Magnesium and vitamin D3 are two of the most popular supplements in America, and plenty of people take both. So it's natural to wonder: can you take them together, and should you?
The short answer is yes. They're commonly taken on the same day, even at the same meal, and there's no reason to keep them apart. Better still, there's a genuine biological reason the two belong in the same routine: your body uses magnesium to process vitamin D. Here's what we know, where the data are still thin, and how to time them.
The short answer
| Question | Answer |
|---|---|
| Can you take them together? | Yes, at the same time or at different times of day |
| Why pair them? | The enzymes that process vitamin D appear to need magnesium |
| Best time | Vitamin D3 with a meal containing fat; magnesium glycinate in the evening. Dinner covers both |
| Safe amounts | Stay at or under 350 mg of supplemental magnesium and 4,000 IU of vitamin D a day |
How magnesium and vitamin D work as a team
Vitamin D from sunlight or a supplement isn't active when it first enters your body. It has to be converted in the liver and then in the kidneys before your body can use it. A review in the Journal of the American Osteopathic Association explains that all the enzymes that metabolize vitamin D seem to require magnesium as a helper, and that magnesium assists in vitamin D activation (Uwitonze and Razzaque, 2018).
A second review describes magnesium as a cofactor for vitamin D's production, transport and activation. It also notes that research on how the two nutrients interact in people is still rare (Rosanoff et al., 2016). So the biology is clear, while the human data on taking them as a pair are still early.
What happened when adults added magnesium
The best human data come from a randomized, placebo-controlled trial at Vanderbilt University Medical Center with 180 adults aged 40 to 85, in which participants took magnesium (dosed to match their usual diet) or a placebo, and the researchers tracked their vitamin D levels (Dai et al., 2018).
The results were interesting. Magnesium raised blood vitamin D in people whose starting levels were around 30 ng/mL, but lowered it in people who started higher, between about 30 and 50 ng/mL. The authors concluded that good magnesium status may be important for optimizing vitamin D status (Dai et al., 2018).
In other words, magnesium didn't simply push vitamin D up. It appeared to help the body keep vitamin D in balance. That's a single trial, so we'd call it promising rather than settled, but it's a real test of the pairing in real people.
Many Americans fall short on magnesium
Why does this matter? Many Americans don't get enough magnesium from their diet. According to national survey data cited in the Vanderbilt trial, 79% of US adults don't meet the Recommended Dietary Allowance for magnesium (Dai et al., 2018). An earlier review estimated that almost half of the US population (48%) got less than the required amount of magnesium from food in 2005-2006 (Rosanoff et al., 2012).
If you take vitamin D3 every day but your magnesium intake is low, adding magnesium is a simple way to round out the routine.
When to take magnesium and vitamin D3
Vitamin D3: with a meal that contains fat. Vitamin D is fat-soluble. In a study of 50 healthy older adults, peak blood vitamin D3 after a supplement was 32% higher when it was taken with a fat-containing meal than with a fat-free one (Dawson-Hughes et al., 2015). In a small clinic study, moving vitamin D to the largest meal of the day was linked to about a 50% rise in blood levels after 2 to 3 months (Mulligan and Licata, 2010).
Magnesium glycinate: in the evening. Most people take magnesium glycinate in the hour or two before bed as part of their wind-down routine. We explain why in our guide to the best time to take magnesium.
The easy answer: take both with dinner. Dinner is often the day's biggest meal, which suits vitamin D3, and it's close enough to bedtime for magnesium. One meal, one habit. If you prefer vitamin D3 with breakfast, that works too. The two don't need to be taken at the same moment to work as a team.
How much of each?
Keep it simple and stay within the adult upper limits for supplements:
- Magnesium: the upper limit for supplemental magnesium is 350 mg a day. Our Magnesium Glycinate gives you 275 mg per three-capsule serving.
- Vitamin D3: the upper limit is 4,000 IU a day. Our Vitamin D3 2,000 IU is one softgel a day.
If you also take a multivitamin, count what it contains. Our Complete Multivitamin includes 400 IU of vitamin D and some magnesium, so check the label and keep your supplement totals under those limits.
Why magnesium glycinate?
Magnesium comes in many forms. Glycinate is magnesium bound to the amino acid glycine. It's a chelated form and a popular choice for an evening routine. For a side-by-side comparison with another common form, see magnesium glycinate vs citrate.
Frequently asked questions
Can I take magnesium and vitamin D3 at the same time?
Yes. You can take them in the same meal, and many people take both with dinner. Just make sure the meal includes some fat for the vitamin D3.
Does vitamin D need magnesium to work?
Your body uses magnesium-dependent enzymes to convert vitamin D into its active form (Uwitonze and Razzaque, 2018). A randomized trial also linked magnesium supplementation with better-balanced vitamin D levels (Dai et al., 2018). That doesn't mean vitamin D does nothing without a supplement, but good magnesium status appears to matter.
Should I take magnesium in the morning or at night with vitamin D?
Most people prefer magnesium glycinate in the evening. Since vitamin D3 works well with any meal that contains fat, taking both with dinner is the simplest option.
Can I take magnesium and vitamin D3 with a multivitamin?
Yes, but add up your totals. Count the vitamin D and magnesium in your multivitamin and stay at or under 4,000 IU of vitamin D and 350 mg of supplemental magnesium a day.
The bottom line
You can absolutely take magnesium and vitamin D3 together, and there's a good reason to: your body relies on magnesium to process vitamin D, and an early randomized trial suggests that magnesium status helps keep vitamin D levels in a healthy range (Dai et al., 2018). Take your Vitamin D3 2,000 IU with a meal that contains fat, take your Magnesium Glycinate in the evening, and if you want the simplest routine of all, take both with dinner.
Sources
- Uwitonze, Razzaque. Role of Magnesium in Vitamin D Activation and Function. The Journal of the American Osteopathic Association. 2018;118(3):181-189. doi:10.7556/jaoa.2018.037 (PubMed 29480918)
- Rosanoff, Dai, Shapses. Essential Nutrient Interactions: Does Low or Suboptimal Magnesium Status Interact with Vitamin D and/or Calcium Status?. Advances in Nutrition. 2016;7(1):25-43. doi:10.3945/an.115.008631 (PubMed 26773013)
- Dai, Zhu, Manson et al. Magnesium status and supplementation influence vitamin D status and metabolism: results from a randomized trial. The American Journal of Clinical Nutrition. 2018;108(6):1249-1258. doi:10.1093/ajcn/nqy274 (PubMed 30541089)
- Rosanoff, Weaver, Rude. Suboptimal magnesium status in the United States: are the health consequences underestimated?. Nutrition Reviews. 2012;70(3):153-64. doi:10.1111/j.1753-4887.2011.00465.x (PubMed 22364157)
- Dawson-Hughes, Harris, Lichtenstein et al. Dietary Fat Increases Vitamin D-3 Absorption. Journal of the Academy of Nutrition and Dietetics. 2015;115(2):225-230. doi:10.1016/j.jand.2014.09.014 (PubMed 25441954)
- Mulligan, Licata. Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25-hydroxyvitamin D. Journal of Bone and Mineral Research. 2010;25(4):928-30. doi:10.1002/jbmr.67 (PubMed 20200983)
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
