Snap Beans Fingered as Calcium Source for
April 9, 1997
Girls and boys absorb two important
bone-building minerals--calcium and magnesium--from snap beans as easily as
they absorb them from milk, according to an Agricultural Research Service study being
reported today at the Experimental Biology 97 meeting in New Orleans.
Thats good news to researchers at the ARS
Childrens Nutrition Research
Center in Houston, Tex. They are looking for good sources of calcium to
replace the 24-35 percent drop in milk consumption among children and teenagers
since the late 1970's. Snap beans are a popular vegetable among this age group.
The researchers measured the rate of calcium absorption from milk and
compared it with snap beans, broccoli and spinach in 12 girls and boys ages 9
to 14. They also looked at magnesium absorption from snap beans and spinach.
Although it takes about five cups of cooked snap beans to equal the calcium
in one cup of milk, the rate of absorption was the same from both sources. The
absorption rate was about 5 percent higher from broccoli, one cup of which
provides about one quarter as much calcium as a cup of milk. But the calcium in
spinach was poorly absorbed because of a high content of absorption-blocking
compounds known as oxylates.
The youths absorbed magnesium from snap beans, spinach and milk at about the
same rate. Snap beans provide nearly as much magnesium as milk, but spinach
provides nearly five times more.
In a related tests, the researchers collaborated with
University of Wisconsin plant breeders to
assess 64 unique types of snap beans, looking for differences in calcium
content. They found wide differences, indicating that calcium content has a
strong genetic basis. This means breeders can develop snap bean varieties with
One discovery: The commercial snap bean variety Hystyle was among those with
the highest calcium levels. In addition, the researchers found that younger,
skinnier snap beans had significantly more calcium than older, fatter pods.
Scientific contact: Steven Abrams or
Childrens Nutrition Research Center, Houston, Texas, (713) 798-7000,