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Linda Lazarides'
Nutritional Health Bible
an essential reference book for everyone serious about health and nutrition
Treat Yourself with
Nutritional Therapy
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Vitamin A (Retinol)
- Vitamin (fat-soluble)
- UK RNI 700 mcg (2300 iu)
- US RDA 1000 mcg (3300 iu)
Functions
- Eyesight
- Growth
- Immune system
- Mucous membranes
- Normal development of tissues
- Protein synthesis
Good food sources
- Butter
- Cheese
- Fish liver oils
- Liver
- Margarine
Deficiency symptoms
- Acne
- Dandruff
- Dry eyes
- Dry scaly skin
- Frequent infections
- Frequent mouth ulcers
- Poor vision in dim light
Preventing deficiency
Preformed (ready-made) vitamin A is known as
retinol, and can only be obtained from animal foods, where it is usually
found in the fatty portion, as it is a fat-soluble vitamin. The
bioavailability of vitamin A and other fat-soluble vitamins is improved by the consumption of fat or oil as well as protein in the same meal. The consumption of vitamins C and E in the same meal helps to protect vitamin A and therefore also enhances its bioavailability. The presence of a zinc deficiency on the other hand impairs the absorption and utilization of vitamin A. Food irradiation also reduces vitamin A bioavailability.
Vitamin A is said to be very quickly depleted by the presence of
infections, and it may be wise to eat liver more frequently during these
times.
Vegetarians have to rely on their body's ability to convert
pro-vitamin A (beta-carotene) found in many fruits and vegetables - to retinol. Most people probably have no problem with this conversion, with the exception of hypothyroid individuals - those whose thyroid gland is underfunctioning. Common symptoms of hypothyroidism are a tendency to put weight on too easily, and abnormal hair loss.
Comments
Animals store vitamin A in their liver, which is why liver is a good source of retinol - sometimes too good a source. Vitamin A supplements are used in modern intensive farming as a growth promoter, which can increase 20-fold the amount of vitamin A which naturally occurs in an animal's liver. This is why pregnant women are warned against consuming liver regularly, although the problem is less likely to occur with liver from organically-reared animals.
SUPPLEMENTATION
In research studies, Vitamin A supplements have been found to:
- Help cure acne
- Help cure psoriasis
- Help prevent the common cold
- Reduce the rate of complications from measles
- Improve eyesight
- Increase the healing rate of gastric ulcers
Preferred form and suggested intake
- Recommended general health supplementation: 1
teaspoon cod liver oil or 1 capsule halibut liver oil daily.
- For acne, 7,500 iu plus 15 mg zinc daily.
- For dry, scaly skin, 7,500 iu plus 15 mg zinc
daily, plus 1-2 tablespoons of cold-pressed, good quality flax seed oil.
Cautions
It is easier to overdose on fat-soluble vitamins
than others because they are stored in the body rather than excreted.
While death is extremely rare, and single doses of several hundred
thousand iu have been used in short trials without problems, headaches,
nausea and loss of appetite may result from an excessive intake taken
over a long period of time. This is toxic to the liver and can cause
birth defects if consumed by pregnant women.
During pregnancy it is best to eat liver only from organically
reared animals, and to take only minimal supplementation, as from a
moderate multivitamin preparation, or in the form of a little cod liver
oil. Although vitamin A requirements are raised by pregnancy, and birth
defects can be linked with vitamin A deficiency as well as vitamin A
excess, your daily supplementation should not exceed a total of 7,500 iu
while pregnant or if planning pregnancy.
Adapted from the Nutritional Health Bible by Linda Lazarides
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