Abstract and Introduction
Background Depression is a common and often disabling disorder. Magnesium supplementation has been linked to improvement in depressive symptoms, but consensus on the relationship between magnesium and depression has not been reached.
Methods The purpose of this study was to test the existence of an association between dietary magnesium intake and depression in the adult US population. A cross-sectional, population-based data set (National Health and Nutrition Examination Survey) was used to explore the relationship of magnesium intake and depression in 8894 US adults (mean age, 46.1 years; 47.4% men) from 2007 to 2010. Using logistic regression to model the relationship between the presence of depression (Patient Health Questionnaire score ≥5) and low magnesium intake (<184 mg/day), we examined the risk ratio (RR) of magnesium intake and its 95% confidence interval.
Results After adjusting for all potential confounders, the strength of the association of very low magnesium intake with depression was statistically significant (RR = 1.16; 95% CI, 1.06–1.30). Adjusting for all other covariates, low magnesium intake was associated with depression in subjects younger than age 65 (RR, 1.22; 95% CI, 1.06–1.40; P = .007) but seemed to be protective in seniors (RR, 0.75; 95% CI, 0.56–0.98; P = .032).
Conclusions We found a significant association between very low magnesium intake and depression, especially in younger adults. The finding of the potential protective effect of low magnesium intake in older adults is surprising and warrants further investigation.
Depression is a common and disabling disorder. Almost 11% of adults older than 60 and 18.8% of those younger than 60 suffer from depression. Although both pharmacologic and behavioral therapies are effective for many patients, they have important limitations. Medications can take weeks to have an effect, often have significant adverse effects, and fail to help many patients. Nonpharmacologic approaches such as cognitive behavioral therapy also are effective but require highly trained therapists and weeks to achieve effectiveness.
As a result of the need for additional treatment options, interest in the role of nutrition in modulating depressive symptoms has grown. Magnesium plays a role in many of the pathways involved in the pathophysiology of depression and is found in several enzymes, hormones, and neurotransmitters. Depression and magnesium both are associated with systemic inflammation.[5,6] National data indicate a significant portion of the population has a magnesium intake below the estimated average requirement (EAR).
Magnesium supplementation has been linked to improvements in symptoms of major depression, premenstrual symptoms, postpartum depression, and chronic fatigue syndrome. Low magnesium status has been associated with increased depressive symptoms in several different age groups and ethnic populations.[11–14]
Issues in study design have led to inconclusive results and skepticism about the role of magnesium in depression. Serum magnesium concentrations were used to indicate magnesium status in some studies,[11,15] but their reliability is questionable.[16,17] Clinical trials have suffered from limited sample sizes,[10,11] the use of the supplement magnesium oxide (which is poorly absorbed), and restrictive inclusion criteria. With varying outcomes, different populations and age ranges, and limited sample sizes, consensus on the relationship between magnesium intake and depression has not been reached.
Some cross-sectional studies have reported an inverse relationship between magnesium intake and standardized depression scores in populations with low magnesium intake.[12–14,19] Because these studies were conducted outside of the United States, their results should be validated in a US population. One longitudinal study did not find an inverse relationship, although the study was underpowered to detect a significant reduction in depression.
If proven effective, increased magnesium consumption through diet or supplementation might address some of the limitations of currently available treatment. Magnesium is found in many common foods, and consumption of these foods can easily affect magnesium status. Although it can lead to hypermagnesemia and diarrhea, magnesium supplementation is, in general, a safe treatment with few unanticipated side effects. Magnesium supplementation provides quick results. Case studies of magnesium supplementation reported improvements in depression, anxiety, and sleep within 1 week.[8,11] Therefore, we sought to test the existence of a relationship between dietary magnesium intake and depression using a large, cross-sectional, population-based data set from the United States.
J Am Board Fam Med. 2015;28(2):249-256. © 2015 American Board of Family Medicine