Wednesday, 23 January 2013

Beta-carotene

Beta-carotene

 http://www.umm.edu/altmed/articles/beta-carotene-000286.htm

Overview:

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. 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 getting more antioxidants through 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.

Therapeutic Uses:

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 be at increased risk for conditions such 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 or 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.
Metabolic Syndrome
A study in 2009 found that higher total carotenoid intakes, mainly those of beta-carotene and lycopene, were associated with a lower prevalence of metabolic syndrome, and with lower measures of body fat and triglycerides among middle-aged and elderly men.
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, research has 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.

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, 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 ensure 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 make dosing recommendations.

Adult

  • For general health, 15 - 50 mg (25,000 - 83,000 IU) per day is recommended. Try to get most of this amount in your diet. 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 provide about 3 - 6 mg of beta-carotene.
  • For adults with erythropoietic protoporphyria, a doctor can measure blood levels of beta-carotene and make dosing recommendations.

Precautions:

So far, studies haven'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, except 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. If you are pregnant, breastfeeding, take beta-carotene supplements only under the supervision of your doctor. 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.

Interactions and Depletions:

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 2 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.

Alternative Names:

B-carotene; Betacarotenum; Provitamin A; Trans-beta-carotene
  • Reviewed last on: 12/11/2010
  • Steven D. Ehrlich, NMD, Solutions Acupuncture, a private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network.

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