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.

Supporting Research

The Alpha-tocopherol, Beta-carotene Cancer Prevention Study Group. The effect of vitamin E and Beta Carotene on incidence of lung cancer and other cancers in male smokers. N Engl J Med. 1994;330:1029-1035.
Bayerl Ch. Beta-carotene in dermatology: Does it help?Acta Dermatovenerol Alp Panonica Adriat. 2008;17(4):160-2.
Bjelakovic G, Nikolova D,Gluud LL, Simonetti RG, Gluud C. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis. JAMA 2007;297:842-57.
Bjelakovic G, Nikolova D, Simonetti RG, Gluud C. Antioxidant supplements for preventing gastrointestinal cancers. Cochrane Database Syst Rev. 2008 Jul 16;(3):CD004183. Review.
Brambilla D, Mancuso C, Scuderi MR, Bosco P, Cantarella G, Lempereur L, et al. The role of antioxidant supplement in immune system, neoplastic, and neurodegenerative disorders: a point of view for an assessment of the risk/benefit profile. Nutr J. 2008 Sep 30;7:29.
Chan R, Lok K, Woo J. Prostate cancer and vegetable consumption. Mol Nutr Food Res. 2008 Dec 8. [Epub ahead of print]
Elinder LS, Hadell K, Johansson J, Molgaard J, Holme I, Olsson AG, et al. Probucol treatment decreases serum concentrations of diet-derived antioxidants. Arterioscler Thromb Vasc Biol. 1995;15(8):1057-1063. (abstract)
Gabriele S, Alberto P, Sergio G, Fernanda F, Marco MC. Emerging potentials for an antioxidant therapy as a new approach to the treatment of systemic sclerosis. Toxicology. 2000; 155(1-3):1-15.
Gallicchio L, Boyd K, Matanoski G, Tao XG, Chen L, Lam TK, et al. Carotenoids and the risk of developing lung cancer: a systematic review. Am J Clin Nutr. 2008 Aug;88(2):372-83. Review.
Hercberg S, Galan P, Preziosi P. Antioxidant vitamins and cardiovascular disease: Dr Jekyll or Mr Hyde? Am J Public Health. 1999; 89(3):289-291.
Herrick AL, Hollis S, Schofield D, Rieley F, Blann A, Griffin K, Moore T, Braganza JM, Jayson MI. A double-blind placebo-controlled trial of antioxidant therapy in limited cutaneous systemic sclerosis. Clin Exp Rheumatol. 2000;18(3):349-356.
Hu G, Cassano PA. Antioxidant nutrients and pulmonary function: the Third National Health and Nutrition Examination Survey (NHANES III). Am J Epidemiol. 200015;151(10):975-981.
Itsiopoulos C, Hodge A, Kaimakamis M. Can the Mediterranean diet prevent prostate cancer? Mol Nutr Food Res. 2008 Dec 2. [Epub ahead of print]
Jeong NH, et al. Preoperative levels of plasma micronutrients are related to endometrial cancer risk. Acta Obstet Gynecol Scand. 2009;88(4):434-9.
Leo MA, Lieber CS. Alcohol, vitamin A, and beta-carotene: Adverse interactions, including hepatotoxicity and carcinogenicity. Am J Clin Nutr. 1999;69(6):1071-1085.
Liede KE, Alfthan G, Hietanen JH, Haukka JK, Saxen LM, Heinonen OP. Beta-carotene concentration in buccal mucosal cells with and without dysplastic oral leukoplakia after long-term beta-carotene supplementation in male smokers. Eur J Clin Nutr. 1998;52(12):872-876.
Liu C, Wang XD, Mucci L, Gaziano JM, Zhang SM. Modulation of lung molecular biomarkers by beta-carotene in the Physicians' Health Study. Cancer. 2009;115(5):1049-58.
Omenn GS, Goodman GE, Thornquist MD, et al. Risk factors for lung cancer and for intervention effects in CARET, the Beta-Carotene and Retinol Efficacy Trial. J Natl Cancer Inst. 1996;88(21):1550-1559. [abstract]
Physician's Desk Reference. 62nd ed. Montvale, NJ: Medical Economics Company, Inc.; 2007.
Pizzorno JE, Murray MT. Textbook of Natural Medicine, Vol 1. 2nd Edition. Edinburgh, UK: Churchill Livingstone; 1999.
Pryor WA, Stahl W, Rock CL. Beta carotene: from biochemistry to clinical trials. [Review] Nutr Rev. 2000;58(2 Pt 1):39-53.
Roodenburg AJ, Leenen R, van het Hof KH, Weststrate JA, Tijburg LB. Amount of fat in the diet affects bioavailability of lutein esters but not of alpha-carotene, beta-carotene, and vitamin E in humans. Am J Clin Nutr. 2000;71(5):1187-1193.
Sluijs I, Beulens JW, Grobbee DE, van der Schouw YT. Dietary carotenoid intake is associated with lower prevalence of metabolic syndrome in middle-aged and elderly men. J Nutr. 2009;139(5):987-92.
Sweetman, SC. Martindale: The Complete Drug Reference. 35th edition. London, UK; Pharmaceutical Press; 2007.
Utsugi MT, Ohkubo T, Kikuya M, Kurimoto A, Sato RI, Suzuki K, et al. Fruit and vegetable consumption and the risk of hypertension determined by self measurement of blood pressure at home: the Ohasama study. Hypertens Res. 2008 Jul;31(7):1435-43.
West KP, Katz J, Khatry SK, LeClerq SC, Pradhan EK, Shrestha SR, et al. Double blind cluster randomised trial of low-dose supplementation with vitamin A or beta carotene on mortality related to pregnancy in Nepal. The NNIPS-2 Study Group. BMJ. 1999;318(7183):570-575.
on

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)