#282 – AMA #54: Magnesium: risks of deficiency, how to correct it, supplement options, potential cognitive and sleep benefits, and more

The more deficient you are in magnesium, the more you will be helped by supplementing magnesium.” —Peter Attia

Read Time 26 minutes

In this “Ask Me Anything” (AMA) episode, Peter tackles essential questions about magnesium, beginning with the important roles it plays in the body and why maintaining proper levels is crucial. Peter discusses the harms of magnesium deficiency, how to determine if you’re deficient, potential causes of deficiency, and how diet and supplementation can be used to increase magnesium levels. Peter unravels the confusion surrounding magnesium supplementation, discussing the optimal forms and recommended daily intake while addressing concerns about excess consumption. He also explores the potential cognitive and sleep benefits associated with magnesium supplementation. Finally, Peter concludes with a look into his recent experimentation with new exercises to serve as benchmarks to assess his progress and fitness levels as he navigates the aging process.

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We discuss:

  • The important roles of magnesium in the body [2:45];
  • How to determine if you might be deficient in magnesium [10:15];
  • Addressing migraines related to low magnesium [14:45];
  • The prevalence of magnesium deficiency [16:30];
  • Various conditions and drugs that can negatively impact magnesium levels [21:30];
  • Magnesium-rich foods and factors that impact absorption of magnesium [24:30];
  • Daily targets for magnesium supplementation and whether it’s possible to take too much [30:15];
  • The different forms of supplemental magnesium [34:00];
  • How absorption of magnesium from food compares to absorption from supplements [36:15];
  • Choosing the right magnesium supplements for optimal absorption [37:15];
  • The unique ability of magnesium L-threonate to increase brain magnesium concentration [40:15];
  • Potential cognitive benefits of magnesium [43:00];
  • Potential sleep benefits of magnesium [48:45];
  • Takeaways on magnesium and a look into Peter’s personal protocol [53:15];
  • Peter’s new benchmarks related to exercise and age [58:30]; and
  • More.


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  1. One negative about Brazil nuts: they contain a lot of selenium, possibly as much as 544 mcg per 1 oz serving, which is over 10x recommended daily value. I eat a lot of nuts every day, and though I love Brazil nuts too, limit to just 1 nut (abt. 0.15-0.2oz) per day.

    • wow, thank you so much for this little nugget of very important knowledge. omitting this while reccomending brazil nuts is not what i would expect from peter. many times people have reccomended brazil nuts without mentioning why they limit themselves to so few a day. its like eating one potato chip. it cant be done, for me its a handfull or nothing.unless there is a good reason. finally!!

  2. It says “Peter is aiming for about 600 to 800 mg (magnesium) per day”, which includes 400-500 mg of magnesium oxide. However, his reference says mag. oxide is only 4% bioavailable, resulting in 16-20 mg magnesium. So, with the 143 mg from SlowMag and 144 mg from mag. L-threonate (totalling abt 300 mg in supplemental mag.), is the rest of the 600-800 mg magnesium coming from dietary intake?

  3. Magnesium glycinate is the form that I’ve found to be the best absorbed with the least risk of causing any diarrhea, especially in the elderly.

    Is there a brand of Mag Threonate that Peter recommends?

    I’m not clear on why one would take Mag Oxide at all when it is so poorly absorbed, unless it’s being taken as an antacid.

    • For Mag L-Threonate look at any Magtein supplement.

      Mag Oxide would be used to regulate bowel movements etc. I would like to know a reputable brand of Mag Oxide.

  4. I’m 78 and trying to improve my condition to the extent that I can. My watch is telling me my VO2max is 30.4. Is it reasonable to expect that I can improve on that and that I can make significant progress on dead hangs (1:30 is record) and farmer carries (carrying 65 lbs in each hand (total body wt. 135)?

  5. What does it mean when the supplement facts say:
    Magnesium (from 1000mg from magnesium-l-threonate)
    And then the amount per serving says: 72 mg

    I am confused as to which number to pay attention to- the 1000mg or 72 mg?

    • 72 mg is the amount of magnesium per serving. 1000 mg is the amount of magnesium-l-threonate per serving of which magnesium is just a small component (ie 72 mg)

  6. Does anyone have insight on why supplemental magnesium, in any form, makes me extremely irritable? For years, I’ve tried to figure this out and work around it, but to no avail.

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