Vitamin B2 or riboflavin is a water soluble vitamin. Since this vitamin can also be found in milk, a term lactoflavin is also sometimes used. Biologically more active forms are flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) and the thyroid hormones promoting the phosphorylation of the forms of coenzymes. B2 is a thermostable vitamin which is poorly soluble in water and also decomposes in alkaline conditions.
Which foods contain the vitamin?
Biological functions of the vitamin
The role of the vitamin is realised through coenzymatic forms, which are then needed by the enzymes of redox processes — the catabolism or decomposition of carbohydrates, amino acids and lipides, the enzymes of breathing circuit and the oxidation of fatty acids.
Riboflavin is also necessary for the normal development of hair, nails and skin, and an essential component in the vision process.
Absorption, storage and excretion
Riboflavin is absorbed with active transport in the small intestine, whereas the absorption is promoted by bile acids. However, the absorption is inhibited by coffee, smoking, antibiotics and oral contraceptives.
The vitamin is stored in liver and kidneys, but since it is a water soluble vitamin, it only has minimum reserves, which means that the vitamin should constantly be obtained with food or additional food supplements must be taken.
Problems resulting from deficiency
- Cracked and broken corners of the mouth and lips
- Glossit, stomatitis
- Dermatitis around nose and eyes
- Hair loss
- Difficulty in urinating
- Weight loss
- Drop of body temperature
- Growth retardation and eczema in children
Risk groups for developing the deficiency
- Pregnant women in the third trimester of pregnancy
- Premature newborn with hyperbilirubinemia which is treated with phototherapy
- Teenagers who do not consume enough dairy products
- People over 65 years of age
- Chronic alcoholics and smokers
- Athletes with high training load and intensity
- People who are engaged in sports for losing weight
- Continuous very large sugar intakes
- People suffering from hypothyroidism
- People who tan a lot
- People with chronic heart diseases
- People under stress
Overdose is not possible if administered orally, since the low solubility of riboflavin prevents the absorption of excessive amounts of riboflavin from the digestive system.
Toxic effects are not observed even when administering large doses because kidneys effectively remove excessive amounts of riboflavin. However, it must be noted that continuous administration of large quantities of riboflavin considerably increases the excretion of other B vitamins with urine, which may lead to the deficiency thereof.
Use of vitamin preparations
Additional need also depends on burnt calories, i.e., the intake of thiamine for every 239 burnt calories is approximately 0.14 mg.
Additional intake is reasonable, if a person drinks excessive amount of coffee and tea, eats abundant amounts of sweets, avoids dairy products and smokes a lot.
As an additional treatment component, riboflavin is also used for treating alcoholism, pellagra, growth retardation, Parkinsonism, diabetes, cataract, nyctalopia, glaucoma, arthritis, nephritis, influenza, acne, dermatitis, skin ulcers, hair loss, foot cramps and Alzheimer.
Figure 1. Vitamin B2: riboflavin
Vitamin B2 content in food
Quantities of food products which should be consumed daily to obtain the recommended daily amount of vitamin B2.
|Milk, 3,5%||294 g||588 g||765 g||824 g||706 g||882 g||941 g|
|Yoghurt, 2,5%||250 g||500 g||650 g||700 g||600 g||750 g||800 g|
|Liver||16 g||31 g||41 g||44 g||38 g||47 g||50 g|
|Salmon||500 g||1000 g||1300 g||1400 g||1200 g||1500 g||1600 g|
|Egg||94 g||189 g||245 g||264 g||226 g||283 g||302 g|
|Peas||278 g||556 g||722 g||778 g||667 g||833 g||889 g|
|Spinach||179 g||357 g||464 g||500 g||429 g||536 g||571 g|
|Milk, 3,5%||882 g||882 g||882 g|
|Yoghurt, 2,5%||750 g||750 g||750 g|
|Liver||47 g||47 g||47 g|
|Salmon||1500 g||1500 g||1500 g|
|Egg||283 g||283 g||283 g|
|Peas||833 g||833 g||833 g|
|Spinach||536 g||536 g||536 g|