Can You Take Magnesium and Vitamin D Together?
Yes, you can take magnesium and vitamin D together, even in the same swallow. Your body needs magnesium to turn vitamin D into its active form. Take both with a meal, and keep supplements at or under 350 mg of magnesium and 4,000 IU of vitamin D a day.
| Magnesium | Vitamin D | |
|---|---|---|
| Daily need (RDA) | 310–320 mg women, 400–420 mg men | 600 IU (15 mcg) to age 70; 800 IU (20 mcg) after |
| Upper limit | 350 mg from supplements; food does not count | 4,000 IU (100 mcg) from all sources |
| Too much causes | Diarrhea first; dangerous levels mostly with weak kidneys | High blood calcium |
| Take it | With a meal (label directions) | With a meal that has some fat |
How magnesium and vitamin D work together
Vitamin D from sun or a pill is not active yet. The liver and then the kidneys change it twice before your body can use it, and the enzymes that do this need magnesium (Uwitonze 2018). NIH puts it more simply: magnesium affects the level of the active form of vitamin D, and both help build bone.
That is why the two are often sold and taken together. It does not mean more magnesium always means more vitamin D, as the trials below show.
What the two trials found
| Trial | Who and what | What happened |
|---|---|---|
| Dai 2018 | 180 adults aged 40 to 85. Magnesium or placebo, with the dose set to each person’s diet. | Magnesium raised vitamin D in people who started near 30 ng/mL and lowered it in people who started higher (about 30 to 50 ng/mL). |
| Cheung 2022 | 95 adults with overweight or obesity, 12 weeks. Magnesium glycinate plus vitamin D, vitamin D alone, or placebo. | Vitamin D rose most in the magnesium plus vitamin D group (by 6.3 ng/mL). Blood pressure fell only in people whose top number started above 132. |
Two things to know about these. Dai 2018 included authors from the Center for Magnesium Education and Research, a group that promotes magnesium. And the Cheung 2022 abstract lists “360 mg magnesium glycinate + 1000 IU vitamin D, 3 × daily” without saying whether 360 mg is the magnesium or the whole compound, so we cannot tell you the magnesium dose.
The plain reading: magnesium seems to help vitamin D most when your vitamin D is low-normal. If your level is already good, adding magnesium to raise it is not supported.
Should you take them at the same time?
You can, but you do not have to. No trial has compared taking them together with taking them hours apart. Two practical rules point to the same meal:
- Vitamin D is absorbed better when the meal has some fat, though some is absorbed without it (NIH).
- Magnesium labels, like Nature Made’s, say to take it with a meal, and food makes stomach upset less likely.
So take both with your largest meal. If magnesium loosens your stools, move half of it to another meal; the vitamin D can stay. More on when to take magnesium.
What about one tablet with both?
Calcium-magnesium-vitamin D tablets are the common “all in one.” We read the label of a USP Verified one, Nature Made Calcium, Magnesium and Zinc with D3 ($0.05 a tablet at list price), in NIH’s label database:
| 1 tablet | 3 tablets | Compared with | |
|---|---|---|---|
| Magnesium (as oxide) | 133 mg | 399 mg | Over the 350 mg limit at 3 tablets |
| Vitamin D3 | 200 IU | 600 IU | 3 tablets meet the 600 IU RDA |
| Calcium | 333 mg | 999 mg | The adult RDA is 1,000 to 1,200 mg (NIH) |
It suits someone whose doctor wants them on calcium. As a magnesium source it is weak: the magnesium is oxide, the least absorbed form in small studies (NIH), and the full label dose goes over the limit. Two tablets give 266 mg of magnesium and 400 IU of vitamin D. If you mainly want magnesium and vitamin D, the two separate pills above give you more control.
Want a big bottle of magnesium glycinate to take next to a separate vitamin D? KAL Magnesium Glycinate 350: A big bottle in capsules: 240 capsules with about 88 mg of magnesium each. One serving is 4 capsules (350 mg), which is the whole 350 mg limit for pills, so count any other magnesium you take. It is on no public testing list, and we found no list price for this bottle.
Count every product toward the limits
People who take magnesium and vitamin D often also take a multivitamin or a calcium tablet. Add them up:
- Magnesium: The upper limit for adults is 350 mg a day of magnesium from supplements and medicines. Food does not count toward it (NIH).
- Vitamin D: the adult upper limit is 4,000 IU a day. Too much vitamin D raises blood calcium (NIH).
- Higher doses on purpose: if a doctor has you on a large vitamin D dose, ask whether your magnesium needs checking. One review says large vitamin D doses can use up magnesium (Reddy 2019); no trial has measured how often.
Frequently Asked Questions
Can you take magnesium and vitamin D together?
Yes. NIH lists no interaction between them, and you can swallow them at the same time. Magnesium helps the body turn vitamin D into its active form, so getting enough magnesium supports vitamin D (NIH; Uwitonze 2018).
Should magnesium and vitamin D be taken at the same time?
They do not have to be. No trial has compared taking them together with taking them apart. Vitamin D is absorbed better with some fat in the meal (NIH), and magnesium labels say to take it with a meal, so taking both with your largest meal is a simple routine.
How much magnesium and vitamin D should I take together?
Adults need 310 to 420 mg of magnesium and 600 to 800 IU of vitamin D a day, from food, sun and supplements. From supplements, stay at or under 350 mg of magnesium and 4,000 IU of vitamin D (NIH). Our two picks together give 200 mg of magnesium and 2,000 IU of vitamin D.
Do magnesium and vitamin D work together?
Yes, in the body. The enzymes in the liver and kidneys that activate vitamin D need magnesium (Uwitonze 2018). Whether adding a magnesium pill raises your vitamin D level depends on where you start: in one trial it raised low-normal levels and lowered higher ones (Dai 2018).
Does taking vitamin D lower your magnesium?
One review says large doses of vitamin D can use up magnesium (Reddy 2019), but we found no trial that measured this. If you take high-dose vitamin D on a doctor’s advice, ask whether you also need magnesium.
Can I take magnesium, vitamin D3 and K2 together?
Yes. None of the three is known to block the others. Count the magnesium in every product you take. Vitamin D with or without K2.
Is a calcium-magnesium-vitamin D tablet a good way to get both?
Only if you also want calcium. Nature Made’s USP Verified version has 133 mg of magnesium per tablet as oxide, the least absorbed form, and 200 IU of vitamin D. Its label allows up to 3 tablets, which is 399 mg of magnesium, more than adults should take from supplements.
Related Guides
- Vitamin D guide · vitamin D dosage guide · vitamin D with or without K2
- Magnesium dosage guide · best time to take magnesium · magnesium side effects
- Best magnesium supplement · magnesium for seniors · magnesium guide
Sources
- NIH Office of Dietary Supplements. Magnesium fact sheet for health professionals (updated January 6, 2026).
- NIH Office of Dietary Supplements. Vitamin D fact sheet for health professionals (updated June 27, 2025).
- Uwitonze AM, Razzaque MS. Role of magnesium in vitamin D activation and function. J Am Osteopath Assoc. 2018. PubMed 29480918
- Dai Q, et al. Magnesium status and supplementation influence vitamin D status and metabolism: results from a randomized trial. Am J Clin Nutr. 2018. PubMed 30541089
- Cheung MM, et al. The effect of combined magnesium and vitamin D supplementation on vitamin D status, systemic inflammation, and blood pressure. Nutrition. 2022. PubMed 35576873
- Reddy P, Edwards LR. Magnesium supplementation in vitamin D deficiency. Am J Ther. 2019. PubMed 28471760
- Nature Made Calcium, Magnesium and Zinc with Vitamin D3: NIH Dietary Supplement Label Database 302762. Prices: each brand’s own list price.