If You Take Vitamin D, You Might Need Magnesium

By Temma Ehrenfeld @temmaehrenfeld
July 13, 2023
If You Take Vitamin D, You Might Need Magnesium

Vitamin D is widely prescribed, but fewer people know they might need to take magnesium as well. Shortages of both are linked to several health problems.

Many doctors are prescribing vitamin D supplements, especially to older people. As you age, your body becomes less efficient at producing and using the sunshine vitamin.

You need magnesium to metabolize vitamin D, however, and surveys suggest that most Americans get too little in their diet. If you are short of magnesium, the extra vitamin D remains stored and inactive and may even be unsafe.

There are good reasons to make sure you have enough of both vitamin D and magnesium. Shortages are linked to heart disease, metabolic syndrome, and osteoporosis.


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Are you short of vitamin D?

You normally get a form of vitamin D through exposure to sun on your skin. Contrary to commercial advertising, you can’t count on food: It would take 30 glasses of milk to match the vitamin D you’d get from 10 minutes in the summer sun. (You still need to make sure you protect yourself from the sun's UV radiation.)

Especially during the winter, and in northern climates, many people don’t get enough sunshine. A simple blood test will allow your doctor to decide if you need a vitamin D supplement.

Your body must convert and activate the sunshine form of vitamin D. Once that happens, it helps cells communicate throughout your body. Vitamin D increases calcium levels, so you can build strong bones, and it helps your body fight infections and regulate blood pressure and inflammation, among other jobs.

Symptoms of magnesium deficiency

We get magnesium from food, but the most recent government survey numbers showed that most Americans get less than they need, with men older than 71 and teenage girls most at risk.

Classic signs of magnesium deficiency include:

  • Lethargy
  • Nausea
  • Vomiting
  • Fatigue and weakness
  • Muscle spasms and cramps
  • All-over muscle pain
  • Tics
  • Eye twitches

Magnesium levels also seem to be low in people with treatment-resistant depression.

Causes of magnesium deficiency

What you can do

Carbonated beverages and some medications also lower magnesium levels. If you are restricting foods to avoid kidney stones, you’ll find that forbidden foods like spinach and avocado are rich in magnesium, so that might be a reason to take a supplement.

Otherwise, try to eat magnesium-rich foods, which include:

  • Almonds and cashews
  • Bananas
  • Beans
  • Broccoli
  • Quinoa
  • Brown rice
  • Egg yolk
  • Fish oil
  • Flaxseed
  • Green vegetables
  • Milk
  • Oatmeal and other whole grains
  • Tofu
  • A variety of seeds

There are many kinds of magnesium supplements. Small studies have found that magnesium in the aspartate, citrate, lactate, and chloride forms is absorbed more completely and is more bioavailable than magnesium oxide and magnesium sulfate.

How to take magnesium supplements

If you take too much magnesium in a tablet, you can end up with diarrhea, or even nausea and vomiting. You’ll read that magnesium spray or oil absorbed through your skin will bypass your digestive system and avoid those effects. Research, however, demonstrates the advantages of an oral magnesium supplement and little evidence of the same benefits for skin products.

To boost your vitamin D, your doctor might prescribe a supplement or give you an injection for an immediate boost. You can also sit under a sunlamp that emits short-wavelength UVB light, which triggers vitamin D production.


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July 13, 2023

Reviewed By:  

Janet O'Dell, RN