BIOTIN
STATUS LONGTITUDINALLY ASSESSED IN PREGNANT WOMEN
Although nutritional
deficiency is often associated with poverty, it is essential
to remember that anyone can suffer from nutritional
disorders. Although diseases of dietary deficiency are
not very common in our society, they still do occur
and should not be ruled out by an examining physician
simply on the basis of a patient's economic status.
Most of you are probably familiar with the basic functions
of the vitamins and minerals which are covered in this
goal and at least some of the diseases which can result
from deficiencies of these nutrients. If this is the
case, then much of the material presented will not be
new. You should also be aware of the fact that "new"
roles are being discovered for many of the vitamins,
such as possible prevention of chemical carcinogenesis
by Vitamin A or a role in the regulation of lipolysis
for Vitamin C. It is not unlikely that RDA's for some
nutrients will be altered as more is learned about their
physiological functions or that new therapeutic uses
will be found for certain of them.
While it is true that a pregnant woman is eating for
two, her nutritional needs do not double. Instead, she
should increase her calorie intake to ensure adequate
weight gain, and make sure her diet provides the extra
vitamins and minerals needed to support the growing
fetus.
Protein is essential for building fetal tissues. A pregnant
woman should increase her protein intake to 60 grams
daily. For the protein to be used in fetal tissues,
sufficient calories must also be consumed to meet the
daily energy requirement of both mother and baby.
In order to get sufficient calcium, necessary for the
baby's bone and tooth development, pregnant women should
drink four cups of milk or the equivalent daily. Young
women in their teens and early 20s, who are still developing
bone themselves, will need five cups of milk daily to
meet their own and their baby's needs.
Folic acid and pyridoxine, two of the B vitamins, are
particularly important in pregnancy. Folic acid is necessary
for protein synthesis in the early months; both vitamins
are needed for proper development of the fetal nervous
system. A lack of folic acid in the early months of
pregnancy has been associated with congenital malformation.
Folic acid is the scarcest vitamin in the human diet,
however, and reserves may be especially low in women
who have been taking birth control pills. Supplements
are recommended, either through fortified foods or in
tablet form. Your doctor can tell you how much folic
acid you should take.
The need for other B vitamins, and for vitamins C, A,
and D, also increases in pregnancy, but these are normally
present in sufficient quantities in a well-balanced
diet. A word of caution: Excessive vitamin A can cause
severe birth defects. High-dose vitamin A supplements
and Retin-A (tretinoin) should be stopped three or more
months before attempting pregnancy.
Liquids are needed in increased quantities during pregnancy.
The requirement-over and above milk-is at least 6 glasses
a day. Latest studies show that there is no harm in
drinking moderate amounts of caffeine-containing products
during pregnancy, but it is wise to limit consumption
to a total of two to three cups per day of all caffeine-containing
drinks, and to distribute them over the course of the
day.
Vegetarian women must pay special attention to nutritional
requirements during pregnancy. Those following a strict
vegetarian diet with no animal products, such as eggs,
cheese and milk, will need vitamin and mineral supplements.
Sufficient calories and protein can be obtained from
a meatless diet if care is taken to balance foods properly.
Complete proteins can be derived from dairy products
and from legumes and grains, when these are combined
at the same meal to provide a proper balance of amino
acids. A woman who consumes no dairy products should
eat generous amounts of green leafy vegetables, nuts,
and seeds. She should also take supplements containing
iron, calcium, vitamin D, and B vitamins (especially
vitamin B12, which is found only in animal products).
Biotin is an essential nutrient that is required for
cell growth and for the production of fatty acids. Biotin
is necessary for the metabolism and release of energy
from carbohydrates, proteins and fats and is essential
for the proper utilization of the other B-complex vitamins.
Biotin contributes to healthy skin and hair, and may
play a role in preventing hair loss. Biotin is essential
for gluconegenesis and fatty acid synthesis. Diabetics
may also benefit from Biotin. Besides hair loss, a deficiency
of Biotin may also cause eczema, dermatitis, skin disorders,
heart and lung problems, anemia, fatigue, mental depression,
muscle pain, conjunctivitis, high blood cholesterol,
loss of appetite and nausea. Skin rashes and acidosis
can develop in infants. A primary source of Biotin is
the healthy bacteria in the intestinal tract. Because
these are often compromised by a Candida Albicans overgrowth,
candida sufferers are particularly prone to a Biotin
deficiency.
Biotin is a water-soluble member of the B-complex group
of vitamins and is commonly referred to as vitamin H.
The biochemical acts as a carrier for carbon dioxide
in the pyruvate carboxylase reaction, where biotin is
linked to the epsilon-amino group of a lysine residue
in the enzyme. Biotin is necessary for both metabolism
and growth in humans, particularly with reference to
production of fatty acids, antibodies, digestive enzymes,
and in niacin (vitamin B-3) metabolism. Food sources
for biotin are liver, kidney, soy flour, egg yolk, cereal,
and yeast. There are suggestions that biotin is also
capable of curing baldness, alleviating muscle pain
and depression, and functions as a cure for dermatitis,
although there is no substantial evidence for any of
these claims. Biotin deficiency results in fatigue,
depression, nausea, muscle pains, hair loss, and anemia.
Biotin is used in two-step detection systems in concert
with conjugated avidin. Biotin is typically conjugated
to proteins via primary amines (i.e., lysines). Usually,
between 3 and 6 biotin molecules are conjugated to each
antibody. The entire conjugation can be performed in
about a half-day. In addition to the materials listed
below, you will need to have a solution of your antibody
at a concentration (optimally) of at least 2 mg/ml.
The extent of biotin conjugation to the antibody may
depend on the concentration of antibody in solution;
for consistent conjugations, use a consistent concentration.
You should be familiar with how to use a desalting column
and how to take absorbance spectra. The reactive biotin
molecule is unstable. Once the biotin is solubilized,
it should be used immediately. When first conjugating
an antibody, a range of biotin to antibody concentrations
should be compared.
Biotin, a water-soluble B vitamin, is critical to human
health. Severe deficiencies in biotin cause skin rash,
hair loss, depression, and failure to thrive, and is
potentially fatal. However, mild cases can be asymptomatic.
Instead, the milder deficiency can manifest as growth
retardation and immune deficiency and potentially as
birth defects. It was developed the capability to precisely
measure 3-hydroxyisovaleric acid (which is produced
in increased quantities when activity of the biotin-dependent
enzyme methylcrotonyl-CoA carboxylase is decreased);
lymphocyte carboxylase activities; lymphocyte biotin
content; and serum odd-chain fatty acid content which
also reflects decreased activity of propionyl-CoA carboxylase.
We are determining the usefulness of these quantities
as indicators of deficiency in animals and in marginally
biotin deficient adult volunteers.
Although biotin deficiency is very rare, the human requirement
for dietary biotin has been demonstrated in two different
situations: prolonged intravenous feeding without biotin
supplementation and consumption of raw egg white for
a prolonged period (many weeks to years). Avidin is
a protein found in egg white, which binds biotin and
prevents its absorption. Cooking egg white denatures
avidin, rendering it susceptible to digestion, and unable
to prevent the absorption of dietary biotin
Symptoms: Symptoms of overt biotin deficiency include
hair loss and a scaly red rash around the eyes, nose,
mouth, and genital area. Neurologic symptoms in adults
have included depression, lethargy, hallucination, and
numbness and tingling of the extremities. The characteristic
facial rash, together with an unusual facial fat distribution,
have been termed the "biotin deficient face"
by some experts . Individuals with hereditary disorders
of biotin metabolism resulting in functional biotin
deficiency have evidence of impaired immune system function,
including increased susceptibility to bacterial and
fungal infections.
Predisposing conditions: Two hereditary disorders, biotinidase
deficiency and holocarboxylase synthetase (HCS) deficiency,
result in an increased biotin requirement. Biotinidase
is an enzyme that catalyzes the release of biotin from
small proteins and the amino acid, lysine, thereby recycling
biotin. There are several ways in which biotinidase
deficiency leads to biotin deficiency. Intestinal absorption
is decreased because a lack of biotinidase inhibits
the release of biotin from dietary protein. Recycling
of one's own biotin bound to protein is impaired, and
urinary loss of biotin is increased because the kidneys
appear to excrete biotin that is not bound to biotinidase
more rapidly. Biotinidase deficiency sometimes requires
supplementation of as much as 5 to 10 milligrams of
oral biotin/day, though smaller doses are often sufficient.
HCS is an enzyme that catalyzes the attachment of biotin
to all four carboxylase enzymes. HCS deficiency results
in decreased formation of all carboxylases at normal
blood levels of biotin, and requires high-dose supplementation
of 40 to 100 mg of biotin/day. In general, the prognosis
of both disorders is good if biotin therapy is introduced
early and continued for life.
Aside from prolonged consumption of raw egg white or
intravenous feedings lacking biotin, other conditions
may increase the risk of biotin depletion. The rapidly
dividing cells of the developing fetus require biotin
for DNA replication and synthesis of essential carboxylases,
thereby increasing the biotin requirement in pregnancy.
Recent research suggests that a substantial number of
women develop marginal or subclininical biotin deficiency
during normal pregnancy. Anticonvulsant medications,
used to prevent seizures in individuals with epilepsy,
increase the risk of biotin depletion. Because it has
been identified at different times Biotin has been given
a variety of names including Coenzyme R, Protective
Factor X, Vitamin H, Vitamin B7 and Bios. All are the
same. Biotin works with folic acid and vitamin B12 to
break down fats, protein, and carbohydrates. Biotin
is found in most foods and also manufactured by bacteria
in the intestinal tract. Most biotin deficiencies are
associated with the consumption of raw egg whites which
contain avidin. Avidin binds with biotin to prevent
its absorption into the blood. Cooking the egg whites
deactivates avidin. Biotin is non-toxic and probably
not required in supplement form. Although Biotin deficiencies
are rare, they can occur when people have malabsorption
problems.
Based on these human and animal studies, the best indicators
of biotin status are being chosen and used in several
clinical studies to test several hypotheses concerning
impaired biotin status. For example, in a biotin intervention
study, we are testing the hypothesis that biotin status
is impaired whenever urinary 3-HIA is abnormally increased
in pregnancy; accordingly, urinary 3-HIA and other biotin-related
indicators of metabolic derangement will return to normal
with biotin supplementation.
It was found out that whether biotin deficiency of similar
severity to that observed in human pregnancy causes
significant increases of fetal malformation in the mouse.
In our pilot mouse study, marginal biotin deficiency
in mouse dams that caused an increase in 3-HIA excretion
similar to that seen in human pregnancy produced 100%
incidence of cleft palate in the fetal mouse. We also
are actively investigating the biochemical pathogenesis
of the bone pathology and the histopathologic consequences
at the macroscopic, microscopic, and cellular level
for bone and cartilaginous tissues.
We also seek to determine the location and characterization
of the enzymes responsible for catalyzing the b-oxidation
of biotin to the inactive metabolite bisnorbiotin. This
catabolic process is of particular interest because
increased biotin breakdown is induced by exposure to
anticonvulsants and during pregnancy and may contribute
to biotin deficiency in these circumstances. We are
actively investigating the effects of cell proliferation
and cell cycle on a newly discovered biotin transporter
as well as pursuing studies concerning the basic molecular
biology of the transporter.
It was also noted that there is a n increased serum
biotin level in early pregnancy compared to that of
late pregnancy. Biotin excretion rates for the control
group and for the study group during early and late
pregnancy. There was no significant difference in biotin
excretion between early pregnancy and the controls,
but excretion rates in 4 of the 13 pregnant women were
greater than the upper limit of normal. In late pregnancy,
biotin excretion was significantly decreased whether
compared with control or early pregnancy.
The serum concentrations of biotin for the control women
and for the pregnant women. During early pregnancy,
the mean serum concentration of biotin was significantly
greater than that of the control group. By late pregnancy,
the mean serum concentration of biotin was significantly
less than in early pregnancy and was not significantly
different from that of the control group. The serum
concentration of biotin decreased I each pregnant woman
and was less than the lower limit of normal in 2 of
the 13 women; the decrease was significant by paired
t test.
To test whether the
increase in the serum concentration of biotin during
the early pregnancy could be attributed to an increase
in reversibly bound biotin , it was noted that the proportion
of biotin free and reversibly bound to serum macromolecules
(presumably proteins) using 3H-biotin and equilibrium
dialysis. Mean biotin binding was 9.1 + 1.0% in five
women from the control group, 11.5 + 2.8% in five women
from the study group in early pregnancy and 9.0 + 1.4%
in the same five women in late pregnancy. There were
no significant differences among these
We have arrived that marginal biotin deficiency induced
experimentally in adult volunteers, the serum concentration
of biotin was not an early or sensitive indicator of
decreased biotin status. The mean serum concentration
of biotin did not decrease significantly, although concentrations
decreased to values less than the lower limit of normal
in 5 of 10 subjects by d 20 of egg-white feeding, because
biotin bind avidly in avidin which is makes them inactive
and readily excretable.
Several studies of biotin-deficient patients have indicated
that increased urinary excretion of 3-HIA can indicate
reduced tissue activity of methylcrotonyl-CoA carboxylase.
This has been the case whether the deficiency was related
to total parenteral nutrition, egg-white feeding or
inborn errors of biotin metabolism. Biotin deficiency,
the expected decrease in hepatic methylcrontonyl-CoA
carboxylase activity was evident (Mock 1990). It was
also noted that in human studies, tissue deficits were
demonstrated in carboxylase activities of lymphocytes.
The study of marginal biotin deficiency cited above
provided evidence that increased urinary excretion of
3-HIA was an early and sensitive indicator of decreased
biotin status.
The study presented here provides evidence that biotin
status decreases from early to late pregnancy. The most
striking changes were decreased biotin excretion, decreased
BNB excretion, and decreased serum concentration of
biotin. The excretion of 3-HIA already greater than
that of controls in early pregnancy did not further
increase in late pregnancy.
It was also proven that decreased biotin status induced
a teratogenic effect at critical times in the third
trimester of pregnancy. Accordingly, we were particularly
interested in assessing biotin status in early pregnancy.
Except of 3-HIA is significantly increased, suggesting
reduced biotin status. However, the serum concentration
of biotin is normal, suggesting adequate biotin status
occurs in early pregnancy but is not yet reflected in
biotin excretion. For example, some factor might reduce
renal reabsorption of biotin. The observed increased
excretion of BNB could also result such a factor. Eventually,
this biotin wasting should reduce plasma concentration
of biotin and filtered load of biotin, and finally,
renal excretion of biotin. However, how quickly this
might evolve during pregnancy is not clear. Moreover,
the relationship between the serum concentration of
biotin and total body pools of biotin is not known.
Even if this hypothesis and explanation are correct,
the mechanism leading to increased serum concentrations
of biotin are not clear.
This study provides evidence that biotin status decrease
is normal pregnancy. O the basis of increased 3-HIA
excretion and decreased biotin excretion, about half
of a small women appeared to become at least marginally
biotin deficient late in pregnancy. The potential mechanism
for this disturbance in biotin nutrition included an
increased biotin biotransformation to inactive catabolites,
reduced renal retention of biotin or fetal accretion
of biotin. The diagnosis of biotin deficiency could
be confirmed by a biotin intervention study in which
pregnant women with increased 3-HIA are provided oral
supplements of biotin and 3-HIA response is assessed.
