There are two dietary forms of vitamin A, retinol and beta carotene. Retinol is fat soluble and is found in animal products, such as fish liver oils, liver, eggs, butter, cheese and milk. Beta carotene is a water-soluble “precursor” to vitamin A and is found in plant foods such as apricots, carrots, spinach, sweet potatoes, pumpkin, dandelion greens, collards, Swiss chard, oat flakes, cantaloupe and other green and yellow fruits and vegetables. Beta carotene has antioxidant properties above and beyond its ability to provide vitamin A.
Diabetics and those with low thyroid function may have difficulty converting beta carotene into retinol; therefore, they need to get most of their vitamin A from retinol sources.
Vitamin A is involved in immune function, vision, reproduction, and cellular communication. Vitamin A is critical for vision because it is an essential component of the protein “rhodopsin” (a protein that absorbs light in the retinal receptors), and because it supports the normal functioning of the conjunctival membranes and the cornea. Vitamin A also supports cell growth, playing a critical role in the normal formation and maintenance of the heart, lungs, kidneys, and other organs.
One of the early signs of vitamin A deficiency is “xerophthalmia” or “night blindness”, the inability to see in low light or darkness. People with vitamin A deficiency tend to have low iron status, which can lead to anemia. Vitamin A deficiency also increases the risk and severity of infections.
Other symptoms of low vitamin A are:
-
Eyes sensitive to glare, sunlight or bright lights
-
Dry eyes
-
Eyelids red, scaly, dry, swollen
-
Eye inflammations, conjunctivitis
-
Styes on eyelids
-
Get colds or respiratory infections easily
-
Sinus problems
-
Abscesses in ears, mouth or salivary glands
-
Brittle or dry hair
-
Dry, rough or scaly skin
-
Hard ‘goosebumps’ on back of arms
-
Acne, pimples or blackheads
-
Warts
-
Kidney, urinary or bladder infections, burning or itching when urinating
Supplementary ranges for beta carotene, if no retinol is taken: 30,000 - 180,000 I.U.
Supplementary ranges for beta carotene if taken with retinol: 3,000 - 30,000 I.U.