Dr. Smith with Your Health

BETA-CAROTENE AND THE IMMUNE RESPONSE

Beta-carotene is a member of the carotenoid family which form part of the coloring pigments of many yellow and green vegetables especially carrots, squash, sweet potatoes, broccoli, spinach, and beet greens. Beta-carotene is most known as a precursor to vitamin A.

For a long time it was thought that any effects of beta-carotene were through it's vitamin A activity solely. While this is partially true, it is not the complete story. Beta-carotene is a potent anti-oxidant. It "captures" free oxygen found in the body thereby decreasing the chance of "free radical" damage by the oxygen. During the initial response to infection neutrophils use free radicals and reactive oxygen as a weapon against invaders. Overproduction of these weapons leads to damage of the membranes and DNA of all cells in the vicinity, including the white blood cells. Beta-carotene is able to absorb this free oxygen and prevent it from damaging the bodies own tissues. Beta-carotene also exerts an anti-tumor effect by two mechanisms. First, macrophages and natural killer cells, capable of recognizing and killing tumor cells, have both been found to be more active when members of the carotenoid family, including beta-carotene, were used. Second, tumor necrosis factor, a substance which directly kills tumor cells, is produced in greater quantities in the presence of carotenoids. Beta-carotene also appears to decrese allergic responses by interfering with the formation of potent inflammatory agents.

Vitamin A has many varied immunological functions. Deficiencies have been shown to lower immunity including lymphocyte activation, lysozyme and complement levels, impaired secretory IgA production, and T cell dependent antibody responses. Vitamin A enhances resistance to infection by increasing phagocytic cell migration, lymphocyte proliferation and it enhances responsiveness to antigenic stimuli.

More recent research has indicated that beta-carotene has several immune enhancing properties that are independent of the effects of vitamin A conversion. T and B lymphocyte responses were consistently enhanced in one study. Another demonstrated "significantly increased" in-vivo frequency of OKT4+ (helper/inducer T-4 lymphocytes) and OKT3+ (all T lymphocytes) after two weeks of beta-carotene supplementation. The frequency of OKT8+ (suppressor/cytotoxic T-8 lymphocytes) was unaffected. Much of this research studied the effects of other members of the carotenoids also, specifically alpha-carotene, canthaxanthin and astaxanthin; and found similar responses. As these other carotenes have virtually no vitamin A activity (with the exception of alpha-carotene which has a very weak conversion ability) it demonstrates that the immune responses were in fact due to the carotenoids rather than vitamin A. Over 20 research papers spanning six decades were presented at the "Biological Actions of Carotenoids" symposium of the 72nd annual meeting of the Federation of American Societies for Experimental Biology in May 1988.

Beta-carotene requires the presence of bile salts and digested fats for absorbtion in the small intestine. Deficiencies may result from excessive mineral oil ingestion, gall bladder dysfunction or removal, and malabsorbtion syndromes. A cytomegalovirus (CMV) infection of the gall bladder or liver would compromise the availability of bile salts and there are a multitude of digestive problems in HIV+ individuals that can result in a malabsorbtion syndrome. Additionally, specific enzyme deficiencies will affect the ability to absorb beta-carotene. These deficiencies may be the result of dietary habits and are correctable.

To achieve the levels of intake approximate to those used in the aforementioned studies, one would have to ingest about 55 raw carrots or 35 boiled sweet potatoes per day!! Most products measure the amount of beta-carotene by vitamin A activity stating "25,000 units beta-carotene" which refers to the conversion of beta-carotene to vitamin A. In other words, if all the beta-carotene was converted to vitamin A, there would be 25,000 I.U.'s of vitamin A. Beta-carotene is superior to vitamin A as a way to benefit from the immune enhancing properties of both. Beta-carotene will be transformed into vitamin A as long as the body needs more vitamin A. When there is enough, no more is made. This is very important as vitamin A supplements may cause problems. Excess amounts of vitamin A must be metabolized by the liver. As many HIV+ individuals are taking medications which must be cleared by the liver, we do not wish to add to this burden with excess vitamin A. Beta-carotene will prevent episodes of vitamin A toxicity and will enhance the immune function bu it's own functions.

The purpose of this article is to provide information only and should not be construed as a recommendation of a course of action. Please consult with a qualified health professional before making any decisions regarding your treatment.

Dr. Brian A. Smith is a chiropractic doctor and naturopathic physicianwho has specialized in the treatment of immune-suppressed individuals since 1987. He is a scientific advisory board member of AIDS ReSEARCH Alliance.

He maintains a private practice in Los Angeles and can be reached at (323) 306-4909. Questions from readers are welcome as are suggestions for future articles. You can also contact him via E-mail at: Send e-mail to Dr. Smith

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Articles by Dr. Brian A. Smith:

HIV and CHIRO † VITAMIN C † BETA-CAROTENE † MINERALS † DMG † PROTEIN † DIET & HIV † MORE ON PROTEIN † NUTRITION † DHEA † LIVER † CHIRO † NAC † SILVER † ALT THERAPIES †