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Photo: Judith Turnlund and William Keyes use thermal ionization mass spectrometry to measure trackable forms of copper in blood plasma. Link to photo information

Read: more about Turnlund's research in the Agricultural Research magazine.

Magnesium — 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 Turnlund’s 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 Agriculture’s 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,