Beta-carotene
Also listed as: B-carotene; Betacarotenum; Provitamin A; Trans-beta-carotene
Overview
Beta-carotene, derived from the Latin name for carrot, belongs to a family of natural chemicals known as carotenes or carotenoids. Members of this family include lycopene, astaxanthin, and zeaxanthin. Widely found in plants, carotenes give yellow and orange fruits and vegetables their rich colors. Beta-carotene is also used as a coloring agent for foods such as margarine.
Beta-carotene is converted to vitamin A (retinol) by the body. While excessive amounts of vitamin A in supplement form can be toxic, the body will convert only as much vitamin A from beta-carotene as it needs. This feature makes beta-carotene a safe source of vitamin A.
Like all other carotenoids, beta-carotene is an antioxidant. Consuming foods rich in beta-carotene appears to protect the body from damaging molecules called free radicals. Free radicals cause damage to cells through a process known as oxidation. Over time, this damage can lead to a variety of chronic illnesses. Some studies suggest that dietary intake of beta-carotene may reduce the risk of two types of chronic illness -- heart disease and cancer. Supplementation, however, is more controversial. See discussion in the section that follows.
Therapeutic Uses
Prevention
Population-based studies suggest that groups of people who eat 4 or more daily servings of fruits and vegetables rich in beta-carotene may have less of a chance of developing heart disease or cancer. Foods rich in beta-carotene include those that are orange or yellow, such as peppers, squashes, and carrots.
Interestingly, however, a few studies indicate that people who take beta-carotene supplements may actually be at an increased risk for such conditions as cancer and heart disease. Researchers speculate that multiple nutrients consumed in a healthy, balanced diet may be more protective than beta-carotene supplements alone.
Treatment
Sun Sensitivity
Studies suggest that high doses of beta-carotene may decrease sensitivity to the sun. This is particularly helpful for people with skin conditions caused by sunlight exposure, such as erythropoietic protoporphyria, a condition characterized, in part, by development of hives or eczema upon exposure to the sun. Under the guidance of an appropriate health care provider, the oral supplement dose of beta-carotene is slowly adjusted over a period of weeks, and exposure to sunlight gradually increased.
Scleroderma
Because people with scleroderma, a connective-tissue disorder characterized by hardened skin, have low levels of beta-carotene in their blood, some researchers speculate that beta-carotene supplements may be beneficial for those with the condition. Due to methodological flaws in the studies that have been conducted to date, however, research has not confirmed this theory. At this time, it is best to obtain beta-carotene from dietary sources and avoid supplementation until more information is available.
Dietary Sources
The richest sources of beta-carotene are yellow, orange, and green leafy fruits and vegetables (such as carrots, spinach, lettuce, tomatoes, sweet potatoes, broccoli, cantaloupe, and winter squash). In general, the greater the intensity of the color of the fruit or vegetable, the more beta-carotene it contains.
Dosage and Administration
Beta-carotene supplements are available in both capsule and gel forms. Beta-carotene is fat-soluble and, therefore, should be taken with meals containing at least 3 g of fat to ensure absorption.
Pediatric
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For children younger than 14 with erythropoietic protoporphyria (see Treatment section for brief description of this condition), 30 - 150 mg per day (50,000 - 250,000 IU) in single or divided oral doses for 2 - 6 weeks is recommended. The supplement may be mixed with orange or tomato juice to facilitate administration. In the case of this sun-sensitive condition, a doctor can measure blood levels of beta-carotene and adjust the dose accordingly.
Adult
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For general health, 15 - 50 mg (25,000 - 83,000 IU) per day is recommended.
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For adults with erythropoietic protoporphyria, 30 - 300 mg (50,000 - 500,000 IU) per day for 2 - 6 weeks is recommended. A health care provider can measure blood levels of beta-carotene and adjust the dose accordingly.
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It is recommended to eat five or more servings of fruits and vegetable every day. This level of intake of fruits and vegetables provides approximately 3 - 6 mg of beta-carotene.
Precautions
Beta-carotene offers protection from cancer only when other important antioxidants, including vitamins C and E, are present in the diet. Since beta-carotene may increase the risk of heart disease and cancer in those who smoke or drink heavily, this supplement should be used with caution, if at all, by heavy smokers or drinkers.
Although beta-carotene affords protection from sunlight for people with certain skin sensitivities, it does not protect against sunburn.
Side Effects
Side effects from beta-carotene include:
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Skin discoloration (yellowing that eventually goes away)
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Loose stools
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Bruising
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Joint pain
Pregnancy and Breastfeeding
While animal studies indicate beta-carotene is not toxic to a fetus or a newborn, there are no human studies to confirm these findings. The supplement may pass into breast milk, but no information on the safety of its use during breastfeeding has been reported. Therefore, while pregnant or breastfeeding, beta-carotene supplements should only be used under the guidance of a physician or other appropriately trained specialist.
Pediatric Use
Side effects in children are the same as those seen in adults.
Geriatric Use
Side effects in older adults are the same as younger adults.
Interactions and Depletions
People taking the following medications should avoid beta-carotene supplements:
Cholestyramine, Colestipol
Cholestyramine, a medication used to lower cholesterol, can lower blood concentrations of dietary beta carotene by 30 - 40 %, according to a 3-year study in Sweden. Colestipol, a cholesterol-lowering medication similar to cholestyramin, may also reduce beta-carotene levels.
Orlistat
You should not take beta-carotene with orlistat, a weight loss medication, because orlistat can reduce the absorption of beta-carotene by as much as 30 %, thereby reducing the amount of this nutrient in the body. If you must take both orlistat and beta-carotene supplements, you should separate the time between taking the medication and the supplements by at least 2 hours.
Other
In addition to these medications, mineral oil (used to treat constipation) may lower blood concentrations of beta-carotene and ongoing use of alcohol may interact with beta-carotene, increasing the likelihood of liver damage.
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Review Date:
11/9/2006
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Reviewed By: Ernest B. Hawkins, MS, BSPharm, RPh, Health Education Resources; and Steven D. Ehrlich, N.M.D., private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network.
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