by Justin Jackson, Science X, Medical Xpress

Credit: Pixabay from Pexels

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

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

Approximately 50% to 60% of adults experience NLCs (sometimes referred to as a Charley horse) in their lifetime, with about 20% encountering significant distress and insomnia that lead them to seek medical intervention. There are no medical treatments without a substantial list of unpleasant side effects.

In a paper, “Vitamin K2 in Managing Nocturnal Leg Cramps: A Randomized Clinical Trial,” published in JAMA Internal Medicine, the researchers investigated whether vitamin K2 is better than a placebo in managing nocturnal leg cramps.

Conducted in China, the multicenter, double-blind, placebo-controlled randomized clinical trial enrolled 199 individuals aged 65 years and older (mean age 72.3) 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 either vitamin K2 (menaquinone 7), 180 μg, or a placebo capsule daily for eight weeks.

Visual Abstract. Credit: JAMA Internal Medicine (2024). DOI: 10.1001/jamainternmed.2024.5726

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

Secondary outcomes included the duration of muscle cramps measured in minutes and the severity of muscle cramps assessed using an analog scale ranging from 1 to 10.

At baseline, the mean number of NLCs per week was comparable in both groups, with 2.60 cramps in the vitamin K2 group and 2.71 in the placebo group.

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

The vitamin K2 group also significantly reduced NLC severity, with a mean decrease of 2.55 points compared to 1.24 points in the placebo group. The duration of NLCs decreased by a mean of 0.90 minutes in the vitamin K2 group, compared to 0.32 minutes in the placebo group. No adverse events related to vitamin K2 use were identified.

Based on the results, the researchers conclude that vitamin K2 supplementation significantly reduces the frequency, intensity, and duration of nocturnal leg cramps in older adults with no adverse events. They recommend future clinical trials to confirm the efficacy of K2 and investigate its impact on the quality of life and sleep in patients with frequent NLCs.