CLINICAL QUESTION

Is vitamin K₂ effective in decreasing nocturnal leg cramps in older people?

BOTTOM LINE

Vitamin K₂ (menaquinone-7), 180 mcg in the evening, halves the average number of nocturnal leg cramps per week in people with frequent bouts. (Level of Evidence = 1b)

SYNOPSIS

The researchers enrolled 199 participants 65 years and older from the community (ie, rather than from a nursing home or hospital) who reported at least two episodes (average 2.6) of nocturnal leg cramps in the previous 2 weeks. The patients were randomized using concealed allocation to receive placebo or vitamin K₂, specifically menaquinone-7, 180 mcg in the evening for 2 months. The average number of cramps dropped to 0.96 per week in the treatment group vs an increase to 3.63 per week in the placebo group (P < .001), with the difference reported in the first week of treatment and continuing to widen over time as the number of episodes decreased in the treatment group. Over 2 months, the patients who received vitamin K₂ had more than 21 fewer episodes of cramps. In addition, duration and severity were reported as lower with treatment, although the difference was not statistically analyzed. Sleep quality and overall quality of life were not assessed.