How much riboflavin (B2) do you need per day?

The RDA for riboflavin is 1.3 mg a day for adult men and 1.1 mg for adult women aged 19 to 50.

These are the reference amounts used on US food labels and in dietary guidance, not personal targets. What you need shifts with age, pregnancy, medication and health conditions. The % Daily Value shown on every food page here is calculated against the FDA Daily Value for riboflavin (B2), which is 1.3 mg a day.

What this means for you

One and a third milligrams a day for men, a little over one for women, and milk is the classic way most people reach it. Yogurt, cheese, eggs, meat, almonds and fortified cereals do the same job.

Because dairy carries so much of it, the people who fall short in wealthy countries are easy to name: vegans, and anyone who has dropped milk without deliberately replacing it. Vegetarian athletes are listed as a separate risk group, since training raises the requirement.

If that is you

Fortified plant drinks, almonds, mushrooms and nutritional yeast close the gap without much thought. The requirement is small enough that one habit is usually enough.

Established. No upper limit was set for riboflavin, because high intakes have not produced harm. The bright yellow urine after a B complex is simply the excess leaving.

One thing riboflavin is often bought for is migraine prevention. Two small randomised studies in children found that 50 to 200 mg a day did not reduce either the number of headaches or their severity.

Why a big tablet cannot do much

Riboflavin has no upper limit, and the reason people usually give for that is wrong in a way worth correcting.

Unsettled. No limit was set, and the honest reason is not that riboflavin's safety was established. No adverse effects have been reported from food or supplements, but the studies using 100 to 400 mg a day asked people how they felt and measured no biochemistry at all. The data are described as insufficient to set a limit. Absence of evidence is doing the work here, rather than evidence of absence.

The reassurance that does hold is simpler and comes from the gut. Absorption in the small intestine saturates at about 25 to 30 mg, so past roughly 27 mg in a single dose the extra riboflavin is not taken up at all. What does get in leaves in urine, which is where the bright yellow comes from. A 400 mg tablet mostly produces expensive yellow urine.

Established. That ceiling has a second lesson in it. Riboflavin from whole food is absorbed at 60 to 70 per cent, while free riboflavin taken on its own at ordinary doses of 2 to 25 mg is absorbed at 50 to 60 per cent. About 95 per cent of the riboflavin in food, as FAD or FMN, is bioavailable up to that same ceiling. The food beats the tablet, which is rarely the case and worth saying when it is.

The vegan question is genuinely open

Unsettled. In Northern Europe riboflavin comes mostly from milk and meat, and intake runs 1.8 to 2.3 mg per 10 MJ in the Nordic countries against 1.4 to 1.7 in the Baltic ones. That makes people who eat no dairy the obvious group to check, and the surveys disagree with each other. One body of work reports that vegan diets may not supply enough. Another reports intake similar between vegans and omnivores. Since no agreed blood test exists to settle it, the useful response is not to pick a side. Build almonds, mushrooms, fortified plant drinks and nutritional yeast into the week and the argument stops mattering to you.

Written from the evidence cards and the data on this page, then checked back against the sources. Bioma Learn has no human medical reviewer at this time and we say so rather than invent one. Information, not medical advice. How we verify.

Foods highest in riboflavin (B2) on this site

• Chicken, liver, all classes, cooked — 1.69 mg per 3 oz (130% DV)
• Almonds, dry roasted — 1.65 mg per 1 cup whole kernels (127% DV)
• Almonds, oil roasted — 1.23 mg per 1 cup whole kernels (94% DV)
• Frankfurter, meatless fortified — 1.17 mg per 1 cup, sliced (90% DV)
• Almonds, blanched — 1.03 mg per 1 cup whole kernels (79% DV)

All riboflavin (B2) sources ranked →

Full guide: Riboflavin: a milk and egg vitamin, and what the migraine trials really show