Vitamin B2 (Riboflavin): Food Sources & Daily Intake

Vitamin B2, better known as riboflavin, is a water-soluble B vitamin the body uses to turn food into energy and to recycle other nutrients — it is the building block of two coenzymes (FAD and FMN) that power dozens of reactions. Because it is water-soluble it is not stored in any quantity, so a steady daily supply matters. The richest sources are organ meats, dairy, with eggs, lean meats, almonds, mushrooms and leafy greens filling in.

Table of Contents

1. How to Read These Tables
2. Recommended Intakes & Upper Limits
3. Bioavailability & Absorption
4. Cooking & Storage
5. Vegetarian & Vegan Sources
6. Who Needs to Pay Attention
7. Data Sources & References
8. Connections
9. Featured Videos

How to Read These Tables

• Water-soluble — little is stored. Like the other B vitamins, surplus riboflavin is excreted in urine (it is what turns urine bright yellow after a B-complex), so a regular daily intake matters more than any single large dose.
• %DV vs RDA. The %DV column compares a serving against the FDA Daily Value of 1.3 mg. Your personal target (the RDA) is 1.3 mg for men and 1.1 mg for women, slightly higher in pregnancy and lactation — see the second table.
• Per 100 g vs per serving. Per-100 g lets you compare foods fairly; the serving size shown beside each food is what you actually eat. A cup of milk, two eggs or an ounce of almonds each deliver a meaningful share of the day’s need, and they add up quickly across normal meals.

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Recommended Intakes & Upper Limits

Your personal target depends on age, sex and pregnancy. The Daily Value used for the %DV column above is a single label figure; the table below is the age-specific guidance.

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Bioavailability & Absorption

Riboflavin from a mixed diet is well absorbed, but the gut has a ceiling: absorption tops out at roughly 27 mg in a single dose, and the percentage absorbed falls as the amount rises — one reason there is little point in mega-doses. Absorption is somewhat better when riboflavin is eaten with a meal rather than on an empty stomach. The vitamin in milk, eggs and meat is largely bound to proteins as the coenzymes FAD and FMN, which digestion frees for uptake; the free riboflavin used to fortify flour is absorbed readily as well.

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Cooking & Storage

Riboflavin is relatively heat-stable, so normal cooking does not destroy much of it — though, like all water-soluble vitamins, some leaches into boiling water (steaming or using the cooking liquid keeps more). Its real weakness is light: riboflavin is rapidly degraded by sunlight and even fluorescent light. This is exactly why milk is sold in opaque cartons and jugs rather than clear glass — a few hours in a sunny window can destroy a large fraction of the riboflavin in clear-bottled milk. Store riboflavin-rich foods away from light.

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Vegetarian & Vegan Sources

Because dairy and eggs are such major contributors, plant-based eaters should be deliberate about riboflavin. The good news is that several strong non-animal sources exist: fortified plant milks (check labels), almonds, mushrooms (especially cooked), nutritional yeast, spinach and other leafy greens, and enriched or whole grains. A varied plant diet that includes some of these comfortably meets the RDA; relying only on unfortified whole foods without nuts, mushrooms or greens is where shortfalls can appear.

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Who Needs to Pay Attention

Frank riboflavin deficiency (ariboflavinosis) is uncommon where diets are adequate, but it rarely occurs alone — it usually travels with other B-vitamin shortfalls. Classic signs include cracks and sores at the corners of the mouth (angular cheilitis), a sore magenta-colored tongue, chapped lips, a scaly rash, sore throat and sometimes anemia. Groups at higher risk include vegans and vegetarians who avoid dairy and eggs, people with heavy alcohol use, pregnant and breastfeeding women with poor diets, and those with conditions that impair absorption. Because excess is simply excreted and no UL has been set, riboflavin is regarded as very safe; the only common “side effect” of high doses is harmless bright-yellow urine.

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Data Sources & References

• NIH Office of Dietary Supplements — Riboflavin Fact Sheet (DV, RDA, no UL)
• Linus Pauling Institute — Riboflavin Micronutrient Information Center
• PubMed — riboflavin absorption, requirements and deficiency

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Connections

• Vitamin B2 (Riboflavin) (Main Page)
• Vitamin B2 (Riboflavin) Benefits
• Vitamin B2 (Riboflavin) History
• All Vitamins
• Vitamin B1 (Thiamin)
• Vitamin B3 (Niacin)
• Milk
• Eggs

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