FOLIC ACID
folic acid
A
vitamin
that is essential for the pro-
duction of red
blood cells
by the
bone
marrow
.
Folic acid is contained in a
variety of foods, particularly liver and
raw vegetables; adequate amounts are
usually included in a norm al diet.
During pregnancy, folic acid is very
important for fetal growth, the devel-
opment of the nervous system, and the
formation of blood cells. The incidence
of
neural tube defects
is reduced if a
woman takes folic acid supplements
before conception and during the first
1 2
weeks of pregnancy.
Folic acid deficiency is a cause of
megaloblastic
anaemia
,
w hich
pro-
duces symptoms such as headaches,
fatigue,
and
pallor.
Deficiency
can
occur during any serious illness or can
be the result of a nutritionally poor
diet, especially in people w ho con-
sume large amounts of alcohol.
folie a deux
A French term that is used to describe
the unusual occurrence of two people
sharing the same psychotic illness (see
psychosis
) .
Often the two people are
closely related and share one or more
paranoid
delusions
.
If the
sufferers
become separated, one of them usually
rapidly
loses
the
symptoms,
w hich
have been imposed by the dominant,
and genuinely psychotic, partner.
folk medicine
Any form of medical treatment that is
based on popular tradition, such as the
charming of warts or the use of copper
bracelets to treat rheumatism.
follicle
A small cavity in the body. For exam-
ple, a
hair
follicle is a pit in the skin
from w hich a single strand of hair
emerges. Another example is an ovar-
ian
follicle,
w hich
is
a
fluid-filled
cavity in the
ovary
in w hich an
ovum
(egg) develops.
follicle-stimulating hormone
A
gonadotrophin hormone
that is pro-
duced by the
pituitary gland
and acts on
the
ovary
or
testis
.
In women, follicle-
stimulating hormone (FSH) causes an
egg follicle to start maturing in the
ovary in the first week of the menstru-
al cycle, ready for
ovulation
.
In men,
FSH stimulates
sperm
production in the
testes. FSH is given medically to treat
certain types of
infertility
.
folliculitis
Inflammation of one or more hair fol-
licles as a result of a
staphylococcal
infection.
Folliculitis can occur almost
anywhere on the skin, but the condition
most commonly affects the neck, arm-
pits, thighs, or buttocks, causing a
boil
;
it may also affect the bearded area of
the face, producing pustules (see
sycosis
barbae
). Treatment of folliculitis is with
antibiotic drugs
.
Because the infection is
easily spread, careful hygiene is im por-
tant, and an affected individual should
wash any clothes worn next to the skin
daily in boiling water until the condi-
tion has cleared up.
fomites
Inanimate objects (for example, bed
linen, clothing, books, or telephone
receivers) that are not in themselves
harm ful but w hich may be capable of
harbouring
harmful
microorganisms
or parasites and, therefore, of convey-
ing an infection from one person to
another. Fomites principally transmit
respiratory infections, such as
influenza
.
The singular form of the word fomites
is “fomes” .
fontanelle
Either one of two membrane-covered
spaces between the bones of a baby’s
skull. At birth, the skull bones are not
yet fully fused, and two soft areas can
be felt through the scalp. These are the
anterior fontanelle, w hich is diamond-
shaped and usually closes up by age 18
months, and the posterior fontanelle,
w hich is triangular and closes up w ith-
in the first two months.
It is normal for the fontanelles to
become tense and bulge out when a
baby cries. Persistent tension at other
times, however, may indicate an abnor-
mality, particularly
hydrocephalus
(the
accumulation of fluid in the skull). A
sunken fontanelle may be a sign of
dehydration
.
If a fontanelle is abnor-
mally large or takes a long time to
close, the cause may be a brain abnor-
mality or a disorder, such as
rickets
,
affecting the skull bones. Early closure
of the fontanelles results in a deform-
ity called
craniosynostosis
.
Occasionally, a third fontanelle is pre-
sent between the other two; this is a
feature of
Down’s syndrome
.
Sometimes a
baby may have extra bones in the ante-
rior fontanelle, but this is not abnormal.
These extra bones fuse into the skull
when the gap between them closes.
Location of the fontanelles
There are two soft areas on the baby’s skull - the
anterior fontanelle is diamond-shaped, the
posterior fontanelle is triangular.
food additives
Any substance that is added to food for
the
purposes
of preservation
or
to
improve its acceptability in terms of
taste, colour, or consistency.
TYPES AND USES
Additives fall into five main groups:
those that preserve food; those that
affect texture; those that affect appear-
ance and taste; added nutrients, such as
vitamins; and miscellaneous additives,
such as rising and glazing agents, flour
improvers,
and anti-foaming
agents.
For further information on the many
different types of food additives, see
the table opposite.
Preservatives, such as sodium nitrate,
are
added
to
food
to
control
the
growth of bacteria, moulds, and yeasts.
Other additives, such as antioxidants,
can improve the keeping quality of
food by preventing any undesirable
chemical changes w ithin it; for exam-
ple, antioxidants prevent rancidity in
some foods containing fat.
Additives that improve the texture of
food
include
thickeners,
emulsifiers,
stabilizers, and gelling agents. Lecithin,
w hich occurs naturally in all animal and
plant cells, is an emulsifier that is added
to margarine to prevent separation.
The appearance and taste of many
foods and drinks may be improved
through the use of colourings, flavour-
ings, sweeteners, and flavour enhancers.
Artificial
sweeteners
,
such as saccharin
and aspartame, may be used instead of
sugar, especially in products that are
aimed at people trying to lose weight.
Many colourings are natural (for exam-
ple, beetroot red).
RISKS
Certain additives may produce an al-
lergic
reaction
in
some
individuals,
although this is relatively rare. Some
substances, particularly food colourings
316
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