Functions
- promotes healthy eyes, skin, hair, teeth, and gums
- maintains integrity of epithelial membranes
- maintains resistance to infections
- necessary for formation of rhodopsin and prevention of night blindness
- cancer prevention
Deficiency
Mild
- retarded growth
- increased susceptibility to infection
- increased risk of cataracts
- abnormal function of gastrointestinal, genitourinary, and respiratory tracts due to altered epithelial membranes
- dry, shriveled, thickened skin, sometimes pustule formation
- poor night vision (night blindness)
Severe
- loss of hearing, taste, and / or smell
- nerve damage
- Xerophthalmia, a characteristic eye disease
- other local infections
Characteristics
- fat-soluble
- not destroyed by ordinary cooking temperatures
- destroyed by high temperatures when oxygen is present
- marked capacity for storage in liver
- carotene is a precursor to vitamin A
Good Sources
Natural
- Retinol
- milk fats
- butter, cheese, cream, whole milk
- egg yolks
- liver
- fatty fish
- milk fats
- Carotene
- vegetables
- green leafy
- escarole, kale, spinach, turnip greens, and parsley
- green, yellow, orange, or red
- carrots, yams, squash
- green leafy
- fruits
- yellow and red
- Pumpkin, cantaloupe, mango
- vegetables
Food | Quantity | mcg RAE |
---|---|---|
Egg | 1 medium | 118 |
Milk (non-fat) | 1 cup | 149 |
Nectarine | 1 medium | 50 |
Watermelon | 1 piece | 27 |
Artificial
- irradiated fish oils, including fish liver oil
Recommended Daily Allowances (RDA)
- Males (11 yrs. and older)
- 900 mcg RAE
- 1,000 mcg retinol equivalents
- Females (11 yrs. and older)
- 700 mcg RAE
- 800 mcg retinol equivalents
- Pregnant females
- 1,000 mcg retinol equivalents
- Lactating females
- 1,200 mcg retinol equivalents
- Children
- 400-700 mcg retinol equivalents
- Infants
- 400 mcg retinol equivalents
- Varied values reflect different references
Tolerable Upper Intake Levels (UL)
- Adults (19 to 50 yrs)
- 3000 mcg RAE
- Intakes above UL may lead to negative health consequences.
- nausea and vomiting
- constipation
- headaches
- insomnia
- dry skin
- joint pain
- Excessive supplementation may also cause osteoporosis and increase risk of cancer
- Excessive intake of carotene, from which vitamin A is formed, may produce yellow discoloration of the skin (carotenemia).
Supplementation
- Not recommended, since toxic in high doses.
- Others suggest 5000 to 10000 IUs
- Best taken with choline, essential fatty acids, vitamin C, vitamin D, vitamin E, and Zinc
Also see detailed report of Vitamin A.