Vitamin A is a fat-soluble vitamin that is broken down into two categories

The functions:

• Helps regulate the immune system to prevent and fight infections
• Helps form and maintain healthy teeth, skin, and tissues
• Produces the pigments in the retina of the eye
• Promotes good vision

How much do I need to consume?

The Recommended Dietary Allowances (RDA) for vitamin A is listed as International Units (IU) of Retinol Activity Equivalents (RAE). This is done to account for the different actions of both forms.

RDA for A:

It can be found in animal and plant foods. The animal food sources are better absorbed and used by the body than the plant sources. There are also many foods that are fortified and enriched with vitamin A.

The content of A in animal and plant foods (from beta-carotene):

It is stored in the liver, so there is a supply that can be used during short-term periods when intake is not adequate to meet your needs. People with medical conditions that interfere with the absorption of this vitamin may need to take a supplement. These conditions include celiac disease, Crohn’s disease, inflammatory bowel disease, and pancreatic disorders. Because this vitamin can be toxic at high levels, it’s best to discuss supplements with your physician.

What happens if I don’t have enough?

Early vitamin A deficiency leads to impaired night vision, and advanced vitamin A deficiency can lead to corneal ulcers, xerophthalmia (dry eye), scarring, night blindness, or total blindness. In developing countries, vitamin A deficiency is an important cause of blindness among children. Children with vitamin A deficiency are also more likely to develop diarrhea and respiratory infections than children who are not vitamin A deficient. This deficiency is rare among healthy adults in the United States.  Vitamin A deficiency can also be a problem for people with Crohn’s disease, celiac disease, pancreatic disorders, and people who do not consume animal foods.

Is there such a thing as too much?

Hypervitaminosis A is when excess amounts are being stored in your body. The harmful effects of hypervitaminosis A are birth defects, the reduced bone density that may result in osteoporosis, central nervous system disorders, and liver abnormalities. Acute toxicity may result from consuming very large quantities of vitamin A over a short period of time. The symptoms are nausea, vomiting, irritability, drowsiness, altered mental status, anorexia, abdominal pain, blurred vision, muscle pain with weakness, and/or a headache. Elderly people and people who drink alcohol heavily are more susceptible to vitamin A toxicity.

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.”