PLEASE NOTE: The Carrot Museum does not recommend self diagnosis or self medication. The information contained in this web site has not been verified for correctness. Some of the information contained herein is hearsay and may not be correct. Use the information from this page only at your own risk!  If in doubt consult a doctor.

Of the 600 known carotenoids, beta-carotene is the most studied and the most physiologically and nutritionally important member of the carotene family.

About 50 carotenoids have been identified in the human diet, 34 have been identified in the human serum, tissues, and breast milk. Of these, alpha-carotene, beta-carotene, and beta-cryptoxanthin are considered "essential " because they serve as precursors of vitamin A (converted to vitamin A by the body).

Beta-carotene (C40 H56) is an orange pigment found in most fruits and vegetables. It was discovered by Heinrich Wilhelm Ferdinand Wackenroder in 1831 in the roots of carrots and named the substance "carotin."  Wackenroder was an analytical chemist at the Pharmaceutical Institute in Jena, Germany (www.life.illinois.edu/govindjee/CarFin 1.html).

In 1907, Richard Willstater assigned the formula C40 H56 to carotin (http://lpi.oregonstate.edu/infocenter/phytochemicals/carotenoids/).

In 1831, beta-carotene was first isolated from the roots of carrots, but it was not until the Nobel prize-winning research of Paul Karrer in the early 1930s that the structure of the substance was determined. The earliest use of synthesized beta-carotene was as a food colorant, but during the 1980s the vitamin precursor’s growing reputation as an antioxidant and a possible cancer-fighter resulted in its frequent inclusion in vitamin supplements. Since that time, however, conflicting findings about the benefits of taking synthesized beta-carotene have surfaced.

Characteristics of Beta-Carotene

Like all carotenoids, beta-carotene is:

• the most common form of carotene

• fat soluble - not water-soluble. In a mixed diet, 3-5 grams of fat is enough to ensure its absorption. Carotenoids suspended in oil are more efficiently absorbed than those in water or food.

• manufactured by plants - not animals. In plants, beta-carotene absorbs light, and energy from singlet oxygen - an unstable form of oxygen - and transfers both energies to chlorophyll for photosynthesis. It also acts as a pesticide.

• present in the all-trans configuration in raw fruits and vegetables

• converted to the cis- configuration during cooking. Cis- isomers are shorter in length and are less susceptible to "binding." They are more stable and are more bioavailable.

• released from the food matrix by: chewing, stomach action, and digestive enzymes. The vitamin A activity of beta-carotene in foods is half that of retinol (pre-formed vitamin A). Biologic Activities of Beta-Carotene

• Beta-carotene is converted to Vitamin A (retinal) in the small intestines of mammals by beta-,carotene 15,15 monooxygenase (an enzyme). In times of plenty, retinal is stored in the liver. It is synthesized into active vitamin A in times of need.

• It quenches singlet oxygen. It also reacts with any radical species present in a biological system. As a powerful antioxidant, it breaks down and converts harmful products to inert substances.

• It prevents the oxidation of fat by breaking down the chain-reaction.

• It facilitates communication between cells by enhancing the expression of a gene that codes for connexin proteins. Connexin proteins forms pores or gap junctions in cell membranes, allowing cells to communicate through the exchange of small molecules.

• It improves immune function by protecting phagocytic cells (white blood cells that protects the body by ingesting harmful bodies, bacteria, dead/dying cells); enhancing the response of T & B cells (immune response cells); by stimulating the effects of T-cell functions, macrophage, and natural killer cell capacities, and by increasing the production of interleukins. Interleukins are signalling molecules on white blood cells. They mediate communication between cells.

• It helps maintain night vision. As vitamin A, beta-carotene maintains the cornea and participates in the conversion of light energy into nerve impulses at the retina. The cells of the retina contain rhodopsin, a pigment molecule. As rhodopsin absorbs light, retinal changes which triggers a nerve impulse that carries information to the brain.

• It protects against sunburn by: quenching radical oxygen species and interferring with several signalling pathways that result in UV-B exposure. Significant Food Sources Sweet potatoes tubers and leaves, carrots, cantaloupes, goji berries, palm oil, spinach, chard, egg yolk, liver,pumpkins, squash, mango, turnip greens.

(References Bendich A & Olson TA "Biological Actions of Carotenoids" FASEB Journal June 1989;3(8):1927-32); http://lpi.oregonstate.edu/infocenter/phytochemicals/carotenoids/)

So what is your carotene need? Meeting your vitamin A requirement from beta carotene is easy: Eat a handful of baby carrots and you've done it! Six ounces of carrot juice (made from two medium-sized carrots) supplies a whopping 28 mg. of beta carotene.
Since juicing eliminates the hard to digest fibre, nutrients are obtainable to the body in a great deal of larger quantities than if the piece of fruit or vegetable was eaten whole. For instance, since a lot of of the nutrients are in the fibre, when you eat a raw carrot, you are only able to absorb about 1% of the beta-carotene. When a carrot is juiced, eliminating the fibre, virtually 100% of the beta-carotene may be assimilated.
 

Carrots - serving size 1/2 cup	Vitamin A (retinol) equivalents (micrograms)	% RDA* for women	% RDA* for men
Fresh, raw	2050	256%	205%
Boiled, raw	1790	223%	179%
Boiled, frozen	1290	161%	129%
Boiled, canned	1005	126%	101%

*RDA = Recommended Daily Amount (The RDA of Vitamin A is 800 micrograms for women and 1,000 micrograms for men.) For more information about Vitamin A click here

The Museum page about Vitamin A is here.

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