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What is Vitamin B2 and What is the Common Signs and Symptoms of Vitamin B2 Deficiency ?

A nutrient in the vitamin B complex that the body needs in small amounts to function and stay healthy.


vitamin B2 ( Riboflavin)
vitamin B2 ( Riboflavin)

Vitamin B2 helps make red blood cells, helps some enzymes work properly, and keeps skin, nails, and hair healthy.

It is found in milk, eggs, malted barley, organ meats, yeast, and leafy vegetables.

Vitamin B2 is water-soluble (can dissolve in water) and must be taken in every day.

Not enough vitamin B2 can cause anemia (a low number of red blood cells), mouth sores, and skin problems. Amounts of vitamin B2 may be higher in the blood of patients with some types of cancer. Also called riboflavin.

Riboflavin is a type of B vitamin. It is water soluble, which means it is not stored in the body. Water-soluble vitamins dissolve in water. Leftover amounts of the vitamin leave the body through the urine. The body keeps a small reserve of these vitamins. They have to be taken on a regular basis to maintain the reserve. Riboflavin (vitamin B2) works with the other B vitamins. It is important for body growth. It helps in red blood cell production. It also aids in the release of energy from proteins.

Recommended Daily Allowance for Riboflavin [1]

  • Adults (age 19 to 70 years): Women: 0.9 to 1.1 mg/dl and Men: 1.1 to 1.3 mg/d. (These values are based on observing clinical evidence of deficiency in intake less than 0.6 mg/d)
  • Adolescents (Age 10 to 18 years): 0.9 to 1.3 mg/dl
  • Children (Age 1 to 9 years): 0.5 to 0.6 mg/d
  • Infants (Age: 0 to 12 mo): 0.3 to 0.4 mg/d


Mechanism of Action of Vitamin B2  [1]

Riboflavin is involved in the metabolism of macronutrients as well as the production of some other B complex vitamins. It is known to participate in redox reactions in the metabolic pathways through cofactors flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), derived from riboflavin, by acting as electron carriers.

Inadequate intake of riboflavin would be expected to lead to a disturbance in the intermediate steps of metabolism, with specific functional implications.

It is also known for its role as an antioxidant due to its involvement in the regeneration of glutathione, a free radical scavenger. Additionally, it is involved in growth and development, especially during fetal life, reproduction, and lactation.


What Can Vitamin B2  do for Us  ?

  • Riboflavin is the precursor of the coenzymes, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). They act as electron carriers in a number of oxidation-reduction (redox) reactions involved in energy production and in numerous metabolic pathways.
  • Riboflavin deficiency can affect multiple pathways in the metabolism of vitamin B6, folate, niacin, and iron.
  • Riboflavin deficiency has been linked to preeclampsia in pregnant women. This condition may progress to eclampsia and cause severe bleeding and death. The risk of preeclampsia has recently been associated with the presence of a genetic variant (C677T) in the methylenetetrahydrofolate reductase (MTHFR) gene. This gene codes for the MTHFR enzyme, which is FAD-dependent.
  • Oxidative stress can cause opacification of the eye lens, leading to cataracts in older individuals. While the results of some observational studies are promising, intervention studies are needed to assess a potential benefit of riboflavin in the prevention of cataracts.
  • Riboflavin (in the form, FAD) is required as a cofactor for the key folate-metabolizing enzyme, MTHFR. A low status of riboflavin status may interfere with the metabolism of folate, particularly in individuals homozygous for the MTHFR C677T gene variant; these individuals exhibit a higher risk of cardiovascular disease (CVD). Emerging evidence from intervention trials supports a protective role for riboflavin against hypertension in individuals with the MTHFR 677TT genotype.
  • Riboflavin has been evaluated as a prophylactic agent in studies with children and adults suffering from migraine headache. Riboflavin supplementation has been shown to decrease the frequency and severity of headache attacks in adults but not in children. [2]
  • Case reports have shown that patients with autosomal recessive disorders of riboflavin metabolism may benefit from riboflavin supplementation.
  • Riboflavin has been evaluated as a potential adjunct therapy in cancer and certain eye disorders.

Riboflavin is a water-soluble B vitamin, also known as vitamin B2. In the body, riboflavin is primarily found as an integral component of the coenzymes, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) . Coenzymes derived from riboflavin are termed flavocoenzymes, and enzymes that use a flavocoenzyme are called flavoproteins.

Riboflavin and Health

This section focuses on two conditions in which riboflavin might play a role: migraine headaches and cancer.

Migraine headaches


Migraine headaches typically produce intense pulsing or throbbing pain in one area of the head. These headaches are sometimes preceded or accompanied by aura (transient focal neurological symptoms before or during the headaches). Mitochondrial dysfunction is thought to play a causal role in some types of migraine . Because riboflavin is required for mitochondrial function, researchers are studying the potential use of riboflavin to prevent or treat migraine headaches .

Some, but not all, of the few small studies conducted to date have found evidence of a beneficial effect of riboflavin supplements on migraine headaches in adults and children. In a randomized trial in 55 adults with migraine, 400 mg/day riboflavin reduced the frequency of migraine attacks by two per month compared to placebo. In a retrospective study in 41 children (mean age 13 years) in Italy, 200 or 400 mg/day riboflavin for 3 to 6 months significantly reduced the frequency (from 21.7 ± 13.7 to 13.2 ± 11.8 migraine attacks over a 3-month period) and intensity of migraine headaches during treatment. The beneficial effects lasted throughout the 1.5-year follow-up period after treatment ended. However, two small randomized studies in children found that 50 to 200 mg/day riboflavin did not reduce the number of migraine headaches or headache severity compared to placebo.

The Quality Standards Subcommittee of the American Academy of Neurology and the American Headache Society concluded that riboflavin is probably effective for preventing migraine headaches and recommended offering it for this purpose [46]. The Canadian Headache Society recommends 400 mg/day riboflavin for migraine headache prevention, noting that although the evidence supporting this recommendation is of low quality, there is some evidence for benefit and side effects (such as discolored urine) are minimal .

Cancer prevention

Experts have theorized that riboflavin might help prevent the DNA damage caused by many carcinogens by acting as a coenzyme with several different cytochrome P450 enzymes [1]. However, data on the relationship between riboflavin and cancer prevention or treatment are limited and study findings are mixed.

A few large observational studies have produced conflicting results on the relationship between riboflavin intakes and lung cancer risk. A prospective study followed 41,514 current, former, and never smokers in the Melbourne Collaborative Cohort Study for 15 years, on average. The average riboflavin intake among all participants was 2.5 mg/day. The results showed a significant inverse association between dietary riboflavin intake and lung cancer risk in current smokers (fifth versus first quintile) but not former or never smokers.

However, another cohort study in 385,747 current, former, and never smokers who were followed for up to 12 years in the European Prospective Investigation into Cancer and Nutrition found no association between riboflavin intakes and colorectal cancer risk in any of the three groups. Moreover, the prospective Canadian National Breast Screening Study showed no association between dietary intakes or serum levels of riboflavin and lung cancer risk in 89,835 women aged 40-59 from the general population over 16.3 years, on average.

Observational studies on the relationship between riboflavin intakes and colorectal cancer risk have not yielded conclusive results either. An analysis of data on 88,045 postmenopausal women in the Women’s Health Initiative Observational Study showed that total intakes of riboflavin from both foods and supplements were associated with a lower risk of colorectal cancer. A study that followed 2,349 individuals with cancer and 4,168 individuals without cancer participating in the Netherlands Cohort Study on Diet and Cancer for 13 years found no significant association between riboflavin and proximal colon cancer risk among women.

Future studies, including clinical trials, are needed to clarify the relationship between riboflavin intakes and various types of cancer and determine whether riboflavin supplements might reduce cancer risk.

Recommended Intakes

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.

Following Table  lists the current RDAs 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.

Table 1: Recommended Dietary Allowances (RDAs) for Riboflavin [3]
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


What is the Common Signs and Symptoms of Vitamin B2 Deficiency ?

Riboflavin Deficiency [3]

Riboflavin deficiency is extremely rare in the United States. In addition to inadequate intake, causes of riboflavin deficiency can include endocrine abnormalities (such as thyroid hormone insufficiency) and some diseases .

The signs and symptoms of riboflavin deficiency (also known as ariboflavinosis) include skin disorders, hyperemia (excess blood) and edema of the mouth and throat, angular stomatitis (lesions at the corners of the mouth), cheilosis (swollen, cracked lips), hair loss, reproductive problems, sore throat, itchy and red eyes, and degeneration of the liver and nervous system.

People with riboflavin deficiency typically have deficiencies of other nutrients, so some of these signs and symptoms might reflect these other deficiencies. Severe riboflavin deficiency can impair the metabolism of other nutrients, especially other B vitamins, through diminished levels of flavin coenzymes.

Anemia and cataracts can develop if riboflavin deficiency is severe and prolonged.

Vitamin B2 or riboflavin is one of the important vitamins among the eight B vitamins, which is not only responsible for maintaining healthy blood cells, protecting the skin and eye health but also in boosting your energy levels. It regulates metabolism and acts as an antioxidant in the body. For pregnant women, riboflavin becomes essential for bone, muscle and nerve development of the baby.

Vitamin B2 is a water-soluble vitamin like all other B vitamins which means that it is flushed out of the body daily so it must be restored each day to avoid any deficiencies. It is important as it is needed for the proper functioning of every single cell within the body. It is used in combination with other B vitamins, which make up the “B Vitamin Complex”. Vitamin B2 changes into vitamin B6 and folate (vitamin B9) so that the body can use it.

Vitamin B2 deficiency is rare as this vitamin is found in almost all common foods, still it can occur in people who are underweight, those who have frequent digestive problems or in adolescent girls who avoid milk and rarely have vegetables.

Common symptoms of Vitamin B2 deficiency

The symptoms can be visible within a few days. Poor intake of Vitamin B2 may cause the following symptoms

1. Weakness or fatigue
2. Change in mood
3. Soreness of throat
4. Skin cracking
5. Dermatitis
6. Anaemia

You should know that it is not difficult to build a diet rich in vitamin B2 . One serving of soya can give you half of your daily requirement. Add green leafy vegetables and milk products to your daily meals and you’ll be able to get the rest of it.


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