What Is Vitamin A: Beta-carotene & Retinol

Vitamin A is a family of compounds that play an important role in vision, bone growth, reproduction, cell division, and cell differentiation. Two of the most common sources are retinol and beta-carotene. The body stores both retinol and beta-carotene in the liver, drawing on this store whenever more vitamin A is needed.

Retinol

Retinol is sometimes called "true" vitamin A because it is nearly ready for the body to use. Retinol is found in such animal foods as liver, eggs, and fatty fish. It also can be found in many fortified foods, such as breakfast cereals, and in dietary supplements.

Beta-carotene

Beta-carotene is a precursor for vitamin A. The body needs to convert it to retinol or vitamin A for use. Beta-carotene is found naturally in mostly orange and dark green plant foods, such as carrots, sweet potatoes, mangos, and kale.

Causes of Vitamin A

Prevalence of vitamin A deficiency. Source: WHO

The major cause is diets which include few animal sources of pre-formed vitamin A. Breast milk of a lactating mother with vitamin A deficiency contains little vitamin A, which provides a breast-fed child with too little vitamin A.

In addition to dietary problems, there are other causes of vitamin A deficiency. Iron deficiency can affect vitamin A uptake. Excess alcohol consumption can deplete vitamin A, and a stressed liver may be more susceptible to vitamin A toxicity. People who consume large amounts of alcohol should seek medical advice before taking vitamin A supplements. In general, people should also seek medical advice before taking vitamin A supplements if they have any condition associated with fat malabsorption such as pancreatitis, cystic fibrosis, tropical sprue & biliary obstruction.

How Much Vitamin A Do I Need?

Most Americans are getting adequate amounts of vitamin A. The National Center for Health Statistics estimates that, on average, U.S. men and women get about 6,064 IU and 5,256 IU of vitamin A, respectively, each day, which is more than twice the RDA. The Institute of Medicine cautions against daily intakes of retinol above 10,000 IU.

The recommended intakes are listed in International Units (IU) Source: Institute of Medicine, 2001:

Children

1 to 3 1,000 IU
4 to 8 1,333 IU
9 to 13 2,000 IU

Men

3000 IU

Women

Vitamin requirements change for women during pregnancy and lactation

Women 2,330 IU Pregnancy 2,565 IU Lactation 4,335

The body can convert beta-carotene into vitamin A to help meet these requirements. Although there is no RDA for beta-carotene, the National Institutes of Health (NIH) Office of Dietary Supplements recommends eating five or more servings of fruits and vegetables per day, including dark green and leafy vegetables and deep yellow or orange fruits to get appropriate amounts of beta-carotene.

How Does Vitamin A Affect My Bones?

Vitamin A is a family of fat-soluble compounds that play an important role in vision, bone growth, reproduction, cell division, and cell differentiation. Vitamin A is important for healthy bones. However, too much vitamin A has been linked to bone loss and an increase in the risk of hip fracture. Scientists believe that excessive amounts of vitamin A trigger an increase in osteoclasts, the cells that break down bone. They also believe that too much vitamin A may interfere with vitamin D, which plays an important role in preserving bone.

How Can I Make Sure I Get the Right Amount of Vitamin A?

The supplement label provides information about how much vitamin A is provided, in both International Units and as a percentage of the RDA. The list of ingredients will contain information about which forms of vitamin A are included. Other names for retinol include retinyl, palmitate, and retinyl acetate.

These statements have not been evaluated by the Food and Drug Administration. The information provided is intended for educational purposes only and is not intended to diagnose, treat, cure or prevent any disease. As always, seek the advice of a qualified practitioner before using any herbs, supplements or other alternatives to health.