THURSDAY, Aug. 1, 2002 (HealthDayNews) -- High blood levels of linoleic acid are associated with a lower risk of stroke, Japanese researchers report.
But don't rush out to buy a supplement, because the odds are that you will be getting something that sounds the same but is actually quite different.
And the Japanese researchers who did the study say a lot more work is needed to prove cause and effect, because of the nature of their work and because they haven't tested for adverse effects of high doses of linoleic acid.
The group at the University of Tsukuba examined frozen blood samples from 7,450 men and women who participated in cardiovascular risk studies over a decade; 197 of them had suffered strokes.
A 5 percent increase in linoleic acid levels was associated with a 28 percent reduction in stroke risk, says a report in tomorrow's issue of Stroke: Journal of the American Heart Association.
Linoleic acid is an essential fatty acid, found in soybeans, corn and safflower oil, that the body uses to make prostaglandins. It is important in growth and development in the first years of life and helps control blood pressure, inflammation and other body functions.
But if you go searching for it, you will encounter a lot of information about conjugated linoleic acid.
That's an entirely different compound, says Michael W. Pariza, director of the University of Wisconsin Food Research Institute.
Pariza should know, because he is the discoverer of conjugated linoleic acid, which is a mixture of various kinds of linoleic acid held together by what biochemists call conjugated double bonds. Because it is made in the stomach of cud-chewing animals, it is found primarily in meat and dairy products.
There are profound differences in the way the molecules act in the body, Pariza says. "In cancer studies, linoleic acid enhances the growth of certain forms of cancer, whereas conjugated linoleic acid opposes it," he says.
In large part because of that cancer-fighting effect, "conjugated linoleic acid is all the rage now," Pariza says.
"A conjugated linoleic acid supplement will not do what linoleic acid does," he adds.
And it seems to do a lot of good, at least in the amounts found in a well-balanced diet, says Dr. Keith Siller, associate professor of neurology at New York University School of Medicine, who welcomes the Japanese study.
"An article like this is good because it reinforces a lot of what we believe to be true, that linoleic acid lowers cholesterol, lowers blood pressure and improves the circulation in the small vessels of the brain," Siller says.
He likes the idea of studying the medical action of natural substances. "These are the kind of studies that physicians in general need to see to validate the purported benefits of natural products," Siller says. "Most traditional physicians do not support their use because there is no scientific proof of their benefits. So there is an ongoing argument between natural remedies and hard science."
Yet he is cautious about putting the Japanese findings to work in medical practice. "We might want to examine a patient's diet to see if it is lacking in linoleic acid," he says. "We need further studies before we start recommending it. First, we have to establish that it is not harmful, then we have to establish efficacy."
What To Do
You can learm more about linoleic acid and conjugated linoleic acid from the Gale Encyclopedia of Alternative Medicine. To learn about stroke, visit the American Stroke Association.
