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beta carotene

 
Dictionary: be·ta car·o·tene  be·ta-car·o·tene ('tə-kăr'ə-tēn', bē'-) pronunciation
 
also n.

The isomeric form of carotene that is widely distributed in nature and most efficiently converted to vitamin A by the body.


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Food and Fitness: beta-carotene
 

A nutrient converted by the body into vitamin A. Beta-carotene is an antioxidant and therefore may offer some protection against certain cancers and other diseases. Foods rich in beta-carotene include orange fruits and vegetables such as apricots, cantaloupes, and carrots, as well as leafy green vegetables such as broccoli and spinach. Beta-carotene is not toxic like vitamin A, but excessive intake may give the skin a yellow hue. See also carotenes.

 

[BAY-tuh KEHR-uh-teen] One of the most important and abundant of the carotenes, a portion of which the liver converts to vitamin A. It should be noted, however, that while excess vitamin A can be toxic to the body, residual beta carotene is quickly eliminated. Scientists now believe that beta carotene is a powerful antioxidant with properties that can contribute to reducing cancer and heart disease. It's found in vegetables like carrots, broccoli, squash, spinach and sweet potatoes. Beta carotene's orange-yellow pigment is also used as a coloring in foods like butter and margarine.

 
Drug Info: Beta-Carotene
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Brand names: A-Caro-25, B-Caro-T®, Caroguard®

Chemical formula:



Beta-Carotene (Vitamin A) Oral capsule

What is this medicine?

BETA-CAROTENE is changed into vitamin A in the body. It is added to a healthy diet to prevent or treat low vitamin A levels.

This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of the following conditions:
• high levels of vitamin A in the body
• kidney disease
• liver disease
• an unusual or allergic reaction to vitamin A, other medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding

How should I use this medicine?

Take this medicine by mouth with a glass of water. Follow the directions on the package or prescription label. For best results take this vitamin with food. Take your medicine at regular intervals. Do not take your medicine more often than directed.

Talk to your pediatrician regarding the use of this medicine in children. While this drug may be prescribed for selected conditions, precautions do apply.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.
NOTE: This medicine is only for you. Do not share this medicine with others.

What if I miss a dose?

This does not apply.

What may interact with this medicine?

cholestyramine
• mineral oil
orlistat
• other vitamin A supplements

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medicine?

Follow a healthy diet. Taking a vitamin supplement does not replace the need for a balanced diet. Some foods that have beta-carotene naturally are green and yellow fruits and vegetables.
Too much of this vitamin can be unsafe. Talk to your doctor or health care provider about how much is right for you.

Any yellow color that develops in the hands, feet or face will disappear within 1 to 2 weeks after you stop taking this vitamin.

What side effects may I notice from receiving this medicine?

Side effects that you should report to your doctor or health care professional as soon as possible:
• allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
• breathing problems
• chest pain, tightness
• joint pain
• dizziness
• unusual bleeding or bruising

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
• diarrhea
• yellowing of the face, palms of the hands, soles of the feet

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medicine?

Keep out of the reach of children.

Store at room temperature between 15 and 30 degrees C (59 and 85 degrees F). Protect from heat and light. Throw away any unused medicine after the expiration date.

Last updated: 7/1/2002

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

 

Description

Beta carotene is one of the most important naturally occurring antioxidants. It is a fat-soluble pigment found in plants (notably carrots and many colorful vegetables and fruits) and in the sea alga Dunaleilla salina and D. bardawil. Naturalbeta carotene supplements are derived primarily from D. salina. Beta carotene is one of the major dietary carotenoids and one of the most biologically active of approximately 800 carotenes and more than 1,000 carotenoids present in food. It is responsible for the orange or yellow colors of many fruits and vegetables. In the human body, beta carotene is found in lipids and in fat tissues. Sometimes beta carotene is called provitamin A because it is more easily converted to vitamin A (retinol) in the liver than other carotenoids. Beta carotene is considered to be a conditionally essential nutrient because it becomes essential when vitamin A intake is low.

Beta carotene consists of a chain of 40 carbon atoms, with conjugated double bonds and a ring structure at each end of the chain. Depending on the positions of the molecular groups attached to the carbon chain, naturally occurring beta carotene may be:

  • All-trans beta-carotene
  • 9-cis beta-carotene
  • 13-cis beta-carotene, in smaller amounts

Synthetic beta carotene is primarily all-trans.

In plants and alga, beta carotene and other carotenoids attract light for photosynthesis and provide protection from toxic forms of oxygen. Beta carotene is a powerful antioxidant because it destroys toxic free radicals, including singlet oxygen—an oxygen atom that is missing an electron and is very damaging to human tissue if not taken up quickly and "deactivated."

General Use

Vitamin a Precursor

Vitamin A is obtained in the diet from animal products or is made in the liver from beta carotene and other carotenoids. Vitamin A is essential for:

  • vision and eye health
  • normal cell division
  • growth
  • reproduction and fertility
  • immune system function
  • skin and mucous membrane health

In sub-Saharan Africa about three million children under the age of five suffer from an eye disorder, caused by vitamin-A deficiency, that can lead to blindness and death. Although red palm oil, a traditional African food, contains high provitamin A, its substitution by imported cooking oils has reduced this dietary source in many homes. Many vegetables and fruits also contain provitamin A, but are not always consumed in adequate amounts. Vitamin A deficiency is the leading cause of blindness worldwide.

In the 1920s vitamin-A deficiency was linked to stomach cancer and to precancerous conditions in the epithelial (lining) cells of the throat and lungs. In 1977 vitamin A supplementation was shown to inhibit certain cancers and to reduce the growth of certain tumors in atrisk animals.

Dietary Beta Carotene

Carotenoids, including beta carotene, that are obtained from food may have:

BETA CAROTENE CONTENT OF SOME COMMON FOODS
VegetableServingInternational Units (IU)Daily Allowance (DA)
Carrot1 whole raw, 7.5 in (19 cm)20,250410%
Carrotsliced and boiled, 0.5 cup (118 ml)19,150380%
Carrot juicecanned, 0.5 cup (118 ml)12,915260%
Spinachfrozed and boiled, 0.5 cup (118 ml)7,395150%
Sweet potatoescanned and drained, 0.5 cup (118 ml)7,015140%
Mangosliced raw, 0.5 cup (118 ml)6,425130%
Vegetable soupcanned, ready-to-serve, 1 cup (237 ml)5,880115%
Cantelouperaw, 1 cup (237 ml)5,160100%
Kalefrozen and boiled, 0.5 cup (118 ml)4,13080%
Spinachraw, 1 cup (237 ml)2,01540%
Apricot nectarcanned, 0.5 cup (118 ml)1,65035%
Oatmeal1 packet instant plain1,51030%
Tomato juicecanned, 6 oz (177 ml)1,01020%
Apricots2 halves with skin packed in juice61010%
Red pepper1 raw ring, 3 in (7.8 cm); 0.25 in (0.64 cm) thick57010%
Peasfrozen and boiled, 0.5 cup (118 ml)53510%
Peaches1 medium raw fruit52510%
Peachescanned halves or slices in water, 1 cup (237 ml)47010%
Papayaraw cubes, 1 cup (237 ml)4008%
  • antioxidant activity
  • immune-system-enhancing activity
  • activity against some cancers and precancerous conditions
  • a role in preventing coronary heart disease, including heart attack and stroke

Epidemiological studies that looked at cancer rates and diet found that at least five daily servings of green, orange, red, and yellow vegetables and fruits appeared to significantly reduce the risk of stomach, lung, prostate, breast, head, and neck cancer. and possibly slow the progression of others. In 1971 a large human study linked cancer death rates to low levels of beta carotene in the blood. Subsequent studies linked high blood levels of dietary beta carotene to lower cancer risks. However more recent evidence links these results to a combination of antioxidants found in fruits and vegetables, rather then to beta carotene alone. High beta carotene levels in the blood may be associated with a reduced risk of asthma.

Supplemental Beta Carotene

Supplemental beta carotene has been claimed to:

  • inhibit precancerous lesions in those at risk of oral cancer
  • protect against gastric and esophageal cancers
  • reduce the risk of prostate cancer
  • lower the overall cancer risk
  • protect against sunburn

However, there is very little evidence that supplemental beta carotene is an effective cancer-preventing substance, except perhaps in those with poor nutrition or low baseline levels of beta carotene in the blood. Additional studies have shown that beta-carotene supplements do not reduce the risk of cancer, heart disease, or cataracts.

Yet supplemental beta carotene does appear to increase the amounts of some types of immune-system cells. Studies have shown that women with low dietary intake or low blood levels of beta carotene are at increased risk for cervical dysplasia (abnormal cell growth) and cervical cancer. Another study found that beta-carotene supplementation provided some protection against the recurrence of colorectal adenoma (benign tumors) in patients who neither smoked nor drank alcohol. However in patients who used tobacco and/or alcohol the risk of recurrence increased with beta-carotene supple-mentation. Studies of smokers and/or those who had been exposed to asbestos initially found an increase in lung cancers among those receiving supplemental beta carotene (at least 20 mg per day), particularly among those who also consumed large quantities of alcohol. However follow-up studies found no such increases in lung cancer in those taking beta carotene.

The Age-Related Eye Disease Study found that a combined supplement of beta carotene, vitamin C, vitamin E, zinc, and copper reduced the risk of disease progression and vision loss in people with advanced macular degeneration. The supplement did not slow disease progression in those with early-stage macular degeneration.

One study found that supplementation with a mixture of antioxidants—beta carotene, alpha-tocopherol, and plant sterols—lowered cholesterol levels in the blood.

Beta carotene at 25,000 international units (IU) daily may be useful for treating psoriasis, a skin condition. Beta carotene supplements also are used to treat acne. Two 25,000-IU supplements daily, in combination with other supplements, sometimes are used to treat stomach ulcers.

Preparations

Measuring Beta Carotene

A recommended dietary allowance (RDA) for beta carotene has not been established and most foods are not labeled as to vitamin A content. There are two incompatible systems for quantifying beta carotene. IUs are used most often for nutritional labeling:

  • 1 IU equals 0.6 µg of all-trans beta carotene
  • 3.33 IU of all-trans beta carotene, 2 µg, is equal to 1 µg of all-trans retinol (vitamin A)
  • 5,000 IU equals 3 mg of beta carotene, the RDA for vitamin A
  • 1 IU equals 1.2 µg of other provitamin A carotenoids

The second system uses retinol equivalents (RE):

  • 1 RE equals 1 µg of all-trans retinol
  • 1 RE equals 6 µg of all-trans beta carotene
  • 1 RE equals 12 µg of other provitamin A carotenoids

Dietary Beta Carotene

Daily values (DVs) are determined from the RDA. They are based on a 2,000-calorie diet and usually are expressed as a percentage of an RDA. The IUs and DVs for beta carotene, per serving, in common foods are listed in table 1.

Carrots and sweet potatoes that are more orange contain more beta carotene. New carrot cultivars that contain more beta carotene have been developed and high-beta-carotene sweet potatoes are being introduced into sub-Saharan Africa to treat vitamin-A deficiency.

Other foods that contain beta carotene include:

  • avocados
  • broccoli
  • chard
  • coffee
  • collard greens
  • palm oil and other food colorants
  • squash
  • string beans
  • watermelon
  • yams

According to the Institute of Medicine, a daily intake of 3–6 mg of beta carotene will keep the blood level within the range associated with a lower risk for chronic diseases. The recommended daily diet of five or more servings of fruits and vegetables provides 3–6 mg of beta carotene (if carrots, sweet potatoes, papaya, apricots or other very high carotenoid food is used, the RDA can be met in a single serving). In contrast, the average American diet contains 1.3–2.9 mg daily. Vegetarians may have twice as much beta carotene in their blood as compared to non-vegetarians, because they generally consume a lot more greens and fruits.

Beta carotene in food is found within an oil or a matrix of sugars and proteins; and, therefore, the absorption of beta carotene by the body varies greatly. The elderly, and those with bad digestion and liver trouble may be at risk for poor absorption from an adequate beta carotene diet.

Animal sources of vitamin A are more easily absorbed than plant sources of beta carotene, particularly if the vegetables and fruits are eaten raw or whole. Although beta carotene can be converted to vitamin A in the body, it has its own unique physiological functions and beta carotene and vitamin A are not totally identical in the health benefits they deliver. So it is good to eat sources of both. While supplementation is helpful to those who have trouble absorbing adequate beta carotene, getting all or some beta carotene through food sources rather than supplements alone is by far the best. This is substantiated by research showing there are many beneficial carotenoids in foods, and that they may also work together synergistically to optimize health.

Supplemental Beta Carotene

Beta carotene supplements are inexpensive and readily available over-the-counter. They are available as pills, powders, and oils and they vary greatly in potency. Some supplements contain a mixture of carotenoids. There is a major problem with shelf life stability for beta carotene, as it "oxidizes" quickly when in pure form. When buying a supplement of it, shelf life stability or the presence of such stabalizers as vitamin E can guarantee biological activity of the capsule.

Supplemental intake of beta carotene probably should not exceed 3–15 mg per day. Common preparation of supplemental beta carotene include:

  • 30- or 60-mg capsules
  • 5,000-, 10,000-, or 25,000-IU capsules
  • 10,000- or 25,000-IU tablets

A typical dosage of beta carotene for treating cancer is 75,000–150,000 IU daily. Absorption of beta carotene in nutritional supplements can be 70% or more. There is no established maximum daily intake for beta carotene.

Some common beta carotene nutritional supplements include:

  • A-Caro-25
  • B-Caro-T
  • Biotene
  • Caroguard
  • Caro-Plete
  • Dry Beta Carotene
  • Lumitene
  • Marine Carotene
  • Mega Carotene
  • Oceanic Beta Carotene
  • Superbeta Carotene
  • Ultra Beta Carotene

Manufacturers often supplement food with beta carotene. One study showed that bakery products enriched with beta carotene increased beta carotene levels in the blood.

Precautions

Antioxidants such as beta carotene often work together with other antioxidants and an excess or deficiency of one can inhibit the other. The Food and Nutrition Board of the Institute of Medicine does not recommend beta carotene supplementation except in cases of vitamin A deficiency.

Pregnant and nursing mothers should limit their intake of supplemental beta carotene to 6 mg per day or less.

Side Effects

Even long-term high-dosage use of supplemental beta carotene appears to be non-toxic. Daily doses of 30 mg or more over a long period may cause carotenosis (carotenodermia), a yellowing of the skin, which is harmless and reversible. In contrast, very high daily doses of vitamin A are very dangerous and damage the liver and other organs, as well as provoke hair loss).

Interactions

Drugs and other substances that may interfere with beta-carotene absorption include:

  • Cholestyramine
  • Colestipol
  • mineral oil
  • Olestra
  • Orlistat
  • pectin

The absorption of luteine, another carotenoid antioxidant, may be reduced if taken in conjunction with beta carotene.

Resources

Books

American Institute for Cancer Research. Nutrition and Cancer Prevention: New Insights into the Role of Phytochemicals. New York: Kluwer Academic/Plenum Publishers, 2001.

Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington: National Academy Press, 2000.

PDR for Nutritional Supplements. Montvale, NJ: Thomson PDR, 2001.

Periodicals

Baron, J. A., et al. "Neoplastic and Antineoplastic Effects of Beta-Carotene on Colorectal Adenoma Recurrence: Results of a Randomized Trial." Journal of the National Cancer Institute 95 (2003): 717–22.

Bendich, Adrianne. "From 1989 to 2001: What Have We Learned about the 'Biological Actions of Beta-carotene?'" Journal of Nutrition 134, no. 1 (January 2004): 125S–130S.

"Disheartening Study." Better Nutrition 65, no. 9 (September 2003): 32.

Heinrich, U., et al. "Supplementation with Beta-carotene or a Similar Amount of Mixed Carotenoids Protects Humans from UV-induced Erythema." Alternative Medicine Review 8, no. 2 (May 2003): 202–203.

"Incidence and Mortality Following Alpha-tocopherol and Beta-carotene Supplementation: A Postintervention Follow-up."Journal of the American Medical Association 290, no. 4 (July 23, 2003): 476–85.

Quilez, Joan, et al. "Bakery Products Enriched with Phytosterol esters, [Alpha]-Tocopherol and [Beta]-Carotene Decrease Plasma LDL-Cholesterol and Maintain Plasma [Beta]-Carotene Concentrations in Normocholesterolemic Men and Women." Journal of Nutrition 133, no. 10 (October 2003): 3103.

Russell, R. M., et al. "The Enigma of Beta-Carotene in Carcinogenesis: What Can Be Learned From Animal Studies." Journal of Nutrition 134, no. 1 (2004): 262S–268S.

"What's Up Doc? Getting to the Root of Carrots." Environmental Nutrition 26, no. 9 (September 2003): 8.

"The Word: Sweet Potato." New Scientist 179, no. 2402 (July 5, 2003): 51.

Other

"Beta Carotene." Making Treatment Decisions. American Cancer Society. 2000 [cited May 4, 2004]. .

Beta Carotene. Mayo Clinic. May 10, 2002 [cited May 4, 2004]. .

Task Force Finds Little Evidence to Support Use of Vitamin Supplements to Prevent Cancer or Heart Disease. Agency for Healthcare Research and Quality. June 30, 2003 [cited May 4, 2004]. .

Vitamin A and Carotenoids. Office of Dietary Supplements, National Institutes of Health. October 6, 2003 [cited May 4, 2004]. .

[Article by: Margaret Alic]

 
Sports Science and Medicine: beta carotene
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A nutrient converted by the body to vitamin A. Valuable sources include orange fruits and vegetables, such as apricots, canteloupes, and carrots, as well as leafy green vegetables, such as broccoli and spinach. Beta carotene lacks the toxicity of vitamin A.

Beta carotene (Click to enlarge)
Beta carotene
(Click to enlarge)

 
Wikipedia: Carotene
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β-Carotene represented by a 3-dimensional stick diagram
Carotene is responsible for the orange colour of the carrots and many other fruits and vegetables.

The term carotene is used for several related substances having the formula C40Hx, which are synthesized by plants but cannot be made by animals. Carotene is an orange photosynthetic pigment important for photosynthesis. Carotenes are responsible for the orange colour of the carrot for which it is named, and many other fruits and vegetables (for example, sweet potatoes and orange cantaloupe melon). Carotenes are also responsible for the orange colours in dry foliage. They also (in lower concentrations) impart the yellow colouration to milk-fat, butter, and egg yolk. Omnivorous animal species which are poor converters of coloured dietary carotenoids to colourless retinoids, have yellowed-coloured body fat as a result of the carotenoid retention. The typical yellow-coloured fat of humans and chickens is a result of fat storage of carotenes from their diets.

Carotenes contributes to photosynthesis by transmitting the light energy they absorb from chlorophyll. They also protect plant tissues by helping to absorb the energy from singlet oxygen, an excited form of the oxygen molecule O2 which is formed during photosynthesis.

Chemically, carotene is a terpene, synthesized biochemically from eight isoprene units. It comes in two primary forms designated by characters from the Greek alphabet: alpha-carotene (α-carotene) and beta-carotene (β-carotene). Gamma, delta, epsilon, and zeta (γ, δ, ε, and ζ-carotene) also exist. As hydrocarbons which contain no oxygen, carotenes are fat-soluble and insoluble in water (in contrast with other carotenoids, such as xanthophylls, which are slightly less chemically hydrophobic).

Beta-carotene is composed of two retinyl groups, and is broken down in the mucosa of the small intestine by beta-carotene 15,15'-monooxygenase to retinal, a form of vitamin A. Carotene can be stored in the liver and body fat and converted to retinal as needed, thus making it a form of vitamin A for humans and some other mammals.

Animal species differ greatly in their ability to convert carotene to retinals. Carnivores in general are poor converters of dietary carotenoids, and pure carnivores such as cats and ferets lack beta-carotene 15,15'-monooxygenase and cannot convert carotenoids to retinals at all (resulting in carotenes not being a form of vitamin A for these species).

Contents

Dietary sources

The following foods are particularly rich in carotenes (see Vitamin A article for amounts):

Absorption from these foods is enhanced if eaten with fats, as carotenes are fat soluble, and if the food is cooked for a few minutes until the plant cell wall splits and the colour is released into any liquid. 6 μg of dietary β-carotene supplies the equivalent of 1 μg of retinol, or 1 RE (Retinol Equivalent). This is equivalent to 3⅓ IU of vitamin A.

The multiple forms

α-carotene
β-carotene

The two primary isomers of carotene, α-carotene and β-carotene, differ in the position of double bonds in the cyclic group at the end.

β-Carotene is the more common form and can be found in yellow, orange, and green leafy fruits and vegetables. As a rule of thumb, the greater the intensity of the orange colour of the fruit or vegetable, the more β-carotene it contains.

Carotene protects plant cells against the destructive effects of ultraviolet light. β-Carotene is an anti-oxidant.

Beta-carotene and cancer

It has been shown in trials that the ingestion of beta-carotene at about 30 mg/day (10 times the Reference Daily Intake) increases the rate of lung cancer and prostate cancer in smokers and people with a history of asbestos exposure.

An article on the American Cancer Society says that The Cancer Research Campaign has called for warning labels on beta-carotene supplements to caution smokers that such supplements may increase the risk of lung cancer.[11]

The New England Journal of Medicine published an article[12] in 1994 about a trial which examined the relationship between daily supplementation of beta-carotene and vitamin E (alpha-tocopherol) and the incidence of lung cancer. The study was done using supplements and researchers were aware of the epidemiological correlation between carotenoid-rich fruits and vegetables and lower lung cancer rates. The research concluded that no reduction in lung cancer was found in the participants using these supplements (beta-carotene), and furthermore, these supplements may, in fact, have harmful effects.

The Journal of the National Cancer Institute and The New England Journal of Medicine published articles in 1996[13][14] about a trial that was conducted to determine if vitamin A (in the form of retinyl palmitate) and beta-carotene had any beneficial effects to prevent cancer. The results indicated an increased risk of lung cancer for the participants who consumed the beta-carotene supplement and who had lung irritation from smoking or asbestos exposure, causing the trial to be stopped early.[14]

A review of all randomized controlled trials in the scientific literature by the Cochrane Collaboration published in JAMA in 2007 found that beta-carotene increased mortality by something between 1 and 8% (Relative Risk 1.05, 95% confidence interval 1.01-1.08).[15] However, this meta-analysis included two large studies of smokers, so it is not clear that the results apply to the general population.[16]

Beta-carotene and cognition

A recent report demonstrated that 50 mg of beta-carotene every other day prevented cognitive decline in a study of over 4000 physicians at a mean treatment duration of 18 years.[17]

Beta-carotene and photosensitivity

Oral beta-carotene is prescribed to people suffering from erythropoietic protoporphyria. It provides them some relief from photosensitivity.[citation needed]

Beta-carotene and nanotechnology

Beta-carotene and lycopene molecules can be encapsulated into carbon nanotubes enhancing the optical properties of carbon nanotubes [18]. Efficient energy transfer occurs between the encapsulated dye and nanotube — light is absorbed by the dye and without significant loss is transferred to the SWCNT. Encapsulation increases chemical and thermal stability of carotene molecules; it also allows their isolation and individual characterization [19].

Carotenemia

Carotenemia or hypercarotenemia is excess carotene, but unlike excess vitamin A, carotene is non-toxic. Although hypercarotenemia is not particularly dangerous, it can lead to an oranging of the skin (carotenodermia), but not the conjunctiva of eyes (thus easily distinguishing it visually from jaundice). It is most commonly associated with consumption of an abundance of carrots, but it also can be a medical sign of more dangerous conditions.

Production

Most of the world's synthetic supply of carotene comes from a manufacturing complex located in Freeport, Texas and owned by DSM. The other major supplier BASF also uses a chemical process to produce beta-carotene. Together these suppliers account for about 85% of the beta-carotene on the market. In Spain Vitatene produces natural beta-carotene from fungus Blakeslea trispora, as does DSM but at much lower amount when compared to its synthetic beta-carotene operation. In Australia, organic beta-carotene is produced by Aquacarotene Limited from dried marine algae Dunaliella salina grown in harvesting ponds situated in Karratha, Western Australia. Cognis Australia Pty. Ltd., a subsidiary of the Germany-based company Cognis, is also producing beta-carotene from microalgae grown in two sites in Australia that are the world’s largest algae farms. In Portugal, the industrial biotechnology company Biotrend is producing natural all-trans beta-carotene from a non genetically modified bacteria of the Sphingomonas genus isolated from soil.

Carotene is also found in palm oil, corn, and in the milk of dairy cows, causing cow's milk to be light yellow, depending on the feed of the cattle, and the amount of fat in the milk (high-fat milks, such as those produced by Guernsey cows, tend to be more yellow because their fat content causes them to contain more carotene).

Carotenes are also found in some species of termites, where they apparently have been picked up from the diet of the insects.

Total synthesis

There are currently two commonly used methods of total synthesis of β-carotene. The first was developed by the Badische Anilin- & Soda-Fabrik (BASF) and is based on the Wittig reaction. The second is a Grignard reaction, elaborated by Hoffman-La Roche from the original synthesis of Inhoffen et al. They are both symmetrical; the BASF synthesis is C20 + C20 , and the Hoffman-La Roche synthesis is C19 + C2 + C19.

Nomenclature

Carotenes are carotenoids containing no oxygen. Carotenoids containing some oxygen are known as xanthophylls.

The two ends of the β-carotene molecule are structurally identical, and are called β-rings. Specifically, the group of nine carbon atoms at each end form a β-ring.

The α-carotene molecule has a β-ring at one end; the other end is called an ε-ring. There is no such thing as an "α-ring".

These and similar names for the ends of the carotenoid molecules form the basis of a systematic naming scheme, according to which:

  • α-carotene is β,ε-carotene;
  • β-carotene is β,β-carotene;
  • γ-carotene (with one β ring and one uncyclized end that is labelled psi) is β,ψ-carotene;
  • δ-carotene (with one ε ring and one uncyclized end) is ε,ψ-carotene;
  • ε-carotene is ε,ε-carotene
  • lycopene is ψ,ψ-carotene

That leaves ζ-carotene; ζ-carotene is the biosynthetic precursor of neurosporene, which is the precursor of lycopene, which, in turn, is the precursor of the carotenes α through ε. ζ comes first.

See also

References

  1. ^ a b c d e f g h i j What can foods rich in beta-carotene do for you?
  2. ^ a b c d e f g h i j k l m Pitchford, Paul (2002), Healing with Whole Foods: Asian Traditions and Modern Nutrition, North Atlantic Books, ISBN 1-55-643471-5 
  3. ^ Ronald, PhD. Lawrence; Young, Gary K.; Marc Schreuder (2005). Discovery of the Ultimate Superfood: How the Ningxia Wolfberry And 4 Other Foods Help Combat Heart Disease, Cancer, Chronic Fatigue, Depression, Diabetes And More. Life Sciences Pr. ISBN 0-943685-44-3. 
  4. ^ Berry Good for You?
  5. ^ James Allen Olson, PhD, Iowa State University (deceased) Cheryl L. Rock, PhD, University of California, San Diego A. Catharine Ross, PhD, The Pennsylvania State University Barbara A. Underwood, PhD (2006-04-23). "Dietary Supplement Fact Sheet: Vitamin A". NIH Office of Dietary Supplements website. United States Department of Agriculture. http://ods.od.nih.gov/factsheets/vitamina.asp. Retrieved on 2007-10-26. 
  6. ^ a b World's Healthiest Foods: Carotenoids
  7. ^ WHFoods: Mustard greens
  8. ^ Artemis P. Simopoulos and C. Gopalan, ed. (2003), Plants in Human Health and Nutrition Policy, Karger Publishers, ISBN 3-80-557554-8 
  9. ^ Rose Hips
  10. ^ Carotenoids in cassava: comparison of open-column and HPLC methods of analysis.
  11. ^ "British Cancer Organization Calls for Warning Labels on Beta-Carotene". 2000-07-31. http://www.cancer.org/docroot/NWS/content/NWS_1_1x_Warning_Labels_on_Beta_Carotene_Called_For.asp. Retrieved on 2007-03-15. 
  12. ^ The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group (1994). "The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers". N Engl J Med. 330 (15): 1029–35. doi:10.1056/NEJM199404143301501. PMID 8127329. 
  13. ^ Omenn GS, Goodman GE, Thornquist MD, et al. (1996). "Risk factors for lung cancer and for intervention effects in CARET, the Beta-Carotene and Retinol Efficacy Trial". J Natl Cancer Inst. 88 (21): 1550–9. doi:10.1093/jnci/88.21.1550. PMID 8901853. http://jncicancerspectrum.oxfordjournals.org/cgi/content/abstract/jnci;88/21/1550. 
  14. ^ a b Omenn GS, Goodman GE, Thornquist MD, et al. (1996). "Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease". N Engl J Med. 334 (18): 1150–5. doi:10.1056/NEJM199605023341802. PMID 8602180. http://content.nejm.org/cgi/content/abstract/334/18/1150. 
  15. ^ Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C (2007). "Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis". JAMA 297 (8): 842–57. doi:10.1001/jama.297.8.842. PMID 17327526. http://jama.ama-assn.org/cgi/content/abstract/297/8/842. 
  16. ^ See the letter to JAMA by Philip Taylor and Sanford Dawsey and the reply by the authors of the original paper.
  17. ^ Grodstein F, Kang JH, Glynn RJ, Cook NR, Gaziano JM (Nov 2007). "A randomized trial of beta carotene supplementation and cognitive function in men: the Physicians' Health Study II". Arch Intern Med. 167 (20): 2184–90. doi:10.1001/archinte.167.20.2184. PMID 17998490. 
  18. ^ K. Yanagi et al. (2006). "Light-Harvesting Function of β-Carotene Inside Carbon Nanotubes". Phys. Rev. B 74: 155420. doi:10.1103/PhysRevB.74.155420. 
  19. ^ Y. Saito et al. (2006). "Vibrational Analysis of Organic Molecules Encapsulated in Carbon Nanotubes by Tip-Enhanced Raman Spectroscopy". Jap. J. Appl. Phys. 45: 9286–9289. doi:10.1143/JJAP.45.9286. 

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