- Vitamin A can aid the immune system in fighting certain
infections and inflammations. This essential nutrient, for example, can
help clobber infections caused by some food-poisoning organisms.
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- However, in the case of pneumonia--and perhaps asthma
and the common cold, as well--vitamin A may not be as helpful.
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- At the ARS Western Human Nutrition Research Center in
Davis, Calif., innovative studies by research physiologist Charles B. Stephensen
are helping solve the puzzle of why vitamin A interacts in these differing
ways with the immune system. Findings from the research may lead to ways
to capitalize on the ability of vitamin A-rich foods to boost the immune
system.
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- Foods that provide Vitamin A include beef, chicken, turkey,
sweet potatoes, pumpkin, carrots, spinach, collard greens and tomato products.
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- Experiments by Stephensen and his university and corporate
colleagues are revealing more clues about vitamin A's influence on the
types and amounts of beneficial cells and compounds that the immune system
produces in response to attack.
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- In one early study, the scientists supplied animal immune
cells with adequate amounts of a form of vitamin A called 9-cis retinoic
acid, and exposed the cells to a simulated attack. This work showed--for
the first time--that more of the cells quickly evolved into what are known
as T-2 helper cells than into T-1 helper cells. This difference is important,
because T-2 helper cells apparently are more proficient in fighting some
pathogens than others.
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- In humans, that difference could strongly affect how
quickly the body is able to overcome a particular pathogen.
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- The researchers used mouse immune cells for these petri
dish tests. They plan to repeat these tests with laboratory mice--not just
their cells. Depending on the outcome, they expect to follow up with studies
of healthy adult volunteers.
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- Details are in Agricultural Research magazine, posted
on the World Wide Web at: http://www.ars.usda.gov/is/AR/archive/mar03/vita0303.htm
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- ARS is the U.S. Department of Agriculture's chief scientific
research agency.
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- Contact Marcia Wood, (301) 504-1662, MarciaWood@ars.usda.gov
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