If something sounds too good to be true, it probably is. This news release from the University of Vermont reports on a study showing an association between taking magnesium supplements and a decrease in depression and anxiety symptoms in people with mild-to-moderate depression. The release simplifies and overstates the benefits of magnesium without offering any comparisons (beyond vague statements) with current pharmaceutical treatments for depression. It also ignores any mention of the study’s limitations.
Because depression is a global problem, an inexpensive, easily accessible supplement with no side effects that could be used to combat depression would be widely welcome — but only if it is viable. This release doesn’t make the case that magnesium is the answer for a condition that affects millions.
According to the CDC, almost 8 percent of Americans age 12 and older have depression in any two-week period. There’s a stigma attached to mental illness, which can prevent some people from seeking treatment. Using magnesium to fight depression is a tempting solution because not only is it low-cost, but it can be bought over-the-counter without the need for a psychological evaluation. Unfortunately, this news release might encourage people to take the treatment of their mental health into their own hands using only supplements, instead of seeing a doctor or psychologist.
Despite claiming the low cost of magnesium supplements as a benefit, the release doesn’t include the cost. A quick google search shows that magnesium tablets can be bought online or in stores for less than $15 per bottle.
According to the news release, consuming magnesium chloride “resulted in a clinically significant improvement in measures of depression and anxiety symptoms.” But the release made no mention of what these measures were, or how the measurements were taken.
The published study notes that the primary outcome measure was a mental health questionnaire given by phone bi-weekly (the Patient Health Questionnaire-9, or PHQ-9). Like any survey, this method of data collection is vulnerable to bias in the form of self-reporting. In the published study, the researchers said that the results of the PHQ-9 survey are clinically significant if there is a 5-point or more difference between treatment and baseline. The net improvement was a difference of 4.2 points, but when the researchers adjusted for other factors (including age, race, gender, smoking, alcohol use, and treatment adherence), the difference rose to 6 points, making it clinically significant. Importantly, however, the duration of this treatment benefit beyond this brief trial is unknown.
None of these nuances were mentioned in the news release.
The news release made no mention of potential harms of magnesium supplements although it notes the treatment is safe on two occasions. The actual results, however, were not quite as straightforward. The authors noted in the published study, “The most common reason for a negative response was that “magnesium did not help mood” (46%), followed by side effects (20%). The most common side effect, diarrhea, was reported by 8 participants. In addition, the published study notes that people with gastrointestinal disorders or kidney disease could not participate in the study since high levels of magnesium are not safe for these patients.
The news release provides a description of the study, “an open-label, blocked, randomized cross-over trial involving 126 adults in outpatient primary care clinics.” While this is adequate for an experienced reader, we would have liked to have seen a bit more information about the actual mechanics of the study and the trial limitations included in the release. The authors of the study did an admirable job in discussing the limitations of their design. Unfortunately, these were not carried over to the release.
Among the limitations:
There was no placebo arm of the trial, and while the participants were randomized, the trial wasn’t blinded for either the participants or the researchers. Both of these can lead to bias in the study results.
The study participants took the magnesium supplement for just 6 weeks. There’s no way to know if the slight benefit extended beyond the study period.
The news release doesn’t mention whether the study volunteers were on other medications or treatment plans to help their depression. This could be an important factor, especially if some participants were on prescription anti-depressant medications or in counseling, and others were not.
No disease-mongering here. The news release called depression an “enormous disease burden.” This is true—depression is a huge problem that affects millions of people. The World Health Organization says more than 300 million people worldwide suffer from depression.
The news release didn’t mention either the funding sources or address conflicts of interest. These were noted in the study and could have been easily included in the release.
The news release makes some statements suggesting magnesium supplements are as effective as SSRI anti-depressants and offer lower cost and fewer side effects. No evidence is offered for this and the study was far too small and too brief to demonstrate magnesium effectiveness.
The release should have delved into this area more, especially because there are so many current treatments for depression. For example, the release offered no mention of other classes of anti-depressant medications or non-drug interventions like cognitive behavioral therapy.
The news release mentioned that magnesium can be found over-the-counter.
The release says that “few clinical trials have studied the supplement’s effects.” It also quotes the lead researcher as saying, “This is the first randomized clinical trial looking at the effect of magnesium supplementation on symptoms of depression in U.S. adults.”
While this might be the first clinical trial in the US, there have been other studies (which the researchers referenced in their paper) that have looked at the effects of magnesium on depression in adults. Specifically, they mention two observational studies–one that took place in Norway, and one that looked at adults with type 2 diabetes.
The news release doesn’t use sensational language.