Vitamin A promotes healthy skin and good
It strengthens immune system
It can help treat acne
How it works
A is needed by the body for the production of rhodpsin, a pigment that
enables us to see in the dark. It is also crucial for keeping the linings of
the mouth and lungs moist, the adequate growth of body tissues, and
maintaining the development of strong bones, a balanced reproductive system,
and healthy skin. It also plays a role in the body's immune response, helping
fight bacterial, viral, and parasitic infections.
Vitamin A is best absorbed together with a little oil or fat in the diet.
Long-term use of the drug cholestyramine, which is prescribed for the
treatment of high cholesterol, can alter the natural balance of vitamin A in
the body. Antacids required for indigestion may also reduce the body's
vitamin A stores, and a lack of the mineral zinc in the diet may lower blood
vitamin A supplements
adult RDA (800mcg) for vitamin A is equivalent to 3 grams of grilled calves'
liver, or eight eggs. The body can also make vitamin A from beta-carotene,
the bright pigment in vegetables and fruit. Vitamin A supplements are usually
oil based and derived from fish oils. Vitamin A is also present in cod liver
Precautions Vitamin A is
stored in the body's fat cells, so excess intakes build up over time and can
become toxic. Doses of 300mg in adults and 100mg in children are harmful,
causing hair loss, vomiting, headaches, bone damage, double vision, and liver
damage. Regular intakes should not exceed 9,000mcg in men and 7,500mcg in
women; the best advice is to not exceed 100 per cent of the RDA. Avoid
combining vitamin A sources - such as multivitamins plus cod liver oil -
which together may contribute to excess intakes. Supplements should be
avoided by pregnant women as intakes of 3,300mcg a day can cause birth
defects in the developing foetus.
Advertisments by sponsors
take this supplement?
on a long-term low-fat diet, or with poor absorption (such as people with
cystic fibrosis), or taking cholestyramine may benefit from this supplement.
Specialist skin doctors may prescribe a course of vitamin A supplements, and
people with the following symptoms may have vitamin A deficiency:
Increased susceptibility to infections
Inability to adjust eyesight to see in the dark
Poor growth in childhood
Dry, scaly skin
Dislike of light
Dull, dry eyes
Follicular hyperkeratosis (bumps on hair follicles
on skin's surface)
Poor development of tooth enamel in children
Psoriasis and acne Psoriasis and acne may improve
from high doses of vitamin A by helping to change the way the skin's surface
is formed. This must be done under a doctor's supervision.
Cancer The action of substances that trigger
cancerous changes to cells in the body may be dampened down if vitamin A is
in good supply. If vitamin A stores are low, supplements may help to prevent
the risk of developing cancer.
Respiratory problems Vitamin A
supplements may reduce the number of respiratory illnesses in children who
regularly suffer this condition.
Glaucoma It is possible that vitamin A
supplements may be beneficial to those with glaucoma if the vitamin is
lacking in the diet.
Measles A course of supplements may dramatically
reduce the risk of measles in children whose diets are poor in vitamin A.
RDA for adults
Top sources of Vitamin A mcg/100g of
Calves' liver 29,730mcg/100g
Egg yolk 535mcg/100g
Cream cheese 385mcg/100g
Whole milk 52mcg/100g