Possible Effects of the Dietary Supplement Magnesium Compared to Placebo

The goal of this clinical trial was to investigate possible outcomes of the nutritional supplement magnesium compared to placebo in healthy, working adults. The main questions it aimed to answer were:

* Are there differences in ratings of health, stress, well-being and work environment indicators between individuals intaking 375 mg magnesium (daily for 3 months) compared to placebo?
* Are there differences in hearing, measured with hearing tests between those receiving 375 mg magnesium compared to placebo?

Participants were asked to ingest 375 mg magnesium or placebo daily for 3 months.

Researchers compared the group ingesting magnesium with the group ingesting placebo pills to see if there were any differences in for example self-rated health, recovery, wellbeing, etc.

Summary: The aim of the sub-study was to investigate possible beneficial effects of magnesium as a nutritional supplement regarding self-reported health, ill-health, pain, hearing, fatigue, signs of long term stress and more. The study was designed as a double-blind placebo-randomized controlled study, meaning that each enrolled individual was randomized to either 375 mg magnesium or placebo pills. Clinical hearing tests, blood pressure, pulse and creatinine were conducted and collected. Extensive questionnaires were distributed at baseline (T1) and after approximately 3 months (T2) of daily pill intake in order to evaluate possible effects. All participants were adults and healthy enough to work.

Previous research studies have shown that magnesium has promising effects to counteract or mitigate for instance headache/migraine, muscle cramps, high blood pressure, asthma as well as hearing problems such as tinnitus and sound sensitivity (hyperacusis). Magnesium deficiency is related to reduced immune function and physical symptoms such as migraine, muscle cramps, osteoporosis and high blood pressure/metabolic syndrome.

Magnesium is one of the body's most common and important minerals. It is involved in the regulation of the nerve activity and the muscle function. As a dietary supplement, it is affordable, easily administrated and safe. Adverse effects in the form of diarrhea can occur if magnesium is greatly overdosed. The participants in this trial were informed about this and possible other adverse effects and were recommended to terminate participation or decrease the intake (e.g., take half a pill) in case of any experienced adverse effects. They were also encouraged to report any adverse effects immediately.

The primary objective with the study was to investigate if there were differences between the treatment group (magnesium) and the control group (placebo) over time in health-related outcomes, recovery and well-being.

The present study was conducted as a separate study within a larger intervention study for employees at 21 schools in Stockholm, Sweden. The purpose of the larger intervention study was to evaluate possible effects of systematic interventions for health promotion and work environment improvements, as well as to counteract harmful stress and long-term sick-leave.

Employees could choose to participate in the larger intervention study, the sub study about magnesium/placebo, both or none of them.

Individuals enrolled in the magnesium/placebo randomized control trial by signing up for a session of hearing tests and other physiological measures approximately one week before the session. The researchers randomized each enrolled individual and prepared a kit containing the randomized jar of pills (magnesium or placebo), a paper adherence calendar, general information about the study along with instructions for intake and a protocol used by the researchers during the session. In some cases, there were some last-minute enrollments who were randomized onsite. During the session (at the participants workplace), hearing tests were performed with portable equipment, and measures of blood pressure, pulse and creatinine were performed. At the end of the session, the participant was provided with the magnesium/placebo kit and was asked to fill out a web-based questionnaire. The same measures were performed after approximately three months, except for the creatinine test. Participants were also asked to fill out another web-based questionnaire and were asked to return the magnesium/placebo kit and the compliance calendar.

Eligibility Criteria:
Inclusion Criteria:

Individuals employed at the participating organizations (21 schools and one white collar organization) who provided their informed consent and were at least 18 years old.

Exclusion Criteria:

1. Individuals with creatinine levels more than195 μmol/L for women and more than 230 μmol/L for men.
2. Individuals who had undergone a liver transplant.
3. Lithium intake or prescription.

Pregnant women were disadvised from participation.