**5. Clinical randomized controlled studies with menaquinone‐7 (MK‐7)**

Japanese menopausal women have traditionally a lower fracture risk than women from the western world [3]. An association with the ingestion of natto (a processed food containing fermented beans) was evaluated by Katsuyama et al. [53] and Ikeda et al. [54] in the so‐called Japanese population‐based osteoporosis (JPOS) study. The dietary natto intake over 3 years was shown to significantly increase the changes of total hip BMD *P* < 0.003. The alleged prevention of postmenopausal bone loss through the effects of MK‐7 is more abundant with natto than other soybean products. More randomized controlled studies are clearly warranted to substantiate this contention [54].

The Norwegian study published by Emaus et al. in 2010. features a 1‐year randomized double‐ blind placebo‐controlled study with 334 early menopausal, but otherwise healthy, women. The patient groups received either MK‐7 (360 μg/day) or placebo. The summary of the present trial disclosed the following: in the MK‐7 group, serum uncarboxylated Osteocalcin (uc‐OC) was significantly reduced (from 4.14 to 2.22 ng/ml, respectively). In contrast, carboxylated Osteo‐ calcin (c‐OC) was significantly increased (from 13.5 to 19.1 ng/ml, respectively). However, there was no statistical difference in bone loss rate between the groups at the "total hip site," nor at any other measurements sites. This was most probably due to the shorter follow‐up time, i.e., after only 1 year of MK‐7 exposure [55].

which is known not to influence the degree of carboxylated osteocalcin. In the AK group, the femoral neck BMD was significantly increased. The small number of patients enrolled, and the short observation time undermines any conclusion drawn from this study. Further investiga‐

Je et al. from Korea published in 2011, a study evaluating the effects of MK‐4 supplementation on bone mineral density and undercarboxylated osteocalcin (ucOC) in 78 postmenopausal Korean women 60‐years‐old plus. These women, not receiving any medical treatment, were randomized into two groups: (1) calcium and vitamin D, *n* = 40) or (2) vitamin K supplemen‐ tation, *n* = 38, receiving 15 mg of MK‐4 three times a day after every meal, calcium carbonate 315 mg twice daily, and active vitamin D3, 400 UI once a day. The dosage of calcium and vitamin D3 was the same in both groups. After 6 months of treatment, the members of the MK‐4 group showed a decrease in ucOC (−1.6 ± 1.6 ng/dl versus −0.4 ± 1.1 ng/dl) with a *P*‐value of 0.008. The vitamin K (MK‐4) group members showed a significant improvement of L3 BMD‐values, however, no significant enhancement of the BMD‐values in L1, L2, and L4. Similarly, no significant increase was observed for femoral BMD, which remained unchanged in the women

In 2012, Fang et al. presented a meta‐analysis of randomized controlled trials published during the period of 1999−2009. The analysis examined the role of vitamin K on bone mineral density (BMD). The study revealed that vitamin MK‐4 supplementation was associated with increased BMD at the lumbar spine, however not necessarily at the femoral neck. This untoward heterogeneity may be the result, may reside within different participant groups, different regions of the skeleton, gender, and type of vitamin K1 and MK‐4 supplementation. Hence, further studies are deemed required to investigate and unravel the detailed effects of vitamin

**5. Clinical randomized controlled studies with menaquinone‐7 (MK‐7)**

Japanese menopausal women have traditionally a lower fracture risk than women from the western world [3]. An association with the ingestion of natto (a processed food containing fermented beans) was evaluated by Katsuyama et al. [53] and Ikeda et al. [54] in the so‐called Japanese population‐based osteoporosis (JPOS) study. The dietary natto intake over 3 years was shown to significantly increase the changes of total hip BMD *P* < 0.003. The alleged prevention of postmenopausal bone loss through the effects of MK‐7 is more abundant with natto than other soybean products. More randomized controlled studies are clearly warranted

The Norwegian study published by Emaus et al. in 2010. features a 1‐year randomized double‐ blind placebo‐controlled study with 334 early menopausal, but otherwise healthy, women. The patient groups received either MK‐7 (360 μg/day) or placebo. The summary of the present trial disclosed the following: in the MK‐7 group, serum uncarboxylated Osteocalcin (uc‐OC) was significantly reduced (from 4.14 to 2.22 ng/ml, respectively). In contrast, carboxylated Osteo‐ calcin (c‐OC) was significantly increased (from 13.5 to 19.1 ng/ml, respectively). However, there was no statistical difference in bone loss rate between the groups at the "total hip site," nor at

tions using this combination therapy were recommended [50].

receiving vitamin D and calcium [51].

112 Vitamin K2 - Vital for Health and Wellbeing

to substantiate this contention [54].

K2 sub"populations" or metabolites on BMD [52].

After solid organ transplantations, loss of bone mass often occurs and may cause substantial health problems. In a study (published in 2010) on such a patients group, Forli et al. from Norway looked at the effect of MK‐7 on bone mass, measured as BMD of the lumbar spine. Despite the fact that the impact of MK‐7 on the measured BMD was not conclusive, it was recommended that further studies over an extended period of time should be conducted. Here, we refer to the main findings in the study.

This study was the first in organ transplantation, featuring the effect of MK‐7 on bone mass, 1 year after lung and heart transplantation. Postoperatively, 35 lung and 59 heart recipients were actively treated with MK‐7 in a prospective and longitudinal study, receiving MK‐7 supple‐ ment, 180 μg/day or placebo. The results reported were the following: 1 year after solid organ transplantation, the difference between MK‐7 and placebo for the lumbar spine (L2–L4) BMD was 0.028 (SE 0.014) g/cm2 , *P* = 0.055, and for L2 to L4, BMC emerged as 1.33 (SE = 1.91) g/cm2 , *P* = 0.5. Scrutinizing the lung recipients separately, the difference for BMC was 3.39 g (SE = 1.65), *P* = 0.048. In the heart recipients, however, observed values were 0.45 (SE = 0.02) g, *P* = 0.9 subsequent to correcting for measures of baseline values.

In a stepwise linear regression analysis, alterations in the L2‐L4 BMD, controlled for alleged confounding variables (which include the use of bisphosphonates), significant predictors turned out to be: (a) organ (if heart = 1, BMD = −0.065 g/cm2 , *P* = 0.001) and (b) MK‐7 versus placebo (BMD = 0.034 g/cm2 , *P* = 0.019). It so happened, that insufficient vitamin D status was frequent, and that PTH (parathyroid hormone) levels were augmented in the MK‐7 group, indicating a more imminent need for ingestion of vitamin D. In conclusion, it turned out that 12 months of MK‐7 ingestion generally suggests a positive effect on BMD of the lumbar spine, but with diverging responses in "cardio‐pulmonary" recipients. Thus, the patients' vitamin D status would benefit from a closer monitoring during vitamin K supplementation [56].

Knapen et al., the Netherlands, published in 2013 the results of their 3 year study on the effect of low‐dose MK‐7 supplementation on bone loss in 244 healthy postmenopausal women. The study was a double‐blind, randomized placebo controlled study, with two groups: (a) active low‐dose vitamin K2 (MK‐7, 180 μg/day), and placebo. Their main task was to investigate whether low‐dose MK‐7 supplements beneficially could affect bone health in general.

Secondary to an improved and favorable vitamin K status, MK‐7 ingestion from supplements should have the possibility to significantly reduced age‐related loss of bone mineral density and ensuing bone mechanical properties. Hence, low‐dose MK‐7 supplements should conse‐ quently result in preventing bone loss in postmenopausal women. In spite of contradictory data emanating from trials with vitamin K supplementation on the status of bone health, the European Food Safety Authorities (EFSA) has accepted the health claim on vitamin K's role in the maintenance of normal and healthy bone structure. In accordance with EFSA's opinion, it was clearly demonstrated that a 3‐year high‐dose of vitamin K1 and MK‐4 supplementation improved bone health after menopause.

Because of the longer half‐life, bioavailability, and greater potency of the long‐chain MK‐7, they also measured the effect of low‐dose MK‐7 supplementation on bone health, as reflected by bone mineral density (BMD) of lumbar spine, total hip, and femoral neck. The assessment of vertebral fractures was performed using DXA. Furthermore, blood levels of ucOC and cOC were also analyzed, and the ucOC/cOC ratio functions as an indicator of vitamin K "health" status. All analyses were performed at baseline, and subsequent to 1, 2, and 3 years of sup‐ plementation, respectively. A carboxylation rate of >50% was achieved during the first year of treatment, and it was maintained throughout the study period.

Large clinical studies on bone mass have given different results, and in early observation studies, the evaluation of duration of warfarin use and other patients receiving treatment for osteoporosis was not included. However, two newer studies showed no further risk on bone mass of warfarin use in elderly patients: In the first one published by Woo et al. in 2008, in a large cohort of elderly community‐dwelling men, no association was observed between current warfarin use and bone mass, bone loss or fracture risk. Although warfarin use was based upon a single assessment, the findings suggest that current warfarin use in older men

Vitamin K2 and Bone Health http://dx.doi.org/10.5772/64876 115

The second experience was summarized by Misra et al. in 2014, featuring long‐term treatment of incident atrial fibrillation without prior history of fractures. Long‐term warfarin use was defined in two ways: (1) warfarin use ≥1 year; (2) warfarin use ≥3 years. Event‐score on 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‐propor‐ tional hazards regression models. Among more than 20,000 participants with incident atrial fibrillation, the hazard ratios (HR) for hip fracture with warfarin use ≥1 and ≥3 years, respec‐

The conclusion of the present trial was as follows: long‐term warfarin use among elders (i.e., >65 years of age) with atrial fibrillation was not associated with any increased risk of osteo‐ porotic fractures and therefore does not appear to necessitate additional surveillance or prophylaxis [61]. These observational studies have focused on clinical fractures as endpoints below follow‐up time at 5–10 years, but the thesis that warfarin‐induced clinical fractures was not confirmed. This may be due to the beneficial effect of MK‐7 on bone mass, which appears to stay unaffected by the impact of warfarin on vitamin K1, which again reinforces the notion that vitamin K2 status (measured as ucOC) per se is a good marker of bone homeostasis [58].

The link between increased calcification of vessels and bone complications changes the definition of CKD‐MBD to better describe the complexity of the syndrome [62]. The link between osteoporosis and cardiovascular morbidity is well described in postmenopausal women with intact renal function [63]. In chronic hemodialysis patients, a lower bone volume is associated with higher coronary calcification scores measured by multislice computed tomography, reflecting a higher risk of cardiovascular events [64]. This association between vascular calcification, arterial stiffness and bone mineral density in chronic kidney disease was also described in 2008 by Toussaint et al. [65]. Furthermore, the mortality of hemodialysis patients was evaluated in 2003 by Taal et al. among 88 hemodialysis patients over a 3.5 years follow‐up period. Here, it appeared that mortality was associated with age, Ca‐P product, lack of transplantation and a low bone mineral density measured at the hip. The leading cause of

The therapeutic options are few, since many women on renal replacement treatment did not accept reinstigation of hormone replacement therapy. However, the efficacy of hormone

**7. Chronic kidney disease and loss of bone mass (CKD‐MBD)**

death (42.5%) appeared to be related to cardiovascular events [66].

does not appear to have clinically important effects on the skeleton [5, 60].

tively, were 1.08 (95% CI 0.87, 1.35) and 1.13 (95% CI 0.84, 1.50).

The main results obtained were as follows: MK‐7 ingestion significantly enhanced vitamin K status and decreased the age‐related reduction in bone mass, as well as both BMC and BMD at the level of lumbar spine and femoral neck. However, total hip BMC and BMD decline could not be "rescued." Bone strength also seemed to be favorably affected by MK‐7 ingestion, significantly decreasing the loss of vertebral height of the lower thoracic region at the mid‐site of the vertebrae**.** These results confirm the hypothesis that long term supplementation with MK‐7 beneficially affects bone health. Whether these results can be extrapolated to other populations with osteoporosis, needs further investigation [57].
