Beta-carotene is a type of pigment found in plants, especially carrots and colorful vegetables. The name beta-carotene is derived from the Latin name for carrot, and it gives yellow and orange fruits and vegetables their rich hues. 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. Vitamin A is needed for good vision and eye health, for a strong immune system, and for healthy skin and mucus membranes. While large 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. That means beta-carotene is considered a safe source of vitamin A. However, too much beta-carotene can be dangerous for people who smoke. (Getting high amounts of either vitamin A or beta-carotene through your diet -- not from supplements -- is safe.)
Like all other carotenoids, beta-carotene is an antioxidant. It protects 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 number of chronic illnesses. There is good evidence that eating more antioxidants in your diet helps boost your immune system, protect against free radicals, and may lower your risk of two types of chronic illness -- heart disease and cancer. But the issue is a little murkier when it comes to taking antioxidant supplements.
Prevention
Population-based studies suggest that people who eat 4 or more daily servings of fruits and vegetables rich in beta-carotene may reduce their risk of developing heart disease or cancer. Foods rich in beta-carotene include those that are orange or yellow, such as peppers, squashes, and carrots.
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 think that may be because the sum total of all the nutrients you eat in a healthy, balanced diet offer more protection than beta-carotene supplements alone.
There is also some evidence that when smokers and people who are exposed to asbestos take beta-carotene supplements, their risk of lung cancer goes up. For now, smokers should avoid taking beta-carotene supplements.
Treatment
Sun Sensitivity
Studies suggest that high doses of beta-carotene may decrease sensitivity to the sun. People with erythropoietic protoporphyria, a rare genetic condition that causes painful sun sensitivity as well as liver problems, are often treated with beta-carotene to reduce sun sensitivity. Under a doctor's guidance, the dose of beta-carotene is slowly adjusted over a period of weeks, and exposure to sunlight gradually increased.
Age-related Macular Degeneration
A major clinical trial, the Age Related Eye Disease Study (AREDS1), found that people who had macular degeneration could slow its progression by taking zinc (80 mg), vitamin C (500 mg), vitamin E (400 mg), beta-carotene (15 mg), and copper (2 mg). Age-related macular degeneration is an eye disease that occurs when the macula, the part of the retina that is responsible for central vision, starts to deteriorate.
Oral leukoplakia
Oral leukoplakia is a condition in which white lesions form in your mouth or on your tongue. It is usually caused by chronic tobacco or alcohol use. One study found that people with leukoplakia who took beta-carotene experienced fewer symptoms than those who took placebo. Because taking beta-carotene might put smokers at higher risk of lung cancer, however, you should not take beta-carotene for leukoplakia without the strict supervision of your doctor.
Scleroderma
People with scleroderma, a connective-tissue disorder characterized by hardened skin, have low levels of beta-carotene in their blood. That has caused some researchers to think beta-carotene supplements may be helpful for people with scleroderma. So far, however, the studies done have not confirmed this theory. For now, it is best to get beta-carotene from foods in your diet and avoid supplements until more studies are done.
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.
So far, studies can't confirm any benefit from beta-carotene supplements alone in preventing cancer. Getting beta-carotene in your diet, along with other antioxidants including vitamins C and E, does seem to protect against some kinds of cancer. However, beta-carotene supplements may increase the risk of heart disease and cancer in those who smoke or drink heavily. This supplement should not be used by heavy smokers or drinkers unless under a doctor's supervision.
Although beta-carotene offers protection from sunlight for people with certain skin sensitivities, it does not protect against sunburn.
Side Effects
Side effects from beta-carotene include:
- Skin discoloration (yellowing that eventually goes away)
- Loose stools
- Bruising
- Joint pain
Pregnancy and Breastfeeding
While animal studies show that beta-carotene is not toxic to a fetus or a newborn, there is not enough data on beta-carotene in humans to know what levels are safe. To be cautious, take beta-carotene supplements only under the supervision of your doctor if you are pregnant or breast-feeding. It's safe to get beta-carotene through the food you eat.
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.
Beta-carotene supplements can interact with the following medications:
Statins -- Taking beta-carotene with selenium and vitamins E and C may decrease the effectiveness of simvastatin (Zocor) and niacin. The same may be true of other statins, such as atorvastatin (Lipitor). If you take statins, talk to your doctor before taking beta-carotene supplements.
Cholestyramine, Colestipol -- Cholestyramine, a medication used to lower cholesterol, can lower levels of dietary beta carotene in the blood 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. Your doctor may monitor your levels of beta-carotene, but taking a supplement usually isn't necessary.
Orlistat -- Orlistat (Xenical or Alli), a weight loss medication, can reduce the absorption of beta-carotene by as much as 30%, thereby reducing the amount of beta-carotene in the body. You may decide to take a multivitamin if you take orlistat. If so, make sure you take it at least two hours before or after you take orlistat.
Other -- In addition to these medications, mineral oil (used to treat constipation) may lower blood concentrations of beta-carotene. Ongoing use of alcohol may interact with beta-carotene, increasing the risk of liver damage.
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