Riboflavin
(B2)
DESCRIPTION:
Riboflavin (vitamin B2) is a member
of the B complex that is naturally a bright yellow colour. It
was isolated from whey by Dr. Khun in 1933.
Riboflavin is relatively unaffected
by cooking processes, but is destroyed by alkalis (e.g.
bicarbonate of soda) and exposure to light.
Riboflavin forms the essential
coenzymes FAD (flavin adenine dinucleotide) and FMN (flavin
mononucleotide). These two are essential for converting
proteins, fats and carbohydrates into energy in the presence of
oxygen.
Typically, deficiency symptoms take
the form of oral complaints such as sore, burning lips and
tongue ailments. An oily-type Dermatitis
is also often present down either side of the nose. Eyes can
also be affected, with burning, itchiness and visual fatigue
present.
Upper safe level for daily
supplementation = 200mg
Recommended Daily Allowance = 1.6mg
Riboflavin supplementation is
necessary in those with a deficiency of this nutrient. Such a
deficiency is not uncommon in people who have undergone total or
partial gastrectomy, and in those being treated with
chloramphenicol or other antibiotics.
In high amounts, riboflavin has been
reported to be of use in eye conditions such as blepharitis
(sore itchy eyelids) and keratitis (Inflammation
of the cornea) (1). Riboflavin is also occasionally effective in
the treatment of Migraines
(2) and muscle Cramps,
but there is no known rationale for this.
Intakes of more than 120 mg/day for
ten months have not been associated with any adverse side
effects. Absorption of riboflavin from the intestine is limited
by poor solubility and so it is unlikely that enough could be
absorbed to be harmful.
INTERACTIONS
AND CONTRA-INDICATIONS
Diuretics:
Thiazide diuretics can increase the excretion of riboflavin.
Antibiotics:
Riboflavin is unstable in the presence of the antibiotics
erythromycin and tetracycline. The vitamin should be taken apart
from these drugs.
Methotrexate:
Riboflavin may affect the way cancer cells respond to the
anti-cancer drug methotrexate.
N.B. Riboflavin supplements may
cause a harmless yellow coloration of the urine.
It is usually recognised that B
vitamins are best taken together for most general purposes.
However there is no detriment in taking riboflavin singly for a
specific reason.
Food (mg/100g)
Yeast extract 11.0
Lamb’s liver 4.64
Pig’s kidney 2.58
Fortified breakfast cereal 1.6
Wheatgerm
0.61
Cheese, cheddar 0.5
Eggs 0.47
Beef, stewing steak 0.23
Milk 0.17
Chicken 0.13
The main sources of riboflavin in
the diet are milk, meat, fortified cereal products and eggs.
REFERENCES:
1. "Handbook of Dietary
Supplements", Pamela Mason, Blackwell Science, 1995.
2. Schoenen J, Lenaerts M, Bastings E. Cephalagia,
1994,14;5:328-329.
