Vitamin B2 (Riboflavin) - Food Sources, Benefits, and Deficiency

by Arpi Gasparyan | Last updated on May 10, 2024

Medically reviewed by Victoria Mazmanyan

Introduction

Vitamin B2, or riboflavin, is a water-soluble and heat-stable vitamin of the B-complex. It is obtained from food and also synthesized by gut bacteria. Vitamin B2 is required for metabolism and energy production (1, 2).

Table of contents

Physiological Role & Absorption

Recommended Intakes

Food Sources

Supplements

Vitamin B2 & Human Health

Migraine Headaches

Cardiovascular Health & Increased Homocysteine Levels

Cancer

Preeclampsia

Vitamin B2 Deficiency: Risk Groups and Symptoms

Vitamin B2 Toxicity

Vitamin B2 Interactions With Medications

Summary

References

Physiological Role & Absorption

Vitamin B2 is a component of 2 coenzymes: flavin mononucleotide or riboflavin-5’-phosphate (FMN) and flavin adenine dinucleotide (FAD). FMN and FAD are required for energy production, cellular function, growth and development, lactation, physical performance, reproduction, the metabolism of proteins, carbs, and fats into glucose for energy, and the metabolism of several drugs and steroids.

Vitamin B2, along with vitamin B12 and folate, also helps maintain normal homocysteine levels in the blood (1,2).

FAD is required to convert the amino acid tryptophan into niacin or vitamin B3 and vitamin B6 to coenzyme pyridoxal 5’-phosphate.

Over 90% of dietary vitamin B2 is in the form of FAD or FMN, whereas the remaining is in the vitamin’s free form and glycosides or esters.

Most vitamin B2 is absorbed in the proximal parts of the small intestines and stored in small quantities in the liver, heart, and kidneys. Excess vitamin B2 is either not absorbed or absorbed and later excreted through the kidneys. Large intestinal bacteria (gut bacteria or microbiota) also produce some amounts of free vitamin B2, which can be absorbed by the large intestine in varying amounts, depending on one’s diet - more vitamin B2 is produced after the consumption of plant-based foods (1, 2).

Vitamin B2 exhibits fluorescence when exposed to ultraviolet light and is rapidly inactivated by UV and visible light (1).

Vitamin B2 also has antioxidant properties and a role in immunity, skin health, and hair (1).

Recommended Intakes

According to the 2020-2025 Dietary Guidelines for Americans, the recommended dietary allowance (RDA) of vitamin B2 is 1.1mg for adult women and 1.3mg for adult men.

The table below shows the RDA of vitamin B2 by age, sex, pregnancy, and lactation (1, 3)․

	2-3 years	4-8 years	9-13 years	14-18 years	19+ years
Men	0.5 mg	0.6 mg	0.9 mg	1.3 mg	1.3 mg
Women	0.5 mg	0.6 mg	0.9 mg	1.0 mg	1.1 mg
Pregnancy and Lactation	-	-	-	1.4 mg	1.6 mg

Food Sources

Vitamin B2-rich foods include eggs, meat, milk, dairy products, and seafood. Vitamin B2 can also be found in some plant-based foods. Moreover, many grain and cereal brands artificially enrich their products with vitamin B2.

The table below shows some vitamin B2-rich foods and their content per serving.

Food Name	Vitamin B2 Content and Serving Size
Liver, pork, cooked	1.87mg in 3oz (85g)
Roe, mixed species, cooked	0.8mg in 3oz
Flour, white	0.6mg in 1 cup (125g)
Soybean, cooked	0.5mg in 1 cup (172g)
Mozzarella	0.5mg in 1 cup (132g)
Goat meat, cooked	0.5mg in 3oz
Yogurt, greek, plain	0.47mg in 1 container (170g)
Milk	0.45mg in 1 cup (244g)
Rye, cooked	0.42mg in 1 cup (169g)
Mussels, blue, cooked	0.36mg in 3oz
Sockeye salmon, cooked	0.2mg in 3oz
Cottage cheese	0.18mg in 4oz (113g)
Ham	0.17mg in 3oz
Oysters, wild, cooked	0.15mg in 3oz
Chicken meat, cooked	0.14mg in 3oz

As vitamin B2 is water-soluble, large amounts of the vitamin may be lost when cooking with water. Cooking by steaming or microwaving will lead to lesser vitamin loss.

Supplements

Vitamin B2 may be found in many dietary supplements both alone and with other vitamins and/or minerals. Supplements usually contain 1.3mg of riboflavin or vitamin B2, 100% of the RDA.

Vitamin B2 in supplements may be in its free form or as riboflavin 5’-phosphate (1).

Vitamin B2 & Human Health

Migraine Headaches

Impaired mitochondrial function, oxidative stress, and inflammation has been associated with several migraine types. Riboflavin might play a role in preventing or treating migraines by blocking these pathological changes.

Several small studies have shown the beneficial effects of vitamin B2 supplements on migraine headaches in adults and children. In a randomized trial with 55 individuals, 400mg daily vitamin B2 reduced the frequency of migraine attacks (2 per month). In a retrospective study of 41 children, 200-400mg daily vitamin B2 for 3-6 months significantly reduced the frequency and intensity of migraine headaches. However, two small studies failed to find positive associations (1, 4, 5).

Cardiovascular Health & Increased Homocysteine Levels

In a study of over 10,000 adults, an inverse association was found between vitamin B2 and folate supplementation and cardiovascular disease and mortality. The association was significant if both vitamins were consumed. Moreover, those with high folate intake and low vitamin B2 intake had a higher risk of heart disease mortality rate (6).

Vitamin B2 is essential in folate metabolism as a cofactor for the enzyme methyltetrahydrofolate reductase (MTHFR). Individuals with reduced MTHFR activity have increased homocysteine levels and, subsequently, an increased risk of heart disease. In a clinical trial of 680 adults, vitamin B2 lowered blood homocysteine levels in those with the MTHFR 677TT genotype (6).

Cancer

According to a theory, vitamin B2 might act as a coenzyme with some P450 enzymes and help prevent DNA damage caused by carcinogenic molecules. However, the evidence is limited and findings are mixed.

A prospective study of over 41,500 current, former, and never-smoking individuals found an inverse association between vitamin B2 intake and a decreased lung cancer risk in current smokers but not former smokers. Another similar study of over 385,000 found no associations between vitamin B2 intake and colorectal cancer risks (1).

An analysis of data on over 88,000 women showed a reduced colorectal cancer risk in those with high vitamin B2 intake or supplementation. However, another study observed an increased risk of colorectal cancer in those with high serum vitamin B2 levels. A third study noted that vitamin B2 intake is not associated with overall colorectal cancer risk (1, 7, 8).

Preeclampsia

Vitamin B2 deficiency in the last weeks of pregnancy may be associated with an increased risk of preeclampsia or toxemia, a complication of pregnancy causing high blood pressure and swollen legs. The underlying mechanism might be impaired mitochondrial function and nitric oxide (NO) release, and increased oxidative stress.

In a study of 154 women, those with vitamin B2 deficiency had a 28.8% increased risk of developing preeclampsia than those with normal riboflavin levels (9).

A study suggested that high-dose vitamin B2 intake might prevent some severe preeclampsia cases (10).

Vitamin B2 Deficiency: Risk Groups and Symptoms

Several groups of people are at risk of vitamin B2 deficiency (1, 2, 11):

Vegans, vegetarians, and individuals with eating disorders.
Vegetarian athletes. Athletes naturally have an increased use of riboflavin and animal products are the major sources of the vitamin. Thus, they often don’t meet the daily requirements of vitamin B2.
Pregnant, lactating women, and infants. As stated in the table above, the RDA of vitamin B2 increases during pregnancy and lactation, and those with inadequate daily intake are at a greater risk of vitamin B2 deficiency. Moreover, their infants are at a greater risk of vitamin deficiency and subsequent birth defects, such as growth and heart defects.
Individuals with riboflavin transport deficiency, a rare neurological disorder formerly known as Brown-Vialetto-Van Laere syndrome (BVVL) is associated with impaired absorption and transport of the vitamin. The symptoms develop from infancy to young adulthood and are associated with hearing loss, motor neuron disease, difficulty breathing, and more.
Newborns with jaundice or individuals with skin disorders undergoing light therapy. IV and visible light might inactivate vitamin B2 and its derivatives.
Individuals with chronic diarrhea.
Those with endocrine abnormalities, such as thyroid hormone insufficiency.
People with liver disease and alcohol use disorder
People undergoing hemodialysis.

Vitamin B2 deficiency or ariboflavinosis manifests with skin disorders (such as seborrheic dermatitis), swelling of the mouth and throat, angular stomatitis, cracked and ulcerated lips, hair loss, reproductive problems, sore throat, hyperpigmentation of the genitals, and red itchy eyes. Vitamin B2 deficiency is also associated with liver and nervous system problems. Severe deficiency may lead to other B complex vitamin deficiencies due to decreased levels of flavin coenzymes (1, 2).

Another side effect of vitamin B2 deficiency is anemia, linked to altered iron absorption and decreased production of red blood cells (2).

In prolonged and severe cases of vitamin B2 deficiency, a decrease in retinal function accompanied by structural changes in the neural retina and epithelium may appear. Chronic vitamin B2 deficiency is associated with an increased risk of cataracts, as well as glaucoma and keratoconus (1, 2, 12).

Vitamin B2 Toxicity

Vitamin B2 toxicity is unlikely to occur due to its limited absorption from the gastrointestinal tract and excretion through urine. Adverse effects of high vitamin B2 intake - 400mg daily for over 3 months - have not been reported, thus, there is no upper intake limit for this vitamin.

Vitamin B2 Interactions With Medications

Long-term use of barbiturates (such as phenobarbital and pentobarbital) may deplete vitamin B2 due to its oxidation (11).

Tricyclic antidepressants (such as amitriptyline and imipramine) might interfere with vitamin B2 utilization (11).

Riboflavin supplementation may decrease the excretion of several medications, such as acyclovir, adefovir, aminohippuric acid, captopril, and cefazolin (13). Riboflavin may also decrease the absorption of tetracycline antibiotics, such as demeclocycline (Declomycin), and minocycline (Minocin) (14).

Summary

Vitamin B2, or riboflavin, is a water-soluble, heat-stable, light-sensitive vitamin of the B-complex. It is obtained from food and also synthesized by gut bacteria. Vitamin B2 is required for metabolism and energy production.

Vitamin B2-rich foods include eggs, meat, milk, dairy products, and seafood. Many grain and cereal brands artificially enrich their products with vitamin B2. As vitamin B2 is water-soluble, large amounts may be lost when cooking with water. Cooking by steaming or microwaving will lead to lesser vitamin loss.

Riboflavin might play a role in decreasing the risk of severe preeclampsia in pregnant women and help manage migraine headaches.

Vitamin B2 deficiency manifests with skin disorders, swelling of the mouth and throat, angular stomatitis, cracked and ulcerated lips, hair loss, reproductive problems, sore throat, hyperpigmentation of the genitals, and red, itchy eyes. It is also linked to impaired liver and neuronal functioning, anemia, and eye disorders such as cataracts.

Barbiturates, tricyclic antidepressants, acyclovir, adefovir, aminohippuric acid, captopril, cefazolin, and tetracyclic antibiotics may interact with riboflavin supplements.

References

Author name: Arpi Gasparyan

Education: General Medicine at YSMU

Last updated: May 10, 2024

Medically reviewed by Victoria Mazmanyan