Medicinal Plants Classification Biosynthesis and ... - Index of

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Rosa Martha Perez Gutierrez, Adriana Maria Neira Gonzalez et al.
were consistent with the findings of previous studies that have reported a positive association
between β-carotene intake and risk of some neoplasms in smokers (Omenn et al., 1996;
Albanes et al., 1996) and with those that observed an interaction between β-carotene intake
and smoking on the risk of some cancers or precancerous lesions (Baron et al., 2003) .
Indeed, long-term follow-up of the β-carotene and retinol efficacy trial suggests a stronger
association between β-carotene intake and risk of tobacco-related cancer in women than in
men (Goodman et al., 2004), which, added to a higher supplement use (Knudsen et al., 2002),
may therefore represent a problem in view of the increasing exposure of women to tobacco.
In another study, it was observed that increased lung cancer risk was associated with low
vegetable and fruit intake in current and recent cigarette smokers and in pipe and/or cigar
users. Risk was not elevated in cigarette smokers who had quit more than 5 years earlier or in
never smokers. The effects of β-carotene intake and of �-carotene intake on lung cancer risk
were similarly modified by smoking history. Thus, as before, the importance of diet was
explored in current (464 case patients and 177 control subjects) and recent (59 case patients
and 31 control subjects) smokers. Current and recent smokers in the lowest quartile of �carotene
intake had a smoking-adjusted risk more than twice that of smokers in the highest
quartile of intake, whereas the corresponding risks associated with intakes of β-carotene and
of lutein/zeaxanthin were increased only about 60% (Ziegler et al., 1996a).
It is also reported that in a group of 258 lung cancer cases and 515 controls,
serum/plasma concentrations were significantly lower among cases than controls for
cryptoxanthin, β-carotene, and lutein/zeaxanthin. Modest nonsignificant case-control
differences in a protective direction were noted for �-carotene and ascorbic acid. There were
only trivial differences for lycopene, �-tocopherol, selenium, and peroxyl radical absorption
capacity. Findings are reported for males and females and for persons who had never smoked
cigarettes, former smokers, and current smokers at baseline. These results and those from
previous studies suggest that β-carotene is a marker for some protective factor(s) against lung
cancer; that cryptoxanthin, �-carotene, and ascorbic acid need to be investigated further as
potentially protective factors or associates of a protective factor; and that lycopene, �tocopherol,
selenium, and peroxyl radical absorption capacity are unlikely to be associated
with lung cancer risk. Until specific preventive factors are identified, the best protection
against lung cancer is still the avoidance of airborne carcinogens, especially tobacco smoke;
second hest is the consumption of a diet rich in fruits and vegetables (Comstock et al., 2008).
In 1957, 3,102 men (aged 40-55 years) were randomly selected for the Western Electric
Study. The effects of β-carotene and retinol intake on lung cancer risk during 19 years no
showed significant differences in mean intake other nutrients. Also this study showed no
association between the level of serum cholesterol and the intake of retinol and β-carotene
(Shekelle et al., 1981).
Discussion
In recent decades the presence of carotenoids in our food supply and their role in human
health have been of unprecedented interest. Some carotenoids are vitamin A precursors and
about a dozen carotenoids are found in human plasma, depending on diets rich in fruits and