Riboflavin is a yellow crystalline substance, slightly soluble in water but not in fats. Though stable to boiling in an acid solution, in an alkaline solution it is readily decomposed by heat. It is also destroyed by exposure to light.
Riboflavin acts in the body as the coenzyme of the flavour proteins that are concerned with tissue oxidation. Riboflavin deficiency in animals always results in a failure to grow optimally.
Degenerative changes in the nervous system and liver, impaired reproduction with congenital malformation in the offspring, loss of hair and cataract of the lens are all lesions possible resulting from riboflavin deficiency.
The best sources are liver, milk, eggs and green vegetables. It differs from other B complex vitamins in that it occurs in good amounts in dairy product, but is relatively lacking in cereal brans. It is also present in beer. Especially good sources of the natural vitamin are yeast and meat extracts.