I've spent the last year researching supplements in an effort to maximize both my physical, mental, and emotional well-being. I had to understand whether the $32 billion dollar supplement industry was a complete sham, or if it was possible to live healthier through supplementation. The following post(s) are being published as a personal reference guide to Examine.com's excellent "Supplement Guides" - which are awesome, but often tough to dig through for the important information.

What is it?

Magnesium is an essential dietary mineral that is often overlooked or supplemented incorrectly, despite being second only to Vitamin D in deficiency rates. Magnesium has an effect on everything from depression to blood pressure, so getting this one right means a better quality of life in general.

Where is it found?

Two places:

  • Diet - Spinach, various types of nuts, brown rice, and avocados all magnesium rich. However, it is difficult to meet the RDA (300-400mg) for magnesium through diet alone.
  • Supplements - This is what we are here to discuss!

A report by the US Nutritional Health and Examination Survey in 2006 (Research: 1) found that 60% of Americans are magnesium deficient (Research: 1). This is second only to Vitamin D deficiency, which I wrote about last week.

Benefits of supplementation

Benefits are listed from best supported to least supported

  • Protects against diabetes and other insulin nastiness - Essentially makes the pancreas more efficient, which results in lowered blood glucose and increased insulin sensitivity in magnesium deficient non-diabetics. (Research:6)
  • Lowers blood pressure - correcting a magnesium deficiency resulted in a blood pressure drop of 7.1% (systolic) and 4.7% (diastolic) in healthy subjects. Cool! (Research:5)
  • Improves sleep quality - Magnesium supplementation increased time spent in slow-wave sleep, which is linked to improvements in overall memory. Also reduced sleeping cortisol levels. (Research:3)
  • Might help with ADHD - Strong correlation was found between ADHD and magnesium deficiency in children. No conclusive evidence has been found regarding a causal relationship. (Research:2)
  • Might help with depression - Weaker correlation here between depression and magnesium deficiency. The neat thing is that magnesium may be synergistic with SSRIs, which would improve depression treatments. (Research:4)

Downsides to supplementation

  • Laxative effects / gastrointestinal discomfort - this can be mitigated by using the right form of magnesium.

Dosages and Toxicity

Dosing for magnesium is a piece of cake. Just shoot for the recommended daily intake of 300-400mg of elemental magnesium. (Research:7) See the "When and how to take" section regarding exactly what this means - picking out the right form of magnesium gets tricky depending on what you are going for.

It is almost impossible to reach the toxicity level for magnesium, as the kidneys are very efficient at filtering out excess quantities. There are extremely rare cases of magnesium toxicity, but only because the patients kidneys failed. The worst thing that will happen if you take too much will be laxative effects, which is more embarrassing than life threatening. (Research:8)

When and how to take?

Magnesium supplements are a little more complicated than one would think. Magnesium is not easily absorbed by the body on its own, so manufacturers often attach it to a transporting substance so that it can be absorbed. This results in many variants of magnesium supplements that all have differing effectiveness. There are two factors that you should watch out for: elemental magnesium and bioavailability. Elemental magnesium is the actual content of magnesium in the supplement - often this is printed on the bottle. Bioavailability, on the other hand, relates to the effectiveness of the transporting substance. High elemental magnesium and high bioavailability is the goal, since taking tons of huge pills sucks.

List sorted from most recommended to least

  • Magnesium Glycinate - Most recommended. Has a high bioavailability (80%), but low elemental magnesium by weight, so you will be taking a couple large pills daily. The "Glycinate" part helps with sleep, so best taken before bed. (Research:10)
  • Magnesium-L-Threonate - Upregulates NMDA receptors and increases brain BDNF levels, which boosts active memory and learning. Only rat studies available, but the nootropics community seems to like it. (Research:11)
  • Magnesium-L-Orotate - Shown to increase physical performance in triathletes and similar extreme athletes. Not much research on this yet. (Research:12)
  • Magnesium Oxide - Cheapest, most common option. Magnesium Oxide is the most common form of magnesium supplementation, but has very poor absorption rates (4-5%) and can cause gastro-intestinal distress (yuck!). You need to take a lot of this to get any of the above benefits. (Research:9)


Magnesium is another major dietary deficiency that can be easily fixed with little cost. The upsides are pretty big in the long run, and honestly the better sleep quality is nice day to day. Overall, highly recommended for daily use.

Recommended brand: Doctors Best Magnesium Glycinate


  1. NHANES What we eat in America: NHANES 2005-2006 http://www.ars.usda.gov/SP2UserFiles/Place/12355000/pdf/0506/usual_nutrient_intake_vitD_ca_phos_mg_2005-06.pdf.
  2. The effects of magnesium physiological supplementation on hyperactivity in children with attention deficit hyperactivity disorder (ADHD).
  3. Positive response to magnesium oral loading test. http://www.ncbi.nlm.nih.gov/pubmed/9368236.
  4. Oral Mg(2+) supplementation reverses age-related neuroendocrine and sleep EEG changes in humans. http://www.ncbi.nlm.nih.gov/pubmed/12163983.
  5. Magnesium for treatment-resistant depression: a review and hypothesis. http://www.ncbi.nlm.nih.gov/pubmed/19944540.
  6. Magnesium concentrations in plasma, erythrocytes, and platelets in hypertensive and normotensive obese patients http://www.ncbi.nlm.nih.gov/pubmed/9397253.
  7. Magnesium improves the beta-cell function to compensate variation of insulin sensitivity: double-blind, randomized clinical trial. http://www.ncbi.nlm.nih.gov/pubmed/21241290.
  8. NIH Factsheet on magnesium - http://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/.
  9. Magnesium homeostasis. Etiopathogeny, clinical diagnosis and treatment of hypomagnesaemia. A case study. http://www.ncbi.nlm.nih.gov/pubmed/19935995.
  10. Bioavailability of US commercial magnesium preparations. http://www.ncbi.nlm.nih.gov/pubmed/11794633. .
  11. Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection. http://www.ncbi.nlm.nih.gov/pubmed/7815675.
  12. Effects of elevation of brain magnesium on fear conditioning, fear extinction, and synaptic plasticity in the infralimbic prefrontal cortex and lateral amygdala. http://www.ncbi.nlm.nih.gov/pubmed/22016520.
  13. On the significance of magnesium in extreme physical stress. Cardiovasc Drugs Ther. (1998) http://www.ncbi.nlm.nih.gov/pubmed/9794094