Information on Beta Carotene - Vitamin A

Vitamins are compounds that you must have for growth and health. They are needed in small amounts only and are usually available in the foods that you eat. Beta-carotene is converted in the body to vitamin A, which is necessary for healthy eyes and skin.

Beta carotene, which is found in plants, is a precursor of vitamin A. The body converts beta carotene to vitamin A. It occurs mainly in fruits and vegetables that are deep yellow, orange, or dark green in color, such as carrots, squash, yams, peaches, apricots, spinach, collard or mustard greens, and broccoli. It is an antioxidant, a compound that may prevent cancer-causing substances from damaging DNA. Epidemiologic studies have linked high intake of foods rich in beta carotene and high serum levels of the micronutrient to a reduced risk of cancer, particularly lung cancer. Ordinary cooking does not destroy beta-carotene.

A lack of vitamin A may cause a rare condition called night blindness (problems seeing in the dark). It may also cause dry eyes, eye infections, skin problems, and slowed growth. Your health care professional may treat these problems by prescribing either beta-carotene, which your body can change into vitamin A, or vitamin A for you.

Some conditions may increase your need for vitamin A. These include:

  • Cystic fibrosis
  • Diarrhea, continuing
  • Illness, long-term
  • Injury, serious
  • Liver disease
  • Malabsorption problems
  • Pancreas disease

Claims that beta-carotene is effective as a sunscreen have not been proven. Although beta-carotene supplements are being studied for their ability to reduce the risk of certain types of cancer and possibly heart disease, there is not enough information to show that this is effective.

Beta-carotene may be used to treat other conditions as determined by your doctor.

It is well documented that people who consume diets high in fruits and vegetables have a reduced risk of heart disease and certain cancers. Fruits and vegetables are rich in beta-carotene and other nutrients that may be beneficial.

Vitamins alone will not take the place of a good diet and will not provide energy. Your body needs other substances found in food, such as protein, minerals, carbohydrates, and fat. Vitamins themselves often cannot work without the presence of other foods. For example, some fat is needed so that beta-carotene can be absorbed into the body.

Daily servings of dark green and deep yellow vegetables and tomatoes boost immune response, a preliminary study suggests. If the findings hold up in further research, eating more vegetables rich in beta carotene and related carotenoids--lutein and lycopene--may help people ward off a cold or flu as well as protect against cancer.



After three weeks, the volunteers had a 33 percent increase in immune response as measured by the ability of their T cells to multiply. This is a good measure of immune system function because T cells play a vital role in the immune response to foreign organisms and cancer cells.

As potent antioxidants, these carotenoids are thought to contribute to the lower rates of heart disease, cancer and other diseases of aging among populations that eat a lot of fruits and vegetables.

Reported in the Proceedings of the UJNR Protein Resources Panel, 25th Annual Meeting, 1996, the findings suggest that carotenoid-rich vegetables also stimulate the immune system.

Researchers also found more evidence suggesting carotenes act as antioxidants to protect the body from harmful oxidation that could contribute to heart attack, stroke and cancer. During the low-carotene stints, researchers recorded several biochemical signs of oxidative damage. For example, they found more carbonyl compounds--breakdown products of oxidation--in the volunteers' blood and breath.

Older people who get plenty of beta carotene may have a better chance of preventing virus infections or a cancerous growth. A wealth of epidemiological evidence has linked a high intake of green leafy and deep yellow vegetables--both rich in beta carotene--with lower rates of many types of cancer.

Men over age 65 who took a 50-milligram beta carotene supplement every other day during the 12-year-long study had natural killer cells that were more active than those in their counterparts who got a placebo. Natural killer cells--or NK cells--are the immune system's sentinels, ever on watch for viruses and cancer cells. They recognize an enemy immediately and destroy it, using proteins to punch holes in its outer membrane. This activity is thought to be an important component of cancer prevention. So ARS researchers tested NK cell activity in 59 men in the physicians study.

The beta carotene dosage used in the physicians study is equivalent to eating two regular-size carrots or one and one-half sweet potatoes daily.

Beta-Carotene has been reported to produce regressions in patients with oral leukoplakia, a premalignant lesion. In this multicenter, double-blind, placebo-controlled trial, subjects were given beta-carotene, 60 mg/d, for 6 months. At 6 months, responders were randomized to continue beta-carotene or placebo therapy for 12 additional months. Nutritional intake was assessed using food frequency questionnaires. There was no change in carotenoid intake during the trial. Responders had a lower intake of dietary fiber, fruits, folate, and vitamin E supplements than did nonresponders. In conclusion, the activity of beta-carotene in patients with oral leukoplakia was confirmed. The responses produced were durable for 1 year.

Known Hazards: Use of beta-carotene has been associated with an increased risk of lung cancer in people who smoke or who have been exposed to asbestos. One study of 29,000 male smokers found an 18% increase in lung cancer in the group receiving 20 mg of beta-carotene a day for 5 to 8 years. Another study of 18,000 people found 28% more lung cancers in people with a history of smoking and/or asbestos exposure. These people took 30 mg of beta-carotene in addition to 25,000 Units of retinol (a form of vitamin A) a day for 4 years. However, one study of 22,000 male physicians, some of them smokers or former smokers, found no increase in lung cancer. These people took 50 mg of beta-carotene every other day for 12 years. If you smoke or have a history of smoking or asbestos exposure, you should not take large amounts of beta-carotene supplements for long periods of time. However, foods that are rich in beta-carotene are considered safe and appear to lower the risk of some types of cancer and possibly heart disease.



The results from the ATBC Study and the Beta-Carotene and Retinol Efficacy Trial (CARET) suggest that smokers should avoid taking beta-carotene supplements. The best advice for smokers who want to reduce their risk of lung cancer and many other cancers is still the most direct: Stop smoking.

Yellowing of palms, hands, or soles of feet, and to a lesser extent the face (this may be a sign that your dose of beta-carotene as a nutritional supplement is too high).

  • U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894. Beta-Carotene (Systemic)
  • U.S. Department of Agriculture Agricultural Research Service. - Carotenoids Show Their True Colors - Beta Carotene Boosts Immunity in Elders
  • Garewal HS; Katz RV; Et al. Beta-carotene produces sustained remissions in patients with oral leukoplakia: results of a multicenter prospective trial. Arch Otolaryngol Head Neck Surg 1999 Dec;125(12):1305-10