Vitamin K: Can It Help You Live Longer?

observational-study PMID: 34785587

Quick Summary: Research suggests that eating more vitamin K, found in foods like leafy greens and fermented foods, may be linked to a lower risk of dying from any cause, especially heart-related issues. This study looked at how much vitamin K people ate and tracked their health over many years.

Vitamin K and Your Health: What the Study Found

This study looked at several previous studies to see if there was a connection between how much vitamin K people ate and how long they lived. The results showed:

More Vitamin K, Less Risk: People who ate more vitamin K, both K1 (from leafy greens) and K2 (from fermented foods and animal products), had a lower risk of dying from any cause.

Heart Health Boost: Higher vitamin K intake was also linked to a lower risk of dying from heart problems.

No Cancer Link: The study didn't find a clear link between vitamin K intake and the risk of dying from cancer.

Study Details

Who was studied: Almost 49,000 people from different studies were included.

How long: Researchers followed the participants for up to 28 years.

What they took: The study looked at how much vitamin K the participants got from their food, not from supplements.

What This Means For You

Eat Your Greens (and Fermented Foods!): This research suggests that eating a diet rich in vitamin K could be good for your health. Focus on including plenty of leafy green vegetables (like spinach and kale) and fermented foods (like sauerkraut, natto, or cheese) in your meals.

Heart Health Matters: If you're concerned about your heart health, making sure you get enough vitamin K could be a smart move.

Talk to Your Doctor: Always talk to your doctor or a registered dietitian before making big changes to your diet or taking supplements.

Study Limitations

Observational Study: This study looked at patterns, but it can't prove that vitamin K causes people to live longer. Other factors could be involved.

Dietary Data: The study relied on what people reported eating, which isn't always perfectly accurate.

More Research Needed: More studies are needed to confirm these findings and understand the best ways to get enough vitamin K.

Key Findings

The study found that higher dietary intake of vitamin K (both phylloquinone [K1] and menaquinones [K2]) was associated with a lower risk of all-cause mortality. Specifically, a 10 μg/day increase in phylloquinone intake correlated with a 9% reduction in mortality risk (relative risk [RR] = 0.91, 95% confidence interval [CI]: 0.85–0.97), while a 5 μg/day increase in menaquinones showed a 16% reduction (RR = 0.84, 95% CI: 0.75–0.95). Inverse associations were also observed for cardiovascular mortality but not cancer mortality.

Study Design

This was a systematic review and dose-response meta-analysis of prospective cohort studies. Data were pooled from 10 studies involving 48,944 participants across general populations. Follow-up durations varied from 7.8 to 27.9 years, depending on the cohort. Observational design limited causal inference, but the large sample size and long-term tracking strengthened trend analysis.

Dosage & Administration

The study analyzed dietary vitamin K intake from food sources, not supplements. Phylloquinone (K1) was primarily derived from leafy green vegetables, while menaquinones (K2) came from fermented foods and animal products. Doses were modeled as incremental increases (10 μg/day for K1, 5 μg/day for K2) rather than fixed amounts.

Results & Efficacy

All-cause mortality:
K1: RR = 0.91 (95% CI: 0.85–0.97; p = 0.005 for trend).
K2: RR = 0.84 (95% CI: 0.75–0.95; p = 0.002 for trend).
Cardiovascular mortality:
K1: RR = 0.88 (95% CI: 0.78–0.99; p = 0.04 for trend).
Cancer mortality: No significant association (p = 0.18 for K1; p = 0.21 for K2).
Effect sizes suggest modest but statistically significant risk reductions, particularly for K2 and cardiovascular outcomes.

Limitations

Observational design precludes establishing causality; residual confounding (e.g., diet quality, comorbidities) may influence results.
Heterogeneity in study populations and dietary assessment methods (food frequency questionnaires vs. 24-hour recalls) could affect accuracy.
Vitamin K intake was self-reported, risking measurement errors.
Limited data on supplement use or specific K2 subtypes (e.g., MK-4, MK-7).
No significant link to cancer mortality suggests potential outcome-specific effects.

Clinical Relevance

For supplement users, this study supports prioritizing dietary vitamin K (especially K2 from fermented foods like natto or cheese) to potentially reduce long-term mortality risk. However, it does not confirm benefits of isolated supplements. The findings align with dietary guidelines advocating for leafy greens and diverse food sources. Clinicians might emphasize vitamin K-rich diets for cardiovascular health, though randomized trials are needed to validate these associations. Users should avoid overinterpreting results for cancer outcomes, as no significant link was found.

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Source: Liu et al., Nutrients (2021) [PMID: 34785587].