Vitamin K2 Safe for Blood Clotting in Healthy Adults

observational-study PMID: 34115006

Quick Summary: A 2021 study tested if Vitamin K2 (MK-7) supplements change blood clotting in healthy people. Researchers gave 90 micrograms daily for 30 days to 40 adults aged 25-40. The main finding: It did not affect clotting factors or times, showing it's safe for healthy folks without blood thinners.

What The Research Found

This study looked at whether Vitamin K2, a form of vitamin K found in some foods and supplements, impacts how blood clots. Doctors sometimes worry vitamin K might make blood clot too easily, raising risks like heart issues. But the results eased those fears for healthy people.

Key findings in simple terms:
- Blood clotting times (like prothrombin time, or PT) stayed the same—no faster or slower clotting.
- Levels of key clotting proteins (factors II, VII, IX, and X) didn't change after a month.
- A marker called PIVKA-II, which shows if vitamin K is working on proteins, remained steady—no big shifts.
Overall, Vitamin K2 at normal doses didn't tip the balance of blood clotting in healthy adults not on medications.

Study Details

Who was studied: 40 healthy volunteers aged 25 to 40 years old. They had no health issues or blood-thinning drugs.

How long: 30 days of daily supplements, with tests before and after.

What they took: 90 micrograms of MK-7 (a type of Vitamin K2) each day by mouth. This matches common recommended amounts from food or pills.

What This Means For You

If you're a healthy adult thinking about Vitamin K2 supplements for bone health or heart support, this study suggests it's unlikely to mess with your blood clotting. You can feel more confident taking the recommended dose without worrying about unwanted clots. But always chat with your doctor first, especially if you have conditions like high blood pressure or take meds. For everyday folks, it means Vitamin K2 is generally safe as part of a balanced diet—think fermented foods like natto or cheese.

Study Limitations

This research has some limits that everyday readers should know:
- Small group: Only 40 people, so results might not apply to everyone.
- Short time: Just one month—longer use could show different effects.
- Narrow focus: Only young, healthy adults; older people, those with illnesses, or on blood thinners might see different results.
- No comparison group: Everyone got the supplement, so it's harder to prove it was the cause of no changes.
Keep in mind, more studies are needed for broader groups. This doesn't cover everyone or long-term use.

Key Findings

This 2021 observational study found that 30 days of 90 μg/day vitamin K2 (menaquinone-7, MK-7) supplementation did not significantly alter coagulation activity in healthy adults aged 25–40. Specifically:
- Prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT) remained unchanged (no p-values reported).
- Activities of vitamin K-dependent factors II, VII, IX, and X showed no statistically significant differences from baseline.
- PIVKA-II levels (marker of undercarboxylated prothrombin) were stable, indicating no enhancement in prothrombin carboxylation.
The study concluded that MK-7 at recommended doses does not disrupt hemostatic balance in healthy individuals not using anticoagulants.

Study Design

Type: Observational cohort study (pre-post intervention).
Sample: 40 healthy volunteers (25–40 years old, no gender/ethnicity details provided).
Duration: 30 days of supplementation.
Methodology: Coagulation parameters and factor activities were measured at baseline and after supplementation. No control group was included, limiting comparative analysis.

Dosage & Administration

Dose: 90 μg/day of MK-7, aligning with common recommended dietary allowances.
Administration: Daily oral supplementation for 30 days.

Results & Efficacy

Coagulation times: PT, APTT, and TT showed no clinically meaningful changes (p > 0.05, inferred from "no significant differences").
Factor activities:
Factor II: Baseline vs. day 30 (no exact values or p-values reported).
Factors VII, IX, X: No significant variation detected.
PIVKA-II: Levels remained unchanged (p > 0.05), suggesting MK-7 did not influence prothrombin undercarboxylation.

Limitations

Small sample size: 40 participants limits statistical power and generalizability.
Short duration: 30 days may be insufficient to detect long-term effects.
Homogeneous population: Exclusively healthy adults aged 25–40; results may not apply to older individuals, those with comorbidities, or on anticoagulants.
No control group: Observational design without a placebo arm weakens causal inference.
Unreported metrics: Missing exact p-values, confidence intervals, and baseline factor activity ranges.
Future research should include larger, diverse cohorts and longitudinal follow-up to assess MK-7 in clinical populations (e.g., vitamin K-deficient individuals).

Clinical Relevance

For healthy adults not on anticoagulant therapy, MK-7 supplementation at 90 μg/day appears safe regarding hemostatic function, as it does not activate or inhibit clotting factors. This supports existing evidence that vitamin K2 does not increase thrombotic risk in normal physiology. However, the lack of improved carboxylation (PIVKA-II) suggests no additional procoagulant benefits in individuals with adequate vitamin K status. Users should note that results may not apply to those with coagulopathies or on medications like warfarin.

Source: PubMed | Date: 2021 | Study Type: Observational