Food source of vitamin A
Vitamin A in food is found as retinol or as carotenes. Retinol is found exclusively in animal foods including eggs, milk and milk products. Vitamin A is present in the fat portion of whole milk, so it is not found in fat-free milk. Most fat-free milk and dried nonfat milk solids sold in the US are fortified with vitamin A.
Fortified food such as cereal can also be good source.
It is important to regularly eat foods that provide vitamin A or beta-carotene even though your body can store vitamin A in the liver. Stored vitamin A will help meet your needs when your intake from food is low.
Carotenoids are found primarily in plants foods whereas meats, fats and dairy products are reportedly low in carotenoid content. The richest known sources of pro-vitamin A are the palm oils.
Other food sources of carotenoid include vegetables such as carrot, tomato, sweet potato, spinach and other green leafy vegetables and fruits such as mango, papaya watermelon and apricots.
According to DRI committee, a man needs a daily average of about 900 micrograms; a woman needs about 700 micrograms.
Vitamin A deficiency
It is a leading cause of childhood blindness. Although dietary deficiency of vitamin A is rare in North America and Western Europe, it is the leading cause of childhood blindness worldwide, especially in Southeast Asia, parts of Africa and Central and South America.
In countries where immunization programs are not widespread and vitamin A deficiency is common, millions of children die each year from complications of infectious diseases such as measles.
Signs of vitamin A deficiency include night blindness, dry skin, and decreased resistance to infections.
Vitamin A deficiency interacts with other nutrient deficiencies and with infection, worsening respiratory infections and diarrhea and causing countless deaths.
Extremely dry skin, dry hair, sloughing off of skin, and broken fingernails are other common signs of vitamin A deficiency. Vitamin A deficiency also decreases resistance to infections, and may contribute to the pneumonia associated with vitamin A deficiency.
Hypervitaminosis
Symptoms of hypervitaminosis A may occur in the skin, nervous system, musculoskeletal, circulatory systems or in internal organs.
Toxicity varies with the dose, body mass, age, sex, diseases conditions, concurrent drugs being taken and environmental chemical exposure.
Toxicity compromises the tissues just as deficiency does and is equally dangerous.
The many symptoms of vitamin A toxicity include abdominal pain, hair loss, joint pain, stunted growth bone and muscle soreness, cessation of menstruation, nausea, diarrhea, rashes, damage to the liver and enlargement of the spleen.
Vitamin A
