Contact:
Dorothy Klimis at 207-581-3124 or [email protected]
ORONO, Maine -- A team of University of Maine nutritionists has found new evidence which underscores the importance of manganese in the diet. As suggested by their studies with rats over the past several years, lack of this trace element may pave the way for damage to arteries and the liver.
The research team led by Dorothy Klimis, an associate professor of clinical nutrition, and former graduate students Peiying Yang, Ranjan Ekanayake and Paul Taylor, was funded by the American Heart Association and the United States Department of Agriculture. Reports of their work were published in the Journal of Nutrition Research in 1997 and the journals Nutritional Biochemistry and Trace Mineral Research in 1996, 1997 and 1998.
Klimis and Yang presented papers on their work at the Federation for American Societies for Experimental Biology in 1996 and 1997 and at the 5th International Symposium on Advances in Lipoproteins and Atherosclerosis in Athens in April 1997.
The team found that rats fed a diet lacking in manganese had reduced concentrations of a cellular building block known as glycosaminoglycans. These compounds make up the connecting tissue in bones, arteries and other organs. Manganese deficient rats had significantly reduced levels of one type of glycosaminoglycan, chondroitin sulfate, which also became chemically altered by additional sulfate.
Manganese is a critical ingredient in glycosaminoglycan synthesis. Other researchers have suggested that this structural change may promote binding of low density cholesterol (LDL) to artery walls.
"We now know that dietary manganese deficiency results in loss of the integrity of the tissue that lines the artery walls. Manganese may be important in keeping arteries healthy, but its physiological meaning is uncertain at the present time. We need to look at its effect on arterial function next," says Klimis. "We also need to study how changes in the sulfation of chondroitin sulfate may affect binding of LDL lipoproteins."
Manganese also seems to have a separate role in lipoprotein metabolism. In these studies in Klimis' laboratory, a low manganese diet led to reduced HDL cholesterol, the beneficial form of cholesterol and to a change in the structure of this particle.
Klimis is the editor of Manganese in Health and Disease, a book published by CRC Press in 1994. "For cardiovascular disease, manganese deficiency could be just the beginning. It appears to prepare the artery for another insult. That could be caused by low density cholesterol or tobacco smoke."
Klimis' work on manganese started during her graduate school years at Penn State when she sought information to help her mother who suffered from Parkinson's Disease. Too much manganese can cause nervous system disorders which mimic the symptoms of Parkinson's, she says.
"I found out there was not very much known about how manganese affects the body. We really didn't know what happens when your body is low in manganese in the long run," she says.
Other studies have shown that the elderly and teenagers in the United States tend to have diets low in the element, she says.
Klimis cautions individuals from taking manganese supplements without the advice of a nutritionist. "There are interactions between manganese and other elements like iron and calcium, and I am concerned when people just take supplements off the shelf. Negative effects from too much or too little manganese can be seen in a period of months."
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