Taking Vitamin D? You'd better be taking Magnesium too.

Taking Vitamin D? You'd better be taking Magnesium too.

Magnesium supplement


In the last 10 years, millions of us started taking Vitamin D supplements. 

We used to think that the little bit of sun we got from going out to the mailbox...or the walk from the car to the grocery store was enough sun exposure for Vitamin D. 

Nope. Not enough. 

We need a lot more sun exposure than that to get our Vitamin D levels up to optimal. 

But there's more to it than just sun exposure. 

Factors Affecting Vitamin D Levels

Vitamin D levels and our bodies' ability to make it from the sun depends on a lot of factors:

  1. Age (a 75 year old may only make a third of the Vitamin as their grandkid)
  2. Weight (the heavier you are, the more sun exposure you need)
  3. Time of year (this influences the amount of Vitamin-D-generating UV hitting your skin)
  4. Where you live (farther north or south away from the equator means less UV)
  5. Skin color (darker skin types need a LOT more sun exposure to make the same amount of Vitamin D from the sun.)
  6. Duration fo sun exposure

 There's the risk of too much sun exposure and the UVA and UVB associated with it. Even though we generally encourage people to get out in the sun, it is not without risk, especially if your diet is not rich in protective antioxidants found in veggies and fruits. 

These antioxidants and compounds like astaxanthin can provide some protection from UV rays. 

So, a lot of us just skip the sun bathing and pop a pill or two of Vitamin D3. 

If you're severely deficient, taking 10,000 IU daily for a month or so can get you up to optimal levels. After that, you should back off to 3000 to 4000 IU daily to maintain that level. 

The most popular dosage is 5000 IU and that has little to do with science. The 5000 IU level is random and driven by marketing. It's also a nice round number.

If you're religious about taking your D, skip a couple of days of the week if your pill has 5000 IU. 

Big News: Your Magnesium Intake is Critical for Vitamin D staus

Taking Vitamin D and calling it a day isn't good enough. 

Scientists have uncovered a huge new factor in Vitamin D status: your magnesium intake. 

A review published in The Journal of the American Osteopathic Association found that low magnesium levels make vitamin D ineffective. 

"People are taking Vitamin D supplements but don't realize how it gets metabolized. Without magnesium, Vitamin D is not really useful or safe," says study co-author Dr. Razzaque, MBBS, PhD, a professor of pathology at Lake Erie College of Osteopathic Medicine.

The problem is that at least half of all Americans are magnesium deficient.

Magnesium deficiency gets worse in older people, with up to 70% not consuming enough.

So, even if you were popping D3 pills, if you are low in magnesium, your D3 may be sitting there doing nothing. 

Some doctors will want to test your magnesium levels first. But keep in mind that most of the magnesium in your body is stored in bones and teeth. 

Only 0.3% of your magnesium is in the blood, so relying on a blood test for magnesium isn't going to reveal much. 

What Happens to All That D3 you Took Without Magnesium? 

Well, the D3 cannot be metabolized without adequate magnesium levels. 

That means the Vitamin D remains stored and inactive. 

Ok, no harm done, you say. Nope. Stored D while magnesium deficient can increase your blood calcium levels, which is not good. 

This means you can increase the risk of calcium depositing in your arteries. Arterial calcification. 

This then increases your need for Vitamin K2, which is the key nutrient that controls arterial calcification. 

You Don't Need to Worry About Any of This if You:

  1. Eat a ton of veggies (magnesium-rich diet)
  2. Eat organ meats and fermented veggies (Vitamin A and K2-rich diet)
  3. Get a lot of sun exposure

But do you really know anyone who does these three things?

We don't!

So, everyone including your doctor is pushing you to take Vitamin D. Great.

There is a caveat. Just don't forget Magnesium. And K2. And A. 

Because they all work together. 

How Much Magnesium Do you Need? 

Most adults need about 400 mg. 

Only half of all Americans reach 400 mg daily. So the other half are deficient to varying degrees. The more vegetables you eat, the less likely you are to be deficient.

Then there is the issue of high-intensity industrialized farming. This has sucked the soil dry of a lot of stored magnesium. This means plants quit growing without added magnesium and farmers add juuuust enough magnesium to get the crops to grow. 

If the soils were richer in magnesium, we'd all be set. But that aint so. 

This means you may have to eat more vegetables than your grand parents did, just to get the same amount of magnesium. 

Not fair. But true. 

The Best Magnesium-rich Foods are:

  • dark green leafy vegetables like spinach and broccoli
  • nuts and seeds
  • peas
  • beans
  • mushrooms
  • bananas

Whole foods are always the best sources of all nutrients, but if you are falling short on magnesium-rich foods, you may want to consider magnesium supplements.

Keep in mind that most magnesium supplements are made with magnesium oxide, which is very poorly absorbed. We joke that you might as well swallow a pebble instead of magnesium oxide pills. 

Magnesium citrate is better absorbed, but it can cause stomach distress. 

Well-absorbed form of magnesium that do not cause digestive distress include malate, glycinate, threonate, aspartate, and oroate. Of these malate and glycinate are the most popular and easy to find. 


Anne Marie Uwitonze, Mohammed S. Razzaque. Role of Magnesium in Vitamin D Activation and Function. The Journal of the American Osteopathic Association, 2018; 118 (3): 181 DOI: 10.7556/jaoa.2018.037

    A note of caution

    If you've read all that and decide to give yourself a triple shot of magnesium pills, you might be staying close to home for a day or so. A sudden excess of magnesium can cause diarrhea along with nausea and abdominal cramping, especially if you use the oxide, carbonate, sulfate or chloride forms. If you follow label instructions on supplement bottles, you are unlikely to have any trouble. Most supplement brands do not recommend more than 400 mg of magnesium daily. 

    Stuff that must be said:

    We sell magnesium supplements on this website. It goes without saying (but we’ll say it anyway) that we do not make any claim that taking our magnesium supplement will cure or prevent any disease. If you feel you are magnesium deficient, and you grab a bottle of magnesium supplement before spinach or other magnesium-rich foods, well, tsk, tsk. 

    Supplements may help, but supplements alone will not restore you to complete health. We think supplements are a small piece of the health puzzle. You cannot outrun a bad diet and inactivity with pills. Most of the heavy lifting involved in restoring your health will have to come from you in the form of healthy eating and lifestyle corrections. In these articles, we are merely sharing our excitement about nutritional science and doing our best to translate dense science into easy-to-read English. We geek out on nutrition science and we think you will too. We hope it makes you a more informed consumer. Our Legal Dept says the same thing in Legalese at the bottom of this page. Enjoy.

    Back to blog

    Leave a comment

    Please note, comments need to be approved before they are published.