Vitamin K reduces frequency, severity of nocturnal leg cramps

Key takeaways:

• Vitamin K₂ markedly reduced the mean weekly frequency of nocturnal leg cramps in the intervention group.
• The vitamin also reduced duration a of cramps while showing no adverse effects.

Vitamin K₂ reduced the frequency, intensity and duration of nocturnal leg cramps in older adults, findings from randomized study published in JAMA Internal Medicine showed.

Study participants who received vitamin K₂ supplements had markedly fewer episodes of nocturnal leg cramps compared with placebo and no treatment-related adverse effects, researchers noted.

According to background information from the Cleveland Clinic, 33% of adults over the age of 60 years experience nocturnal leg cramps at least once every 2 months while almost every adult aged 50 years or older will have them at least one time.

“Given the generally benign characteristics of [nocturnal leg cramps], treatment modality must be both effective and safe, thus minimizing the risk of iatrogenic harm,” Jing Tan, MD, from the Third People’s Hospital of Chengdu in China, and colleagues wrote. “Quinine, which used to be effective in treating [nocturnal leg cramps], is no longer recommended due to its severe adverse effects.”

A previous study conducted by the researchers showed that vitamin K₂ — a “fat-soluble vitamin involved in carboxylation that also activates several vitamin K dependent proteins” — effectively reduced dialysis-related muscle cramps while demonstrating safety.

Tan and colleagues conducted a multicenter, double-blind randomized controlled trial to determine the effectiveness of vitamin K₂ supplementation for treatment of nocturnal leg cramps. The study included 199 adults aged 65 years or older who had two or more episodes of nocturnal leg cramps during 2 weeks of screening at one of two medical centers in China. Study participants received daily capsules containing either 180 g of vitamin K₂ or placebo for 8 weeks.

The mean number of nocturnal leg cramps per week served as the study’s primary outcome measurement, while secondary outcomes included the duration of nocturnal leg cramps and severity of nocturnal leg cramps, the latter measured with an analog scale ranging from 1 to 10.

Results showed similar mean weekly frequency of cramps in both the vitamin K₂ group (2.6) and the placebo group (2.71) at baseline.

The researchers found that the mean frequency of nocturnal leg cramps in the vitamin K₂ group decreased to 0.96 during the intervention, with a mean frequency in the placebo group of 3.63 (difference = 2.67; 95% CI, 2.86 to 2.49).

“Notably, cramping frequency was significantly reduced compared with the placebo group, starting from the first week of intervention with vitamin K₂,” Tan and colleagues wrote.

Meanwhile, the vitamin K₂ group had greater decreases in the severity (2.55 vs. 1.24 points) and duration (0.9 vs. 0.32 minutes) of NLCs vs. the placebo group.

Study investigators reported that no adverse events related to vitamin K₂ occurred during the study — ultimately showing its safety — but they noted that vitamin K₂ is not recommended for those receiving warfarin therapy due to the vitamin’s potential “to compromise the anticoagulant effectiveness” of the medication, they wrote.

Tan and colleagues acknowledged some study limitations, including the mild severity of nocturnal leg cramps experienced in the participant sample.

As such, more clinical trials are warranted “to confirm the efficacy of cramping management and its impact on the quality of life and sleep in patients with [nocturnal leg cramps],” they concluded.

References:

• Leg cramps. Available at: https://my.clevelandclinic.org/health/diseases/14170-leg-cramps. Accessed Nov. 7, 2024.
• Tan J, et al. JAMA Intern Med. 2024;doi:10.1001/jamainternmed.2024.5726.