In a photo from a
previous study, research leader Beverly Clevidence prepares to check frozen
kale for consistency of carotenoid content. Human nutrition feeding studies use
kale for its high beta-carotene and lutein content. The new study used kale for
several additional reasons. Researchers can grow a greenhouse crop of fresh
kale that is very rich in nutrients, and kale has a fairly short growth cycle.
Also, the plant is nearly all edible--allowing for economical use of costly
isotopes incorporated into the plant material. Click the image for more
information about it.
New Method Leads to New Findings Concerning
Carotenoid Absorption By
Jim Core October
A pioneering method developed by Agricultural Research Service (ARS) scientists has revealed new findings
about how carotenoids are absorbed in the body.
Using isotopes to tag carotenoids from kale, researchers at the ARS
Beltsville (Md.) Human Nutrition Research Center (BHNRC)
monitored the nutrients' absorption within the body. Physiologist
Novotny and research leader
Clevidence of BHNRC's
and Human Performance Laboratory joined BHNRC plant physiologist
Britz and post-doctoral researcher Anne Kurilich, formerly with ARS, in
studying beta-carotene and lutein, two important carotenoids.
Carotenoids are fat-soluble pigments responsible for many of the hues
of plant leaves, fruits and flowers. Beta-carotene gives carrots their orange
color, while lutein is a major yellow pigment of corn and leafy green
Carotenoids act as biological antioxidants, protecting cells and
tissues from damage caused by naturally occurring oxygen free radicals in the
body. Beta-carotene is a potentially important means of lessening vitamin A
deficiency (the most serious nutritional deficiency problem worldwide), though
its specific vitamin A value can vary. Lutein is believed to protect the human
retina's macular region, reducing risk of macular degeneration, the most common
age-related cause of blindness.
Other potential health benefits of carotenoids include enhancing
immune system function, protecting from sunburn, and inhibiting the development
of certain cancers.
Results from a feeding study at BHNRC have helped researchers better
understand how these important compounds are absorbed by the body. The study
showed that the best lutein absorbers in the body are also the best
beta-carotene absorbers, suggesting similarities in their processing. In
addition, lutein is absorbed much better than beta-carotene is from kale. The
study demonstrated the formation of vitamin A from the tagged beta-carotene,
helping to reveal information about how well plant foods provide vitamin A.
A report on this study appears in the September issue of the Journal of Lipid Research.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.