Vitamin K2 for Leg Cramps: Does It Really Work?

clinical-trial PMID: 39466236

Quick Summary: A recent study found that taking vitamin K2 daily can significantly reduce nighttime leg cramps in older adults. Compared to a placebo (a dummy pill), vitamin K2 helped people experience fewer, less intense, and shorter-lasting cramps.

What The Research Found

This study looked at whether vitamin K2 could help people with those annoying nighttime leg cramps, also known as nocturnal leg cramps (NLCs). The researchers found that:

People taking vitamin K2 had significantly fewer leg cramps each week.

The leg cramps were less painful for those taking vitamin K2.

The cramps didn't last as long for those taking vitamin K2.

No one in the study experienced any negative side effects from the vitamin K2.

Study Details

Who was studied: The study included 199 adults, mostly women, aged 65 and older who had experienced leg cramps at night.

How long: The study lasted for 8 weeks.

What they took: Participants took a daily capsule containing either 180 micrograms of vitamin K2 or a placebo (a pill with no active ingredients).

What This Means For You

If you're an older adult struggling with nighttime leg cramps, this research suggests that vitamin K2 might be a helpful option. Talk to your doctor about whether taking a vitamin K2 supplement could be right for you. It's a potentially safe and effective way to reduce the frequency, severity, and duration of those bothersome cramps.

Study Limitations

It's important to keep these things in mind:

The study only looked at older adults, so it's not clear if vitamin K2 would have the same effect on younger people.

The study was only 8 weeks long, so we don't know if the benefits would last longer.

The study was conducted in China, so the results might not be exactly the same for people of other ethnicities.

More research is needed to fully understand how vitamin K2 works to reduce leg cramps.

Key Findings

This randomized clinical trial demonstrated that daily supplementation with 180 μg of vitamin K2 (menaquinone-7) significantly reduced the frequency, severity, and duration of nocturnal leg cramps (NLCs) in adults aged ≥65 years. Compared to placebo, vitamin K2 lowered the mean weekly NLC frequency by 2.67 episodes (95% CI: -2.86 to -2.49; P < .001), reduced severity by 2.55 points on a 1–10 scale, and shortened cramp duration by 0.90 minutes. No adverse events linked to vitamin K2 were reported, indicating strong safety.

Study Design

A multicenter, double-blind, placebo-controlled randomized clinical trial conducted in China (September 2022–December 2023). Of 310 screened participants, 199 (54.3% female; mean age 72.3 ± 5.5 years) with ≥2 NLC episodes during a 2-week screening period were randomized 1:1 to vitamin K2 (n = 103) or placebo (n = 96). The 8-week intervention included community-dwelling adults aged ≥65 years.

Dosage & Administration

Participants received one daily oral capsule containing either 180 μg of vitamin K2 (menaquinone-7) or a placebo with identical packaging, appearance, taste, and excipients. Supplementation was self-administered at home, ensuring blinding.

Results & Efficacy

Frequency: Vitamin K2 reduced weekly NLCs from 2.60 (baseline) to 0.96 (SD: 1.41), while placebo increased to 3.63 (SD: 2.20). Between-group difference: -2.67 (P < .001).
Severity: Vitamin K2 decreased severity by -2.55 (SD: 2.12) vs. -1.24 (SD: 1.16) in placebo (P < .001).
Duration: Cramp duration decreased by -0.90 minutes (SD: 0.88) in the K2 group vs. -0.32 minutes (SD: 0.78) in placebo (P < .001).
All outcomes showed statistically significant improvements with vitamin K2, supported by narrow confidence intervals.

Limitations

High exclusion rate: 111/310 screened participants were excluded, potentially limiting generalizability.
Short duration: Effects beyond 8 weeks remain unexamined.
Self-reported outcomes: Subjective measures (e.g., severity via analog scale) may introduce bias.
Population specificity: Conducted in China; results may not apply to other ethnicities or younger populations.
Mechanistic gaps: The biological pathways underlying K2’s efficacy were not explored.

Clinical Relevance

For older adults experiencing NLCs, vitamin K2 (180 μg/day) offers a safe, evidence-based option to reduce cramp frequency, intensity, and duration. The study’s rigorous design supports its use as a non-pharmacological intervention. However, further research is needed to confirm long-term benefits, optimal dosing, and efficacy in broader demographics. Clinicians may consider K2 supplementation for elderly patients seeking relief from NLCs without significant safety concerns.

Source: PubMed (ClinicalTrials.gov Identifier: NCT05547750).