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

Menstrual Blood as a Non-Invasive Alternative for Monitoring Vitamin Levels

Background/Objectives: Menstrual blood has recently emerged as a novel specimen for diagnostics, offering a non-invasive alternative to traditional blood testing methods. Despite the importance of vitamins and monitoring their levels in preventative healthcare measures, the feasibility of measuring them in menstrual blood has yet to be explored. In this study, we aimed to assess the potential of using menstrual blood for determining vitamin levels by comparing their levels in menstrual blood to those in matched capillary blood samples. Methods: A prospective, monocentric, observational study was conducted with healthy, reproductive-aged voluntary participants. Menstrual blood was collected from 30 participants using a menstrual cup, and the corresponding capillary blood samples were obtained using a finger prick. The samples were transferred to dried blood spot (DBS) cards and analyzed using mass spectrometry to determine vitamin levels. Statistical analyses were performed to compare menstrual blood vitamin A and D levels, and hemoglobin, to those in capillary blood. Results: The vitamin levels could be ascertained from the menstrual blood, and were observed to significantly correlate with those from the capillary blood for both vitamin A (r = 0.77, p < 0.001) and vitamin D (r = 0.66, p < 0.001), despite being statistically different. Conclusions: The results of this pilot study demonstrate the potential utility of menstrual blood in estimating vitamin A and D levels, illustrating the prospect of a non-invasive menstrual blood-based vitamin test following larger clinical and analytical validation studies.

Vitamin D and vitamin K status in postmenopausal women with normal and low bone mineral density

OBJECTIVES

Vitamin D and K are believed to promote bone health, but existing evidence is controversial. This study aimed to measure several metabolites of both vitamins by liquid chromatography tandem mass spectrometry (LC-MS/MS) in a cohort of postmenopausal women with low and normal bone mineral density (BMD).

METHODS

Vitamin metabolites (25-hydroxyvitamin D (25[OH]D), 24,25-dihydroxyvitamin D (24,25(OH)2D), phylloquinone (K1), menaquinone-4 (MK-4) and MK-7) were measured in 131 serum samples by LC-MS/MS. The vitamin D metabolite ratio (VMR) was calculated. Parathyroid hormone (PTH), type I procollagen-N-terminal-peptide (PINP) and C-terminal telopeptides of type I collagen (CTX-I) were measured by immunoassay. Dual X-ray absorptiometry was performed to identify participants with normal (T-score>-1) and low (T-score<-1) BMD.

RESULTS

Mean age was 58.2±8.5 years. BMD was normal in 68 and low in 63 women. Median (interquartile range) for 25(OH)D and total vitamin K concentrations were 53.5 (39.6-65.9) nmol/L and 1.33 (0.99-2.39) nmol/L. All vitamin metabolites were comparable in individuals with normal and low BMD. Furthermore, BMD and trabecular bone score were comparable in participants with adequate and inadequate vitamin status (at least one criterion was met: 25(OH)D <50 nmol/L, 24,25(OH)2D <3 nmol/L, VMR <4 %, total vitamin K <0.91 nmol/L). PTH, but not PINP or CTX-I, was inversely correlated with 25(OH)D, 24,25(OH)2D and VMR. Synergistic effects between vitamin D and K were not observed.

CONCLUSIONS

Vitamin D and K status is not related to BMD and trabecular bone quality in postmenopausal women. Inverse associations were only seen between vitamin D metabolites and PTH.

The Potential of Vitamin K as a Regulatory Factor of Bone Metabolism-A Review

Vitamin K (VK), a fat-soluble vitamin, is essential for the clotting of blood because of its role in the production of clotting factors in the liver. Moreover, researchers continue to explore the role of VK as an emerging novel bioactive molecule with the potential function of improving bone health. This review focuses on the effects of VK on bone health and related mechanisms, covering VK research history, homologous analogs, dietary sources, bioavailability, recommended intake, and deficiency. The information summarized here could contribute to the basic and clinical research on VK as a natural dietary additive and drug candidate for bone health. Future research is needed to extend the dietary VK database and explore the pharmacological safety of VK and factors affecting VK bioavailability to provide more support for the bone health benefits of VK through more clinical trials.