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Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women


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We have investigated whether low-dose vitamin K2 supplements (menaquinone-7, MK-7) could beneficially affect bone health. Next to an improved vitamin K status, MK-7 supplementation significantly decreased the age-related decline in bone mineral density and bone strength. Low-dose MK-7 supplements may therefore help postmenopausal women prevent bone loss. Introduction Despite contradictory data on vitamin K supplementation and bone health, the European Food Safety Authorities (EFSA) accepted the health claim on vitamin K’s role in maintenance of normal bone. In line with EFSA’s opinion, we showed that 3-year high-dose vitamin K1 (phylloquinone) and K2 (short-chain menaquinone-4) supplementation improved bone health after menopause. Because of the longer half-life and greater potency of the long-chain MK-7, we have extended these investigations by measuring the effect of low-dose MK-7 supplementation on bone health. Methods Healthy postmenopausal women (n = 244) received for 3 years placebo or MK-7 (180 μg MK-7/day) capsules. Bone mineral density of lumbar spine, total hip, and femoral neck was measured by DXA; bone strength indices of the femoral neck were calculated. Vertebral fracture assessment was performed by DXA and used as measure for vertebral fractures. Circulating uncarboxylated osteocalcin (ucOC) and carboxylated OC (cOC) were measured; the ucOC/cOC ratio served as marker of vitamin K status. Measurements occurred at baseline and after 1, 2, and 3 years of treatment. Results MK-7 intake significantly improved vitamin K status and decreased the age-related decline in BMC and BMD at the lumbar spine and femoral neck, but not at the total hip. Bone strength was also favorably affected by MK-7. MK-7 significantly decreased the loss in vertebral height of the lower thoracic region at the mid-site of the vertebrae. Conclusions MK-7 supplements may help postmenopausal women to prevent bone loss. Whether these results can be extrapolated to other populations, e.g., children and men, needs further investigation.
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Three-year low-dose menaquinone-7 supplementation helps
decrease bone loss in healthy postmenopausal women
M. H. J. Knapen &N. E. Drummen &E. Smit &
C. Vermeer &E. Theuwissen
Received: 29 November 2012 /Accepted: 12 February 2013 / Published online: 23 March 2013
#International Osteoporosis Foundation and National Osteoporosis Foundation 2013
Summary We have investigated whether low-dose vitamin
K2 supplements (menaquinone-7, MK-7) could beneficially
affect bone health. Next to an improved vitamin K status,
MK-7 supplementation significantly decreased the age-
related decline in bone mineral density and bone strength.
Low-dose MK-7 supplements may therefore help postmen-
opausal women prevent bone loss.
Introduction Despite contradictory data on vitamin K supple-
mentation and bone health, the European Food Safety Author-
ities (EFSA) accepted the health claim on vitamin Ksrolein
maintenance of normal bone. In line with EFSAs opinion, we
showed that 3-year high-dose vitamin K1 (phylloquinone) and
K2 (short-chain menaquinone-4) supplementation improved
bone health after menopause. Because of the longer half-life
and greater potency of the long-chain MK-7, we have extended
these investigations by measuring the effect of low-dose MK-7
supplementation on bone health.
Methods Healthy postmenopausal women (n=244) received
for 3 years placebo or MK-7 (180 μg MK-7/day) capsules.
Bone mineral density of lumbar spine, total hip, and femoral
neck was measured by DXA; bone strength indices of the
femoral neck were calculated. Vertebral fracture assessment
was performed by DXA and used as measure for vertebral
fractures. Circulating uncarboxylated osteocalcin (ucOC)
and carboxylated OC (cOC) were measured; the
ucOC/cOC ratio served as marker of vitamin K status.
Measurements occurred at baseline and after 1, 2, and
3 years of treatment.
Results MK-7 intake significantly improved vitamin K
status and decreased the age-related decline in BMC
and BMD at the lumbar spine and femoral neck, but
not at the total hip. Bone strength was also favorably
affected by MK-7. MK-7 significantly decreased the
loss in vertebral height of the lower thoracic region at
the mid-site of the vertebrae.
Conclusions MK-7 supplements may help postmenopausal
women to prevent bone loss. Whether these results can be
extrapolated to other populations, e.g., children and men,
needs further investigation.
Keywords Bone mineral density .Bone strength .
Osteocalcin .Postmenopausal .Ve r t e b ra l f r a c t u r e .Vit am in K
The prevalence of osteoporosis increases markedly with
age, and despite advances in diagnosis and treatment, a
minority of patients at high fracture risk is identified for
treatment. Long-term vitamin K inadequacy has been
indicated as an independent but modifiable risk factor
for the development of age-related diseases, including
osteoporosis and cardiovascular disease [1]. Vitamin K
is required for the posttranslational carboxylation of glu-
tamate into γ-carboxyglutamate (Gla) residues in so-
called Gla-proteins [2]. Seventeen Gla-proteins have been
identified to date, and the vitamin K-dependent carbox-
ylation is essential for their function. Dietary vitamin K
intake is too low, however, to support full carboxylation
of at least some of these Gla-proteins, including
osteocalcin (OC) and matrix Gla-protein [3]. OC is gen-
erally regarded as a local inhibitor of mineralization in
bone [4], and the uncarboxylated form (ucOC) is an
M. H. J. Knapen :N. E. Drummen :E. Smit :C. Vermeer :
E. Theuwissen (*)
VitaK, Maastricht University, Oxfordlaan 70,
6229 EV Maastricht, The Netherlands
Osteoporos Int (2013) 24:24992507
DOI 10.1007/s00198-013-2325-6
accepted marker for poor (bone) vitamin K status. Low
vitamin K intake and high circulating ucOC have been
associated with low bone mass and increased fracture
risk [59]. Improvement of vitamin K status as measured
by increased carboxylation of OC is readily achievable
by dietary supplementation with vitamin K [1014]. Con-
sistently, the European Food Safety Authorities (EFSA)
accepted the health claim on vitamin Ks role in mainte-
nance of normal bone [15]. Unfortunately, the molecular
mechanism of vitamin K and/or OC on bone health has
yet to be elucidated.
Despite the observational link between vitamin K status
and bone health, intervention studies have been contradic-
tory regarding supplemental effects on BMD and fracture
risk. Most studies have been carried out in Japan with
pharmacological doses of synthetic vitamin K2 (short-chain
menaquinone-4, MK-4). As summarized in the meta-
analysis by Cockayne, these studies showed an overall
benefit on reducing fracture risk [16]. A more recent meta-
analysis on K1 and K2 supplementation showed modest
treatment effects for vitamin K on BMD [17]. Next to the
high-dose MK-4 trials, four studies with nutritional amounts
of K1 and the long-chain menaquinone-7 (MK-7) were in-
cluded; these studies showed conflicting results [11,1820].
Even with the contradictory findings on BMD, all studies
reported a reduction in circulating ucOC in response to
vitamin K supplementation. The utility of ucOC as a
marker of bone health has however been questioned as
improved OC carboxylation did not give concomitant
effects on BMD [21]. Still, it could be that improving
vitamin K status may have greater effects on bone qual-
ity than on bone mass. On the other hand, carboxylation-
independent actions have also been reported for vitamin
The efficacy of MK-7 to improve bone health has re-
ceived far less attention than K1 and MK-4. In view of its
longer half-life in the circulation and its higher efficacy [23,
24], it is important to study the effects of long-term low-
dose MK-7 supplementation on bone health. Small amounts
of MK-7 can be found in fermented (curd) cheeses, but large
amounts occur in natto, i.e., Japanese fermented soybeans.
Lower fracture rates were reported in Japanese regions with
high natto intake [25]. Additionally, observational studies
suggest that natto may prevent osteoporosis in Japanese
women [26]. Only two 1-year intervention studies are
known on supplemental MK-7 intake and bone health in
healthy elderly, but both lacked a beneficial effect. Similar
to other forms of vitamin K, MK-7 supplementation signif-
icantly improved OC carboxylation in these studies. The
short treatment period may explain the lack of effect of
supplemental MK-7 intake on BMD. We hypothesized that
long-term supplementation with MK-7 at a nutritionally
relevant dosage will beneficially affect bone health.
Study participants
Healthy postmenopausal women aged between 55 and
65 years were recruited from the southern region of the
province of Limburg (The Netherlands). Exclusion criteria
were <2 years postmenopausal, BMI >30 kg/m
at baseline (T-score≤−2.5 SD), coagulation disorders, chronic
diseases, metabolic bone diseases, gastrointestinal diseases,
medication that interferes with vitamin K and/or blood coag-
ulation, use of corticosteroids, bisphosphonates, or hormone
replacement therapy, use of supplements containing vitamin
K, participation in a clinical study 3 months prior to this study,
and soy allergy. Based on these exclusion criteria and a prior
health check (interviews and questionnaires), 244 women
were included in the study and randomly assigned to either
nontreatment (n=124) or treatment (n=120). Figure 1repre-
sents the flow diagram of the study.
This study was conducted according to the guidelines
laid down in the Declaration of Helsinki, and all procedures
involving human subjects were approved by the Medical
Ethics Committee of the Maastricht University (Maastricht,
The Netherlands). Written informed consent was obtained
from all subjects before entering the study. Trial registration
code: NCT00642551.
Study design
The study had a double-blind, randomized, placebo-
controlled, parallel design. Participants were randomized
into two groups to receive either placebo capsules or cap-
sules containing 180 μgMK-7(MenaQ7,NattoPharma
ASA, Høvik, Norway) per capsule. One capsule was taken
daily either with breakfast or dinner during a period of
36 months. Participants came to the research site every year
for measurements of body weight and height, blood sam-
pling, and DXA measurements. During the visits to our
research site, all noticeable changes in health, dietary
pattern, physical activity, and/or medication use were
Study products
The capsules were manufactured by EuroPharma Alliance
(Wroclaw, Poland) for Nattopharma (Høvik, Norway). The
study products, containing 180 μg MK-7 in the form of
MenaQ7 (Nattopharma, Høvik, Norway) and matching pla-
cebo capsules, were delivered to VitaK (Maastricht, The
Netherlands) as complete ready-to-use end products (closed
bottles). The proprietary product MenaQ7 utilized in the
study was provided by NattoPharma. To verify the stability
of MK-7, three capsules of each batch were analyzed at the
2500 Osteoporos Int (2013) 24:24992507
start, half-way, and at the end of the intervention period.
Before, during, and after the study, the MK-7 content of the
capsules was determined to be stable, and the mean content
was 180±3 μg/capsule.
Blood sampling
Fasting venous blood was collected once a year for the
preparation of serum and plasma (Vacutainers, Greiner
Bio-One BV, Alphen a/d Rijn, The Netherlands). All blood
samples were drawn between 8:00 a.m. and 11:00 a.m. by
experienced research nurses. For plasma preparation, blood
(10 ml) was collected in citrate tubes, centrifuged for 15 min
at 3,000×g, aliquoted, and stored at 80 °C until analysis.
For serum preparation, blood (10 ml) was allowed to clot for
30 min at room temperature, centrifuged, and stored as
described above.
Circulating markers
Serum uncarboxylated and carboxylated OC (ucOC and
cOC) concentrations were determined by separate com-
mercial dual-antibody ELISA tests (Takara Shuzo Co.
Ltd., Otsu, Shiga, Japan). An in-house control serum
pool was run on all ELISA plates. The ucOC/cOC ratio
was calculated from circulating ucOC and cOC values,
minimize scattering, samples from four different time
points of each subject were analyzed on the same
ELISA plate. Baseline plasma 25(OH)D and serum
iPTH were determined by using the automated chemilu-
minescent immunoassays on an iSYS system (IDS Ltd.,
Boldon, UK).
Bone measurements
BMC and BMD of the femoral neck, total hip, and lumbar
spine (L1L4) were determined at baseline and at years 1, 2,
and 3 by DXA (Hologic Discovery A, Waltham, MA, USA).
APEX software version 12.7 was used for acquisition and
analysis. The geometry of the hip bone comprising femoral
neck width (FNW) and hip-axis length (HAL) were assessed
by the scanner software. Indices of femoral neck bone
strength (compression strength, CSI; bending strength,
BSI; and impact strength, ISI) were calculated from body
weight and height, BMD, FNW, and HAL data [12,27].
Fig. 1 Flow diagram
Osteoporos Int (2013) 24:24992507 2501
Vertebral fracture (VF) assessment (VFA) was performed
immediately after BMC and BMD measurements. Making
use of Hologics software, six markers were placed on the
cranial and caudal sides of the vertebral bodies in anterior,
posterior, and middle positions. Subsequently, the anterior,
posterior, and middle vertebral heights were determined
from the marker points. The Genants semiquantitative
method was used to define VF as mild (height reduction
2025 %), moderate (height reduction 2540 %), or severe
(height reduction >40 %) [28]. Furthermore, a distinction
was made in fracture site (mid thoracic, T7T9; low thorac-
ic, T10T12; lumbar, L1L3) and type of VF (wedge,
biconcave, crush). L4 was excluded from data analyses,
because the accurate positioning of the markers on the sides
of L4 was difficult in 32 women due to the disappearance of
the disk space between L4 and L5.
Based on preliminary estimates of SD in bone strength in
postmenopausal women, we determined that 120 partici-
pants were required in each group for the study to have a
statistical power of 90 % to detect clinically meaningful
differences of 20 % between treatment groups while
allowing for a projected withdrawal of 10 % per year.
Normality was tested by the KolmogorovSmirnov test.
Data that were not normally distributed were log-
transformed before statistical analyses (ucOC/cOC).
Between-group differences were tested by the independent
samples ttest. The paired samples ttest was used to study
within-group effects. Linear regression analysis was
performed to study associations between supplemental
MK-7 intake and the measures of interest (ucOC, cOC,
ucOC/cOC, BMD, BMC, and bone strength indices). The
measure of interest was used as the dependent variable. The
concomitant baseline value and the treatment code were
included as independent variables. Age and BMI (if appli-
cable) were included as covariates. Years since menopause,
smoking, 25(OH)D, and iPTH were non-significant contrib-
utors to the statistical model and were therefore not included
in the analyses. Data are presented as means with SD (SE in
figures). A p<0.05 was considered statistically significant.
Statistics were performed using SPSS for Windows, version
19 (SPSS Inc., Chicago, Illinois, USA).
Baseline characteristics
Baseline characteristics of the total group as well as the
placebo and MK-7 groups are presented in Table 1. Mean
values of the variables at baseline were similar (p> 0.05) in
both treatment groups.
At the end of the study, twelve women in the placebo
group and nine women in the MK-7 group had withdrawn
from the study. The overall drop-out rate was 8.6 %. Only a
few women reported complaints during the study. The com-
plaints in the placebo group were: hair loss and/or brittle
nails (n=2), hot flashes (n=1), knee pain (n=1), numb
sensation in arms and legs, washed-out (n= 1), and weight
gain (n=2) and in the MK-7 group: bone pain (n=1), hot
flashes (n=1), rash around eyes and ears (n=1), smelly
capsules (n=1), and weight gain (n=1). Five women with-
drew due to these complaints; four women in the placebo
group and one in the MK-7 group. Compliance was mea-
sured by capsule counts at the end of every half-year period;
the mean compliance for both treatment groups was 97 %.
There were no crush deformations at baseline in this
cohort. Within the total group, the prevalence of biconcave
deformations was the highest in the vertebrae T11 and T12,
whereas wedge deformations occurred mainly in T7 and T8.
Effects of treatment on circulating osteocalcin
MK-7 supplementation significantly decreased circulating
ucOC levels by 51± 21 % as compared to placebo (+ 4±
49 %) (p<0.001; Fig. 2a). Circulating cOC was increased by
21± 19 % as compared to placebo (+ 3±16 %) (p<0.001;
Fig. 2b). Vitamin K status of bone, determined as the
ucOC/cOC ratio, was significantly improved by 58± 18 %
after MK-7 supplementation, whereas placebo supplements
did not alter the ratio (+ 2±47 %) (p< 0.001; data not shown).
The maximal effect on osteocalcin carboxylation was already
reached during the first year and was maintained throughout
the next 2 years of supplementation.
Effects of treatment on BMC and BMD
Both the placebo group and the MK-7 group experienced
bone loss (decrease in BMC and BMD) at the site of the
femoral neck (Fig. 2c, d). During the first year, the rate of
bone loss was similar in both groups. After the first year, the
lines started to diverge with slower bone loss in the MK-7
group. Only after 3 years, MK-7 intake beneficially affected
bone health as compared to the placebo group (p= 0.011 for
BMC, p=0.012 for BMD). After adjusting for age and BMI,
the effect of MK-7 was still significant (p=0.023 for BMC
and p=0.014 for BMD). BMC and BMD of the total hip
steadily decreased during the 3-year study period in both
treatment groups with no significant differences between the
groups (data not shown). In the MK-7 group, the decrease in
BMC and BMD at the lumbar spine was less than 1 % after
the 3-year supplementation period compared to baseline (p=
0.001 and p=0.111, respectively; paired samples ttest). The
2502 Osteoporos Int (2013) 24:24992507
placebo group confirmed the expected age-related decline in
BMC and BMD (Fig. 2e, f). Between-group analysis
showed significant differences at the site of the lumbar spine
after the first year of supplementation for BMC (p= 0.019)
and after the second year for BMD (p=0.008). After
adjusting for age and BMI, the beneficial effect of MK-7
on BMC remained significant (p= 0.042), whereas the effect
on BMD became borderline significant (p= 0.070).
Table 1 Baseline characteristics
of the subjects
Data are means±SD or percent-
age of total. No significant dif-
ferences were found between the
treatment groups
BSI bending strength index, CSI
compression strength index, cOC
carboxylated osteocalcin, FNW
femoral neck width, HAL hip axes
length, ISI impact strength index,
ucOC uncarboxylated osteocalcin
Total (n=244) Placebo (n=124) MK-7 (n= 120)
Clinical parameters
Age (years) 60± 3 59± 3 60± 4
Years since menopause 6 5 9±6
Weight (kg) 69± 10 68± 9 69± 10
Height (cm) 165±6 165±6 166± 6
BMI (kg/m
) 25±3 25±3 25±3
Current smoker (%) 13 (n=32) 15 (n=19) 11 (n=13)
Cigarettes per day 7 11± 7 7±8
Former smoker (%) 55 (n=135) 58 (n=72) 53 (n=63)
Alcohol consumption (%) 76 (n=185) 78 (n=97) 73 (n=88)
Units of alcohol per week 5.6± 5.5 5.6± 5.0 5.5±6.0
Circulating markers
cOC (ng/ml) 5.5± 1.3 5.6 ±1.3 5.4 ±1.2
ucOC (ng/ml) 3.6± 1.9 3.6 ±1.9 3.6 ±1.9
ucOC/cOC ratio 0.69± 0.41 0.69±0.41 0.69± 0.41
25(OH)D (ng/ml) 30.3± 11.0 30.8±11.2 29.8± 10.9
iPTH (pg/ml) 43.0±15.6 42.5± 15.1 43.4± 16.2
Bone density parameters
BMC femoral neck (g) 3.77± 0.60 3.74± 0.53 3.79 ±0.67
BMC total hip (g) 32.1±4.9 31.9± 4.3 32.4± 5.4
BMC lumbar spine (g) 56.0±8.7 55.5± 7.8 56.5± 9.6
BMD femoral neck (g/cm
) 0.732 ±0.101 0.728± 0.085 0.737± 0.115
BMD total hip (g/cm
) 0.872± 0.102 0.867±0.088 0.877 ±0.115
BMD lumbar spine (g/cm
) 0.933± 0.119 0.926± 0.105 0.939 ±0.132
Hip geometry
FNW (cm) 3.43± 0.27 3.43±0.28 3.43 ±0.26
HAL (cm) 11.2± 0.7 11.2±0.7 11.3 ±0.7
BSI (g/kg.M) 1.13±0.21 1.13± 0.21 1.13± 0.21
CSI (g/kg.m) 3.70 ±0.58 3.69 ±0.54 3.70 ± 0.63
ISI (g/kg.M) 0.25±0.04 0.25 ±0.04 0.25 ± 0.05
Vertebral Fracture Assessment
Height (mm) at the posterior site of
T7T9 61.5± 3.8 61.3 ±3.9 61.7 ±3.7
T10T12 71.9± 4.0 71.6 ±3.8 72.1 ±4.2
L1L3 83.1± 4.6 82.7 ±4.6 83.5 ±4.5
Height (mm) at the midst site of
T7T9 55.5± 2.9 55.3 ±2.6 55.6 ±3.2
T10T12 64.4± 3.7 64.3 ±3.3 64.4 ±4.1
L1L3 75.3± 4.5 75.1 ±4.2 75.6 ±4.7
Height (mm) at the anterior site of
T7T9 55.4± 3.5 55.5 ±3.4 55.3 ±3.6
T10T12 66.0± 4.6 65.9 ±4.3 66.1 ±4.6
L1L3 80.2± 4.5 80.0 ±4.7 80.5 ±4.2
Osteoporos Int (2013) 24:24992507 2503
Effects of treatment on bone strength indices
The FNW as well as the HAL did not change signifi-
cantly during the treatment with either placebo or MK-7
(data not shown). For the CSI (Fig. 2g), significant
differences were seen after the second year of MK-7
supplementation (p=0.026) and remained significant
(p=0.045). For the ISI (Fig. 2h), between-group differ-
ences were significant after 1, 2, and 3 years of treatment
(p=0.021, p=0.016, p=0.019, respectively). After
adjusting for age, the difference in ISI between placebo
and MK-7 remained significant (p<0.05), whereas the
effects on CSI became less pronounced (p= 0.022 and
p=0.075 for years 2 and 3, respectively). No significant
effects were found on the BSI (data not shown).
Effects of treatment on vertebral fractures
In six participants of the placebo group, moderate
wedge/biconcave VF occurred in T11 (n=4), in T12 (n=1),
and in T7+ T10 (n=1) during the trial; these vertebrae had
normal heights at baseline. Only in one participant from the
Fig. 2 Effect of MK-7
supplementation on osteocalcin,
BMC and BMD of the femoral
neck and lumbar spine, and bone
strength indices. CSI
compression strength index, ISI
impact strength index, cOC
carboxylated osteocalcin, ucOC
uncarboxylated osteocalcin,
FeNe femoral neck, LS lumbar
spine. Mean (SE) % change in
osteocalcin, BMC and BMD of
femoral neck and lumbar spine
and bone strength indices relative
to baseline during 3 years of
supplementation with MK-7
(white circles) and placebo (black
circles). aand bcirculating ucOC
and cOC; cand dBMC and
BMD of the femoral neck; eand f
BMC and BMD of the lumbar
spine; gand hCSIandISIofthe
femoral neck. *p<0.05,
**p<0.005, #p<0.0001 as
compared to placebo
2504 Osteoporos Int (2013) 24:24992507
MK-7 group, T10 showed a moderate wedge VF after 3 years
of treatment. The numbers are however too small to perform
To investigate the effects of MK-7 supplementation on
the vertebral heights, we divided the spine in three parts:
mid thoracic (T7T9), lower thoracic (T10T12), and lum-
bar (L1L3) spine. The losses of height (mean loss in T7
T9, T10T12, and L1L3) at the posterior and anterior sites
of the spine were comparable for both treatment groups
(p>0.05; data not shown). The height loss of the middle site
of the vertebrae at T10T12 was significantly lower in the
MK-7 group than in the placebo group after 2 (MK-7, 2.5±
1.8 %; placebo, 3.1± 2.2 %; p=0.044) and 3 years
(MK-7, 3.3±2.0 %; placebo, 4.1±2.2 %; p=0.003).
In this paper, we demonstrate that 3-year supplementation of
low-dose vitamin K2 as MK-7 significantly decreased the
age-related loss in bone mass. Participants taking the MK-7
supplements showed a 3-year preservation of lumbar spine-
BMD, while the placebo group confirmed the expected age-
related decline in BMD. Though both intervention groups
experienced bone loss at the site of the femoral neck, MK-7
intake beneficially affected the rate of bone lossbut the
difference became only significant after 3 years of supple-
mentation. Also, bone strength of the femoral neck was
positively affected by MK-7 supplementation. These results
confirm the hypothesis that long-term supplementation with
MK-7 beneficially affects bone health. Our findings support
EFSAs acceptance of the health claim that a cause and
effect relationship has been established between vitamin K
and maintenance of normal bone[15]. EFSAs opinion was
mainly based on observational data showing a link between
vitamin K (status) and bone health, as supplementation
studies showed contradictory results. In view of the increas-
ing retail availability of MK-7 supplements intended for
bone health, it is also important to substantiate their effec-
tiveness. The only comparable MK-7 trials published thus
far are the Postmenopausal Health Study II (PHSII) [29] and
a Norwegian study in healthy postmenopausal women [19],
which were both 1-year trials showing conflicting results.
The PHSII showed that 1-year consumption of milk and
yogurt enriched with CaD and MK-7 (100 μg/day) together
with nutrition and lifestyle counseling significantly im-
proved lumbar spine-BMD as compared to the control group
(no vitamin fortification and no counseling). It should be
noted that similar results were seen with products enriched
with CaD and products fortified with CaD and K1
(100 μg/day). In the Norwegian study, 1-year supplementa-
tion with MK-7 (360 μg/day) capsules did not influence
BMD of total hip, femoral neck, lumbar spine, and total
body. The short follow-up period of 1 year was mentioned
as a major limitation. Indeed, we did show that effects of
MK-7 supplementation on bone mass only became signifi-
cant after at least 2 years of intervention.
Subgroup analysis in the most recent meta-analysis on
vitamin K and bone health revealed that K2, but not K1
supplementation, had favorable effects on lumbar spine-
BMD [17]. It is important to note that only two placebo-
controlled trials with MK-7 supplementation were included
[19,20], and outcomes were mainly based on MK-4 in-
terventions. Most of the MK-4 trials were performed in
Japanese osteoporotic women and/or used a pharmacologi-
cal dose of MK-4 making direct comparison to trials with
nutritional dosages and/or healthy participants difficult. Ad-
ditionally, two supplementation trials with K1 at nutritional
doses were included in the meta-analysis. In healthy older
Scottish women, 2-year supplementation of CaD and K1
(200 μg/day) significantly increased distal radius-BMD, but
this change did not differ from that in the control group [11].
In line, no beneficial effect was seen on BMD of lumbar
spine and femoral neck after 3-year supplementation with
CaD and K1 (500 μg/day) in healthy American elderly [13].
K1 and MK-7 differ with respect to their chemical structure
and pharmacokinetics [23,24], which may account for the
differences in effects on bone mass when administrated in
nutritional dosages. Actually, we previously showed greater
bioactivity of MK-7 as compared to K1 when administrating
the same molar dose to healthy adults: higher serum levels
were reached with MK-7, and MK-7 had a higher efficacy in
both hepatic and extra-hepatic protein carboxylation [23].
Recent in vitro data also suggested superiority of MK-7 as
compared to MK-4 and K1 in inhibiting NF-ĸB activation
related to osteoclast development [22].
Despite the heterogeneity in bone mass outcomes, all
studies that measured ucOC (expressed as total circulating
ucOC or percentage ucOC of total circulating osteocalcin)
reported a significant reduction of 2085 % in this bone
marker in response to vitamin K supplementation [1013,
19,2932]. In agreement, we found that 3-year MK-7
supplementation at a daily dose of 180 μg significantly
lowered circulating ucOC by ~50 %. The maximal effect
on osteocalcin carboxylation was already reached during the
first year and was maintained over the next 2 years of
supplementation. Recently, we described a similar reduction
in serum ucOC levels after 3-month supplementation with
the same dose of MK-7 [33]. Although significant positive
effects were seen on both osteocalcin carboxylation and
bone mass, no association was found between the vitamin
K-induced changes in serum ucOC levels and bone param-
eters. Such correlation analyses are however lacking in other
published intervention trials studying vitamin K effects on
bone mass. On the other hand, cross-sectional analyses have
shown an inverse relationship between circulating ucOC
Osteoporos Int (2013) 24:24992507 2505
and bone health, measured as BMD or hip fracture [5].
However, the physiological implications for (maximally)
improved carboxylation of circulating ucOC have remained
unknown. Next to the suggested primary mechanism
through OC carboxylation, vitamin K was described to have
carboxylation-independent effects on bone health as well.
Next to superiority of MK-7, the in vitro data showed that
MK-7s action on osteoblast and osteoclast formation and
activity was accomplished by downregulating NF-ĸB acti-
vation in a carboxylation-independent manner [22].
VF are the most common osteoporotic fractures; they are
mostly asymptomatic, but strongly predict risks for subse-
quent fractures independent of BMD [34]. VFA by DXA
can be used to classify vertebral deformity consistent with
fractures, but has not yet become standard practice. Neverthe-
less, this method was considered a new patient-friendly diag-
nostic tool as it can detect unknown VF in one out of each six
patients [35]. In our study population, the thoracic vertebrae
showed more VF as compared to the lumbar spine. Regarding
the thoracic spine, biconcave deformations were mostly seen
in the lower region (T10T12) and wedge deformations in the
mid region (T7T9). Low dietary intake of MK-7 significantly
reduced the loss in vertebral height of the lower thoracic
region (T10T12) at the mid-site of the vertebrae. This could
however be a chance finding. It should be noted that the
number of participants was not calculated to detect changes
in VF (or fracture risk). More studies are warranted to assess
the relation between K2 intake and VF (or fracture risk).
There are certain limitations to consider. Although sev-
eral bone parameters were investigated in this study, we did
not perform measurements of bone quality, including frac-
ture risk or markers of bone formation/resorption. As men-
tioned before, improving vitamin K status may have more
pronounced effects on bone quality than on bone mass.
Further, we targeted participants in a group generally known
to be at increased risk for accelerated bone loss: healthy
early postmenopausal women. Whether these data can be
extrapolated to other study populations, including children,
men, osteoporotic subjects, or other patient groups needs
further investigation. Nevertheless, the targeted study pop-
ulation may explain why we found positive results [12,30]
in contrast to other long-term studies (23 years of treat-
ment) in late postmenopausal women [11,18], and
osteopenic/osteoporotic women [10]. Finally, our study
products were not enriched with CaD, while most studied
K1 supplements did contain CaD. A subjects CaD environ-
ment may influence vitamin Ks effect on bone health.
Long-term use of MK-7 supplements significantly decreased
the age-related decline in bone mass and strength.
Additionally, the loss in vertebral height of the lower thoracic
region was significantly reduced at the mid-site of the verte-
brae after intake of the MK-7 capsules. We conclude therefore
that postmenopausal women may benefit from taking MK-7
supplements to prevent the age-related bone loss. Since the
efficacy of MK-7 supplements is poorly documented, our
results significantly contribute to substantiating the marketed
anti-osteoporotic properties of vitamin K2.
Acknowledgments The study was funded by Nattopharma ASA
(Høvik, Norway).
Conflicts of interest None.
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Osteoporos Int (2013) 24:24992507 2507
... Long-term supplementation of MK-7 may help postmenopausal women to prevent bone loss by significantly decreasing the age-related decline in BMD and BMC at the lumbar spine and femoral neck, but not at the total hip Knapen et al. (2013) Bone health in postmenopausal women ...
... A meta-analysis of 19 randomized, placebo-controlled clinical trials encompassing 6759 participants showed that VitK2 plays an important preventive and therapeutic role for postmenopausal women with osteoporosis (Huang et al., 2015). Intake of MK-4 daily for 3 years improved hip bone geometry and bone strength in postmenopausal women by increasing bone mineral content (BMC), but no increase in bone mineral density (BMD) was observed (Knapen et al., 2007); MK-7 showed comparable effects in terms of improvement in both BMC and BMD (Knapen et al., 2013(Knapen et al., , 2015. Contrarily, no effects ...
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Vitamin K1 (VitK1) and Vitamin K2 (VitK2), two important naturally occurring micronutrients in the VitK family, found, respectively, in green leafy plants and algae (VitK1) and animal and fermented foods (VitK2). The present review explores the multiple biological functions of VitK2 from recently published in vitro and in vivo studies, including promotion of osteogenesis, prevention of calcification, relief of menopausal symptoms, enhancement of mitochondrial energy release, hepato‐ and neuro‐protective effects, and possible use in treatment of coronavirus disease. The mechanisms of action associated with these biological effects are also explored. Overall, the findings presented here suggest that VitK, especially VitK2, is an important nutrient family for the normal functioning of human health. It acts on almost all major body systems and directly or indirectly participates in and regulates hundreds of physiological or pathological processes. However, as biological and clinical data are still inconsistent and conflicting, more in‐depth investigations are warranted to elucidate its potential as a therapeutic strategy to prevent and treat a range of disease conditions. This paper provides insight into the potential beneficial roles of vitamin K2 in human health by reviewing, comparing, and contrasting available in vitro, in vivo, and clinical data. This review also provides a guidance to agencies to review the current recommendation of vitamin K2 daily intake as a supplement.
... For example, Cockayne et al. [20] showed that the MK-4 supplementation significantly reduces the incidence of hip fractures. In the light of the results of research by Sato [8] as well as Knapen, [58] the MK-7 supplementation improves bone strength and reduces vertebral height loss in the lower thoracic vertebrae in postmenopausal women. ...
... Recently there have been published many papers related to quantification of vitamin K in different solid, semi-solid and liquid samples undertaken as part of the research aiming at studying its biological activity, [29,30,39] controlling quality of dietary supplements, drugs and food, [21,[31][32][33][34][35][36][68][69][70] development of new formulae of drugs and supplements [24,[71][72][73] as well as medical and clinical, both observational and interventional studies, [2,3,5,6,10,17,37,[41][42][43]45,46,49,[54][55][56][57][58] and chemical studies focused on ensuring the best possible analytical results. [14,22,[24][25][26]28,[68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85] Regardless of the reasons for the research, the analysis of vitamin K, like other fat-soluble vitamins, is a difficult and tedious issue, being a challenge for the researcher. ...
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.
... Furthermore, another study conducted by Leinders, et al. [54] showed the upregulation of hsa-miR-146a and has-miR- 21 ...
... Studies on the effect of VK supplementation on BMD are limited and inconclusive. In some research, an increase in BMD [31][32][33][34][35][36] or bone mineral content (BMC) [37] was observed under the influence of VK supplementation. However, in other studies, the above relationship was not shown [38,39]. ...
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Chronic kidney disease (CKD) commonly occurs with vitamin K (VK) deficiency and impaired bone mineralization. However, there are no data explaining the metabolism of endogenous VK and its role in bone mineralization in CKD. In this study, we measured serum levels of phylloquinone (VK1), menaquinone 4 and 7 (MK4, MK7), and VK-dependent proteins: osteocalcin, undercarboxylated osteocalcin (Glu-OC), and undercarboxylated matrix Gla protein (ucMGP). The carboxylated osteocalcin (Gla-OC), Glu-OC, and the expression of genes involved in VK cycle were determined in bone. The obtained results were juxtaposed with the bone mineral status of rats with CKD. The obtained results suggest that the reduced VK1 level observed in CKD rats may be caused by the accelerated conversion of VK1 to the form of menaquinones. The bone tissue possesses all enzymes, enabling the conversion of VK1 to menaquinones and VK recycling. However, in the course of CKD with hyperparathyroidism, the intensified osteoblastogenesis causes the generation of immature osteoblasts with impaired mineralization. The particular clinical significance seems to have a finding that serum osteocalcin and Glu-OC, commonly used biomarkers of VK deficiency, could be inappropriate in CKD conditions, whereas Gla-OC synthesized in bone appears to have an adverse impact on bone mineral status in this model.
... While vitamin K1 (phylloquinone) is plant derived, vitamin K2 (menaquinone) is produced by the gut microbiota. This K2 improves bone mineral density [61], but supplementation through oral intake of both K2 and D in the elderly has been shown to be ineffective at ameliorating aortic valve calcification [62]. This may also be the case in astronauts who have been in space for 6 months or more who develop arterial stiffness during flight [63], while other astronauts present improvements in bone metabolism markers upon vitamin K supplementation [50]. ...
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The microbiota is important for immune modulation, nutrient acquisition, vitamin production, and other aspects for long-term human health. Isolated model organisms can lose microbial diversity over time and humans are likely the same. Decreasing microbial diversity and the subsequent loss of function may accelerate disease progression on Earth, and to an even greater degree in space. For this reason, maintaining a healthy microbiome during spaceflight has recently garnered consideration. Diet, lifestyle, and consumption of beneficial microbes can shape the microbiota, but the replenishment we attain from environmental exposure to microbes is important too. Probiotics, prebiotics, fermented foods, fecal microbiota transplantation (FMT), and other methods of microbiota modulation currently available may be of benefit for shorter trips, but may not be viable options to overcome the unique challenges faced in long-term space travel. Novel fermented food products with particular impact on gut health, immune modulation, and other space-targeted health outcomes are worthy of exploration. Further consideration of potential microbial replenishment to humans, including from environmental sources to maintain a healthy microbiome, may also be required.
... It is known to have excellent protein secretion ability, making it an important host for the production of some molecules such as proteins, vitamins, and antibiotics. In pharmaceuticals, menaquinone-7, a vitamin produced by B. subtilis, has shown beneficial effects in osteoporosis (Knapen et al., 2013) and can reduce the risk of coronary heart disease (Geleijnse et al., 2004). In the food industry, proteases from B. subtilis can be used in the production of cheese (milk-clotting) (Meng et al., 2018) and as a meat tenderizer (Bureros et al., 2020). ...
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This study investigated the antiradical and antioxidant potential of the three families of lipopeptides (i.e., surfactin, mycosubtilin, and plipastatin/fengycin) produced by Bacillus subtilis strains. The antiradical/antioxidant activities of highly purified lipopeptides were studied in acellular models using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, superoxide anion (O2.-), hydrogen peroxide, (H2O2) and hydroxyl radical (HO.). At a lipopeptide concentration of 500 mg.L−1, the maximum inhibition of DPPH reached 22.88% (obtained for plipastatin). Moreover, the scavenging effects of O2.-, H2O2, and HO. at the highest concentration tested (250 mg.L−1) were found to be 6, 21, and 3% for surfactin, 19, 9, and 15% for mycosubtilin, 21, 18, and 59% for plipastatin, 21, 31, and 61% for the mixture of surfactin/plipastatin, and 13, 16, and 15% for the mixture of surfactin/mycosubtilin, respectively. These results showed that plipastatin was the best candidate due to its antioxidant activities.
Vitamin K (VK) is a fat-soluble vitamin that is indispensable for the activation of vitamin K-dependent proteins (VKDPs). It has been shown to play an important role in the proper calcium deposit at the bone level, hindering that on the vascular walls. The deficiency of this vitamin in European populations is frequent and unknown. It is related to several factors, poor dietary intake, altered intestinal absorption or altered production by bacteria, indicating possible dysbiosis. For Vitamin K2 (VK2), there is currently no official reference daily intake (RDI). However, the effects of VK2 on the improvement of health in cardiovascular diseases, on bone metabolism, on chronic kidney diseases have been the subject of research in recent decades. The microbiota in the gastrointestinal tract plays an important role: Bacteroides are primarily capable of synthetizing very long chain forms of menaquinones and, in addition to the bacteria present in the intestinal flora, VK2 is also produced by bacteria used in food fermentation processes. This review provides an update on the current literature regarding the origin of VK2 and its implications in what is called the “calcium paradox”, namely the lack of calcium in the bone and its storage in the wall of the vessel.
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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.
After thousands of years of evolution and development, traditional fermented soybean foods, with their unique charm, have gained a stable place in the global market. With the explosive development of modern biological technologies, some traditional fermented soybean foods that possess health-promoting benefits are gradually appearing. Physiologically active substances in fermented soybean foods have received extensive attention in recent decades. This review addresses the potential health benefits of several representative fermented soybean foods, as well as the action mechanism and influencing factors of their functional components. Phenolic compounds, low-molecular-weight peptides, melanoidins, furanones and 3-hydroxyanthranilic acid are the antioxidative components predominantly found in fermented soybean foods. Angiotensin I-converting enzyme inhibitory peptides and γ-aminobutyric acid isolated from fermented soy foods provide potential selectivity for hypertension therapy. The potential anti-inflammatory bioactive components in fermented soybean foods include γ-linolenic acid, butyric acid, soy sauce polysaccharides, 2S albumin and isoflavone glycones. Deoxynojirimycin, genistein, and betaine possess high activity against α-glucosidase. Additionally, fermented soybean foods contain neuroprotective constituents, including indole alkaloids, nattokinase, arbutin, and isoflavone vitamin B12. The anticancer activities of fermented soybean foods are associated with surfactin, isolavone, furanones, trypsin inhibitors, and 3-hydroxyanthranilic acid. Nattokinase is highly correlated with antioxidant activity. And a high level of menaquinones-7 is linked to protection against neurodegenerative diseases. Sufficiently recognizing and exploiting the health benefits and functional components of traditional fermented soybean foods could provide a new strategy in the development of the food fermentation industry.
Zusammenfassung Osteoporose ist eine Skeletterkrankung, die durch ein Missverhältnis in der Aktivität der knochenauf- und -abbauenden Zellen, einer niedrigen Knochenmasse mit Verschlechterung der Mikroarchitektur des Knochengewebes gekennzeichnet ist. Sie manifestiert sich durch dünne Knochen mit einem hohen Risiko für Knochenbrüche. Zur Prävention und Therapie gehört neben einer kalziumreichen Ernährung und regelmäßiger körperlicher Aktivität auch eine adäquate Versorgung des Organismus mit einem komplexen Spektrum knochenrelevanter Mikronährstoffe.
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Background Vitamin K2 contributes to bone and cardiovascular health. Therefore, two vitamin K2 homologues, menaquinone-4 (MK-4) and menaquinone-7 (MK-7), have been used as nutrients by the food industry and as nutritional supplements to support bone and cardiovascular health. However, little is known about the bioavailability of nutritional MK-4. To investigate MK-4 and MK-7 bioavailability, nutritional doses were administered to healthy Japanese women. Findings Single dose administration of MK-4 (420 μg; 945 nmol) or MK-7 (420 μg; 647 nmol) was given in the morning together with standardized breakfast. MK-7 was well absorbed and reached maximal serum level at 6 h after intake and was detected up to 48 h after intake. MK-4 was not detectable in the serum of all subjects at any time point. Consecutive administration of MK-4 (60 μg; 135 nmol) or MK-7 (60 μg; 92 nmol) for 7 days demonstrated that MK-4 supplementation did not increase serum MK-4 levels. However, consecutive administration of MK-7 increased serum MK-7 levels significantly in all subjects. Conclusions We conclude that MK-4 present in food does not contribute to the vitamin K status as measured by serum vitamin K levels. MK-7, however significantly increases serum MK-7 levels and therefore may be of particular importance for extrahepatic tissues.
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Seventeen vitamin K-dependent proteins have been identified to date of which several are involved in regulating soft-tissue calcification. Osteocalcin, matrix Gla protein (MGP), and possibly Gla-rich protein are all inhibitors of soft-tissue calcification and need vitamin K-dependent carboxylation for activity. A common characteristic is their low molecular weight, and it has been postulated that their small size is essential for calcification inhibition within tissues. MGP is synthesized by vascular smooth muscle cells and is the most important inhibitor of arterial mineralization currently known. Remarkably, the extrahepatic Gla proteins mentioned are only partly carboxylated in the healthy adult population, suggesting vitamin K insufficiency. Because carboxylation of the most essential Gla proteins is localized in the liver and that of the less essential Gla proteins in the extrahepatic tissues, a transport system has evolved ensuring preferential distribution of dietary vitamin K to the liver when vitamin K is limiting. This is why the first signs of vitamin K insufficiency are seen as undercarboxylation of the extrahepatic Gla proteins. New conformation-specific assays for circulating uncarboxylated MGP were developed; an assay for desphospho-uncarboxylated matrix Gla protein and another assay for total uncarboxylated matrix Gla protein. Circulating desphospho-uncarboxylated matrix Gla protein was found to be predictive of cardiovascular risk and mortality, whereas circulating total uncarboxylated matrix Gla protein was associated with the extent of prevalent arterial calcification. Vitamin K intervention studies have shown that MGP carboxylation can be increased dose dependently, but thus far only 1 study with clinical endpoints has been completed. This study showed maintenance of vascular elasticity during a 3-y supplementation period, with a parallel 12% loss of elasticity in the placebo group. More studies, both in healthy subjects and in patients at risk of vascular calcification, are required before conclusions can be drawn.
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Osteocalcin originates from osteoblastic synthesis and is deposited into bone or released into circulation, where it correlates with histological measures of bone formation. The presence of 3 vitamin K-dependent γ carboxyglutamic acid residues is critical for osteocalcin's structure, which appears to regulate the maturation of bone mineral. In humans, the percentage of the circulating osteocalcin that is not γ-carboxylated (percent ucOC) is used as a biomarker of vitamin K status. In contrast, when ucOC is not corrected for total osteocalcin, the interpretation of this measure is confounded by osteoblastic activity, independent of vitamin K. Observational studies using percent ucOC have led to the conclusion that vitamin K insufficiency leads to age-related bone loss. However, clinical trials do not provide overall support for the suggestion that vitamin K supplementation of the general population will reduce bone loss or fracture risk. More recently, results from in vitro and in vivo studies using animal models indicate that ucOC is an active hormone with a positive role in glucose metabolism. By inference, vitamin K, which decreases ucOC, would have a detrimental effect. However, in humans this hypothesis is not supported by the limited data available, nor is it supported by what has been established regarding osteocalcin chemistry. In summary, the specific function of osteocalcin in bone and glucose metabolism has yet to be elucidated.
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The objective of the present study was to examine the effect of dairy products enriched with calcium, vitamin D(3), and phylloquinone (vitamin K(1)) or menaquinone-7 (vitamin K(2)) on parameters of bone metabolism in postmenopausal women following a 12-month intervention. Postmenopausal women were divided into three intervention groups and a control group (CG). All three intervention groups attended biweekly sessions and received fortified dairy products providing daily 800 mg of calcium and 10 μg of vitamin D(3) (CaD). Furthermore, in two of the three intervention groups the dairy products were also enriched with vitamin K, providing daily 100 μg of either phylloquinone (CaDK1) or menaquinone-7 (CaDK2). The increase observed for serum 25(OH)D levels in all intervention groups and the increase observed for serum IGF-I levels in the CaDK2 group differed significantly compared to the changes observed in CG (P = 0.010 and P = 0.028, respectively). Furthermore, both the CaDK1 and CaDK2 groups had a significantly lower mean serum undercarboxylated osteocalcin to osteocalcin ratio and urine deoxypyridinoline levels at follow-up compared to the CaD and CG groups (P = 0.001 and P = 0.047, respectively). Significant increases in total-body BMD were observed in all intervention groups compared to CG (P < 0.05), while significant increases in lumbar spine BMD were observed only for CaDK1 and CaDK2 compared to CG (P < 0.05) after controlling for changes in serum 25(OH)D levels and dietary calcium intake. In conclusion, the present study revealed more favorable changes in bone metabolism and bone mass indices for the two vitamin K-supplemented groups, mainly reflected in the suppression of serum levels of bone remodeling indices and in the more positive changes in lumbar spine BMD for these two study groups.
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Vitamin K is required for the carboxylation of Gla-proteins in the liver (coagulation factors) and extra-hepatic tissues, such as bone (osteocalcin, OC), and arterial wall (matrix Gla-protein, MGP). Although the coagulation factors are essentially fully carboxylated under normal conditions, 10-40 % of OC and MGP remains undercarboxylated. We were therefore interested to study the dose-response effects of extra intake of menaquinones on the carboxylation of the extra-hepatic Gla-proteins. A total of forty-two healthy Dutch men and women aged between 18 and 45 years were randomised into seven groups to receive: placebo capsules or menaquinone-7 (MK-7) capsules at a daily dose of 10, 20, 45, 90, 180 or 360 μg. Circulating uncarboxylated OC (ucOC), carboxylated OC (cOC) and desphospho-uncarboxylated MGP were measured by ELISA. The ucOC:cOC ratio was calculated from circulating ucOC and cOC values. Endogenous thrombin potential and peak height were determined by calibrated automated thrombography. To increase the statistical power, we collapsed the treatment groups into three dosage groups: placebo, low-dose supplementation (doses below RDA, Commission Directive 2008/100/EC), and high-dose supplementation (doses around RDA, Commission Directive 2008/100/EC). MK-7 supplementation at doses in the order of the RDA (Commission Directive 2008/100/EC) increased the carboxylation of circulating OC and MGP. No adverse effects on thrombin generation were observed. Extra MK-7 intake at nutritional doses around the RDA (Commission Directive 2008/100/EC) improved the carboxylation of the extra-hepatic vitamin K-dependent proteins. Whether this improvement contributes to public health, i.e. increasing the protection against age-related diseases needs further investigation in specifically designed intervention trials.
Increasing evidence indicates a significant role for vitamin K in bone metabolism and osteoporosis. In this study, we found a large geographic difference in serum vitamin K2 (menaquinone-7; MK-7) levels in postmenopausal women. Serum MK-7 concentrations were 5.26 ± 6.13 ng/mL (mean ± SD) in Japanese women in Tokyo, 1.22 ± 1.85 in Japanese women in Hiroshima, and 0.37 ± 0.20 in British women. We investigated the effect of Japanese fermented soybean food, natto, on serum vitamin K levels. Natto contains a large amount of MK-7 and is eaten frequently in eastern (Tokyo) but seldom in western (Hiroshima) Japan. Serum concentrations of MK-7 were significantly higher in frequent natto eaters, and natto intake resulted in a marked, sustained increase in serum MK-7 concentration. We analyzed the relation between the regional difference in natto intake and fracture incidence. A statistically significant inverse correlation was found between incidence of hip fractures in women and natto consumption in each prefecture throughout Japan. These findings indicate that the large geographic difference in MK-7 levels may be ascribed, at least in part, to natto intake and suggest the possibility that higher MK-7 level resulting from natto consumption may contribute to the relatively lower fracture risk in Japanese women.
The aim of this study was to investigate the diagnostic performance of new dual-energy X-ray absorptiometry (DXA) technologies in the detection of vertebral fractures (VFs). Sixty-eight patients were submitted to DXA and conventional radiography (XR) on the same day. Lateral images of the spine were independently evaluated by three radiologists with different experience in skeletal imaging, in two sessions with 7 days between evaluations of the same anonymous images. The most expert physician repeated the analysis in a subsequent reading session after further 7 days. Results from expert XR evaluation were considered as gold standard. A semiquantitative approach was used to interpret images and morphometric analysis was performed when a VF was suspected. Seventy vertebrae (70/884, 7.9%) were excluded from the lesion-based analysis, as not evaluable: 11/70 (15.7%) missed by XR only, 56/70 (80.0%) missed by DXA only, 3/70 (4.3%) missed by both techniques (upper thoracic spine). Forty "true" fractures were detected (4.9% out of 814 vertebrae) in 26 patients (38.2% of the 68 studied patients). Twenty-five (62.5%) were mild fractures. DXA sensitivity and specificity were 70.0% and 98.3% on a lesion-based analysis, 73.1% and 90.5% on a patient-based analysis. Intra-observer agreement was excellent with no significant difference between the two techniques. Inter-observer agreement among the 3 observers was higher for XR (k=0.824 versus 0.720 in the detection of VFs, p=0.011). DXA accuracy was not influenced by radiologist experience; T4-L4 assessability as well as reproducibility and repeatability of the two techniques and accuracy of DXA were independent from sex, age, body mass index, grade of arthrosis. However DXA sensitivity was affected by mild VFs. Vertebral level did not affect the diagnostic performance with exception of vertebral body assessability. Latest improvements make VFs assessment by DXA competitive with traditional radiographic gold standard, providing consistent advantages and attractions. Few limitations still affect DXA performance and need to be overcome.