Magnesium-Rich Diet May Reduce Metabolic Syndrome Risk

March 28, 2006

Magnesium-Rich Diet May Reduce Metabolic Syndrome Risk

CHICAGO—A magnesium rich-diet may help reduce the risk of metabolic syndrome and, perhaps, a heart attack or diabetes, Northwestern University researchers report in Circulation: Journal of the American Heart Association.

Metabolic syndrome is a cluster of cardiovascular disease and diabetes risk factors, including excess waist circumference, high blood pressure, elevated triglycerides, low levels of high-density lipoprotein (HDL, the “good cholesterol”), and increased fasting glucose levels. The presence of three or more of the factors increases a person’s risk of developing diabetes and cardiovascular disease.

Previous studies indicate that magnesium can reduce the risk of the individual components of metabolic syndrome, but scientists lacked evidence of its efficacy against the syndrome.

“As far as we can determine, this is the first prospective evidence that shows magnesium intake provides a beneficial effect in the syndrome,” said Ka He, MD, lead author of the study and assistant professor of preventive medicine at Northwestern University’s Feinberg School of Medicine.

“We also saw that a higher magnesium intake was associated with a reduced risk of each individual component of the metabolic syndrome,” Dr. He said.

The observational study initially included 5,115 blacks and whites ages 18 to 30 enrolled in 1985 and 1986 in the Coronary Artery Risk Development in Young Adults Study (CARDIA). After excluding those with metabolic syndrome and diabetes at the beginning, and pregnancy in the study period, 4,637 participants (53.8 percent female) remained in the study.

Reporting 15-year follow-up data, Dr. He and co-researchers found that 50 percent of participants with the highest intake of magnesium had a significantly lower rate of metabolic syndrome than the 25 percent who consumed the least magnesium.

The age of the participants at enrollment was important because “most of the evidence that magnesium lowers the risk of cardiovascular disease or diabetes comes from studies using older adults,” Dr. He said. “People middle-aged or older are more likely to already have had the onset of disease.”

Dr. He added: “Their lifestyle choice and health conditions may be affected by perceived ill health or treatment for existing disease that related to individual components of the metabolic syndrome.”

Fifteen years after enrollment, 608 of the participants had developed metabolic syndrome. For analysis, the researchers divided the volunteers into four groups based on their magnesium intake. Only 16 percent took dietary supplements that contained magnesium.

The researchers found an inverse relationship between magnesium intake and the development of metabolic syndrome—the more of the nutrient consumed, the lower a person’s risk.

The National Institutes of Health recommends various dietary allowances (RDAs) for magnesium by gender and age group:

•For ages 14 to 18, the RDAs are 410 milligrams daily for males and 360 milligrams for

females.

•For ages 19 to 30, the RDAs are 400 milligrams for males and 310 milligrams for females.

•After age 30, the RDAs increase to 420 mg for males and 320 mg for females.

•RDAs are higher for females during pregnancy and lactation.

“This is an observational study,” Dr. He said. “Without data from randomized clinical trials, we are not comfortable making any recommendation on a daily dose of magnesium intake in terms of metabolic syndrome prevention.”

Magnesium can come from foods or supplements. Foods rich in magnesium include halibut, dry-roasted almonds and cashews, spinach, whole-grain cereals, blackeyed peas, long-grain brown rice, kidney and pinto beans, avocadoes, bananas, and raisins.

However, Dr. He warned against relying on magnesium to lower the risk of metabolic syndrome.

“Magnesium is just one component of a healthy diet, and a healthy diet is just one component of a healthy lifestyle,” Dr. He said.

“In general, people should eat more fruits and vegetables and reduce their intake of saturated fats and trans fats, exercise, and stop smoking because a healthy lifestyle is important in disease prevention,” he said.

Dr. He’s co-authors at the Feinberg School were Kiang Liu, PhD, professor of preventive medicine; Martha L. Daviglus, MD, associate professor of preventive medicine; and Linda Van Horn, PhD, professor of preventive medicine. Other authors included Catherine M. Loria and Peter J. Savage, MD, National Heart, Lung, and Blood Institute; David R. Jacobs Jr., University of Minnesota School of Public Health, Minneapolis, and the University of Norway, Oslo; and Steven J. Morris, University of Missouri-Columbia Research Reactor Center, Columbia.

This study was supported by National Institutes of Health grants N01-HC-48047, No1-HC-48048, N01-HC-48049, N01-HC-48050, and N01-HC-95095.