Vitamin A

Vitamin A is fat-soluble and has the following functions:

1. It is necessary for day, night and colour vision. In particular, it is essential for night vision, as it makes the visual purple of our eyes.
2. It safeguards skin and mucus membranes of the mouth, throat, gut and lungs thus protecting against infection.
3. It is important in cell growth, reproduction and enhancing the immune system.
4. It is involved in making RNA (Ribo Nucleic Acid), steroid synthesis, and antibody production.

RDA: 5,000-10,000 I.U. is required daily to be effective. The dosage unit is changing to micro-gram and is as follows. 1 retinol equivalent = 1 mcg retinol = 3.33 IU = 6 mcg beta-carotene.

Therapeutic range: 10,000-50,000 I.U.

Safety: Vitamin A is stored in body fat, hence could be toxic at or above 25,000 I.U. The amount to produce toxicity varies with individuals and chronic toxicity can occur taking 25,000 - 1,000,000 IU per day after two years.²⁶ In Australia TGA (Therapeutic & Goods Administration) has placed a warning on usage of vitamin A for above 2,500 IU per day could cause birth defects.

Best sources are the liver, fish liver oils, salmon, cod and halibut.

Indications for vitamin A supplementation are to fight infection, help cell development, and soft tissue and bone growth. It is good for skin conditions like acne, eczema and psoriasis. It is used for cervical dysplasia (pre-cancerous lesion of the cervix), cancer prevention, infertility, sperm production and fibrocystic disease of the breast. It is also prescribed for asthma, allergies, rhinitis, migraine, Crohn’s disease and ulcerative colitis.

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