Two 2023 human studies used different measurement techniques to find similar results regarding Vitamin K2 MK-7. The first compared 100 premenopausal women with 100 postmenopausal women with osteoporosis:
“Vitamin K (VK) as well as vitamin D (VD) plays an important role in osteoporosis. We developed a simple LC-MS/MS method for determination of VK1, MK-4, MK-7, 25(OH)D2, and 25(OH)D3 levels in human serum and validated the method in a study cohort of 200 patients.
MK-7 in plasma decreased earlier than VD in postmenopausal osteoporosis patients. MK-7 status is significantly associated with osteoporosis, and could be considered a predictable biomarker in diagnosis of osteoporosis in postmenopausal women.”
https://karger.com/anm/article-abstract/79/3/334/843963/Determination-of-Vitamin-K1-MK-4-MK-7-and-D-Levels?redirectedFrom=fulltext “Determination of Vitamin K1, MK-4, MK-7, and D Levels in Human Serum of Postmenopausal Osteoporosis Women Based on High Stability LC-MS/MS: MK-7 May Be a New Marker of Bone Metabolism” (not freely available)
Comparisons of postmenopausal women with and without osteoporosis are a necessary step before assigning MK-7 status as a diagnosis biomarker.
A second study sampled 518 people of various ages with unspecified health status:
“Biological properties of menaquinone-7, both those proven and those that remain to be investigated, arouse extensive interest. The most important of them is the prevention of age-related diseases.
A simple sample preparation method followed by liquid chromatography-tandem mass spectrometry-based method (LC-MS/MS) was used for selective and sensitive determination of K2MK-7 from 518 samples.
The highest degree of agreement of results with the lowest number of outliers and shortest whiskers is visible for the youngest age group. The lowest degree of agreement with the longest whiskers can be observed in males in the middle age group, i.e., 41–50 years old, with the highest values of outliers, not shown in Figure 4 for the sake of legibility, obtained in the oldest age group of females (11.7 ng/mL). The difference in the amount of vitamin K2MK-7 in females and males is noticeable in age group 41–50, which is when menopause often begins.
K2MK-7 values are significantly related to age of both females and males. Higher F-test values obtained for females not only confirmed the relationship between age and gender with content of vitamin K, but also indicated that in females, there is a greater distribution of K2MK-7 values depending on age.”
https://www.mdpi.com/1420-3049/28/18/6523 “Development, Validation, and Two-Year Application of Rapid and Simple LC-MS/MS-Based Method for the Determination of K2MK-7 in Blood Samples”
This study had more to do with establishing a simpler MK-7 measurement method than making other findings. Arbitrary age buckets weren’t informative without additional information regarding health status. Maybe these researchers’ workplace was similar to Labcorp or Quest where they didn’t interact with the blood donor?
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