Vitamin K₂ reduces dreaded nighttime leg cramps in clinical trials

They strike in the middle of the night, without warning. A painful contraction of the calf muscle wrenches sleepers from dreamland and throws them into a Greco-Roman wrestling match with an unseen opponent. The dreaded leg cramps have struck again.

Researchers led by the Third People’s Hospital of Chengdu, China, discovered that vitamin K₂ supplementation reduces the frequency, intensity, and duration of nocturnal leg cramps (NLCs) in older individuals.

About 50% to 60% of adults experience NLCs (also called Charley horse) during their lifetime, with about 20% experiencing significant problems and insomnia that lead them to seek medical attention. There are no medical treatments without a long list of unpleasant side effects.

In an article: “Vitamin K₂ in controlling nocturnal leg cramps: a randomized clinical trial,” published in JAMA Internal Medicinethe researchers investigated whether vitamin K₂ is better than a placebo in controlling nighttime leg cramps.

The multicenter, double-blind, placebo-controlled, randomized clinical trial, conducted in China, included 199 individuals aged 65 years and older (mean age 72.3 years) who experienced two or more documented episodes of NLCs during a two-week screening period. Participants were randomly assigned in a 1:1 ratio to receive vitamin K₂ (menaquinone 7), 180 μg, or a placebo capsule daily for eight weeks.

The primary outcome of the study was the average number of NLCs per week between vitamin K₂ and placebo groups.

Secondary outcomes included duration of muscle cramps, measured in minutes, and severity of muscle cramps assessed using an analogue scale of 1 to 10.

At baseline, the mean number of NLCs per week was similar in both groups, with 2.60 cramps in the vitamin K group.₂ group and 2.71 in the placebo group.

During the eight-week intervention, vitamin K₂ group experienced a reduction in the average weekly frequency of cramps to 0.96. In contrast, the placebo group maintained an average weekly cramp frequency of 3.63. A difference of 2.67 fewer cramps per week between the groups was statistically significant, and the trend was visible in the first week alone.

The vitamin K₂ group also significantly reduced the severity of NLC, with an average reduction of 2.55 points compared to 1.24 points in the placebo group. The duration of NLCs decreased by an average of 0.90 minutes in the vitamin K₂ group, compared to 0.32 minutes in the placebo group. No side effects related to vitamin K₂ uses were identified.

Based on the results, the researchers conclude that vitamin K₂ Supplementation significantly reduces the frequency, intensity and duration of nighttime leg cramps in older adults, without side effects. They recommend future clinical trials to evaluate the efficacy of K₂ and investigate its impact on quality of life and sleep in patients with frequent NLCs.

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