Beta-carotene
B-carotene; Betacarotenum; Provitamin A; Trans-beta-carotene
Beta-carotene is a pigment found in plants that gives them their color. The name beta-carotene is derived from the Latin name for carrot. It gives yellow and orange fruits and vegetables their rich hues. Beta-carotene is also used to color foods such as margarine.
In the body, beta-carotene converts into vitamin A (retinol). We need vitamin A for good vision and eye health, for a strong immune system, and for healthy skin and mucous membranes. Taking big doses of vitamin A can be toxic, but your body only converts 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 from food, not from supplements, is safe.)
Beta-carotene is an antioxidant. It protects the body from damaging molecules called free radicals. Free radicals damage 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 from foods helps boost your immune system, protect against free radicals, and may lower your risk of heart disease and cancer. But the issue is a little more complicated when it comes to taking antioxidant supplements.
Therapeutic Uses
Prevention
Studies that look at big groups of people suggest that those 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. Other preliminary studies suggest that eating foods rich in beta-carotene reduces the risk of Sporadic ALS (Lou Gehrig Disease). Foods rich in beta-carotene include those that are orange or yellow, such as peppers, squashes, and carrots.
However, a few studies have found that people who take beta-carotene supplements may have a higher risk for conditions such as cancer and heart disease. Researchers think that may be because the total of all the nutrients you eat in a healthy, balanced diet gives more protection than just 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 not take beta-carotene supplements.
Treatment
Sun Sensitivity
Studies suggest that high doses of beta-carotene may make people with a particular condition less sensitive 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 care, the dose of beta-carotene is slowly adjusted over a period of weeks, and the person can have more exposure to sunlight.
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 happens when the macula, the part of the retina that is responsible for central vision, starts to break down. Use this regimen only under a doctor's supervision.
Metabolic Syndrome
In one study of middle-aged and older men, those who ate more foods with carotenoids, mainly beta-carotene and lycopene, were less likely to have metabolic syndrome. Metabolic syndrome is a group of symptoms and risk factors that increase your chance of heart disease and diabetes. The men also had lower measures of body fat and triglycerides, a kind of blood fat.
Oral leukoplakia
People with oral leukoplakia have white lesions in their mouths or on their tongues. It is usually caused by years of smoking or drinking alcohol. One study found that people with leukoplakia who took beta-carotene had 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 on your own. Ask your doctor if it would be safe for you.
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, research has not confirmed that theory. For now, it is best to get beta-carotene from foods in your diet and avoid supplements until more studies are done.
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 more intense the color of the fruit or vegetable, the more beta-carotene it has.
Dosage and Administration
Beta-carotene supplements are available in both capsule and gel forms. Beta-carotene is fat-soluble, so you should take it with meals containing at least 3 g of fat to ensure absorption.
Pediatric
- Children should eat a healthy diet to make sure they get enough beta-carotene.
- For children younger than 14 with erythropoietic protoporphyria (see Treatment section for brief description of this condition), your doctor can measure blood levels of beta-carotene and tell you the right dose.
Adult
- There is no Recommended Daily Allowance of beta-carotene. Some doctors may prescribe between 10,000 IU per day up to 83,000 IU. Try to get most of your daily dose from the foods you eat. Eating more fruits and vegetables will ensure you get enough beta-carotene, and will also give you the added benefits of other nutrients and antioxidants.
- Eat 5 or more servings of fruits and vegetables every day to get about 3 to 6 mg of beta-carotene.
- For adults with erythropoietic protoporphyria, a doctor can measure blood levels of beta-carotene and tell you the right dose.
Precautions
So far, studies have not confirmed that beta-carotene supplements by themselves help prevent cancer. Eating foods rich in beta-carotene, along with other antioxidants, including vitamins C and E, seems to protect against some kinds of cancer. However, beta-carotene supplements may increase the risk of heart disease and cancer in people who smoke or drink heavily. Those people should not take beta-carotene, except under a doctor's supervision.
Beta-carotene reduces sun sensitivity for people with certain skin problems, but 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 information to know what levels are safe. If you are pregnant or breastfeeding, take beta-carotene supplements only if your doctor tells you to. It is 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.
Interactions and Depletions
Beta-carotene supplements can interact with the following medications:
Statins: Taking beta-carotene with selenium and vitamins E and C may make simvastatin (Zocor) and niacin less effective. The same may be true of other statins, such as atorvastatin (Lipitor). If you take statins to lower cholesterol, talk to your doctor before taking beta-carotene supplements.
Cholestyramine and Colestipol: Cholestyramine, a medication used to lower cholesterol, can lower levels of dietary beta-carotene in the blood by 30 to 40%, according to one study. Colestipol, a cholesterol-lowering medication similar to cholestyramin, may also reduce beta-carotene levels. Your doctor may monitor your levels of beta-carotene, but you do not usually need to take a supplement.
Orlistat: Orlistat (Xenical or Alli), a weight loss medication, can reduce the absorption of beta-carotene by as much as 30%, meaning your body would get less beta-carotene. You may want to take a multivitamin if you take orlistat. If so, make sure you take it at least 2 hours before or after you take orlistat.
Other: In addition to these medications, mineral oil (used to treat constipation) may lower blood levels of beta-carotene. Ongoing use of alcohol may interact with beta-carotene, increasing the risk of liver damage.
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