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When it comes to good health, vitamin
C may be the key ingredient of a diet rich in fruits and vegetables.
While a plant-rich diet is associated
with better health overall, and a lower risk of heart disease
and certain cancers specifically, exactly how such a diet
affects blood levels of specific nutrients is not clear.
The new findings suggest that "raising
(vitamin C) levels may be an important mechanism by which
fruit and vegetable consumption confers protective benefits."
Researchers measured blood levels of vitamin
C, beta-carotene, vitamin E and beta-cryptoxanthin -- a nutrient
found in oranges and orange juice -- in 116 nonsmoking men
aged 35 to 72, who did not take vitamin supplements. Smoking,
the researchers explain, lowers blood levels of certain nutrients,
while taking supplements increases nutrient levels.
The average fruit and vegetable intake
was about three times daily. Blood levels of ascorbic acid
(vitamin C) and carotenoids, which are converted to vitamin
A in the body, were significantly associated with the frequency
of eating foods containing these nutrients. The association
was particularly strong
for vitamin C.
In the study, ascorbic acid was considerably
more highly associated with fruit and vegetable intake than
were the carotenoids. Thus, it is possible that ascorbic acid
is as important as or more important than carotenoids in conferring
the protective benefit of fruits and vegetables.
American Journal
of Epidemiology 2001;154:1113-1118
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