Magnesium Intake and Depression in Adults

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Figure 1.
Inclusion flow diagram. NHANES, National Health and Nutrition Examination Survey; PHQ-9, 9-item Patient Health Questionnaire.
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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.

Table 1. Subject Characteristics by Quintile of Magnesium Intake^*

Characteristics	Quintile					Total
Characteristics	1	2	3	4	5	Total
Sample size (n)	1,681	1,727	1,834	1,816	1,836	8,894
Magnesium intake
Mean (mg/day)	138	216	281	361	581	334
Range (mg/day)	0–183	184–246	247–315	316–417	418–2437	0–2437
Deficient intake (%)	100	100	58.5	18.1	0	54.0
Depression (PHQ-9 score)
Mean	4.1	3.3	2.8	2.8	2.8	3.1
Range	0–27	0–27	0–24	0–25	0–27	0–27
Depressed (score ≥5) (%)	32.2	24.5	20.5	20.5	21.1	23.2
Mean age (years)	44.6	45.8	46.2	46.9	46.5	46.1
Senior (≥65 years old) (%)	16.6	16.5	16.7	14.7	13.9	15.5
Race/ethnicity (%)
Mexican-American	15.9	17.4	18.5	18.2	17.7	17.6
Other Hispanic	12.6	12.4	11.1	9.3	8.7	10.8
Non-Hispanic white	39.2	44.1	46.6	52.1	57.3	48.1
Non-Hispanic black	28.7	21.8	18.9	15.9	12.1	19.3
Other	3.6	4.2	4.9	4.5	4.3	4.3
Male sex (%)	26.9	38.8	46.2	53.5	63.2	47.4
Social (%)
High school graduate	73.6	80.8	82	86.5	86.7	82.5
Married (or living as married)	54.9	58.2	62.7	66.1	68.0	62.6
Food insecurity	23.4	16.3	13.5	11.0	10.8	14.4
Household income <$35,000/year	47.8	33.2	29.6	23.2	24.4	30.5
Habits
Current smoker (%)	31.2	20.9	20.5	20	17.7	21.5
Mean drinks per day	0.4	0.5	0.5	0.7	0.7	0.6
Chronic disease (%)
Diabetes	11	9.6	8.4	8.4	8.2	9
Kidney disease	3.7	1.9	1.2	0.7	1.1	1.6
Dietary folate equivalent intake^{^†} (%)	58.6	23.2	9.1	3.4	1.5	16.5

↵* The trend across quintiles of magnesium intake is significant with P ≤ .001 for all characteristics using an unadjusted nonparametric test of trend.²⁵
↵† Lowest quintile (<230 μg/day).
PHQ-9, 9-item Patient Health Questionnaire.

Table 2. Logistic regressions on depression

Independent Variables	Odds Ratio	95% CI	P Value
Univariate model
Low magnesium	1.73	1.48–2.02	<.001
Multivariate model
Low magnesium	1.21	1.02–1.42	.026
Male	0.61	0.53–0.70	<.001
Age ≥65 years	0.65	0.54–0.77	<.001
Non-Hispanic white	0.95	0.68–1.32	.75
High school graduate	0.77	0.64–0.93	.007
Married	0.70	0.61–0.80	<.001
Drinker	1.06	0.99–1.12	<.073
Chronic kidney disease	2.50	1.66–3.79	<.001
Smoker	1.78	1.52–2.10	<.001
Diabetes	1.63	1.29–2.06	<.001
Food insecurity	2.30	1.90–2.78	<.001
Low folate intake	1.11	0.92–1.35	.28

Table 3. Adjusted Odds of Depression by Age and Magnesium Intake^*

Magnesium Intake (mg/day)	Odds Ratio	95% CI	P Value
Age <65
0–183	1
184–246	0.81	0.67–0.98	0.032
247–315	0.69	0.52–0.92	0.012
316–417	0.76	0.63–0.91	0.005
418–2437	0.80	0.59–1.09	0.15
Age ≥65
0–183	1
184–246	1.38	0.87–2.18	0.17
247–315	1.29	0.79–2.10	0.29
316–417	1.30	0.83–2.03	0.24
418–2437	2.15	1.34–3.45	0.002

↵* Odds ratios and confidence intervals (CIs) were adjusted for sex, race, ethnicity, education, marital status, alcohol intake, smoking, kidney disease, diabetes, food insecurity, and low dietary folate.