"Vitamin A - Necessary For Good Vision But Does It Prevent Cancer?"
As it dissolves in fat, Vitamin A is considered to be a fat-soluble vitamin. In 1913 it was the first fat-soluble vitamin to be discovered.
It consists of two forms, the preformed retinoids and the provitamin carotenoids. It is also called retinol as it produces pigments in the retina of the eye.
Preformed retinoids are used by the body immediately and are derived from fish oil.
Provitamin carotenoids are considered precursors to Vitamin A and are converted into an active form of this vitamin in the body. Provitamin carotenoids are typically found in plant sources.
In the United States, deficiencies of this vitamin are rare.
However it is considered to be a major health problem in developing countries and may affect some 120 million children worldwide.
Anemia is common in babies in these countries and has many causes, one of which is a lack of Vitamin A.
Additionally, in these countries, a deficiency of retinol is also a major cause of Childhood Blindness.
Metabolic Functions
It is best known for the role it plays in healthy vision but it plays other important metabolic roles as well.
For example, it is needed for the development of strong bones and teeth, skeletal and soft tissues, and the mucous membranes and skin.
It stimulates the immune system possibly because of the effect it has on the Thymus gland. It stimulates the growth of this gland, minimizing shrinkage normally occuring as an individual ages.
This is one of several vitamins that are considered to be Asthma home remedies. However, research in this area has been mixed.
A healthy Thymus is essential for a vigorous immune system.
It is found to increase our resistance to infectious diseases. For almost every infectious disease studied, a deficiency of Vitamin A has been found to increase the severity and frequency of diseases.
Several studies have shown a decrease in the mortality rate of malnourished children from diseases such as Measles by simply supplementing their diets with additional retinol.
Here again, this protective quality is probably related to its effectiveness in insuring normal functioning of the immune system.
It helps to maintain the outer linings of the eye, the urinary tract, and the respiratory and digestive tracts. If these areas break down, it becomes very easy for bacteria to enter the body and cause an infection.
Protection From Cancer and Heart Disease?
Vitamin A was once thought to provide protection from Cancer.
However, in a recent study of 29,000 male smokers, it was found those individuals receiving supplementation of beta-carotene and vitamin A were 46 percent more likely to develop Lung Cancer.
Preliminary research suggests retinol may help those individuals that already have Coronary Heart Disease.
The American Heart Association doesn't recommend supplementation with this vitamin for these individuals until more research is done.
Other Conditions
Google news reports the University of Michigan has found Vitamin A, along with vitamins C, E, and the mineral Magnesium may protect against hearing loss.
In animal studies, guinea pigs given those vitamins an hour before exposing them to loud noise were protected from hearing loss.
It is thought to be a very important vitamin for pregnant women.
Pregnant women lacking in this vitamin may experience night blindness, problems in the placenta; possibly resulting in a low birth weight of her newborn child.
Recent research has found this vitamin may be helpful in preventing some birth defects.
However, if taken in doses greater than 5,000 IUs, it may contribute to birth defects in women that are pregnant.
Good food sources of retinol are broccoli, eggs, chicken, turkey, liver, and pork.
Carrots do not contain this vitamin but contain beta-carotene which is converted into retinol after consumption.
Dosage
Infants up to 1 year old - 1,250 IU per day
Children 1 to 3 years old - 1,333 IU per day
Children 4 to 6 years old - 1,667 IU per day
Children 7 to 10 years old - 2,333 IU per day
Males 11 years and older - 3,333 IU per day
Females 11 years and older - 3,333 IU per day
Pregnant and breast-feeding women 1st 6 months - 4,333 IU per day
Pregnant and breast-feeding women 2nd 6 months - 4,000 IU per day
Most people consuming a normal diet do not need supplementation with this vitamin unless they have problems absorbing food. Cautions and Contraindications
If your eyes are dry and itchy, that may indicate a deficiency in retinol.
Consumption of large amounts of this vitamin may lead to Jaundice, Headaches, Nausea, and may damage your red blood corpuscles.
Talk to your physician if you are pregnant, breast-feeding or are planning on becoming pregnant before taking this vitamin.
Do not take it without talking to a physician if you are taking:
Targretin(R)
Accutane(R)
Blood thinners such as Coumadin(R)
Soriatane(R)
Tetracycline antibiotics such as Minocycline, Tetracycline and Doxycycline
Vesanoid(R)
Colestid(R)
Side Effects
Stop taking it if you experience any of the following side effects:
As it dissolves in fat, Vitamin A is considered to be a fat-soluble vitamin. In 1913 it was the first fat-soluble vitamin to be discovered.
It is found to increase our resistance to infectious diseases. For almost every infectious disease studied, a deficiency of Vitamin A has been found to increase the severity and frequency of diseases.
