Beta-Carotene

Other Name(s):

vitamin A, b-carotene, provitamin A

General :

Beta-carotene belongs to a group of chemicals, related to vitamin A, called carotenoids. Their reddish-violet pigment imparts color to plants, which can be seen in some of its food sources such as carrots, sweet potatoes and apricots.

Beta-carotene is a precursor of vitamin A. Beta-carotene is fat soluble, but does not accumulate in the body to toxic levels like vitamin A can. Also, beta-carotene is an important antioxidant with a significant role in maintaining the health of cells.

Main Functions:

Beta-carotene and vitamin A play an important part in the reproductive process and in maintaining healthy skin, eyes, and immune system.

See vitamin A for more information.

Demonstrated Uses:

Beta-carotene provides approximately 50% of vitamin A in the diet. It also provides antioxidant functions.

Taking beta-carotene is a safe way of ensuring adequate levels of vitamin A while avoiding any toxic side effects.

Reasons for Increased Need:

Malnutrition is a leading cause of beta-carotene (and vitamin A) deficiency.

Malnutrition is a leading cause of vitamin A deficiency in many parts of the world. Malabsorption syndromes, such as lactose intolerance, tropical and non-tropical sprue, and cystic fibrosis, may deplete all four fat-soluble vitamins, A, D, E and K.

See vitamin A for more information.

Women who are pregnant or breast-feeding may need to take vitamin supplements, but must consult a physician before doing so.

Claims:

Increased levels of beta-carotene are claimed to reduce the risk of certain types of cancer, heart disease, and stroke. However, studies neither support not reject these claims.

One study has pointed to an increased risk of lung cancer among smokers who increase their intake of beta-carotene.

Recommended Intake:

There is no Recommended Daily Allowance (RDA) or Dietary Reference Intake (DRI) for this vitamin. However, the recommended amounts (Recommended Daily Intake) are indicated below in International Units (IUs).

Group	RDI (IU)
Adults	5000 - 25,000 IU
Children	10,000 or less IU

Food Sources:

Source	Nutrient Content per 100 grams++
Carrots	11000 IU*
Sweet potatoes	8800 IU*
Spinach	8100 IU*
Apricots	IU*
Broccoli	IU*

*IU = International Unit.

++These amounts are for vitamin A.

In general, increasing fruits and vegetables in the diet provides good sources of beta-carotene.

Signs of Deficiency:

Signs of vitamin A deficiency include night blindness, fatigue, skin disorders, and a weakened immune system. Xerophthalmia results from severe vitamin A deficiency and is a leading cause of blindness in the underdeveloped parts of the world.

See vitamin A for more information.

Toxicity:

Beta-carotene is considered safe and does not appear to be toxic in large doses. However, high doses over a long period of time can lead to a condition known as carotenemia in which the skin becomes yellowish orange.

An excess of beta-carotene can pose a risk in individuals who cannot convert beta-carotene to vitamin A. This can be the case with individuals who suffer from hypothyroidism.

Warnings:

There are no known contraindications to beta-carotene.

Medication Interactions:

Orlistat, a new drug for weight loss, has been shown to decrease absorption of both beta-carotene and vitamin E. It is unknown at this time if it reduces absorption of vitamin A.

Patients taking Accutane (isotretinoin), Soriatane (acitretin), or Tegison (etretinate) are advised against using either vitamin A or beta-carotene supplements while on the medication.

See vitamin A for more information.

Web Sites with Additional Information

Click here for a list of reputable Web sites with general information on nutrition.

References:

1. Murray M., Pizzorno J. Encyclopedia of Natural Medicine. Revised 2nd ed. Rocklin, CA: Prima Health; 1998.

2. Balch JF, Balch P. Prescription for Nutritional Healing. 2nd ed. Garden City Park, NJ: Avery Publishing Group; 1997.

3. Lide DR, Frederikse HPR, eds. Handbook of Chemistry and Physics. 75th ed. Boca Raton, FL: CRC Press, Inc.; 1994.

4. Albanes D. Beta-carotene and lung cancer: a case study. Am J Clin Nutr. 1999;69(6):1345S-1350S.

5. Hennekens CH, Buring JE, Manson JE. Lack of effect of long-term supplementation with beta carotene on the incidence of malignant neoplasms and cardiovascular disease. N Engl J Med. 1996;334(18):1145-9.

6. Daviglus ML, Orencia AJ, Dyer AR. Dietary vitamin C, beta-carotene and 30-year risk of stroke: results from the Western Electric Study. Neuroepidemiology. 1997;16(2):69-77.

7. Cooper DA, Eldridge AL, Peters JC. Dietary carotenoids and certain cancers, heart disease, and age-related macular degeneration: a review of recent research. Nutr Rev. 1999;57(7):201-14.