Can Vitamin K2 prevent leg cramps?

The 2 minute update looks at a study evaluating Vitamin K2 supplements to prevent nocturnal leg cramps.

Nocturnal leg cramps are common in older patients, and we have few interventions to help treat them. Stretching appears beneficial, and there’s mixed data regarding magnesium supplements. Here, researchers looked at Vitamin K2 to help prevent nocturnal leg cramps.

This is a double-blind placebo-controlled trial including 199 patients. About 54% were women, and the average age was 72. They were having about 2.65 nocturnal leg cramps each week. Participants were randomized to 180 micrograms of vitamin K2 or placebo daily for 8 weeks. Researchers assessed the frequency, severity and duration of patients’ leg cramps. Anyone taking warfarin was excluded, as were those with a known etiology for their cramps such as alcohol abuse or Parkinson’s disease.

With vitamin K2, leg cramps fell from about 2.65 each week down to slightly less than one per week. The placebo group experienced more cramps, rising from about 2.65 per week up to 3.6 per week. With vitamin K2, the severity of the cramps also improved, and the cramps were shorter in duration with vitamin K2 compared to placebo. During week 8 with vitamin K2, the severity of cramps was only 0.39 on a 10 point scale and the average duration was only a few seconds. All of the differences were statistically significant.

This is a very simple intervention – just take one capsule of vitamin K2 daily, here researchers used 180 micrograms daily. A quick search online shows that vitamin K2 most commonly comes in 100 microgram capsules, so patients may need to take two each day, although optimal dosing is not known.

This is very inexpensive, probably less than $10 per month. And vitamin K2 appears safe, although it should probably not be used in patients on warfarin, or perhaps in those with high clotting risk, such as cancer patients.

Reference: Tan et al. Vitamin k2 in Managing Nocturnal Leg Cramps: A Randomized Controlled Trial. JAMA Intern Med. 2024 Oct. 28; Online ahead of Print.