Vitamin K2 reduces the frequency, intensity, and duration of nighttime leg cramps

By Priyanjana Pramanik, MSc.Reviewed by Danielle Ellis, B.Sc.Oct 30 2024

Findings indicate that the vitamin is effective and safe for managing NLCs in people over 65.

In a recent study published in JAMA Internal Medicine, researchers examined the effects of vitamin K₂ on the severity, duration, and frequency of nocturnal leg cramps (NLCs) among older people.

Background

Between 60 and 70% of adults experience NLCs at some point, with approximately 20% reporting severe symptoms that can cause distress and affect their sleep, leading them to seek medical help.

There is limited evidence for the effectiveness of medications such as calcium channel blockers or magnesium to relieve symptoms. Quinine, while effective, has been discouraged due to serious adverse effects, while other treatments lack evidence of effectiveness or safety, leading to challenges in primary care.

Previous studies have found vitamin K₂ to be a safe and effective therapy for reducing muscle cramps experienced by people undergoing dialysis, indicating its potential to relieve LNC symptoms.

About the study

In this study, researchers conducted a randomized, double-blind clinical trial controlled by placebos in two hospitals in China.

Participants were over 65 and had experienced at least two NLC episodes in the two weeks before recruitment. Screenings excluded people with recent vitamin K2 use, malignancies, metabolic disease, and other specific medical conditions, and eligibility was confirmed through physical exams.

Half of the confirmed participants were randomly assigned to receive a daily dose of 180 μg vitamin K_2, while the others received a placebo for eight weeks. The placebo and vitamin K₂ capsules were identical in appearance and packaging, and both the research staff and participants were blinded to the assignment of groups.

Participants consumed one capsule per night and tracked NLC events, pain level, and duration. Research staff contacted them weekly to ensure adherence, collect reports, and enquire about any side effects.

The main outcome was the average number of NLCs experienced each week during the eight weeks of the study, with the severity (scored between 1 and 10) and the duration in minutes of the cramps as secondary outcomes.

Findings

After eligibility screening, 199 participants with an average age of 72.3 years were included in the study, of whom slightly over 54% were female. The placebo was given to 96 people, while 103 received the vitamin K₂ capsules. Compliance was high at 86-92% in the two groups.

The groups were similar in terms of baseline characteristics and also experienced similar cramp frequencies initially, with those in the intervention group reporting 2.6 events per week and those who received the placebo reporting 2.71.

However, the group receiving vitamin K₂ reported that their mean cramp frequency reduced to 0.96 events per week over the eight weeks, while the placebo group’s average number of events increased to 3.63. Statistical tests established that this difference was significant.

Those receiving the vitamin capsule also reported greater reductions in the severity of pain and duration of NLC events. No adverse events were reported by the participants related to the consumption of vitamin K₂.

Conclusions

NLCs are a common experience but are currently difficult to manage as their causes remain unclear, and there are few safe and effective therapies. While developing new treatments, minimization of harm is critical.

Following previous findings that vitamin K₂ relieves hemodialysis-related cramps, researchers explored whether they can alleviate discomfort from NLCs. They found that from the first week of the trial, vitamin K₂ reduced the intensity, duration, and frequency of NLC events. The mechanism could be the lowering of calcium levels, leading to muscle relaxation.

Encouragingly, the therapy appeared safe for older adults, with no observed adverse effects during the study. However, it is not recommended for people on certain blood thinners, as it may interfere with its effects.

Researchers did not assess sleep or quality of life as impacts, as this could have reduced compliance and participation in the study. Further, all participants experienced mild NLC symptoms, and further research is needed to see if supplementation can relieve more severe cramping.

In conclusion, vitamin K₂ shows the potential to safely and effectively reduce NLC symptoms, supporting further trials to evaluate its impact on sleep quality and overall quality of life for those who experience these events.