Biotin deficiency
was first recognized not because of inadequate amounts in the diet but
because of the effects of a chemical called avidin, which is found in
raw eggs. Avidin binds and inactivates biotin. Biotin can be made by
gut bacteria and absorbed from the large bowel, so that not all biotin
needs to be obtained from food. Theoretically, antibiotics that affect
gut bacteria could reduce the amount of biotin available.
Biotin is water
soluble, sensitive to air and oxygen and also to alkaline conditions.
The vitamin acts
as part of enzyme (natural substances that speed up chemical reactions
in the body) systems involved in building up chemicals containing carbon
and oxygen, such as fats and glucose.
Infants may be
at risk from biotin deficiency, which shows up as a 'seborrhoeic dermatitis'
that responds to biotin. Also, some infants have a metabolic disorder
requiring extra biotin. There has been some suggestion that 'cot deaths'
or the sudden infant death syndrome may be due, in some cases, to an
inadequate intake of biotin.
The biotin in human
milk averages about 10 micrograms per 1000 kilocalories (4200 kilojoules)
and in infant formulae is usually at least 15 micrograms per 1000 kilocalories.
However, a higher concentration of biotin may be preferable for infant
formulae because nutrients can be more biologically available to the
infant from human milk than from infant formulae.
BIOTIN
INTAKE
Safe and adequate
daily intake of biotin (U.S.A.): |
Infants:
Children:
Adolescents:
Adults:
|
35-50 micrograms
65-120 micrograms
100-200 micrograms
100-200 micrograms
|