What is Vitamin A ?
Vitamin A, is also called retinol, has multiple functions. it is important for growth and development, for the maintenance of the immune system and good vision.Vitamin A is needed by the retina of the eye in the form of retinal, necessary for both low-light and color vision. In addition to helping the eyes adjust to dim light , vitamin A plays an important role in bone growth and metabolism , tooth development, reproduction, cell division, gene transcription, and regulation of the immune function by strengthening it against infections. The skin, eyes, and mucous membranes of the mouth, nose, throat and lungs depend on vitamin A to remain moist and healthy. Vitamin A is also an important antioxidant that may play a role in the prevention of certain cancers.
Deficiency of Vitamin A
Night blindness and very dry, rough skin may indicate a lack of vitamin A. Other signs of possible vitamin A deficiency include decreased resistance to infections, faulty tooth development, and slower bone growth. Since vitamin A is stored in the liver, it may take up to 2 years for signs of deficiency to appear. Xerophthalmia is very rare and usually due to malnutrition. Deficiencies cannot be compensated by postnatal supplementation.Vitamin A deficiency can occur as either a primary or a secondary deficiency. primary deficiency occurs among children and adults.Secondary vitamin A deficiency is associated with chronic malabsorption of lipids, impaired bile production and release, and chronic exposure to oxidants, such as cigarette smoke, and chronic alcoholism.
Good sources of vitamin A
- Cod Liver oil
- Ripe yellow fruits,
- Leafy vegetables,
- Soy milk,
- fortified low-fat spreads
Eating a wide variety of foods is the best way to ensure that the body gets enough vitamin A. The retinol, retinal, and retinoic acid forms of vitamin A are supplied primarily by foods of animal origin such as dairy products, fish and liver. Liver is a particularly rich source of vitamin A, it is advisable to have once in a week, as you may be at risk of having too much vitamin A. Some foods of plant origin contain the antioxidant, beta-carotene, which the body converts to vitamin A. Beta-carotene, comes from fruits and vegetables, especially those that are orange or dark green in color. Vitamin A sources also include carrots, pumpkin, winter squash, dark green leafy vegetables and apricots, all of which are rich in beta-carotene.
How much Vitamin A do you need?
- 0.7mg a day for men
- 0.6mg a day for women
Recent studies indicate that vitamin A requirements may be increased due to hyperthyroidism, fever, infection, cold, and exposure to excessive amounts of sunlight. Those that consume excess alcohol or have renal disease should also increase intake of vitamin A.
Effects on having too much Vitamin A
Symptoms of vitamin A toxicity include dry, itchy skin, headache, nausea, and loss of appetite. Signs of severe overuse over a short period of time include dizziness, blurred vision and slowed growth. Vitamin A toxicity also can cause severe birth defects and may increase the risk for hip fractures.
Daily intake of vitamin A from food and supplements does not exceed 1.5mg. Having more than 1.5 mg allows for toxic levels of vitamin A to accumulate and affect your bones – osteoporosis especially for older people and women. This is where your bone density reduces and you have a higher risk of fractures.If you eat liver every week, do not take supplements that contain vitamin A.If you are pregnant, do not take multivitamins containing vitamin A.