Taking magnesium and zinc together, and what about iron and calcium?

If you take several minerals, sooner or later you’ll wonder whether they get in each other’s way. It’s a fair question: some minerals compete for absorption in the gut, and that can reduce their bioavailability. What matters is the combination and, above all, the amount. Below, we answer the questions people ask most often.

Can you take magnesium and zinc together?

One study on this question dates from 1994. Men on a metabolic ward were given 142 mg of zinc a day and, calculated across all three study groups, they absorbed measurably less magnesium¹.

That said, 142 mg of zinc a day is a very high amount. We didn’t find a study showing inhibition at usual amounts, so, as far as we currently know, there’s no reason not to take zinc and magnesium together. You’ll find the different forms of magnesium explained in our article comparing the forms of magnesium.

Can you take zinc and iron together?

Here the picture is different. In an older study, iron slowed the absorption of zinc when both were given as simple salts. With equal amounts of iron and zinc (1:1) the effect was small, but with twice or three times as much iron (2:1 or 3:1) it was clear². When the zinc came from oysters, in other words from a food, iron had no notable effect on its absorption².

A review sums it up: high amounts of iron can reduce zinc absorption when both are given in solution, but this effect wasn’t seen when they were taken with a meal³.

Can you take iron and magnesium together?

We found no meaningful studies in people on iron and magnesium in usual amounts. In practice, the question rarely comes up, because researchers recommend taking iron in the morning anyway, well away from breakfast and coffee⁴. Magnesium can then simply be taken at another time of day. There’s more on this in our article on the best time to take iron.

Can you take magnesium and calcium together?

Here the available studies are reassuring, even though they’re very small. In five men, a high total magnesium intake of about 800 mg a day didn’t change how much calcium they absorbed in the gut⁵. The other way round, in five teenage girls, a high calcium intake of 1,800 mg a day made no measurable difference to magnesium absorption or balance⁶.

Based on these data, there’s no reason not to take magnesium and calcium together, for example in the evening. The two are also often combined in one product.

Calcium and iron: why it makes sense to space them out

The effect of calcium on iron, by contrast, is clear. In a study with 126 participants, 300 to 600 mg of calcium reduced the iron absorbed from a meal by 50 to 60%⁷. Even 165 mg of calcium from milk or cheese had this effect, and it also applied to haem iron, the kind found in meat⁷.

So if you take iron and calcium, it’s better to spread them across different times of day. The same goes for dairy products: don’t have them at the same time as your iron.

Can you take selenium and zinc together?

We found no study showing that selenium and zinc inhibit each other’s absorption. The two are often combined in products, and they share, for example, the same authorised health claim: selenium and zinc contribute to the normal function of the immune system⁸. As far as we currently know, there’s no reason not to take them together.

How to plan your minerals day to day

• Take iron in the morning on its own, away from calcium, dairy products and coffee.
• Take zinc at a different time of day from higher-dose iron.
• Magnesium and calcium are fine to take together, for example in the evening.
• Selenium and zinc can be taken together.

Most of the studies above looked at simple mineral salts, often in high amounts. As far as our research shows, whether the results apply to other forms, such as liposomal products, hasn’t been specifically studied. The plan above is a good guide for liposomal minerals too, together with the directions and recommended daily amount on the label.

Frequently asked questions about magnesium and zinc