Combining Magnesium: Taking It with Zinc, Vitamin D, Iron and Calcium

You can take magnesium together with almost everything else in your routine: zinc, vitamin D3 and K2, calcium, potassium and vitamin B6, in normal amounts and happily with the same meal. Only with iron do we recommend keeping about two hours apart, and even that is more of a precaution, because nobody has actually measured it for normal capsules yet.

The strict spacing rules you'll find online almost all come from studies with amounts that don't show up in any normal routine. What magnesium does on its own is explained in our magnesium guide. On this page, we look at what you can take alongside it.

What can you take with magnesium?

You can take magnesium at the same time as six of the seven partners in this overview. Only iron gets a different time of day from us.

Medications aren't in the table. Separate, and in some cases stricter, spacing rules apply to them.

Can you take magnesium and zinc together?

Yes, you can take magnesium and zinc together, as long as the zinc stays at a normal amount. Zinc getting in magnesium's way was measured at 142 mg a day, almost six times the European upper limit.

Behind the worry is the idea that all minerals in the gut want to go through the same door and hold each other up on the way. That's not entirely made up. In a metabolic study from 1994, men on a strictly controlled diet were given exactly that amount, and their bodies really did absorb less magnesium afterward and retained less of it, too. But the upper limit for zinc in Europe is 25 mg a day. So things only get crowded at the door at almost six times that.

BASE, our multi-nutrient, contains just 5 mg of zinc, which is 3.5% of the amount in the study. A few hours apart won't hurt, of course, it's just that based on everything that's been measured, it isn't necessary either.

Can you take magnesium and calcium together?

Yes, in normal amounts that works too. It has only been studied in two small studies with different results, and neither supports a fixed spacing rule.

In a metabolic study with five men, calcium absorption didn't change, even though the men got around 800 mg of magnesium a day from food and supplement combined. In a South African study with 20 women whose magnesium levels in their red blood cells were low, on the other hand, the share of calcium absorbed dropped by just under a quarter with 250 mg of magnesium a day, without any change in their bone markers. There was no comparison group in that study.

You hear it the other way around much more often, that calcium blocks magnesium. But we don't know of any solid human study showing that. In normal amounts, go ahead and take both together, and if you take high doses of both, split them between morning and evening just to be safe.

How far apart should you take magnesium and iron?

We recommend keeping magnesium and iron about two hours apart. For food supplements, this rule isn't backed by evidence. It's inherited from antacids given in gram amounts.

The two studies behind it come from emergency medicine and were asking a completely different question. They were about magnesium hydroxide, an antacid for heartburn, and whether it stops iron from getting into the blood after an iron overdose. In the first study with 13 volunteers, about half as much iron reached the blood, while a second with 16 volunteers showed no difference at all under similar conditions. Fortunately, an iron overdose in the ER has very little to do with two magnesium capsules at dinner.

We still keep them apart. Alkaline forms like magnesium oxide or carbonate make the stomach less acidic, and iron is absorbed better in an acidic environment. That's the reasoning behind the rule, at least, even if nobody has measured it for normal capsule amounts. And if you take iron, it's usually because a level is too low, so you don't want to waste anything when the solution is as simple as iron in the morning and magnesium in the evening.

Vitamin D3, K2 and magnesium: can you take them together?

Yes, all three work together. With vitamin D, there's actually a good reason to keep an eye on magnesium: your body apparently can only process vitamin D with magnesium.

Vitamin D3 from the sun or from a capsule starts out as a precursor that the liver and kidneys still have to convert. The enzymes that do this probably all depend on magnesium, as a 2018 review sums it up. In a double-blind study with 180 adults aged 40 to 85, vitamin D levels rose with magnesium when they started out on the lower side, and dropped when they were already higher. A genuinely interesting finding, from which the authors cautiously conclude that good magnesium status could be important for vitamin D balance.

In a second study with 95 overweight adults, vitamin D levels rose most over twelve weeks in those who took vitamin D together with magnesium, by an average of 6.3 ng/ml. For the blood level, that's a really positive result, although in the follow-up analysis of the same study, the combination had no additional effect on bone metabolism and blood sugar. Our advice from this is still simple: if you take vitamin D, you should be well supplied with magnesium.

In this group, vitamin K2 belongs with vitamin D. It hasn't yet been studied specifically as a pair with magnesium. Why D3 and K2 belong together and how much you need is covered in our guide to vitamin D3 and K2.

Magnesium and potassium: do they go together?

The two go together, and potassium actually depends on magnesium, because when magnesium is low, the kidneys lose potassium more easily.

This is described in a review from kidney research. Magnesium inside the cell slows down the channels through which the kidneys release potassium into the urine, and that brake loosens when magnesium is low. From clinical settings, a 1992 review reports that around four in ten patients with low potassium were also low in magnesium. Whether healthy people benefit from supplementing both together hasn't been studied yet, but none of this is a reason to keep them apart. Only if you take blood pressure medication or diuretics, or your kidneys don't work fully, talk to your doctor before taking extra potassium and magnesium.

Magnesium with vitamin B6: does the combination do more?

You can take magnesium and vitamin B6 together, after all they're the classic pair on the pharmacy shelf. In the largest study on it, B6 did make a difference for those with severe stress, but across everyone there was no measurable difference.

The participants were 264 adults, healthy but highly stressed, and all with fairly low magnesium in their blood. For eight weeks they took 300 mg of magnesium a day, and some of them took an additional 30 mg of vitamin B6. The stress score on the questionnaire dropped clearly in both groups, by 45% with B6 and by 42% without, which statistically isn't a difference. The combination did better in the subgroup with severe stress, and at 162 of the 264, that was actually the majority.

There was no placebo group, so it's impossible to say how much of the drop was due to the magnesium. The study was also paid for by the manufacturer of a supplement with magnesium and B6. And the 30 mg is more than twice the 12 mg a day that has applied as the upper limit across Europe since 2023. B6 has its own jobs in the nervous system and energy metabolism anyway, and for those it doesn't need 30 mg.

What does the EU list say about combinations?

The EU has a list of reviewed health claims, and for magnesium it contains exactly ten, including that it contributes to the maintenance of normal bones, to electrolyte balance and to normal functioning of the nervous system. For vitamin D, it says that it contributes to normal absorption and utilization of calcium, and for vitamin B6, that it contributes to normal functioning of the nervous system and to normal energy-yielding metabolism. None of the ten magnesium claims is about a combination. So everything about the pairs above comes from individual studies, and how far each one goes is always stated alongside.

What does a routine without doubling up look like?

In a good routine, you know which supplement each nutrient comes from, and together they deliver no more than 250 mg of magnesium per day. Because when combining, the problem is rarely an interaction. Much more often, it's doubling up.

A multivitamin with some magnesium, plus a magnesium supplement and a vitamin D product with added magnesium, and you're already above the 250 mg at which the European Food Safety Authority (EFSA) sets the upper limit for supplements. Ten of the 13 supplements we worked through for our magnesium complex comparison reached 400 mg on their own. A good part already comes from foods high in magnesium anyway, and what happens if it does get to be too much is answered in our article on daily needs and the upper limit.

How we solved it with our four essentials

With our four essentials, you shouldn't have to do any math in the first place, which is why magnesium, vitamin D, zinc and omega-3 each sit in exactly one jar. BASE by Fifty Five is our multi-nutrient for the morning or midday, 16 vitamins and minerals in one mini capsule, including zinc, selenium, vitamin C and B12. We deliberately left magnesium out of it, because an effective dose needs a sufficient amount and therefore a capsule of its own.

That's why there's CALM by Fifty Five: two capsules that together deliver 206 mg of elemental magnesium, bound as bisglycinate and citrate, and cost you just €0.93 a day. Oxide doesn't even make it into our jar. Why it's these two forms is explained in our comparison of magnesium forms. It contains 2.0 mg of vitamin B6 as pyridoxal 5'-phosphate, and because BASE contains the same amount again, you end up at 4 mg with both together, a third of the upper limit. For us, CALM comes to the table with dinner, and if you'd rather split it, take one capsule in the morning and the other in the evening. More on that in our article on when to take magnesium.

RISE by Fifty Five brings vitamin D3 and K2 together and belongs in your routine all year round, because vitamin D levels build up over weeks and not in a few sunny days. The micro capsule goes with a meal, just like PULSE by Fifty Five, our vegan omega-3 from algae oil, ideally with one that has a bit of fat.

In everyday life it looks like this: BASE in the morning, RISE in the morning or at lunch, PULSE with lunch or dinner, CALM in the evening. We didn't separate them because the nutrients would interfere with each other. Two times of day are just easier to remember than five. How a routine like this with BASE and CALM works in everyday life is told by Julia, who works as a graphic designer between deadlines.

FAQ

Can I take magnesium, zinc and vitamin D at the same time?

Yes, in normal amounts all three can go with the same meal. More important than spacing is that none of the three is doubled up in your supplements, because zinc should stay at no more than 25 mg a day and magnesium from supplements at no more than 250 mg.

What should you not take with magnesium?

Iron and some medications are better not taken at the same time as magnesium. With iron, we keep about two hours apart as a precaution. For medications such as certain antibiotics or thyroid hormones, separate spacing rules apply, which are covered in our article on magnesium side effects and interactions. What coffee does to magnesium belongs to the question of the right time to take it.

Should you take magnesium if you take vitamin D?

You should definitely be well supplied then, because according to a 2018 review, the enzymes that convert vitamin D in the body probably all depend on magnesium. In a double-blind study with 180 adults, vitamin D levels rose with magnesium when they started out on the lower side. Whether the magnesium comes from your plate or from a supplement is secondary. That's why, for us, RISE and CALM naturally belong in the same routine.

Why do people say you shouldn't take vitamin D and magnesium together?

We don't know of any study that supports this warning. When 95 overweight adults in one study were given both together, their vitamin D levels actually rose the most. You can take both with the same meal or at different times of day, whatever fits your day.

Do I need vitamin K2 if I take vitamin D3 and magnesium?

You don't need it for the magnesium, K2 is a complement to vitamin D. Whether it fits with your vitamin D and how much of it is explained in our guide to vitamin D3 and K2.

How much magnesium is OK if I combine several supplements?

No more than 250 mg a day from all supplements combined, and magnesium from food doesn't count toward it. So include your multivitamin and your vitamin D supplement in the calculation, too, in case magnesium has been added to them. Germany's Federal Institute for Risk Assessment (BfR) gives the same maximum daily amount for food supplements.

Disclaimer:

This article is for informational purposes only and does not replace medical advice, diagnosis, or treatment by a physician or pharmacist. The information provided here should not be used for self-diagnosis or self-treatment. Food supplements are no substitute for a balanced, varied diet and a healthy lifestyle. For any health questions or complaints, please always consult a doctor you trust. Fifty Five accepts no liability for any inconvenience or harm resulting from the use of the information presented here.

Sources

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