Focus On: Vitamin A
WHAT IT IS: Vitamin A is a group of fat-soluble retinoids. (It is known as a retinoid because vitamin A is what produces the pigments in the retina of the eye.) There are two forms of vitamin A: preformed vitamin A and provitamin A carotenoids like beta-carotene and lycopene. Provitamins are precursors, something the body converts to a vitamin.
[ Benefits ]
Vitamin A comes with a host of benefits. This vitamin will form and maintain healthy skin, teeth, mucous membranes, and soft tissue. Vitamin A is also used for improving vision and eye disorders, skin conditions, ulcers, diabetes, gum disease, protecting the skin against UV radiation, and boosting the immune system. For women, this vitamin helps with heavy menstrual periods, PMS, yeast infections, and fibrocystic breast disease.
[ Sources ]
Preformed vitamin A comes from animal sources like dairy products, eggs, kidneys, and liver. Provitamin A carotenoids come from vegetable sources that are dark or yellow, like carrots, butternut squash, sweet potatoes, and dark leafy greens.
[ Recommended Dosage ]
0-6 months: 400 mcg/day (1,300 IU)
7-12 months: 500 mcg/day (1,650 IU)
1-3 years: 300 mcg/day (1,000 IU)
4-8 years: 400 mcg/day (1,300 IU)
9-13 years: 600 mcg/day (2,000 IU)
Males 14+: 900 mcg/day (3,000 IU)
Females 14+: 700 mcg/day (2,300 IU)
[ Warnings ]
Preformed vitamin A is rapidly absorbed and slowly cleared from the body. Long-term overconsumption can result in dry, itchy skin; loss of appetite; dizziness; cerebral edema; and bone and joint pain. The Linus Pauling Institute recommends taking a multivitamin with no more than 2,500 IU of preformed vitamin A (usually labeled vitamin A acetate or vitamin A palmitate) and no more than an additional 2,500 IU of supplemental beta-carotene.
Zinc deficiency will interfere with vitamin A metabolism. Deficiency in vitamin A can result in xerophthalmia (dry eye), night blindness or total blindness, skin disorders, infections, and respiratory disorders. Vitamin A deficiency can also exacerbate iron deficiency (anemia). This is more common in developing countries.