Vitamin A

Retinol, Provitamin, Carotene

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

Vitamin A

Natural

  • Retinol
    • milk fats
      • butter, cheese, cream, whole milk
    • egg yolks
    • liver
    • fatty fish
  • Carotene
    • vegetables
      • green leafy
        • escarole, kale, spinach, turnip greens, and parsley
      • green, yellow, orange, or red
        • carrots, yams, squash
    • fruits
      • yellow and red
      • Pumpkin, cantaloupe, mango
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

Also see detailed report of Vitamin A.

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