Can You Take Riboflavin With Magnesium?

Quick answer

NIH's fact sheets for riboflavin and magnesium do not mention each other, and we found no study of the pair in healthy people. Riboflavin has no upper limit, and the gut absorbs at most about 27 mg at once; supplemental magnesium has an adult limit of 350 mg a day. High-dose plans for the two need a doctor.^1,2,3

Key facts

Riboflavin becomes the coenzymes FMN and FAD, and NIH says magnesium is required for energy production, including glycolysis, the first stage of breaking down sugar.^1,2
The gut absorbs at most about 27 mg of riboflavin from a single dose, and the rest leaves in urine.¹
The share of magnesium absorbed falls as the amount taken rises: from 65% to 11% across the amounts tested in one study.⁴
Extra riboflavin turns urine bright yellow, a minimal side effect, while too much supplemental magnesium tends to loosen stools.^1,3

What the sources say about this pair

NIH's fact sheets describe no effect of riboflavin on magnesium, or of magnesium on riboflavin, and we found no study that gave the two together to healthy people. NIH also says riboflavin is not known to have clinically relevant interactions with medicines, while magnesium has several.^1,2

They meet in energy metabolism, by different routes. Riboflavin is built into FMN and FAD, coenzymes that many enzymes need to produce energy. Magnesium is a cofactor in more than 300 enzyme systems, and NIH says it is required for energy production, including glycolysis.^1,2

Where their roles overlap

Both nutrients are on the EU list for normal nervous system function. The two statements are quoted below with their grades, and neither means that extra helps someone who already gets enough.^5,6

Contributes to normal functioning of the nervous system*⁵

Moderate evidence

A role accepted by EFSA and included in the EU list of permitted nutrient-function statements. It describes what riboflavin does when you get enough. It does not mean extra riboflavin changes how the brain or nerves work in people who already get enough.

Amount studied: Recommended daily intake from food and supplements

Contributes to normal muscle and nerve function*^2,6,7

Moderate evidence

A long-established role of the mineral, described by NIH and included in the EU list of permitted nutrient-function statements. It does not mean extra magnesium improves performance in people who already get enough: a meta-analysis of 14 trials found no significant gains in muscle strength or power, with benefits appearing only in groups likely to be short of magnesium, such as older adults.

Amount studied: Recommended daily intake from food and supplements

How each is absorbed

The gut absorbs at most about 27 mg of riboflavin from a single dose or meal. Uptake rises in step with the dose up to about 25 to 30 mg and then levels off.^1,8,9

In healthy adults, riboflavin taken by mouth had an absorption half-life of 1.1 hours, and absorption from the gut was 95% complete within about 4.4 hours.^8,9

In a study of magnesium taken with a standard meal, the share absorbed fell from 65% at the lowest amount to 11% at the highest, although the total absorbed still rose.⁴

Both reward smaller doses. Past about 27 mg of riboflavin at once the extra is not absorbed, and magnesium's share absorbed shrinks as the dose grows. A multivitamin's riboflavin, commonly 1.3 mg, sits far below that ceiling.^1,4

We found no study that settles whether food changes riboflavin absorption, and NIH gives no timing advice for it. In one study, plasma riboflavin rose over the 4 hours after a multivitamin taken with breakfast.^1,10

Adding up the amounts

Riboflavin and magnesium for adults^1,3,4
Adults	Riboflavin	Magnesium
Recommended a day	1.3 mg for men, 1.1 mg for women	400 to 420 mg for men, 310 to 320 mg for women
Upper limit	None set	350 mg a day from supplements and medicines
Most absorbed from one dose	About 27 mg	No fixed ceiling, but the share falls as the dose rises
Sign of a high intake	Bright yellow urine	Loose stools, nausea, cramping

What’s in ours

Men's Multi: Vitamin B2, 7.5 mg per serving, from the label

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

Men's Multi has both. Its riboflavin is well below the absorption ceiling, while its magnesium adds to Magnesium Glycinate's:

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.

High doses and who should ask first

Much of the interest in this pair comes from migraine, where both have been studied at high doses: 400 mg of riboflavin a day, and up to 600 mg of magnesium. Those are treatment amounts to be chosen with a doctor. NIH says the magnesium doses used for migraine exceed the upper limit and should be taken only under a health care provider's direction.^1,2

In a three-month trial of 400 mg a day in 55 adults, two minor side effects were reported with riboflavin, diarrhea and passing more urine, against one with placebo. None was serious.¹¹

Urine often turns bright yellow, because riboflavin is yellow and the body passes the extra in urine. Medical experts describe this discoloration as a minimal side effect.¹

High intakes of magnesium from supplements and medicines can cause diarrhea, nausea and abdominal cramping.³

Your doctor may want to check on you

Proton pump inhibitors such as omeprazole and esomeprazole can cause low blood magnesium when taken for a long time, usually more than a year. The omeprazole label says this has been reported rarely after at least three months and that doctors may check magnesium before and during long-term use.^2,3,12

On the medicine's label

Ask first if you take an antibiotic, a bisphosphonate, a diuretic, gabapentin or levothyroxine, which magnesium can affect.³
Ask first if you have kidney disease or reduced kidney function.
Ask first if you have riboflavin transporter deficiency or low thyroid hormone, which change how riboflavin is absorbed or used.¹³
Ask first if you are pregnant or breastfeeding and want more than a prenatal vitamin or multivitamin provides.

Questions people ask

Can you take riboflavin and magnesium at the same time?

Nothing in NIH's fact sheets suggests spacing them. If you take more than about 27 mg of riboflavin, the extra in one dose is not absorbed, and magnesium is absorbed in a larger share when it is split into smaller amounts.^1,14

What is the best time to take magnesium and riboflavin?

No study has tested a best time for the pair. In the one sleep trial of magnesium bisglycinate, people took it half an hour to an hour before going to bed, and riboflavin has no tested best time.^1,15

Is 400 mg of riboflavin with magnesium too much?

No upper limit is set for riboflavin, and 400 mg a day for three months caused only minor effects in one trial. Still, amounts like this are a medical plan, not an everyday supplement. Ask your doctor, especially before taking more than 350 mg of magnesium a day from supplements.^1,2,11

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.