What Happens If You Don’t Get Enough Vitamin B2

What Happens If You Don’t Get Enough Vitamin B2/Riboflavin is an essential human nutrient that is a heat-stable and water-soluble flavin belonging to the vitamin B family? Riboflavin is a precursor of the coenzymes flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These coenzymes are of vital importance in normal tissue respiration, pyridoxine activation, tryptophan to niacin conversion, fat, carbohydrate, and protein metabolism, and glutathione reductase-mediated detoxification. Riboflavin may also be involved in maintaining erythrocyte integrity. This vitamin is essential for healthy skin, nails, and hair.

Riboflavin is d-Ribitol in which the hydroxy group at position 5 is substituted by a 7,8-dimethyl-2,4-dioxo-3,4-dihydrobenzo[g]pteridin-10(2H)-aryl moiety. It is a nutritional factor found in milk, eggs, malted barley, liver, kidney, heart, and leafy vegetables, but the richest natural source is yeast. The free form occurs only in the retina of the eye, in whey, and in urine; its principal forms in tissues and cells are as flavin mononucleotide and flavin adenine dinucleotide. It has a role as a photosensitizing agent, a metabolite, a B vitamin, a food coloring, an Escherichia coli metabolite, and a mouse metabolite. It is conjugate acid of riboflavin(1-).

Riboflavin is yellow and naturally fluorescent when exposed to ultraviolet light. Moreover, ultraviolet and visible light can rapidly inactivate riboflavin and its derivatives. Because of this sensitivity, lengthy light therapy to treat jaundice in newborns or skin disorders can lead to riboflavin deficiency. The risk of riboflavin loss from exposure to light is the reason why milk is not typically stored in a glass container

Deficiency Symptoms of Riboflavin/vitamin B2

Riboflavin deficiency is also known as ariboflavinosis.

  • Primary riboflavin deficiency happens when the person’s diet is poor in vitamin B2
  • Secondary riboflavin deficiency happens for another reason, maybe because the intestines cannot absorb the vitamin properly, or the body cannot use it, or because it is being excreted too rapidly
  • Angular cheilitis, or cracks at the corners of the mouth
  • Cracked lips
  • Dry skin
  • Nerve damage
  • A sluggish metabolism
  • Mouth or lip sores or cracks
  • Skin inflammation and skin disorders, especially around the nose and face
  • Inflamed mouth and tongue
  • Inflammation of the lining of the mouth
  • Inflammation of the tongue
  • Mouth ulcers
  • Red Lips
  • Sore throat
  • Scrotal dermatitis
  • Fluid in mucous membranes
  • Iron-deficiency anemia
  • Eyes may be sensitive to bright light, and they may be itchy, watery, or bloodshot
  • Weakness or fatigue
  • Change in mood
  • Skin cracking
  • Dermatitis
  • Anemia
  • Throat swelling/soreness
  • Swollen tongue
  • Skin cracking (including cracked corners of the mouth)
  • Dermatitis
  • Blurred vision and itching, watering, sore, or bloodshot eyes
  • Eyes becoming light-sensitive and easily fatigued

Riboflavin deficiency (also called ariboflavinosis) results in stomatitis including painful red tongue with a sore throat, chapped and fissured lips (cheilosis), and inflammation of the corners of the mouth (angular stomatitis). There can be oily scaly skin rashes on the scrotum, vulva, philtrum of the lip, or the nasolabial folds. The eyes can become itchy, watery, bloodshot and sensitive to light. Due to interference with iron absorption, even mild to moderate riboflavin deficiency results in an anemia with normal cell size and normal hemoglobin content (i.e. normochromic normocytic anemia). This is distinct from anemia caused by a deficiency of folic acid (B9) or cyanocobalamin (B12), which causes anemia with large blood cells (megaloblastic anemia). Deficiency of riboflavin during pregnancy can result in birth defects including congenital heart defects and limb deformities.

The stomatitis symptoms are similar to those seen in pellagra, which is caused by niacin (B3) deficiency. Therefore, riboflavin deficiency is sometimes called “pellagra sine pellagra” (pellagra without pellagra), because it causes stomatitis but not widespread peripheral skin lesions characteristic of niacin deficiency. Riboflavin deficiency prolongs recovery from malaria, despite preventing the growth of Plasmodium (the malaria parasite).

Daily Requirement of Riboflavin/vitamin B2

Intake recommendations for riboflavin and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies. DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. These values, which vary by age and sex, include:

  • Recommended Dietary Allowance (RDA) –  Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals; often used to plan nutritionally adequate diets for individuals.
  • Adequate Intake (AI) – Intake at this level is assumed to ensure nutritional adequacy; established when evidence is insufficient to develop an RDA.
  • Estimated Average Requirement (EAR) – Average daily level of intake estimated to meet the requirements of 50% of healthy individuals; usually used to assess the nutrient intakes of groups of people and to plan nutritionally adequate diets for them; can also be used to assess the nutrient intakes of individuals.
  • Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse health effects.

Table 1 lists the current RDA for riboflavin. For infants from birth to 12 months, the FNB established an AI for riboflavin that is equivalent to the mean intake of riboflavin in healthy, breastfed infants.

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Recommended Dietary Allowances (RDAs) for Riboflavin 
Age Male Female Pregnancy Lactation
Birth to 6 months* 0.3 mg 0.3 mg
7–12 months* 0.4 mg 0.4 mg
1–3 years 0.5 mg 0.5 mg
4–8 years 0.6 mg 0.6 mg
9–13 years 0.9 mg 0.9 mg
14–18 years 1.3 mg 1.0 mg 1.4 mg 1.6 mg
19-50 years 1.3 mg 1.1 mg 1.4 mg 1.6 mg
51+ years 1.3 mg 1.1 mg

About 95% of riboflavin in the form of FAD or FMN from food is bioavailable up to a maximum of about 27 mg of riboflavin per meal or dose. The bioavailability of free riboflavin is similar to that of FAD and FMN. Because riboflavin is soluble in water, about twice as much riboflavin content is lost in cooking water when foods are boiled as when they are prepared in other ways, such as by steaming or microwaving.

 Selected Food Sources of Riboflavin 
Food Milligrams
(mg) per
Beef liver, pan fried, 3 ounces 2.9 171
Breakfast cereals, fortified with 100% of the DV for riboflavin, 1 serving 1.7 100
Oats, instant, fortified, cooked with water, 1 cup 1.1 65
Yogurt, plain, fat free, 1 cup 0.6 35
Milk, 2% fat, 1 cup 0.5 29
Beef, tenderloin steak, boneless, trimmed of fat, grilled, 3 ounces 0.4 24
Clams, mixed species, cooked, moist heat, 3 ounces 0.4 24
Mushrooms, portabella, sliced, grilled, ½ cup 0.3 18
Almonds, dry roasted, 1 ounce 0.3 18
Cheese, Swiss, 3 ounces 0.3 18
Rotisserie chicken, breast meat only, 3 ounces 0.2 12
Egg, whole, scrambled, 1 large 0.2 12
Quinoa, cooked, 1 cup 0.2 12
Bagel, plain, enriched, 1 medium (3½”–4” diameter) 0.2 12
Salmon, pink, canned, 3 ounces 0.2 12
Spinach, raw, 1 cup 0.1 6
Apple, with skin, 1 large 0.1 6
Kidney beans, canned, 1 cup 0.1 6
Macaroni, elbow shaped, whole wheat, cooked, 1 cup 0.1 6
Bread, whole wheat, 1 slice 0.1 6
Cod, Atlantic, cooked, dry heat, 3 ounces 0.1 6
Sunflower seeds, toasted, 1 ounce 0.1 6
Tomatoes, crushed, canned, ½ cup 0.1 6
Rice, white, enriched, long grain, cooked, ½ cup 0.1 6
Rice, brown, long grain, cooked, ½ cup 0 0

DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration (FDA) to help consumers compare the nutrient contents of products within the context of a total diet. The DV for riboflavin is 1.7 mg for adults and children age 4 and older. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.

The U.S. Department of Agriculture’s (USDA’s) National Nutrient Database for Standard Reference website lists the nutrient content of many foods and provides a comprehensive list of foods containing riboflavin arranged by nutrient content and food name.


Natural Food Source

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United States
Age group (years) RDA for riboflavin (mg/d) Tolerable upper intake level
Infants 0–6 months 0.3* ND
Infants 6–12 months 0.4*
1–3 0.5
4–8 0.6
9–13 0.9
Females 14–18 1.0
Males 14–18 1.3
Females 19+ 1.1
Males 19+ 1.3
Pregnant females 14–50 1.4
Lactating females 14–50 1.6
European Food Safety Authority
Age group (years) Adequate Intake of riboflavin (mg/d) Tolerable upper limit
7–11 months 0.4 ND
1–3 0.6
4–6 0.7
7–10 1.0
11–14 1.4
15–17 1.6
Australia and New Zealand
Age group (years) Adequate Intake of riboflavin (mg/d) Upper level of intake
0–6 months 0.3* ND
7–12 months 0.4*
1–3 0.5
4–8 0.6
9–13 0.9
Females 14–70 1.1
Males 14–70 1.3
Females >70 1.3
Males >70 1.6
Pregnant females 14–50 1.4
Lactating females 14–50 1.6
* Adequate intake for infants, no RDA/RDI yet established


Uses & Health Benefit

  • Prevent riboflavin deficiency and to treat ariboflavinosis – Whenever possible, poor dietary habits should be corrected, and many clinicians recommend administration of multivitamin preparations containing riboflavin in patients with vitamin deficiencies since poor dietary habits often result in concurrent deficiencies.
  • Riboflavin – may be useful in treating microcytic anemia that occurs in patients with a familial metabolic disease associated with splenomegaly and glutathione reductase deficiency. Although riboflavin has not been shown by well-controlled trials to have any therapeutic value, the drug also has been used for the management of acne, congenital methemoglobinemia, muscle cramps, and burning feet syndrome.
  • People undergoing hemodialysis – or peritoneal dialysis and those with severe malabsorption are likely to require extra riboflavin. Women who are carrying more than one fetus or breastfeeding more than one infant are also likely to require more riboflavin. It is possible that individuals who are ordinarily extremely physically active may also have increased needs for riboflavin.
  • Preventing and treating low riboflavin levels (riboflavin deficiency) – In adults and children who have too little riboflavin in their body, taking riboflavin by mouth can increase levels of riboflavin in the body.
  • Cataracts – People who eat more riboflavin as part of their diet seem to have a lower risk of developing cataracts. Also, taking supplements containing riboflavin plus niacin seems to help prevent cataracts.
  • High amounts of homocysteine in the blood (hyperhomocysteinemia) – Taking riboflavin by mouth for 12 weeks decrease levels of homocysteine by up to 40% in some people. Also, taking riboflavin along with folic acid and pyridoxine seems to lower homocysteine levels by 26% in people with high homocysteine levels caused by drugs that are used to prevent seizures.
  • Migraine headaches – Taking high-dose riboflavin by mouth seems to reduce the number of migraine headache attacks, by about 2 attacks per month. Taking riboflavin in combination with other vitamin and minerals seems to also reduce the amount of pain experienced during a migraine.

Possibly Ineffective for

  • Stomach cancer – Taking riboflavin along with niacin does help prevent gastric cancer.
  • Malnutrition caused by too little protein in the diet (kwashiorkor) – Some research suggests that taking riboflavin, vitamin E, selenium, and N-acetyl cysteine by mouth does not reduce fluid, increase height or weight, or decrease infections in children at risk for kwashiorkor.
  • Lung cancer -Taking riboflavin by mouth along with niacin does not help prevent lung cancer.
  • Malaria – Taking riboflavin along with iron, thiamine, and vitamin C by mouth does not reduce the number or seriousness of malaria infections in children at risk of being exposed to malaria.
  • High blood pressure during pregnancy (pre-eclampsia) – In women that are 4 months pregnant, starting to take riboflavin by mouth does reduce the risk of pre-eclampsia during pregnancy.
  •  Early research shows that taking riboflavin by mouth might be helpful for treating lactic acidosis caused by drugs called nucleoside analog reverse transcriptase inhibitors (NRTIs) in patients with acquired immunodeficiency syndrome (AIDS).
  • Increasing intake of riboflavin from dietary and supplement sources, along with thiamine, folic acid, and vitamin B12, might decrease the risk of developing cervical cancer.
  • Research on the effects of riboflavin for preventing esophageal cancer is conflicting. Some research shows that taking riboflavin by mouth may decrease the risk of getting esophageal cancer, while other research shows that it has no effect.
  • Early research shows that taking riboflavin by mouth in certain patients at higher risk of high blood pressure due to genetic differences may lower blood pressure when used in addition to prescribed blood pressure medications.
  • Early research shows that taking riboflavin and niacin by mouth might reduce the risk of liver cancer in people less than 55 years old. However, it does not seem to reduce the risk of liver cancer in older people.
  • Early research shows that taking riboflavin by mouth for 6 months does not improve disability in patients with multiple sclerosis.
  • Early research shows that low levels of riboflavin in the blood are linked with an increased risk of oral leukoplakia. However, taking riboflavin supplements by mouth for 20 months does not seem to prevent or treat oral leukoplakia.
  • Early research shows that taking riboflavin, iron, and folic acid by mouth does not increase iron levels in pregnant women more than taking just iron and folic acid.
  • Early research shows that taking riboflavin by mouth for 8 weeks increases iron levels in people with low iron levels due to sickle cell disease.
  • Early research shows that taking riboflavin and niacin by mouth does not prevent stroke-related death in people at risk for stroke.
  • Acne.
  • Aging.
  • Boosting the immune system.
  • Canker sores.
  • Maintaining healthy skin and hair.
  • Memory loss including Alzheimer’s disease.
  • Muscle cramps.

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Drug Warnings

Riboflavin may cause urine to have a more yellow color than normal, especially if large doses are taken. This is to be expected and is no cause for alarm. Usually, however, riboflavin does not cause any side effects.



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What Happens If You Don't Get Enough Vitamin B2

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