Fact Sheet

Vitamin A

The deep yellow pigment in most fruits and vegetables can be attributed to Beta-carotene, the precursor to Vitamin A. Beta-carotene can be metabolised to vitamin A in the human body but only one sixth of dietary beta-carotene is converted to Vitamin A. The best source of Vitamin A is fish and animal products: liver, oily fish – such as halibut, herring, tuna, pilchards and sardines. Here are some important functions of vitamin A:

Deficiency

Severe vitamin A deficiency leads to various physical changes in the eye and eventually leads to blindness. A marginal vitamin A deficiency will lead to increased susceptibility to respiratory tract Infections and skin problems.

Benefits

Vitamin A has also been used successfully in the treatment of certain Skin conditions, e.g. Acne and Psoriasis (1,2).

Vitamin A & Asthma

Use of vitamin A supplements have been shown to be beneficial to respiratory tract infections. The use of Vitamin A with vitamins C & E are a good combination for asthma prevention.

Sources of Vitamin A

The main sources of vitamin A in the diet are animal products: milk, fortified margarines, cheese, egg yolk, liver, oily fish – such as herring, tuna, pilchards and sardines. Vitamin A (as beta-carotene) is found in carrots, tomatoes, red peppers, green leafy vegetables, mangoes, apricots, broccoli, sweet potatoes. Table 1 shows the animal foods and vitamin A. These are better sources for vitamin A since no conversion is required by the body. Fruits and vegetables are listed in Table 2, but note the available vitamin A content is only one sixth the beta-carotene level. Diabetics are incapable of converting carotene to vitamin A.

Table 1: Animal foods and vitamin A content:

Food (i.u./100g)
Halibut liver oil 4000000
Cod liver oil 200000
Liver (sheep) 45000
Liver (pig) 5000
Liver (calf) 4000
Butter 3500
Cheese (whole fat) 1500
Eggs 1100
Salmon- canned 250
Milk 150
Herrings 100
Beef 20
Sardines canned 7

Table 2: Fruits and vegetables and beta-carotene + available Vitamin A.

Food (i.u. beta-carotine/100g) (i.u. available vitamin A/100g)
Carrots (mature) 20000 3300
Spinach 13000

2200

Beet leaves 11000 1800
Carrots (young) 10000 1700
Cress 8000 1300
Kale 8000 1300
Sweet potato 6000 1000
Watercress 5000 830
Apricot 2000 330
Lettuce 2000 330
Tomato 1200 200
Peach 800 130

References

1. Futoryan T, Gilchrest BA. Retinoids and the skin. Nutr Rev, 52;9:299-310, 1994.
2. Fleischer AB Jr et al. Alternative therapy is commonly used within a population of patients with Psoriasis. Cutis, 58;3:216-220, 1996.
3. Tables 1 & 2 data extracted from "Give Asthma the Big A" Marian Shepherd Slee.

 

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