Beta Carotene

"The most famous of the Carotenoids"

What is it?

The carotenoids give the yellow and orange color to plants such as carrots and squash, in which they areespecially abundant. However, some of them are green in color and you can find them in most plants.They have numerous biologic effects and are very active free radical scavengers.

Beta-carotene and the carotenoids

Until recently, beta-carotene got all the pressbecause it was the only carotenoid manufacturedin great bulk, and therefore easily available to thevitamin manufacturers and researchers. Inaddition, it can be converted into twice as muchvitamin A as any other carotenoid.

However, we are learning that other carotenoids,such as lycopene, lutein, and zeaxanthin areextremely important, too. Lycopene has beenshown to decrease the incidence of certaincancers. Lutein and zeaxanthin protect us frommacular degeneration, the leading cause ofblindness in the aged.

Who should take beta-carotene? And how much?

This is why itÕs best to obtain your beta-carotene(and all your other carotenoids) through thedaily consumption of yellow vegetables such assquash, pumpkin and carrots and greenvegetables such as spinach and broccoli. Thereare many beneficial substances in our foodbesides vitamins; attempting to obtain all ournutrients from a supplement is unwise. For theaverage person I do not recommend betacarotenesupplementation. Having said that, IÕvenever found a daily vitamin that didnÕt include it.

Beta-carotene and vitamin A

Beta-carotene is a very effective free-radicalscavenger and vitamin A is less so. Betacarotene,in addition, can be transformed by thebody into vitamin A, and thus provide us with asafe source of vitamin A activity. Thisconversion into vitamin A can only occur if wehave proper thyroid function and an adequateintake of protein, zinc and vitamin C. Betacarotenewill not be transformed into vitamin Aunless we are deficient in vitamin A. Therefore,one can take large amounts of beta-carotenewithout fear of vitamin A toxicity.

There are conditions, such as retinitis pigmentosa(an eye disease), that respond to vitamin A andnot beta-carotene.

Prevention with beta-carotene

Those who consume at least five servings ofgreen leafy vegetables a week (rich in lutein andzeaxanthin) have one fifth the chance ofdeveloping visual loss due to maculardegeneration. Macular degeneration is theleading cause of blindness in the aged.

A study in the Archives of Ophthalmology(1988;106:337) suggested that people with highlevels of at least 2 of the 3 antioxidant vitamins(beta-carotene, vitamin E, and vitamin C) haveonly a fifth of the chance of developing a cataractas those people with low levels. The BritishMedical Journal in 1992 (305:335) confirmedthat beta-carotene and vitamin C were protectiveagainst cataracts. Spinich was noted to be aparticularly protective food.

Lancet (1991;337:1197), in a study fromSingapore, reported that high intake of betacarotenewas associated with a low risk of breastcancer.

Nutrition and Cancer (1984;6:49) found thatwomen consuming less beta-carotene andvitamin A were almost three times more likely todevelop cancer of the cervix.

The New England Journal Of Medicine in1993(328:1450) reported that for smokers, intakeof beta-carotene was protective against coronaryheart disease.

The Proceedings of the National Academy ofSciences in 1984 (81:7627) reported that incomparing species of mammals, those with thehighest levels of beta-carotene have the longestlife span. And that this relationship is especiallystrong for human beings.

Adverse effects of beta-carotene

People who eat large amounts of beta-carotene(as in carrots or squash) can develop a yellowishcolor around the nose, on the palms and soles, oreven more extensively. This does not affect thewhites of the eyes. Most frequently this is seenin children. It causes no harm and slowlydiminishes once intake of beta-carotene isdiminished.

Nutrition and Cancer (1988;11:207) reportedthat many people had taken doses between 30and 180 milligrams per day for many yearswithout adverse effect. These capsules contain15 milligrams of beta-carotene, providing 25,000IU vitamin A activity.

Male smokers who took large doses of betacaroteneappeared to suffer higher rates of lungcancer. I believe the explanation is that higherdoses of beta-carotene have been shown tointerfere with lycopene, which has an anti-cancereffect. The higher doses may have interferedwith other protective carotenoids as well.

Medical use of beta-carotene

Beta-carotene should not be used to treat medicalconditions without the advice of your physician.However, you should know that research hasshown benefits from beta-carotene for manymedical conditions, including ulcers, variousdermatologic diseases, and lupus dermatitis,especially lupus dermatitis caused by sensitivityto the sun. People with DownÕs syndrome andthose undergoing various forms of cancer therapyhave been shown to have increased need forbeta-carotene. Beta-carotene has been shown toincrease the count of T4 lymphocytes; numerousstudies have shown that beta-carotene improvesthe functioning of the immune system in manyother ways as well.