Vitamin B2, or riboflavin, is an essential nutrient and plays a key role in energy production.
Free riboflavin is found in milk, beef liver and in enriched breads and cereals. In most foods riboflavin occurs as one of its coenzyme derivatives, flavin mononucleotide (FMN) or flavin adenine dinucleotide (FAD). FMN is metabolized in the body to form FAD.
Most dietary riboflavin is efficiently absorbed by a saturable carrier mechanism primarily in the proximal small intestine. A small amount of FAD is unavailable for absorption as it is covalently bound to certain tissue enzymes.
Some riboflavin is lost during heating in alkaline solution. Riboflavin is easily destroyed by light. Foods rich in riboflavin should be stored in opaque containers and foods should be covered when cooking.
FAD and FMN act as intermediate hydrogen acceptors in the mitochondrial electron transport chain and pass on electrons to the cytochrome system in cellular respiration.
Riboflavin has antioxidant activity, which is derived from its role as a precursor to FAD and as a cofactor in the production of glutathione. Riboflavin deficiency increases lipid peroxidation and decreases the regeneration of reduced glutathione, which is necessary for the function of the antioxidant glutathione peroxidases.
Males 9 to 13 years 14 to 18 years 18+ years Females 9 to 13 years 14 to 18 years 18+ years
0.9 1.3 1.3
0.9 1.0 1.1
Pregnancy <= 18 years 19 to 30 years 31 to 50 years
1.4 1.4
Lactation <= 18 years 19 to 30 years 31 to 50 years
1.6 1.6 1.6
*Values are Adequate Intakes (AI), others are RDA. There are no determinable Tolerable Upper Intake Levels
(UL) for riboflavin due to lack of data of adverse effects in all age groups.
The most common signs of riboflavin deficiency are pallor and cracking of the mucosa at the corners of the mouth and surfaces of the lips, followed by linear fissures. Lesions may become infected and the tongue may have a magenta hue. Areas of the body including the nasolabial folds, alae nasi, ears, eyelids, scrotum, and labia major may become red, scaly, and greasy. Sebaceous material accumulates in the hair follicles which produces dyssebacea or shark skin.
Riboflavin deficiency may cause neovascularization of the cornea and epithelial kerititis that can result in tearing and photophobia.
Urinary excretion of more than 30 mcg of riboflavin/g creatinine is associated with clinical signs of riboflavin deficiency.
Increased activation of red blood cell glutathione reductase by riboflavin is an early sign of riboflavin deficiency.
No danger of toxicity appears to be associated with large doses of oral riboflavin. Riboflavin is readily excreted in the urine and absorption by the digestive tract may be less than 20 mg for one dose.
Primary riboflavin deficiency is associated with inadequate milk, egg, and animal protein consumption.
One study found that 10% of omnivores and vegetarians had low riboflavin levels. However, 30% of vegans were riboflavin deficient. These results indicate that vegans are at an increased risk for riboflavin deficiency. 12
Deficiency frequently occurs in people with chronic diarrhea, alcoholism, or liver disease. Lack of supplemental nutrients in post-operative nutrient infusions also increases the risk of riboflavin deficiency.
Consumption of propantheline bromide (Pro-Banthine), a proton pump inhibitor (PPI) for ulcers, causes a delay in the rate of absorption of riboflavin but the total amount of absorption is increased due to an increased residence time of riboflavin at gastrointestinal (GI) absorption sites. It is advisable to take riboflavin 1 to 2 hours before or 3 to 4 hours after drug administration.
Information on the relationship between substances and disease is provided for general information, in order to convey a balanced review of the scientific literature. In many cases the relationship between a substance and a disease is tentative and additional research is needed to confirm such a relationship.
Assessment of vitamin B2 status in performance athletes of various types of sports.
A study with 62 athletes and 16 non-athletes investigated riboflavin status during strenuous training programs. Riboflavin status was assessed. The results indicated that most performance athletes had sufficient riboflavin concentrations compared to the non-athletes, but it did not identify whether performance athletes have a higher riboflavin requirement.5
Riboflavin status of female athletes consuming normal diets.
In a study with female athletes, riboflavin status was evaluated. The total riboflavin intake per 24 hours was significantly greater in the athletic group than in the non-athletic group. The total riboflavin excretion did not differ between the athletes and the untrained females, although riboflavin excretion per g of creatinine was somewhat lower in athletes than in untrained females. Overall, the study indicated that female athletes maintained adequate riboflavin concentrations from diet alone. The results suggest that the riboflavin requirement of athletes may be higher than that of non-athletes.6
Topic: Pregnancy and Lactation
Riboflavin levels in maternal milk: the influence of vitamin B2 status during the third trimester of pregnancy.
A study investigated the effects of riboflavin status on lactation during the third trimester of pregnancy. Fifty-seven healthy pregnant women, aged 18 to 35 years, participated in the trial. The riboflavin concentrations of transition and mature milk were higher in the subjects with higher milk and riboflavin intake (948.1±700.1 nmol/L for transition milk and 993.8±436.6 nmol/L for mature milk) compared to subjects with lower milk and riboflavin intake (574.9±258.7 nmol/L for transition milk and 725.4±254.3 nmol/L for mature milk). The results of this study confirm that riboflavin intake during pregnancy and lactation affects breast milk riboflavin concentrations.8
Topic: Health in Advancing Years
Riboflavin and vitamin B6 intakes and status and biochemical response to riboflavin supplementation in free-living elderly people.
A study monitored riboflavin and vitamin B6 assessed intake and status in 83 elderly subjects. Diet histories of both vitamins were considered to be adequate based on the current reference values, but abnormal concentrations of riboflavin were identified in 49% of participants. A subset of 45 of the original participants enrolled in a double-blind, placebo-controlled trial to investigate the effect of riboflavin supplementation. Participants consumed 1.6 mg riboflavin, 25 mg riboflavin, or a placebo daily for 12 weeks. For those with low baseline riboflavin status, low-dose supplementation improved status of the limiting nutrient significantly (P<0.0001 and P=0.020 for erythrocyte glutathione reductase activity coefficient (EGRAC) and plasma PLP responses, respectively). Researchers concluded that a high proportion of healthy elderly people have suboptimal status for nutrients such as riboflavin, despite having adequate dietary intakes. The current recommendations for riboflavin in the U.S. and U.K. may be inadequate for the elderly population.9
Topic: Migraines
Effectiveness of high-dose riboflavin in migraine prophylaxis.
A randomized, controlled trial evaluated the efficacy of riboflavin supplements for migraine prevention. Fifty-five adults participated in the three month trial. Participants consumed a daily supplement of 400 mg riboflavin or a placebo. Riboflavin was found to be better than placebo for reducing both attack frequency (p=0.005) and number of days with headache (p=0.012). The proportion of participants responding to treatment (i.e. reporting 50% or greater improvement in symptoms) was 15% for placebo and 59% for riboflavin (p=0.002). Thus, riboflavin supplements were found to be superior to placebo for migraine prophylaxis.10
A combination of riboflavin, magnesium, and feverfew for migraine prophylaxis: a randomized trial.
A trial investigated the effect of two riboflavin-containing treatments on migraine incidence. Forty-nine participants completed the three month trial. Subjects were randomized to receive either a so-called placebo containing 25 mg riboflavin or a supplement containing 400 mg riboflavin, 300 mg magnesium, and 100 mg feverfew. No difference between groups was detected for migraine incidence, migraine days, or migraine severity. Compared with baseline, both treatment groups demonstrated significant reductions in number of migraines, migraine days, and migraine index. These results suggest that a supplement of 25 mg riboflavin is sufficient to improve migraine symptoms.13
High-dose riboflavin treatment is efficacious in migraine prophylaxis: an open study in a tertiary care centre.
An open label study investigated the efficacy of riboflavin for migraine prevention. Subjects consumed 400 mg riboflavin daily during the six month trial. After six months, headache frequency was significantly reduced from 4 days/month to 2 days/month (P<0.05). The use of abortive drugs was also significantly reduced (P<0.05). Headache hours and intensity did not change during the trial. The results of this trial indicate that 400 mg riboflavin daily significantly improved migraine frequency and the necessity of drugs for treatment.7
Topic: Stroke
Riboflavin status in acute ischaemic stroke.
A recent study investigated riboflavin levels and the effect of short-term supplementation on people with acute ischemic stroke. Ninety-six people presenting with acute ischemic stroke participated in the study. Riboflavin status was measured at baseline, after 7 days, and after 14 days. Participants were randomized to receive 5 mg riboflavin plus other B vitamins daily for 14 days or a placebo. The first dose of riboflavin plus B vitamins or placebo was given within 12 hours of the stroke onset. At baseline, 51% of participants were riboflavin deficient. Riboflavin supplements significantly improved riboflavin status. After supplementation, 19% of the riboflavin plus B vitamin group participants remained riboflavin deficient; in the placebo group, 56% of participants were riboflavin deficient at the end of the trial (P=0.035 for the differences in cumulative changes between groups). These results suggest that improving riboflavin status may be beneficial for those at risk for stroke.11
The dietary supplement information contained on this site has been compiled from published sources thought to be reliable, but it cannot be guaranteed. Efforts have been made to assure this information is accurate and current. However, some of this information may be purported or outdated due to ongoing research or discoveries. The authors, editors and publishers cannot accept responsibility for errors or omissions or for any consequences from applications of the information in this site and make no warranty, expressed or implied, with respect to the contents herein.
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