VITAMIN K2 RELIEVES NOCTURNAL LEG CRAMPS IN SMALL STUDY
Straight Healthcare
December 2024
December 2024
Nocturnal leg cramps are a common complaint, affecting 50% to 60% of adults at some point during their lifetime. When asked about treatment, providers struggle to provide meaningful advice, as there are no FDA-approved therapies, and traditional remedies like quinine have potentially serious adverse events, including arrhythmias and sensory disturbances (e.g., tinnitus). Given the lack of options, there has been interest in using a form of vitamin K that may have anti-spasmodic properties.
Vitamin K exists in two primary forms:
Menaquinone-7, a subtype of vitamin K2, is believed to inhibit calcium uptake by muscle cells, thereby preventing excessive contraction and potentially alleviating nocturnal leg cramps. To test this theory, researchers randomized 199 adults aged 65 and older with nocturnal leg cramps (baseline average 2.65 cramps/week) to menaquinone-7 180 mcg at bedtime or placebo. At the end of the study, the average number of weekly leg cramps in the menaquinone-7 group decreased to 0.96, while the placebo group saw an increase to 3.6 (p<0.001). No adverse events were reported in either group.
Even though this study was small, it provides useful information, as there is a lack of evidence-based therapies for leg cramps. Menaquinone-7 (also called MK-7 or menaquinone for short) is available on Amazon from numerous manufacturers in doses of 100 and 200 mcg. In the future, I will suggest that patients with bothersome cramps give it a try. The only apparent major precaution is its potential to interfere with vitamin K antagonists, precluding its use in patients on warfarin.
Vitamin K exists in two primary forms:
- Vitamin K1 (phylloquinone): Most common form; found in plants, especially green leafy vegetables; essential for blood clotting
- Vitamin K2 (menaquinone): Present in some animal products and fermented foods; has ten subtypes, designated menaquinone-4 through menaquinone-13, based on the length of the side chain; plays a role in blood clotting and calcium regulation
Menaquinone-7, a subtype of vitamin K2, is believed to inhibit calcium uptake by muscle cells, thereby preventing excessive contraction and potentially alleviating nocturnal leg cramps. To test this theory, researchers randomized 199 adults aged 65 and older with nocturnal leg cramps (baseline average 2.65 cramps/week) to menaquinone-7 180 mcg at bedtime or placebo. At the end of the study, the average number of weekly leg cramps in the menaquinone-7 group decreased to 0.96, while the placebo group saw an increase to 3.6 (p<0.001). No adverse events were reported in either group.
Even though this study was small, it provides useful information, as there is a lack of evidence-based therapies for leg cramps. Menaquinone-7 (also called MK-7 or menaquinone for short) is available on Amazon from numerous manufacturers in doses of 100 and 200 mcg. In the future, I will suggest that patients with bothersome cramps give it a try. The only apparent major precaution is its potential to interfere with vitamin K antagonists, precluding its use in patients on warfarin.
