According to the American Academy of Ophthalmology , vision issues are common in those with vitamin A deficiency. Night blindness may also occur as a result of vitamin A deficiency. This causes the person to be unable to see or have trouble seeing in low light, eventually leading to complete blindness at night.
In severe cases, the eye continues to dry out, and tissues may build up in the cornea. This in turn may lead to the cornea becoming hazy, developing lesions, and being destroyed. Vitamin A plays a key role in immune function. A person with a vitamin A deficiency may experience more frequent infections , as they cannot fight off these infections as easily.
Some people with vitamin A deficiency may notice problems with their skin, such as dryness, itching, and scaling. Some may experience similar issues on the hair and scalp as well.
Vitamin A plays a role in reproduction, and a deficiency may cause infertility and difficulty conceiving a child. Vitamin A plays a part in creating healthy cells. Not having enough of the key vitamin may delay growth or cause children to experience stunted growth or slow bone growth. The cause of vitamin A deficiency is not getting enough vitamin A in the body or having an underlying issue that results in the body not absorbing or utilizing vitamin A effectively.
According to the World Health Organization WHO , vitamin A deficiency is rare in developed nations, such as the United States, and common in developing nations, where people do not have as much access to vitamin A. Young children and pregnant people in low income countries are at the highest risk of severe effects from vitamin A deficiency. Vitamin A plays a significant role in many functions in the body.
There is an important link between vitamin A and vision. In addition to helping create the membranes of the eye and cornea, vitamin A is a key compound of a protein in the body called rhodopsin, which absorbs light in the retina.
Vitamin A also plays a crucial role in cell growth in other areas and helps with the normal formation and functioning of the cells in the heart, lungs, kidneys, and other organs. Learn more about vitamin A and its functions here. There are two forms of vitamin A in the human diet. The first is preformed vitamin A, such as retinol, which comes from animal sources, including meat, fish, and dairy.
The second form is provitamin A carotenoids, such as beta carotene. These compounds are not usable forms of vitamin A as they exist naturally, but the body converts them into a usable form of vitamin A. Both forms of the vitamin will go through an additional metabolization in the body, becoming active retinal and retinoic acid.
GB HealthWatch urges you to consult with a qualified physician for diagnosis and for answers to your personal health questions. If you think you may have a medical emergency, call your doctor or immediately. Free - In Google Play. Your session has timed out. Please log in again. Don't have a GB account? Register here. Such invaders include Microorganisms commonly called germs, such as bacteria, viruses, and fungi Parasites More than half of children with severe vitamin A deficiency may die.
Doctors measure the level of vitamin A in the blood. However, levels do not decrease until the deficiency is severe because the body stores large amounts of vitamin A. If people have problems seeing in the dark, eye tests, such as electroretinography Electroretinography A variety of tests can be done to confirm an eye problem or to determine the extent or severity of an eye disorder.
Each eye is tested separately. In general, angiography involves injecting To help confirm vitamin A deficiency, doctors may give people vitamin A supplements to see whether they relieve symptoms. To help prevent vitamin A deficiency, people should eat dark green leafy vegetables, yellow and orange fruits such as papayas and oranges , carrots, and yellow vegetables such as squash and pumpkin.
Other food sources include milk and cereals that are fortified with vitamin A, liver, egg yolks, and fish liver oils. The carotenoids that give fruits and vegetables their yellow, orange, or red color and that are converted to vitamin A in the body, are best absorbed from cooked or homogenized vegetables served with some fat or oil.
Children who live in developing countries and are at risk of vitamin A deficiency should take vitamin A supplements. People who have vitamin A deficiency are given high doses of vitamin A, usually by mouth, for several days, followed by lower doses until vision and skin improve. Infants should not be given high doses repeatedly because such doses can be toxic. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world.
The Merck Manual was first published in as a service to the community. Learn more about our commitment to Global Medical Knowledge. This site complies with the HONcode standard for trustworthy health information: verify here. Common Health Topics. Commonly searched drugs. Test your knowledge. Chromium is a mineral required in small quantities by the body, and it enables insulin to function.
People with which of the following disorders should avoid taking chromium?
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