Chemistry Reference
In-Depth Information
Table 13.8.
Recommended daily uptake of biotin
Biotin (mg day
-1
)
Age
Sucklings
<
4 months
5
Sucklings 4-12 months
5-10
Children 1-4 years
10-15
Children 4-7 years
10-15
Children 7-10 years
15-20
Children 10-13 years
20-30
Children 13-15 years
25-35
Adults 15-25 years
30-60
Adults 25-51 years
30-60
Adults 51-65 years
30-60
Adults
>
65 years
30-60
Pregnant
30-60
Breast feeding
30-60
From DGE (2007)
In humans, biotin deficiency is very rarely detected in industrial countries
with an average biotin intake of 35-70 mgday
-1
,
which exceeds the recommended
daily intake (see Table 13.8). However, it has to be taken into account that such
recommendations are difficult to calculate, as the sources of biotin (diet, micro-
organisms, bioavailability) are quite variable. In general, biotin uptake seems to
be adaptively regulated and the sodium-dependent multivitamin transporter
(hSMVT) is involved in this regulation (Reidling et al., 2007).
Besides the excessive uptake of raw egg white, persons on long-term
parenteral nutrition with insufficient biotin supplementation, people suffer-
ing from congenital biotinidase deficiency (''secondary biotin deficiency''; see
below) or patients on a long-term anti-convulsant therapy are at risk of
developing biotin deficiency symptoms, although only after longer periods
of biotin deprivation of months or even years. Symptoms are scaly/sebor-
rhoeic and red/eczematous skin rash around the eyes, nose and mouth,
anorexia, and also neurological symptoms like depression, lethargy, halluci-
nations and paraesthesiasis of the extremities have been described. In chil-
dren, generally comparable symptoms appear under parenteral nutrition, but
earlier (within 3-6 months).
Biotinidase is an enzyme which catalyses the hydrolysis of biocytine to
biotin and lysine in the intestine, making biotin bioavailable. In addition,
biotinidase plays a role in biotin recycling; a deficiency of this enzyme is
therapeutically treated by a daily supplementation with 50-150 mg of free
biotin. In this context, it is interesting that in these patients intestinal biotin
production is insufficient.
