Minor Nutrient Has Major Importance
By Marcia Wood
March 16, 2001
For strong bones, a healthy heart and
a smoothly functioning nervous system, our bodies rely on magnesium, an
essential mineral. Now, studies by Agricultural Research Service scientists
may reveal how much magnesium we can absorb from everyday foods.
This new information can be used in fine-tuning the recommended intake of
this mineral for Americans, according to research chemist Judith R. Turnlund.
Based at the ARS Western Human Nutrition
Research Center at Davis, Calif., Turnlund leads the magnesium studies. She
is an international authority on the role of minerals in human nutrition.
Good sources of magnesium include green, leafy vegetables; whole-grain
breads, and nuts.
Turnlund is collaborating in the magnesium research with the producers of
Perrier, a premium bottled water. Perrier
researchers want to know if bottled water is a good source of magnesium. Like
Turnlunds team, they need a good way to measure magnesium absorption.
The best bet so far is a urine test, Turnlund has found. To evaluate this
test, the researchers provided volunteers with a food or beverage spiked with a
traceable form of magnesium. The scientists also injected a tiny quantity of
the tracer magnesium into the volunteers blood, then collected urine
specimens about two days later.
To measure the amount of tracer magnesium in the urine samples, the
scientists used a high-tech instrument known as an inductively coupled plasma
mass spectrometer. They compared the amount detected by the spectrometer to the
amount given to the volunteers, in order to calculate how much magnesium was
absorbed and used.
An article in the ARS Agricultural Research magazine
tells more about Turnlund's research with magnesium and two other essential
minerals--copper and molybdenum.
ARS is the U.S. Department of
Agricultures chief scientific research agency.
Scientific contact: Judith R. Turnlund, ARS Western Human Nutrition
Research Center, Davis, Calif.; phone (415) 665-6274, fax: (530) 752-5271,