Can you take iron and magnesium glycinate together?

The evidence doesn't support a meaningful interaction between magnesium glycinate and iron at ordinary supplement doses. No controlled human trial has tested the two taken together. The mineral most clearly documented to interfere with iron absorption is calcium, not magnesium — and one review found low magnesium levels linked to worse iron deficiency, the opposite of what a magnesium-blocks-iron story would predict.

What the evidence doesn't support

It doesn't support the idea that magnesium glycinate meaningfully blocks iron absorption, and it doesn't support a documented need to separate the two by a specific number of hours. Both claims circulate widely online, but neither comes from a trial that actually measured iron status or absorption after co-administering the two supplements.

What the research found

A 2025 review of how iron shares absorption and transport machinery with other minerals looked specifically at calcium, magnesium, copper, zinc and several heavy metals. It describes calcium as able to inhibit the divalent metal transporter (DMT1) that iron also uses, reducing iron absorption in a dose-dependent way — that's the clearest documented mineral-mineral competitor for iron in the literature. Magnesium isn't described the same way. The same review notes that low magnesium concentrations can make iron deficiency worse, which points the relationship in the opposite direction from a magnesium-blocks-iron mechanism.

No trial in the literature we reviewed gave magnesium glycinate and an iron supplement to the same group of people and measured what happened to iron absorption or magnesium absorption as a result. The "take them a few hours apart" advice commonly given for minerals in general is a reasonable precaution based on how divalent minerals share gut transporters, but it isn't backed by a study of this specific pair.

Questions people ask

Can I take iron and magnesium glycinate together?

There's no trial showing a problem with taking them at the same time, and no trial showing a benefit to separating them either. The mineral with the clearest documented effect on reducing iron absorption in the research is calcium, not magnesium.

How long after taking iron can I take magnesium glycinate?

There's no study establishing a required gap specifically for this pair. General advice for spacing out minerals — often a few hours — comes from the broader principle that divalent minerals can share absorption pathways, not from a trial of iron and magnesium glycinate together.

Does magnesium glycinate interfere with iron absorption?

No human trial has tested that question directly. The mineral with clear, dose-dependent evidence of reducing iron absorption is calcium. One review found the opposite association for magnesium: low magnesium levels were linked to worse iron deficiency, not to better iron absorption.

When to talk to a doctor

Iron deficiency needs a diagnosis and monitoring from a doctor, usually with bloodwork before and during treatment — a magnesium supplement is not a treatment for it. If you're taking a prescribed iron supplement for diagnosed anemia or low iron, ask your doctor or pharmacist how it fits with anything else you take, including magnesium, rather than relying on general timing advice found online.

Related reading: magnesium glycinate and medications: what to check and magnesium glycinate and zinc.