Gabriella Rao, RD

This week I’m focusing on a micronutrient that has literally hundreds of functions in the body — magnesium!

Functions of Magnesium:

• Muscle contraction; assists in the production of energy from ATP
• Enhances the availability of glucose 
• Improves blood pressure, heart rate, and oxygen uptake
• Bone health; enhances calcium absorption
• Hormone health
• Nervous system function
• Muscle protein synthesis
• Assists with the removal of lactic acid from muscles
• Helps improve sleep
• Involved in 300-600+ reactions in the body!

Inadequate magnesium intake in athletes, and in the general population, is quite common. In fact, it’s estimated that 45-50% of the US population does not meet the RDA for magnesium. Athletes are particularly at risk for deficiency, as magnesium is lost in sweat (2-18 mg in ~2 lb of sweat). Inadequate intake of magnesium can lead to muscle damage and inflammation. 

Symptoms of Deficiency:

• Fatigue and weakness
• Pins and needs
• Muscle cramps and spasms
• Loss of appetite 
• irregular heartbeat 
• Migraines
• Nausea

Food Sources:

• Nuts (100-130 mg per 1/4 cup)
• Pumpkin seeds (315 mg per 1/4 cup!)
• Beans (50-60 mg per 1/2 cup)
• Whole grains (e.g., amaranth and buckwheat both have ~80 mg per 1/2 cup)
• Dark leafy greens (~80 mg per 1/2 cup)
• 70-85% dark chocolate (65 mg per 1 oz)
• Tofu (100 mg per 4 oz)
• Avocados (60 mg per 1 medium sized)
• Bananas (32 mg in 1 medium sized

We need about 300-400 mg of magnesium per day!

Red Blood Cell (RBC) Magnesium is the most accurate laboratory assessment for magnesium. RBC magnesium assesses the Mg inside cells, so it is the best reflection of total body magnesium storage (in bones/tissues). Meanwhile, serum magnesium is prone to fluctuations of Mg levels in the blood, so is not a very accurate assessment of magnesium status.

What to do if you think you may be magnesium deficient:

• Get some labs!
  • RBC magnesium levels
• Add more magnesium-rich foods into your diet 
  • Seeds, nuts, beans, dark leafy greens, tofu, etc.
• If unable to improve magnesium status through diet modification, work with your RD or doctor to obtain an appropriate supplement — never supplement blindly!
  • Always make sure any supplement you take is third-party approved (meaning that it has been tested in a lab to ensure that it contains the correct ingredients in the amounts advertised on the label)
  • Below is listed the types of magnesium supplements and their general uses:
    • Mg glycinate —> bioavailable with little laxative effect
    • Mg L threonate —> best for brain and cognitive function, anxiety and sleep
    • Mg citrate —> aids digestion; laxative effect (would not recommend for mg supplementation)
    • Mg chloride —> use topically for muscle aches and pains (can be taken orally)
    • Mg oxide —> cheap and poorly absorbed
    • Mg malate —> bioavailable; also used for muscle pain
    • Mg sulfate —> taken as pill or powder as a soothing bath (Epsom salt)

Hope this was helpful. If you have any questions or topic suggestions, don’t hesitate to reach out.