Vitamin A is a fat-soluble micronutrient that your body uses to support the functions of your skin, immune system and lining tissues. You obtain vitamin A from animal-derived foods. Brightly colored vegetables and some types of fruit supply you with beta carotene and other precursor chemicals that your body converts to vitamin A. Vitamin A deficiency can impair your vision and may cause other signs of impaired organ and tissue function.
Poor Night Vision
Your body requires vitamin A to produce the light-sensitive protein rhodopsin, which enables your eyes to detect low light. If you do not consume adequate amounts of vitamin A or beta carotene, rhodopsin production decreases and your ability to see in low light diminishes. Driving at night may become difficult and dangerous. Reduced night vision is typically the earliest sign of a vitamin A deficiency.
Cloudy, Dry Eyes
Epithelia are tissues that cover your body or line your organs. Vitamin A supports the normal growth and maintenance of epithelial tissues throughout your body, including those of your eyes. Specialized epithelial cells cover the surface of your eyeball and line your eyelids. These tissues do not function properly if you have a vitamin A deficiency, causing severe eye dryness, or xerophthalmia. The normally clear, moist eye tissue becomes cloudy and erodes, potentially leading to blindness unless you receive treatment.
Thick Skin and Rashes
Your skin requires vitamin A to maintain the normal cycle of sloughing old cells and replacing them with new skin cells. Vitamin A deficiency disturbs this process, leading to increased skin thickness. Your skin typically appears rough and dry; it may itch. Rashes may also develop.
Paleness and Shortness of Breath
Vitamin A is one of several vitamins and minerals needed to produce red blood cells. Lack of vitamin A and beta carotene in your diet can lead to a low red blood cell count, or anemia. Common signs and symptoms include paleness, shortness of breath, lack of energy and becoming easily fatigued when you exert yourself.
Frequent, Prolonged Infections
The epithelial linings of your airways, digestive tract and urinary system do not function normally when you lack vitamin A. This can lead to frequent head colds and infections of your lungs, intestines, kidneys and bladder. Your immune system also suffers with vitamin A deficiency, reducing your ability to fight infections when they occur. The time required to recover from an infection, therefore, may be longer than expected.
How Much You Need
You are unlikely to experience a vitamin A deficiency or lack dietary beta carotene unless you are profoundly malnourished or have a medical condition that interferes with intestinal vitamin A absorption. The recommended daily intake for vitamin A is 700 micrograms or 2,310 international units for women and 900 micrograms or 3,000 IU for men. Good dietary sources of vitamin A and beta carotene include carrots, pumpkin, spinach, apricots, cantaloupe, beef and chicken liver, eggs, milk and cheese.
- "The Merck Manual for Healthcare Professionals"; Vitamin A; Larry E. Johnson, M.D., Ph.D.; April 2007
- "Color Atlas of Genetics"; Eberhard Passarge, M.D.; 2007
- Oregon State University: Linus Pauling Institute: Vitamin A; Jane Higdon, Ph.D.; December 2003
- National Heart Lung and Blood Institute: What Are the Signs and Symptoms of Anemia?
- National Institutes of Health: Office of Dietary Supplements: Vitamin A and Carotenoids