VITANIN B2 (RIBOFLAVIN) 

Riboflavin helps enzymes facilitate the release of energy from nutrients in all cells of the body. The
coenzyme forms of riboflavin are flavin mononucleotide (FMN) and flavin adeninedinucleotide (FAD).
These coenzymes accept and donate 2 hydrogen atoms during metabolism. In energy metabolism FAD
accepts 2 hydrogen atoms from the TCA or Krebs cycle and donates them to the electron transport chain.

R.D.A. 1.2 mg/day (based on 2,000 cal diet)
Men (19-50) 1.7 mg/day
Woman (19-50) 1.3 mg/day

Sources
-Milk
-Yogurt
-Cottage cheese
-Meat
-Leafy green vegetables
-Whole grain or enriched breads and cereals

Deficiency -----> Ariboflavinosis

symptoms

• (Cracked and red corners of the mouth)
• glossitis (purpilish, red, smooth tongue)
• Inflamed eyelids and sensitivity to light
• Reddening of the cornea
• Skin rash

Some facts about riboflavin

-Riboflavin or its phosphate known as FMN are effectively absorbed from the upper regions of the intestinal
tract. The absorption of riboflavin is assumed to increase with age.
-Riboflavin reserves are very stable in the body.
-Riboflavin serves as a prosthetic group in flavoenzymes, which are important in cell redox reactions, when
biochemical energy is released fromcarbohydrates fats and proteins.
-If the bodies cells do not contain enough riboflavin then a decrease in protein synthesis will be the first
symptom.

Recent study shows active, weight reducing women need more riboflavin than the suggested R.D.A. of .6 mg

The study that was performed used 12 female subject with the desire to lose weight. The 12 subjects were
broken up into 2 groups of 6. Group 1 was to take .96mg/1000kcal and group 2 was to take
1.16mg/1000kcal. The average caloric intake was reduced to 1250 kcal, to create the calorie deficit. The
study was performed for three weeks and during each week the individual women would either be in an
exercise period or a non exercise period for each week of the experiment. The subjects exercised for thirty
minutes a day at 75-80 % of their max. heart rate. The average weight loss at the end of the experiment
for each subject was about 14 to 15 lbs, of which 11 to 12 lbs were fat. The riboflavin measurements were
taken the last two days of each experiment. The methods that were used to measure were urinary excretion
of riboflavin and erythrocyte glutathione reductase activity coefficient (EGRAC). The excretion of
riboflavin should fall after an exercise period, while the EGRAC should increase. The results of the
experiment are as follows. Group 2 during a nonexercise week had 1.16mg of EGRAC and .326mg/day
in urinary excretion, after exercise EGRAC was at 1.20 mg and .176 mg/day of urinary excretion. Group
1, which had the lower riboflavin intake, reported a 1.31 mg EGRAC and .127 mg/day of urinary
excretion during the non exercise week and 1.36 mg EGRAC and .072 mg/day of urinary excretion during
the exercise weeks. The results show that the EGRAC is normal in group 2 during exercise. However in
group 1 the EGRAC is greater than 1.25 mg and the urinary excretion has fallen below safe levels, which
suggests a biochemical riboflavin deficiency. The conclusion of this experiment is that weight reducing
women require more than the R.D.A. of .6 mg/1000kcal day during periods of exercise. In this experiment
there was no evidence to suggest that supplementation of riboflavin would improve performance as max.
aerobic capacity was measured and no difference was found between the groups.