Document Detail

Procarcinogenic and anticarcinogenic effects of beta-carotene.
MedLine Citation:
PMID:  10568335     Owner:  NLM     Status:  MEDLINE    
A large body of observational epidemiologic studies has consistently demonstrated that individuals who eat more fruits and vegetables, which are rich in carotenoids, and people who have higher serum beta-carotene levels have a lower risk of cancer, particularly lung cancer. In contrast to these observations, two human intervention studies that used high-dose beta-carotene supplements reported an increased risk for lung cancer among smokers. Recently, in vitro and in vivo studies have shed light on the present conundrum regarding the potential chemopreventive activity of beta-carotene; that is, beta-carotene itself may act as an anticarcinogen, but its oxidized products may facilitate carcinogenesis. These studies support the hypothesis that the carcinogenic response to high-dose beta-carotene supplementation reported in the human intervention trials is related to the instability of the beta-carotene molecule in the free radical-rich environment in the lungs of cigarette smokers. This is especially possible because smoke also causes decreased tissue levels of other antioxidants, such as ascorbate and alpha-tocopherol, which normally have a stabilizing effect on the unoxidized form of beta-carotene. Nutritional intervention using a combination of antioxidants (beta-carotene, alpha-tocopherol, and vitamin C) as anticarcinogenic agents could be an appropriate way to rationally and realistically reduce cancer risk.
X D Wang; R M Russell
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Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  Nutrition reviews     Volume:  57     ISSN:  0029-6643     ISO Abbreviation:  Nutr. Rev.     Publication Date:  1999 Sep 
Date Detail:
Created Date:  1999-12-07     Completed Date:  1999-12-07     Revised Date:  2005-11-16    
Medline Journal Info:
Nlm Unique ID:  0376405     Medline TA:  Nutr Rev     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  263-72     Citation Subset:  IM    
Jean Mayer USDA Human Nutrition Research Center on Aging, Boston, MA, USA.
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MeSH Terms
Antioxidants* / adverse effects,  metabolism,  therapeutic use
Dose-Response Relationship, Drug
Lung Neoplasms / etiology*,  prevention & control*
Signal Transduction / drug effects
Smoking / adverse effects
beta Carotene* / adverse effects,  metabolism,  therapeutic use
Reg. No./Substance:
0/Antioxidants; 7235-40-7/beta Carotene

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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