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                Recommended Dietary Allowances (RDA) - USA - Vitamins and Mineral nutrients
              Recommended Dietary Intake of Vitamins and Mineral Nutrients for Germany (DGE*)

Vitamin A (Retinol) und Provitamin A (Carotenoid)

Vitamin A is important for various functions in the body including normal cell division, growth, good vision and an efficient immune system. Carotenoids are powerful antioxidants.

Vitamin A: In-depth

Vitamin A is a fat-soluble vitamin. It is important for growth, reproduction and for keeping the skin healthy.

Vitamin A is indispensable for good vision as it plays a decisive role in the transformation of light into electrical nerve impulse. Vitamin A is used in all vision-related processes.

Vitamin A (retinol) can only be found in a natural form in animal tissue. Plant foods only contain the precursor form of vitamin A which is called beta-carotene along with ca. 300 other carotenes. These carotenoids, (provitamin = vitamin in its precursor form) are converted into vitamin A in the intestinal mucosa if the body requires it. As opposed to vitamin A, unconverted carotenoids have anti-oxidative properties which mean that they destroy free radicals thus decreasing the risk of getting cancer and protecting the skin from UV-radiation.

240 - 540 mg of vitamin A are stored in the body most of which goes to the liver. This amount lasts for several months.

Besides supplying the body with vitamin A, beta-carotene also plays an important role as an antioxidant. Natural sources of beta-carotene can help to decrease the risk of getting certain types of cancer. However, this does not seem to apply to foods added with beta-carotene.

It is important to know that vitamin A is sensitive to oxygen, acid and light. It is not sensitive to heat.

Vitamin A: Requirements, deficiency, oversupply

Recommended intake of vitamin A according to the DGE*

Age

Men

Women

19 - 25

1,0 mg

0,8 mg

25 - 51

1,0 mg

0,8 mg

51 - 65

1,0 mg

0,8 mg

over 65

1,0 mg

0,8 mg

*Deutsche Gesellschaft für Ernährung - a German Nutrition Society.

Vitamin A deficiencies do not occur often in industrialised countries. If they do occur, they are usually linked to alcoholism.

A vitamin A deficiency can lead to night blindness, flaking and drying up of the skin and the mucous membranes.

Overdoses of vitamin A can cause precarious health problems. Exceeding the storage capacity of the liver as a result of an acute of chronic overdose can result in vitamin A poisoning. This can have serious consequences such as headaches, skin changes, bone changes and bleeding. A high consumption of vitamin A during pregnancy can cause birth defects. Pregnant women should therefore not take more than 3000 µg of vitamin A (do not eat liver!).

Carotene is not toxic, even if it is consumed in larger amounts. At worst, it can turn the skin to a yellowish colour.

Antibiotics, laxatives and certain cholesterol lowering medications can inhibit the absorption of vitamin A.

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Vitamin A in food

Vitamin A is only found in animal tissues (e.g. liver, pollock) and animal products (e.g. milk, eggs, butter).

Carotenoids or provitamins are only found in red-orangey or green vegetables (e.g. carrots, tomatoes, broccoli, spinach) which can be converted in the body into vitamin A if need be.

Provitamins are only partly as effective as vitamin A and so for this reason most vitamin tables will show how much vitamin A is needed for the same effect (Retinol equivalent).

Vitamin A in 100 g food:

Liver: 9,500 - 39,100 µg
Curly kale: 1,447 µg
Carrots: 1,700 µg
Smoked eel: 940 µg
Pumpkin: 833 µg
Watercress: 823 µg
Dog roses: 800 µg
Honey dew melon: 783 µg
Savoy cabbage: 783
Lamb's lettuce: 663 µg
Butter: 653 µg
Chicory: 572 µg
Tuna: 450 µg

Units: 1,000,000 µg = 1 g

The nutritional value of beta-carotene in food is dependant on the method of preparation. Beta-carotene is fat-soluble, therefore it is ideal to prepare the meal with a little bit of oil or milk. This also makes the beta-carotene easier for the body to absorb. Beta-carotene cannot be absorbed from raw vegetables such as potatoes. It is therefore recommended to cut carrots into small piece before steaming them briefly.

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The Complete Book of Food Counts, 9th Edition: The Book That Counts It All



Earl Mindell's New Vitamin Bible,
Earl Mindell, Hester Mundis



Prescription for Nutritional Healing, Fifth Edition: A Practical A-to-Z Reference to Drug-Free Remedies Using Vitamins, Minerals, Herbs & Food Supplements, Phyllis A. Balch CNC

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