Researchers randomly selected 94 people with nocturnal leg cramps to
take either magnesium oxide tablets or similar looking pills without
any active ingredients for four weeks. At the end of treatment, they
didn’t find any meaningful differences between the groups in the
severity or duration of leg cramps, quality of life, or quality of
sleep.
“Magnesium supplements are widely marketed for nocturnal leg cramps
despite no evidence of significant benefit,” said senior study
author Dr. Uzi Milman, director of the clinical research unit at
Clalit Health Services, Haifa and Western Galilee District in
Israel.
Nocturnal leg cramps are painful, involuntary contractions of
muscles occurring at rest, mostly at night, and causing a palpable
knot in the muscle. Up to 60 percent of adults experience these
cramps, researchers note in JAMA Internal Medicine.
Magnesium is found in a variety of foods like leafy greens, fish,
nuts and whole grains. Supplements containing the mineral are widely
available in a variety of formulations including tablets and
powders.
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Previous studies of magnesium for muscle cramps have had mixed
results, with some research finding little to no benefit but one
trial done in pregnant women suggesting the remedy might help.
For the current study, researchers screened participants for two
weeks without treatment and documented all episodes of nocturnal leg
cramps.
Participants were around 65 years old on average and many of them
had high blood pressure or diabetes.
During the screening phase, participants typically had about eight
to nine episodes of nocturnal leg cramps a week, with each episode
lasting about six or seven minutes.
After four weeks of treatment with magnesium oxide, people in that
group experienced 4.4 weekly episodes, compared with 7.8 during the
screening part of the study.
The group taking a dummy pill, meanwhile, experienced 5.5 weekly
episodes at the end of the treatment period compared with 8.5 during
the screening period.
Differences in the reduction of weekly episodes between the groups
weren’t big enough to rule out the possibility that they were due to
chance. There also wasn’t a meaningful difference in the severity or
duration of individual episodes of cramping.
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This might be because not enough magnesium got absorbed by muscle
cells, said Dr. Andrea Romani, a researcher at Case Western Reserve
University in Cleveland, Ohio, who wasn’t involved in the study.
“If a person has lower than normal magnesium level, the amount taken
as a supplement is used to restore the normal level within tissues,”
Romani said by email. “The time necessary for this to happen depends
on how low is the magnesium level in that person, the diet that
person follows, and the type of magnesium supplement the person
takes.”
There are differences in how well the body can use different forms
of magnesium, such as citrate, aspartate, and oxide salts, she said.
During the treatment phase of the study, there were two people with
adverse events in each treatment group, although all
hospitalizations were for other medical problems common in elderly
people.
In addition, 14 people in the magnesium group and 13 in the placebo
group experienced minor side effects such as gastrointestinal
problems.
Because magnesium wasn’t better than the placebo, this suggests that
people who experience a reduction in nocturnal leg cramps after
taking magnesium may just be experiencing a placebo effect, the
researchers conclude. This means they essentially feel better
because they think the pill is helping, and not because the pill is
actually treating their symptoms.
SOURCE: http://bit.ly/2lPvCsK JAMA Internal Medicine, online
February 20, 2017.
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