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11/29/16
VITAMIN A
Filed under: General
Posted by: @ 2:23 am

Dr.Abhay Kumar Pati, Author, Best Nutrition Inc USA
www.bestnutrition.com, www.nutritionbest.com, www.ayurvedicsupplements.com, www.biotechayur.com

VITAMIN A DESCRIPTION

Vitamin A occurs in two forms: preformed vitamin A, known as retinol, and provitamin A, also known as beta carotene. Vitamin A is also known as “the vision vitamin” for its role in aiding eyesight. Because it is fat-soluble and stored in the liver, it need not be replenished every day.

Vitamin A helps maintain healthy skin, teeth and bones, as well as mucous membranes, such as those in the nose, throat and lungs. It is necessary in the formation of an eye pigment involved in night vision, and is therefore essential for vision in dim light. Vitamin A is needed for proper development of the fetus in the womb.

DEFICIENCY SYMPTOMS

Severe deficiency leads to various physical changes in the eye and will eventually lead to blindness. Marginal deficiency will lead to increased susceptibility to respiratory tract infections and skin problems.

THERAPEUTIC USES

THOSE  WHO MAY NEED TO SUPPLEMENT

RECOMMENDED DIETARY ALLOWANCE

Age Retinol/Vitamin A (mcg/day)
0-12 months 375
 1-3 years  400
 4-6 years  500
 7-10 years  500
 11+ years (male)  1000
 11+ years (female)  800
 Pregnancy  800
 Lactation, 0-6 months  1300
 Lactation, 6-12 months  1200

 

BEST FOOD SOURCES

Food Retinol (mcg/100g)
halibut liver oil 900,000
lamb’s liver 19,900
cod liver oil 18,000
butter 985
margarine 800
cheese, cheddar 363
eggs 190
pig’s kidney 160
milk 56
mackerel 45
beef 10
sardines, canned 7

 

SAFETY

Taken in excess, vitamin A can lead to toxicity because it is stored in the liver. However, it still has a high safety margin in that regular daily intake generally has to exceed 7,500 mcg in women and 9,000 mcg in men before toxic effects are experienced. Vitamin A toxicity is usually fully reversible.  The vitamin A intake of pregnant women should not exceed 3,300 mcg per day (from food and supplements combined) unless directed by a health care professional.

 

INTERACTIONS & CONTRAINDICATIONS

Vitamins A and D (both fat-soluble vitamins) are found together in many food sources, although they are not actually dependent upon one another for their absorption or utilization. A zinc deficiency can affect the function of vitamin A and vice versa. Vitamin A should not be taken with vitamin-A-derived acne medications. The need for vitamin A is decreased if the individual is using the contraceptive pill.

 

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