Two human studies using two forms of Vitamin K2. The first published in 2021 was with premenopausal women taking the MK-7 form:
“The aim of this 6-month randomised, controlled trial was to examine effects on bone metabolism of a nutritional supplement in women aged 25 to 44. The nutritional supplement was a protein-rich beverage powder fortified with multi-micronutrients including calcium (600 mg), vitamin D (400 IU), and vitamin K (55 mcg) per daily serving.
Co-primary outcome variables were the changes from baseline after 6 months of treatment in:
- Bone resorption marker serum C-terminal cross-linking telopeptide of type I collagen (s-CTX-I); and
- Bone formation marker expressed as ratio of carboxylated osteocalcin to under carboxylated-osteocalcin (c-OC/uc-OC).
The ratio of carboxylated to undercarboxylated OC is a marker of vitamin K status:
A meta-analysis of randomised controlled trials indicated that vitamin K2 administration reduces uc-OC and increases c-OC, and is associated with reduced bone loss and possibly a reduction in risk of fractures. The MK-7 dose of 55 mcg given in this study had a significant benefit (increase) at 3 months, but not at 6 months.
This randomised controlled 6-month trial of a nutritional supplement showed favorable changes in bone turnover markers (decreased) and calcium homeostasis. Such changes in older adults have been associated with slowing of bone loss and reduced fracture risk.”
https://www.mdpi.com/2072-6643/13/2/364/htm “Randomised Controlled Trial of Nutritional Supplement on Bone Turnover Markers in Indian Premenopausal Women”
A second study published in 2019 was with postmenopausal women taking the MK-4 form:
“This study assessed improvement in carboxylation of osteocalcin (OC) in response to escalating doses of MK-4 supplementation. A nine-week, open-labeled, prospective cohort study was conducted in 29 postmenopausal women who suffered hip or vertebral compression fractures. Mean ± SD age of participants was 69 ± 9 years.
- Low-dose MK-4 (0.5 mg) for 3 weeks; then
- Medium-dose MK-4 (5 mg) for 3 weeks; then
- High-dose MK-4 (45 mg) for 3 weeks.
MK-4 dose, but neither age nor other relevant medications (e.g. bisphosphonates), correlated with improvement in %ucOC. Compared with baseline concentrations of 16.8 ± 2.4:
- 0.5 mg supplementation halved %ucOC to 8.7 ± 2.2; and
- 5-mg dose halved %ucOC again to 3.9 ± 2.2.
However, compared to 5 mg/day, there was no additional benefit of 45 mg/day (%ucOC 4.6).
MK-4 supplementation resulted in borderline increases in γ-carboxylated osteocalcin (glaOC; p = 0.07). There were no major side effects of MK-4 supplementation.
In postmenopausal women with osteoporotic fractures, supplementation with either 5 or 45 mg/day of MK-4 reduced ucOC to concentrations typical of healthy premenopausal women.”
https://econtent.hogrefe.com/doi/10.1024/0300-9831/a000554 “Maximal dose-response of vitamin K2 (menaquinone-4) on undercarboxylated osteocalcin in women with osteoporosis” (not freely available)
I asked coauthors of the first study for an estimate of MK-7 trans isomer content. Will update with their answer.