Did You Know Just That Many Cancers Are Linked To A Vitamin Deficiency?
Vitamin
A (retinol and beta-carotene) information page
Vitamin A and carotene can be obtained from either animal
or vegetable sources. The animal form is divided between
retinol and dehydroretinol whereas the vegetable carotene
can be split into four very potent groups - alpha-carotene,
beta-carotene, gamma-carotene and crypto-carotene. With
enough beta-carotene available in the body, the body can
manufacture its own vitamin A.
Vitamin
A is required for
Vitamin A is required for night vision, and for a healthy
skin. It assists the immune system, and because of its antioxidant
properties is great to protect against pollution and cancer
formation and other diseases. It also assists your sense
of taste as well as helping the digestive and urinary tract
and many believe that it helps slow aging.
It
is required for development and maintenance of the epithelial
cells, in the mucus membranes, and your skin, and is important
in the formation of bone and teeth, storage of fat and the
synthesis of protein and glycogen.
Deficiency
of vitamin A
A deficiency of vitamin A may lead to eye problems with
dryness of the conjunctiva and cornea, dry skin and hair,
night blindness as well as poor growth.
Dry
itchy eyes that tire easily are normally a warning of too
little vitamin A. If the deficiency become severe, the cornea
can ulcerate and permanent blindness can follow.
Abscesses
forming in the ear, sinusitis, frequent cold and respiratory
infections as well as skin disorders, such as acne, boils
and a bumpy skin, as well as weight loss might be indicative
of the vitamin being in short supply.
Insomnia,
fatigue and reproductive difficulties may also be indicative
of the vitamin in short supply. Your hair and scalp can
also become dry with a deficiency, especially if protein
is also lacking.
Dosage
The dosage underneath is the Recommended Dietary Allowance
(RDA), but be aware that this dosage is the minimum that
you require per day, to ward off serious deficiency of this
particular nutrient. In the therapeutic use of this nutrient,
the dosage is usually increased considerably, but the toxicity
level must be kept in mind.
Male
5,000 IU per day (1,000 µg equivalent), female 4,000
IU per day (800 µg retinol equivalent), although 10,000
IU per day is normally used in supplementation.
Toxicity
and symptoms of high intake
Dosages exceeding 15,000 IU per day must be taken under
medical supervision. Toxicity can appear in some individuals
at relatively low dosages and the symptoms may include nausea,
dizziness, menstrual problems, skin changes and dryness,
itchiness, irritability, vomiting, headaches and long term
use can cause hair loss, bone and muscle pain, headache,
liver damage, and an increase in blood lipid concentrations.
Pregnant
women must be careful as a high intake of this vitamin can
cause birth defects.
Pro-vitamin
A - beta-carotene does not cause toxicity.
Be
careful if you in the unlikely event run across polar bear
on a menu - 500 gram (about ½ a pound) of polar bear
liver will deliver about 9,000,000 IU to your diet - a very
lethal dose. Headaches, blurred vision, loss of hair, drowsiness
and diarrhea, enlargement of the spleen and liver can all
be indications when your intake is too high.
Best
used with
Take vitamin A with B group vitamins, vitamins C, D and
E, choline, essential fatty acids together with calcium,
phosphorus and zinc for the best results.
When
more may be required
More of this vitamin is required when you consume alcohol,
on a low-fat diet, or a diet high in polyunsaturated fatty
acids, if you smoke or live in a polluted area. It may also
be indicated if you suffer from diabetes or have an under-active
thyroid gland. Be careful of vitamin A in pregnancy.
Enemy
of vitamin A
Retinol is destroyed by light, high temperatures as well
as when using copper or iron cooking utensils. Beta-carotene
rich vegetables and fruit must not be soaked in water for
long periods, since the nutrients can be lost like that.
Other
interesting points
There seems to be no toxicity when ingesting large amounts
of beta-carotene - you might however have a slightly orange
colored skin, as the carotene gets stored in your skin.
Food
sources of vitamin A
Liver, milk, egg-yolk, carrots, dark green leafy vegetables
and yellow fruits are high in vitamin A or beta-carotene.
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