Magnesium intake from either a quality diet or supplementation has been shown to significantly improve the symptoms of depression and reduce the risk of depression, but not all of the studies seem to agree.

Findings from a 2018 systematic review and meta analysis reveal the following:

• Adherence to a diet high in magnesium is associated with a lower occurrence of depression in cross-sectional studies;
• Combined results from eleven studies shows that magnesium supplementation is associated with a decline in depression symptoms but only in uncontrolled studies and not in placebo controlled studies.¹

Findings from previous clinical trials and systematic reviews reveal:

• Moderate magnesium intake from foods is associated with a reduced risk of developing depression.^2–4
• Magnesium improves symptoms of depression.⁵
• Magnesium improves symptoms of anxiety.^6,7
• Magnesium improves mood.⁸
• Magnesium provides mood stabilising properties.⁹
• Low levels of magnesium have been shown in patients with anxiety, irritability, depression and psychological complaints.⁶

So why the conflicting results?

Potential reasons for conflicting results

• Magnesium can be difficult to test as 99% of total magnesium is found within the cell. This means that plasma or serum magnesium levels do not reflect total body magnesium content and can produce misleading results.¹⁰
• Magnesium can be high, normal or low in blood tests of depressed patients, and these results are not representative of brain magnesium levels.⁶
• Anti-depressants work at least in part by increasing intracellular magnesium. Studies investigating magnesium for depression in patients taking anti-depressant medications can provide conflicting conclusions.^1,10
• Magnesium levels are influenced by dietary intake, gut absorption, kidney regulation, endocrine parameters, alcohol intake and certain medications. ^6,10
• Depression is complex and studies looking at one single component are always at risk of missing the whole picture.

How much do I need?

The recommended dosage for adults is as follows:

• 250 mg – 320 mg to decrease the risk of depression.⁵
• 450 mg for comparable effects to the antidepressant imipramine in older adults with diabetes.¹¹

Note: Magnesium aspartate, citrate, lactate, and chloride are considered to have a higher bioavailability – increased absorption – in comparison with that of either magnesium oxide or sulphate.¹²

How long does it take to work?

• Studies have shown improvements in depression symptoms in as little as two weeks.⁸
• Results are generally achieved from 6 weeks to 6 months, depending upon the person and other lifestyle factors.

How magnesium works for depression

According to the research, magnesium is said to:

• Play an important role in neurotransmission.⁵
• Play an important role in neuronal plasticity.⁵
• Be involved in the regulation of the hypothalamic–pituitary–adrenal (HPA) system, the main stress response system in the body.^4,6,9,13
• Be an important modulator of N-methyl-D-aspartate (NMDA)-receptor activity.¹²
• Block NMDA’s nonselective ionotropic channels in the brain (inhibits NMDA ionotropic channels, thereby preventing the excessive entrance of calcium into the cell and subsequent neuronal injury, neural dysfunction, depression and other psychiatric illnesses).^5,6,10,14
• Increase the secretion of brain-derived neurotrophic factor (BDNF).^4,5
• Support healthy mood.⁵
• Be involved in the binding of the majority of monoamines to their receptors (e.g. is necessary for serotonin receptor binding).^4,6
• Reduce inflammation.⁴

Can I get sufficient magnesium through diet?

In short, the answer is yes.

As described above, studies indicate that sufficient magnesium intake from the diet is associated with a reduced risk of depression.

But to ensure you are getting enough magnesium from your diet, the key is to reduce or avoid processed foods as much as possible as this ultimately removes a significant portion of magnesium from your food.

Factors to be aware of include:

• Magnesium intake has steadily declined over the past century, due to the refining of grains to make processed foods, which removes 85% of the original magnesium.⁶
• Drinking water processed by distillation and reverse osmosis removes magnesium.⁶
• Unhealthy western diets containing sweetened drinks, refined food, fried food, processed meat, refined grain, and high fat dairy, biscuits and pastries have low magnesium and have been shown to be associated with an increased risk of depression in longitudinal studies.¹⁵
• Evidence demonstrates that mood disorders often co-exist with a low-quality diet, which is low in magnesium.¹

It all seems pretty straight forward, but unfortunately, as with most things that provide real benefits, you can’t take the easy option.

The science clearly indicates that the quick and easy foods we see popping up on  shop shelves are low in magnesium and setting you up for failure. To get the most out of you food you need to take control of your diet and incorporate non-refined foods with plenty of fresh fruits and vegetables.

In general, green leafy vegetables are rich in magnesium as are unrefined grains and nuts. ¹⁶

For a full list of foods go to:

• Food Standards Australia New Zealand¹⁷and choose Magnesium on the browse nutrient list; OR
• United States Department of Agriculture Food Composition Database¹⁸and search magnesium in the Nutrient search;

or check out our post Discover What Nutrients Are Hidden in Your Food.

References & further resources

1. Phelan D, Molero P, Martínez-gonzález MA, Molendijk M. Magnesium and mood disorders : systematic review and meta-analysis. BJPsych Open. 2018;4(4):167-179. doi:10.1192/bjo.2018.22.
2. Li B, Lv J, Wang W, Zhang D. Dietary magnesium and calcium intake and risk of depression in the general population : A meta-analysis. Aust New Zeal J Psychiatry. 2017;51(3):219-229. doi:10.1177/0004867416676895.
3. Tarleton EK, Littenberg B. Magnesium Intake and Depression in Adults. J Am Board Fam Med. 2015;28(2):249-256. doi:10.3122/jabfm.2015.02.140176.
4. Yary T, Lehto SM, Tolmunen T, Tuomainen T. Dietary magnesium intake and the incidence of depression : A 20-year follow-up study. J Affect Disord. 2016;193:94-98.
5. Rajizadeh A, Sc M, D HMP, D MYM, Dehghani A, Ph D. Effect of magnesium supplementation on depression status in depressed patients with magnesium deficiency: A randomized, double-blind, placebo-controlled trial. Nutrition. 2017;35:56-60. doi:10.1016/j.nut.2016.10.014.
6. Iii GAE, Eby KL. Magnesium for treatment-resistant depression : A review and hypothesis.Med Hypotheses. 2010;74(4):649-660. doi:10.1016/j.mehy.2009.10.051.
7. Kirkland AE, Sarlo GL, Holton KF. The Role of Magnesium in Neurological Disorders. Nutrients. 2018;10(6):1-23. doi:10.3390/nu10060730.
8. Tarleton EK, Littenberg B, Maclean CD. Role of magnesium supplementation in the treatment of depression : A randomized clinical trial. PLoS One. 2017;12(6):1-16.
9. Murck H. Magnesium and Affective Disorders. Nutr Neurosci. 2002;5(6):375-389. doi:10.1080/1028415021000039194.
10. Derom M, Sayón-orea C, Martínez-ortega JM, Martínez-gonzález MA. Magnesium and depression : a systematic review. Nutr Neurosci. 2013;16(5):191-206.
11. Barragán-rodríguez L, Rodríguez-morán M, Guerrero-romero F. Efficacy and safety of oral magnesium supplementation in the treatment of depression in the elderly with type 2 diabetes : a randomized, equivalent trial. Magnes Res. 2008;21(4):218-223.
12. Ryszewska-pokra B, Id ZMW, Poleszak E, Nowak G, Pilc A, Radziwo M. Effects of Magnesium Supplementation on Unipolar Depression : A Placebo-Controlled Study and Review of the Importance of Dosing and Magnesium Status in the Therapeutic Response. Nutrients. 2018;10(8):1-14. doi:10.3390/nu10081014.
13. Wang J, Um P, Dickerman B, Liu J. Zinc, Magnesium, Selenium and Depression: A Review of the Evidence, Potential Mechanisms and Implications. Nutrients. 2018;10(5):1-19. doi:10.3390/nu10050584.
14. Cheungpasitporn W, Thongprayoon C, Mao MA, et al. Hypomagnesaemia linked to depression : a systematic review and meta-analysis. Intern Med J. 2015;45(4):436-440. doi:10.1111/imj.12682.
15. Lang U, Beglinger C, Walter M, Borgwardt S. Nutritional Aspects of Depression. Cell Physiol Biochem. 2015;7(3):1029-1043. doi:10.1159/000430229.
16. Higdon J. An Evidence-Based Approach to Vitamins and Minerals. Thieme; 2003.
17. FSANZ. Magnesium. NUTTAB. http://www.foodstandards.gov.au/science/monitoringnutrients/nutrientables/nuttab/Pages/default.aspx. Published 2010. Accessed November 5, 2018.
18. USDA. USDA Food Composition Database. https://ndb.nal.usda.gov/ndb/. Published 2018. Accessed November 5, 2018.