Calcium May Lessen Stroke's Toll

Study finds less severe attacks, better outcomes in patients with high intakes

THURSDAY, April 6, 2006 (HealthDay News) -- High dietary calcium intake appears to lessen the severity of a stroke should one occur, and improve the likelihood of good post-stroke recovery, a new study finds.

Patients who had consumed calcium as part of their routine diet and had relatively high levels of the mineral in their blood at the time of a stroke endured attacks that were only one-third as severe as those experienced by patients with relatively low blood-calcium levels, researchers found.

The high-calcium patients were also 50 percent to 70 percent less likely to be functioning poorly when they ultimately left the hospital.

"Calcium levels definitely correlated with severity of stroke and predicted how well patients would be once they were released from the hospital," said study author Dr. Bruce Ovbiagele, an assistant professor of neurology at the stroke center in the department of neurology at the University of California, Los Angeles.

However, efforts to find a similar association between consumption of magnesium and stroke protection were not successful. The finding is intriguing because "both magnesium and calcium are involved in the development of stroke at the molecular level -- that is well-established, and we know that people who have levels of each are at less risk for experiencing a stroke in the first place," Ovbiagele said.

He was to present the findings Wednesday at the American Academy of Neurology annual meeting, in San Diego.

According to 2003 figures from the American Heart Association, strokes killed nearly 160,000 men and women in the United States, making it the No. 3 killer of Americans -- behind heart disease and all cancers.

Stroke remains the No. 1 cause of long-term disability in the United States, with approximately 700,000 Americans suffering a new or recurrent stroke each year.

According to the American Stroke Association, high blood pressure, smoking, diabetes, heart and arterial disease, high cholesterol, obesity, and excessive drinking are some of the principle -- and potentially treatable -- risk factors contributing to higher stroke risk.

In its study, Ovbiagele's team examined calcium and magnesium blood levels among 240 men and women who were treated at the UCLA Stroke Center within 24 hours of a stroke.

Blood level measurements were taken solely to assess mineral consumption and absorption prior to a stroke, and neither mineral was offered as a part of treatment at the time of the stroke.

After dividing the patients into four groups according to their respective mineral levels, the researchers correlated stroke severity and treatment outcomes with the presence of calcium and magnesium upon admission.

They found that magnesium did not appear to play a role in how strokes played out.

But the study authors did find a clear association between higher calcium levels and a better stroke prognosis. This association held even after the researchers accounted for other factors that could potentially influence stroke severity, such as age, type of stroke, or prior use of anti-stroke medications.

However, they cautioned that it's not yet clear whether adjusting diets to include more calcium would help those at high risk for stroke.

"We don't know if this is a reflection of their normal dietary intake or not," said Ovbiagele. "We only have a relative analysis, in which higher suggests better."

"The big issue now, of course, is to find out if this is the primary effect of calcium or a secondary effect -- is it just a marker of something else going on when patients have stroke?" he noted. "Now, we know that rats that have been given calcium have a reduced size of stroke and are less likely to die from strokes. And so it suggests that perhaps it might be a primary effect. And it might be that calcium given at the time of a stroke might help as part of a treatment. Of course, that hasn't yet been proven, but perhaps there may be an avenue for this," he added.

Dr. Eric Smith, a neurologist and associate director of acute stroke services at Massachusetts General Hospital, in Boston, said the results struck him as being both interesting and important.

"I think it is a surprising result, and it bears repeating in other studies and looking at this affect in animal models as well," said Smith. "We thought for a while that having higher levels of magnesium might have a protective effect on stroke, because in high levels it may help blood vessels to relax and therefore increase flow of blood to the brain -- which is important because strokes are a result of artery blockage."

"In contrast," noted Smith, "to my knowledge there is not a body of literature that suggests that calcium is related to stroke severity. And actually, to a certain extent, magnesium and calcium have opposite effects. In fact, calcium is thought to help blood vessels restrict. So it perhaps this suggests that the biology of calcium and magnesium in stroke is more complicated than originally thought, and warrants further study. Because if this is confirmed in other studies, this could perhaps be a potential treatment for stroke."

According to the U.S. National Institutes of Health, calcium-rich foods include dairy products, green vegetables such as broccoli or kale, legumes, canned fish and some nuts and seeds.

More information

For more on strokes, visit the American Dietetic Association.

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