Vitamin K2 supplementation eases leg cramps in seniors

Daily supplementation with vitamin K2 helps minimize the frequency, intensity, and duration of nocturnal leg cramps in older adults while having a good safety profile, as shown in a study.

In a cohort of 199 participants (mean age 72.3 years, 54.3 percent female) from China who underwent an 8-week randomized intervention, the primary outcome of mean number of leg cramps per week dropped from 2.60 at baseline to 0.96 among those who received vitamin K2 180 μg (n=103). On the other hand, those who received a similar-looking placebo (n=96), the frequency remained consistent, increasing slightly from a mean of 2.71 to 3.63 per week. [JAMA Intern Med 2024;doi:10.1001/jamainternmed.2024.5726]

Vitamin K2 significantly reduced cramping frequency, with a mean reduction of 2.67 cramps per week (95 percent confidence interval [CI], −2.86 to −2.49) compared with placebo (p<0.001), according to the investigators.

Likewise, the secondary outcomes were better in the vitamin K2 arm than in the placebo arm. At week 8, cramping duration was 0.25 vs 0.98 min (difference –0.73, 95 percent CI, –0.80 to –0.65), while cramping severity as measured on a 1–10 visual analogue scale was 1.12 vs 2.08 (–0.97, 95 percent CI, –1.14 to –0.79).

No adverse events related to vitamin K2 use were documented.

“Vitamin K2 has been well-documented to be a safe supplement, as the lack of adverse effects in healthy humans precluded the World Health Organization and the Food and Agriculture Organization of the United Nations from setting a tolerable upper intake level for vitamin K2,” the investigators said. [Nutr Rev. 2017;75:553-578]

“[However,] vitamin K2 has the potential to compromise the anticoagulant effectiveness of warfarin, a widely prescribed medication for older individuals. Therefore, vitamin K2 is not recommended for those undergoing warfarin therapy,” they continued.

Overall, the findings provide evidence of the efficacy and safety of vitamin K2 for managing leg cramps in older adults, the investigators said. This may have important implications, given that nocturnal leg cramps are common and can be quite challenging to manage due to uncertainties related to precise pathophysiology, they added.

Previous research has shown the beneficial effect of vitamin K2 in relieving cramps. An in vitro study suggests that vitamin K exerts its anticontraction effect possibly by inhibiting calcium intake from the external medium, an action mediated by blocking the voltage-dependent calcium channels and thus attenuating intracellular calcium levels in muscle cells. [Biochem Biophys Res Commun 2016;476:393-399]

“Further research is required to confirm whether vitamin K2 can demonstrate efficacy in other populations with more pronounced symptoms,” the investigators said.