When Can Vitamin A Deficiency Happen?
Vitamin A deficiency rarely occurs in the United States, but it is still a major public health problem in the developing world. At least 3 million children develop xeropthalmia, damage to the cornea of the eye, and 250,000 to 500,000 go blind each year from a deficiency of vitamin A.
Night blindness is one of the first signs of a deficiency. This symptom occurs by making the cornea very dry and promoting damage to the retina and cornea. In ancient Egypt, it was known that night blindness could be cured by eating liver, which was later found to be a rich source of vitamin A.
Vitamin A deficiency diminishes the ability to fight infections.
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.
When there is not enough vitamin A, cells lining the lung lose their ability to remove disease-causing microorganisms. This may contribute to the pneumonia associated with vitamin A deficiency.
There is increased interest in sub-clinical forms of vitamin A deficiency, described as low storage levels of vitamin A that do not cause overt deficiency symptoms. This mild degree of vitamin A deficiency may increase children’s risk of developing respiratory and diarrheal infections, decrease growth rate, slow bone development, and decrease likelihood of survival from serious illness.
Children living in the United States who are considered to be at increased risk for sub-clinical vitamin A deficiency include:
- Toddlers and preschool age children
- Children living at or below the poverty level
- Children with inadequate health care or immunizations
- Children living in areas with known nutritional deficiencies
- Recent immigrants or refugees from developing countries with high incidence of vitamin A deficiency or measles
- Children with diseases of the pancreas, liver, intestines, or with inadequate fat digestion/absorption
Vitamin A deficiency can occur when vitamin A is lost through chronic diarrhea, and through an overall inadequate intake, as is often seen with protein-calorie malnutrition.
Low plasma retinol concentrations indicate depleted levels of vitamin A. This occurs with vitamin A deficiency but also can result from an inadequate intake of protein, calories and zinc.
These nutrients are needed to make Retinol Binding Protein (RBP), which is essential for mobilizing vitamin A from your liver and transporting vitamin A to your general circulation.
Iron deficiency can also limit the metabolism of vitamin A, and iron supplements provided to iron deficient individuals may improve vitamin A nutritive as well as iron status.
Excess alcohol intake depletes vitamin A stores. Also, diets high in alcohol usually do not provide recommended amounts of vitamin A. It is very important for anyone who consumes excessive amounts of alcohol to include good sources of vitamin A in his or her diet.
However, Vitamin A supplementation may not be recommended for individuals who abuse alcohol because alcohol may increase liver toxicity associated with excess intakes of vitamin A.
Medical doctors would need to evaluate this situation and determine the need for vitamin A supplementation.
Who may need extra vitamin A to prevent a deficiency?
Vitamin A deficiency rarely occurs in the United States, but the World Health Organization and the United Nations International Children’s Emergency Fund have issued joint statements about vitamin A and children’s health.
Both agencies recommend vitamin A administration for all children diagnosed with measles in communities where vitamin A deficiency is a serious problem and where death from measles is greater than 1%.
In 1994, the American Academy of Pediatrics recommended vitamin A supplementation for two subgroups of children likely to be at high risk for sub-clinical vitamin A deficiency.
These subgroups were children 6-24 months of age who had been hospitalized with measles and hospitalized children older than 6 months.
Fat malabsorption can promote diarrhea and prevent normal absorption of vitamin A.
This is most often seen with cystic fibrosis, sprue, pancreatic disorders, and after stomach surgery. Healthy adults usually have a reserve of vitamin A stored in their livers and should not be at risk of deficiency during periods of temporary or short term fat malabsorption.
Long-term problems absorbing fat, however, may result in deficiency, and in these instances physicians may advise vitamin A supplementation.
Vegetarians who do not consume eggs and dairy foods need greater amounts of provitamin A carotenoids to meet their need for vitamin A.
It is important for vegetarians to include a minimum of five servings of fruits and vegetables daily and to regularly choose dark green leafy vegetables and orange and yellow fruits to consume recommended amounts of vitamin A.
What is the connection between vitamin A, beta carotene and cancer?
Surveys suggest an connection between diets rich in beta-carotene and vitamin A and a lower risk of some types of cancer.
There is evidence that a higher intake of green and yellow vegetables or other food sources of beta-carotene and/or vitamin A may decrease the risk of lung cancer.
However, a number of studies that tested the role of beta-carotene supplements in cancer prevention did not find it to be protective. In a study of 29,000 men, incidence of lung cancer was greater in the group of smokers who took a daily supplement of beta-carotene.
The Carotene and Retinol Efficacy Trial, a lung cancer chemoprevention trial that provided randomized subjects with supplements of beta-carotene and vitamin A, was stopped after researchers discovered that subjects receiving beta-carotene had a 46% higher risk of dying from lung cancer than those who did not receive beta-carotene.
The Institute of Medicine states that beta-carotene supplements are not advisable for the general population, although they also state that this advice does not pertain to the possible use of supplemental beta-carotene as a provitamin A source for the prevention of vitamin A deficiency in populations with inadequate vitamin A sources.
If your worried about meeting the Recommended Dietary Allowances, why not try supplementation. Here is a website that has great prices on vitamin supplements.
Additional Vitamin Information
- Vitamin Supplements
- Vitamin A Facts
- Vitamin A Foods
- Vitamin A Deficiency
- Vitamin A Overdose
- Vitamin B12 Facts
- Vitamin B12 Deficiency
Vitamin Supplements Guide © 2006
