose and composition or in study population characteristics. The skeletal benefit of black cohosh and red clover are unknown. Dehydroepiandrosterone (DHEA) use may benefit elderly individuals with low serum dehydroepiandrosterone-sulfate levels, but even in this group, there are inconsistent benefits to bone density (BMD). Higher fruit and vegetable intakes may relate to higher BMD. The skeletal benefit of flavonoids, carotenoids, omega-3-fatty acids, and vitamins A, C, E and K are limited to observational data or a few clinical trials, in some cases investigating pharmacologic doses. Given limited data, it would be better to get these nutrients from fruits and vegetables. Potassium bicarbonate may improve calcium homeostasis but with little impact on bone loss. High homocysteine may relate to fracture risk, but the skeletal benefit of each B vitamin is unclear. Magnesium supplementation is likely only required in persons with low magnesium levels. Data are very limited for the role of nutritional levels of boron, strontium, silicon and phosphorus in bone health. A nutrient rich diet with adequate fruits and vegetables will generally meet skeletal needs in healthy individuals. For most healthy adults, supplementation with nutrients other than calcium and vitamin D may not be required, except in those with chronic disease and the frail elderly.

Update on nutrients involved in maintaining healthy bone

Osteoporosis is a leading cause of morbidity and mortality in the elderly and influences quality of life, as well as life expectancy. Currently, there is a growing interest among the medical scientists in search of specific nutrients and/or bioactive compounds of natural origin for the prevention of disease and maintenance of bone health. Although calcium and vitamin D have been the primary focus of nutritional prevention of osteoporosis, a recent research has clarified the importance of several additional nutrients and food constituents. Based on this review of the literature, supplementation with vitamins B, C, K, and silicon could be recommended for proper maintenance of bone health, although further clinical studies are needed. The results of studies on long-chain polyunsaturated fatty acids, potassium, magnesium, copper, selenium, and strontium are not conclusive, although studies in vitro and in animal models are interesting and promising.

Vitamin K, vertebral fractures, vascular calcifications, and mortality: VItamin K Italian (VIKI) dialysis study

Vitamin K (vitamin K1 or phylloquinone and vitamin K2, a series of menaquinones [MKs]) is involved in the production of bone and matrix amino acid γ-carboxy-glutamic acid (Gla) proteins, regulating bone and vascular calcification. Low vitamin K concentrations are associated with increased risks of fractures and vascular calcification, and frequent complications in hemodialysis patients. We carried out an observational study to establish the prevalence of vitamin K deficiency and to assess the relationship between vitamin K status, vertebral fractures, vascular calcification, and survival in 387 patients on hemodialysis for ≥1 year. We determined plasma levels of vitamin K compound, bone-Gla-protein, matrix-Gla-protein, and routine biochemistry. Vertebral fractures (reduction in vertebral body height by ≥20%) and aortic and iliac calcifications were also investigated in a spine (D(5) -L(4)) radiograph. Three-year patient survival was analyzed. Important proportions of patients had deficiency of MK7 (35.4%), vitamin K1 (23.5%), and MK4 (14.5%). A total of 55.3% of patients had vertebral fractures, 80.6% had abdominal aorta calcification, and 56.1% had iliac calcification. Vitamin K1 deficiency was the strongest predictor of vertebral fractures (odds ratio [OR], 2.94; 95% confidence interval [CI], 1.38-6.26). MK4 deficiency was a predictor of aortic calcification (OR, 2.82; 95% CI, 1.14-7.01), whereas MK5 deficiency actually protected against it (OR, 0.38; 95% CI, 0.15-0.95). MK7 deficiency was a predictor of iliac calcification (OR, 1.64; 95% CI, 1.03-2.60). The presence of vertebral fractures was also a predictor of vascular calcifications (OR, 1.76; 95% CI, 1.00-3.08). Increased alkaline phosphatase and C reactive protein (CRP), age, and cerebrovascular events were predictors of mortality. Our study suggests that the vitamin K system may be important for preserving bone mass and avoiding vascular calcification in hemodialysis patients, pointing out a possible role of vitamin K in bone and vascular health. Based on our results, we suggest that the general population should also be studied for vitamin K deficiency as a possible cause of both vertebral fractures and vascular calcification.

Micronutrient deficiencies in inflammatory bowel disease: from A to zinc

Inflammatory bowel disease (IBD) has classically been associated with malnutrition and weight loss, although this has become less common with advances in treatment and greater proportions of patients attaining clinical remission. However, micronutrient deficiencies are still relatively common, particularly in CD patients with active small bowel disease and/or multiple resections. This is an updated literature review of the prevalence of major micronutrient deficiencies in IBD patients, focusing on those associated with important extraintestinal complications, including anemia (iron, folate, vitamin B12) bone disease (calcium, vitamin D, and possibly vitamin K), hypercoagulability (folate, vitamins B6, and B12), wound healing (zinc, vitamins A and C), and colorectal cancer risk (folate and possibly vitamin D and calcium).