Magnesium Intake and Depression in Adults

Emily K. Tarleton, MS, RD; Benjamin Littenberg, MD


J Am Board Fam Med. 2015;28(2):249-256. 

In This Article


Of the adult subjects in the NHANES data set, 73% met eligibility criteria, for a final sample size of 8894 (Figure 1). The characteristics of the sample are described in Table 1. All the selected covariates showed significant trends across the quintiles of magnesium intake. Depression was most prevalent in the lowest quintile of magnesium intake.

Figure 1.

Inclusion flow diagram. NHANES, National Health and Nutrition Examination Survey; PHQ-9, 9-item Patient Health Questionnaire.

The univariate regression of low magnesium intake and depression demonstrated a strong, statistically significant association, with an OR of 1.73 (95% CI, 1.48–2.02) and an RR of 1.49 (95% CI, 1.35–1.66) (Table 2). All the potential confounders were associated with both low magnesium and depression (P < .1) and were retained in the multivariate model (except household income because it was highly correlated with food insecurity). After adjusting for all potential confounders, the strength of the association of low magnesium intake with depression was attenuated but remained statistically significant, with an OR of 1.21 (95% CI, 1.02–1.42) and an RR of 1.16 (95% CI, 1.06–1.30). The use of magnesium as a function of energy gave similar results.

Over half of the population (54%) reported deficient magnesium intake (less than the EAR). Deficiency was significantly associated with depression in the univariate model (OR, 1.13 [95% CI, 1.01–1.27]; RR, 1.10 [95% CI, 1.01–1.20]) but not in the multivariate-adjusted analyses (OR, 0.97 [95% CI, 0.85–1.09]; RR, 0.98 [95% CI, 0.88–1.07]).

Only one of the covariates had a significant interaction. Older age interacted significantly with low magnesium intake (OR, 0.51; 95% CI, 0.37–0.72). Adjusting for all other covariates, low magnesium intake was associated with depression in subjects younger than age 65 (OR, 1.31 [95% CI, 1.08–1.58]; RR, 1.22 [95% CI, 1.06–1.40]) but seemed to be protective in seniors (OR, 0.69 [95% CI, 0.49–0.97]; RR, 0.75 [95% CI, 0.56–0.98]) (Figure 2).

Figure 2.

Prevalence of depression adjusted by magnesium intake and age. The prevalence estimates for each quintile of magnesium intake for each age group were adjusted for sex, race, ethnicity, education, marital status, alcohol intake, smoking, kidney disease, diabetes, food insecurity, and low dietary folate. Quintiles of magnesium intake (by age) are presented as milligrams per day.