Culprit Compounds That Block Beans' Healthful Iron
Probed By Marcia
Wood September 24, 2009
Familiar beans like reds, whites and pintos are rich in iron, a
nutrient essential for our health. But not all of the little legumes' treasure
trove of iron is bioaccessible—that is, available for our bodies to readily
In ongoing investigations, Agricultural Research Service (ARS) animal
P. Glahn and Cornell University
co-investigators are discovering more about natural compounds in foods that
increase or, problematically, decrease absorption of iron from those foods.
Glahn is based at the ARS
W. Holley Center for Agriculture and Health in Ithaca, N.Y.
Earlier this year, Glahn, along with former ARS research plant
physiologist Ross M. Welch—now retired and working as a collaborator with the
Ithaca laboratory—and their university collaborators began tests with poultry
as a followup to experiments that relied on Caco-2 human digestive system
cells, cultured in petri dishes.
One current study with poultry builds upon a Caco-2 study from several
years ago in which Glahn, Welch and colleagues determined that a natural
compound known as kaempferol may be a key culprit in decreasing absorption of
iron from red and pinto beans.
Kaempferol belongs to a class of natural substances known as
polyphenols. Though scientists have known for decades that polyphenols
interfere with absorption of iron from beans, the Ithaca study was apparently
the first to pinpoint a specific polyphenol in beans as a possible major
There's another side to polyphenols, however. They are antioxidants,
and thus are potentially important food components, according to Glahn. So, the
scientists are investigating them further.
The Ithaca research is highlighted in the September 2009 issue of
Agricultural Research magazine. Scroll down to the title beginning "A New Slant on Sustainability."
ARS is the U.S.
Department of Agriculture's principal intramural scientific research