Can You Take Vitamin D With Magnesium?

Quick answer

Many people take both, and NIH's fact sheets give no reason to keep them apart. The enzymes that activate vitamin D appear to need magnesium. Keep magnesium from supplements under 350 mg a day and total vitamin D under 100 mcg (4,000 IU), and take vitamin D with a meal that contains some fat.^1,2,3

Key facts

Magnesium is a cofactor for more than 300 enzyme systems, and a 2018 review says the enzymes that process vitamin D are among them.^1,4
In a randomized trial of 180 adults aged 40 to 85, extra magnesium raised blood vitamin D in people who started near 30 ng/mL and lowered it in those who started higher.⁵
The 350 mg magnesium limit counts supplements and medicines only, while the 100 mcg vitamin D limit counts food as well.^2,3
Thiazide water pills change how the body handles both nutrients, so ask your doctor first if you take one.^3,4

How magnesium and vitamin D work together

Vitamin D from sun, food or a capsule is inactive until the body converts it twice: first in the liver, into the form measured in blood tests, then mainly in the kidneys, into the active hormone. A 2018 review concluded that all of the enzymes doing this work seem to need magnesium as a cofactor.^1,6

That conclusion rests on laboratory and animal studies, as the authors of a later trial point out. It explains why the two are linked. It does not by itself show that a magnesium supplement changes what vitamin D does in a person who already gets enough magnesium.⁵

Magnesium takes part in bone formation and affects the levels of parathyroid hormone and the active form of vitamin D, the main regulators of bone.⁴

What trials of the two together found

We found two trials that gave magnesium and then measured vitamin D. The larger randomized 180 adults aged 40 to 85 and set each person's magnesium dose from what they already ate. The result depended on the starting point. Blood vitamin D rose in people who began near 30 ng/mL and fell in those who began between about 30 and 50 ng/mL, and the authors concluded that adequate magnesium status may matter for vitamin D status.⁵

The second, a 12 week trial in 95 adults with a higher body weight, compared vitamin D3 plus magnesium glycinate with vitamin D3 alone and with a placebo. Blood vitamin D rose most in the group taking both, by about 6.3 ng/mL on average. Both trials measured vitamin D in blood, not bone.⁷

Read together, these short trials suggest that magnesium status can shift blood vitamin D in either direction. They do not show that magnesium has to be taken with every vitamin D dose.^5,7

What each one does, with grades

Both statements below are quoted from our ingredient pages, with the grade and the amount behind each.

Helps the body absorb calcium and maintain normal bones*^6,8,9

Moderate evidence

This is vitamin D's best-established role and the basis of official intake recommendations. It matters most when intake and sun exposure are low. In adults who mostly had adequate levels already, extra vitamin D gave no added benefit for bones: VITAL tested 2,000 IU a day in 25,871 people for about five years and found no difference from placebo.

Amount studied: The recommended 15 to 20 mcg (600 to 800 IU) a day from all sources; VITAL tested 2,000 IU a day on top of diet

Contributes to the normal structure of bone*^2,4

Moderate evidence

A long-established role of the mineral, described by NIH: half or more of the body's magnesium is held in bone, where it is part of the bone's structure and takes part in bone formation. This is a role of the nutrient. NIH describes the trials of whether extra magnesium changes bone density as few and small, and says more research is needed.

Amount studied: Recommended daily intake from food and supplements

When to take them

No study in our sources compared taking the two at the same moment with taking them hours apart. What the sources do give is advice for each one on its own.

Vitamin D is fat soluble, so it is best absorbed with a meal or snack that includes some fat. Some is absorbed even without fat.^3,6

The share of magnesium the gut absorbs is higher when it is taken in several small amounts through the day than in one large amount.¹⁰

In the one trial of magnesium bisglycinate for sleep, people took their two capsules, 250 mg of magnesium in all, 30 to 60 minutes before bedtime.¹¹

That leaves room for whatever routine you will keep: vitamin D with a meal that has some fat, and magnesium at one time or split across the day, including before bed. If your routine includes vitamin K2, it is fat soluble too and can go with the same meal as vitamin D.¹²

Adding up the amounts

Magnesium and vitamin D for adults, per day^2,3
Per day, adults	Magnesium	Vitamin D
Recommended amount	400 to 420 mg for men, 310 to 320 mg for women	15 mcg (600 IU), or 20 mcg (800 IU) from age 71
Upper limit	350 mg from supplements and medicines	100 mcg (4,000 IU) from all sources
Does the limit count food?	No	Yes
Signs of too much	Loose stools, nausea, cramping	Nausea, vomiting, muscle weakness, great thirst

Supplemental magnesium can look high next to its limit because the recommended amount counts food and the limit does not. Vitamin D works the other way round: fortified milk and cereal count toward its limit along with every capsule.^2,3

What’s in ours

Magnesium Glycinate: Magnesium, 275 mg per serving, from the label
Men's Multi: Magnesium, 50 mg per serving, from the label
Creatine + Electrolytes: Magnesium, 60 mg per serving, from the label

What’s in ours

Vitamin D3: Vitamin D-3, 50 mcg (2,000 IU) per serving, from the label
Men's Multi: Vitamin D, 10 mcg per serving, from the label
Ashwagandha Complex: Vitamin D3, 20 mcg per serving, from the label
Immune Support: Vitamin D3, 40 mcg per serving, from the label

Men's Multi contains both. Taken with Magnesium Glycinate, its magnesium brings the total close to the limit, as the check below shows.

Our Magnesium Glycinate with our Men's Multi

Magnesium Glycinate and Men's Multi together provide 325 mg of magnesium a day, close to the 350 mg upper limit for magnesium from supplements. Do not add another magnesium product.

Who should ask a doctor first

Ask your pharmacist or doctor first

Thiazide diuretics, water pills such as hydrochlorothiazide, chlorthalidone and indapamide, reduce the calcium lost in urine. Together with vitamin D supplements, which raise calcium absorption, they might push blood calcium too high, especially in older adults and people with reduced kidney function or an overactive parathyroid gland. This applies to thiazides, not to every kind of water pill.^3,6

Expected from how the two work, not shown in studies

The same water pills act on magnesium. NIH says long-term use of thiazide and loop diuretics, such as hydrochlorothiazide and furosemide, can raise the magnesium lost in urine, while potassium-sparing diuretics lower it. With one medicine shifting both nutrients, ask before adding either supplement.⁴

You have kidney disease or reduced kidney function. Kidneys that work poorly cannot clear extra magnesium, and NIH names reduced kidney function in its caution on vitamin D with thiazides.^4,6
You take a tetracycline or quinolone antibiotic, a bisphosphonate, gabapentin or levothyroxine. Magnesium can lower how much of these the body absorbs, so ask your pharmacist about spacing them.^4,13,14
You take a statin, steroid tablets, orlistat or a bile acid sequestrant such as cholestyramine, which can change how vitamin D is absorbed or used.^3,15
You have high blood calcium, kidney stones or an overactive parathyroid gland.
You are pregnant or breastfeeding, or the supplements are for a child.

Questions people ask

Can you take vitamin D3 with magnesium glycinate?

Nothing in our sources warns against it, and a 12 week trial gave vitamin D3 together with magnesium glycinate. Add up the labels: magnesium from supplements should stay under 350 mg a day, and vitamin D under 100 mcg (4,000 IU) from all sources.^2,3,7

What is the best time to take magnesium glycinate and vitamin D3?

There is no tested best time for the pair. Vitamin D3 is absorbed better with a meal that has some fat, and the sleep trial of magnesium bisglycinate gave it 30 to 60 minutes before bed. Our sources give no reason to take the two at the same moment.^11,16

Should vitamin K2 be added to vitamin D3 and magnesium?

That is a separate decision with its own page. Vitamin K2 has no separate recommended amount, and anyone taking warfarin should not start, stop or change a vitamin K supplement without their doctor.^12,17

See what we make

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See the Full Measure line Creatine + Electrolytes Magnesium Glycinate Men's Multi

Sources

*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.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.