Carrots contain beta-carotene, the precursor of Vitamin A, and are well known for helping you see in the dark.
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Vitamin A may be shown on labels as Retinol. It is often also found in supplements in the form of beta-carotene, its precursor.
1 unit of Retinol is equivalent to 6 units of beta-carotene - ie. a tablet containing 100mcg of Retinol is equivalent to another tablet containing 600mcg of beta-carotene. To avoid confusion, some authorities use RE (Retinol Equivalents) as the unit of measurement. 1RE is equal to 1mcg of Retinol (6mcg of beta-carotene). You may also find labels quoting IU (International Units); 3RE=10IU, so 3mcg Retinol (or 18mcg beta-carotene) is the same as 10IU.
Vitamin A is stored in the liver and kidneys, and is fat-soluble. It is only found in animal products and fish. Beta-carotene, which is converted into Vitamin A in the body, is found in fruit and vegetables, and needs both protein and fat in the diet before it can be used.
Beta-carotene is one of the four main antioxidant nutrients.
Vitamin A is involved in:
sight, night vision
maintaining health of skin (prevents acne and dermatitis)
maintaining health of mucous membranes
fighting infection
bones
helping to prevent anaemia
growth
reproduction
may also reduce breast cancer
A deficiency of Vitamin A results in dry or rough skin, poor hair quality, red itchy eyes, night blindness, problems in bone growth, weak tooth enamel, low resistance to infection, kidney stones, diarrhoea and loss of appetite.
Some studies of Vitamin A have concluded:
Vitamin A causes significant changes in the skin when applied directly. Increases in collagen, DNA, thickness nd elasticity were all seen, resulting in a reduction in the signs of ageing (Retinyl palmitate is preferred to Retinol for this purpose, as it is more stable and is absorbed easily by the skin).
A study by the American Heart Association published on 21 June 2004 showed that higher levels of carotenoids (such as beta-carotene) reduce the risk of ischaemic stroke.
Medically, Vitamin A is used in the treatment of skin cancer, acne, eczema, psoriasis, gastric ulcers and night blindness. Many studies show that Vitamin A is also an effective treatment for hearing loss and tinnitus (ringing in the ears).
Best food sources in order of importance:
Vitamin A
Beta-carotene
Halibut liver oil, Liver, Butter, Cheese, Eggs
Carrots, Dried apricots, Pumpkin, Broccoli, Sweet potatoes, Tomatoes, Kale, Collards, Melon, Peaches and Apricots, Red peppers, Mango and Dark green leafy vegetables
Minimum Recommended intake:
Child 0-1 year
350RE
Child 1-3 years
400RE
Child 4-6 years
450IU
Child 7-9 years
500IU
1RE = 1mcg Retinol
Child 10-12 years
550IU
1RE = 6mcg beta-carotene
Male 13-15 years
700IU
Male 20+
800IU
3RE = 10IU
Female 13+
600IU
Pregnant woman
700IU
Nursing mother
950IU
The maximum recommended intake is 2,250RE (7,500IU) per day. Exceeding this level may cause loss of appetite, dry itchy skin, hair loss, headaches, vomiting, a change in skin colour of the face and palms of the hands to orange. In extreme cases, death can occur (but only after a very long period on a massive overdose).
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