TUESDAY, Aug. 27, 2002 (HealthDayNews) -- The essential fats found in fish and nuts help more than your heart.
They can also reduce memory loss and strokes, claims a new study.
"When we don't have enough omega-3 and omega-6 fatty acids in our system, it can lead to a heart attack or a stroke. You're not getting enough oxygen to your brain, and you are overloading your heart," explains study author Vallie Holloway, a researcher at Loyola University Medical Center in Maywood, Ill.
Those two fatty acids, which are found in fish, nuts, seeds and some oils, are needed for a long list of body functions. However, while the human body manufactures most of the fats it needs, it does not make these two elements, requiring people to get them from their diets.
A string of recent studies have linked these essential fats to healthy hearts and blood vessels, but Holloway's study also targeted the effects of one of them, omega-6, on brain function.
"I would like to either stop or retard Alzheimer's disease," says the researcher, who was to present her findings today at the American Physiological Society's convention in San Diego.
Holloway studied 180 rats for a year to examine how their diets influenced their blood pressure and memory. Half of the rats were bred to have high blood pressure, and the other half were bred for low blood pressure. While all of the rats were given a normal diet and a regular regimen of maze-running, half of each group also got a supplement of omega-6 fatty acids.
The results were striking. The hypertensive rats that didn't get the omega-6 supplement saw their blood pressure increase as their brain function decreased. At four months, the rats had already forgotten part of the maze, and at six months their memory functions were badly deteriorated.
"It was like they were aging before your eyes," Holloway says.
By contrast, the hypertensive rats that got the supplement realized a drop in blood pressure and held onto their memory functions much longer. Rather than four months, these rats started forgetting parts of the maze at six months.
Holloway explained her results by focusing on the fats that clog blood vessels. In the feeder blood vessels in the brain, plaque buildup can cause clotting, which leads to strokes and Alzheimer's. At the same time, clogging of the arteries forces the heart to work harder in pumping blood, leading to possible heart failure.
Ironically, the body has a mechanism to limit this buildup, but poor nutrition often stands in the way, she says. When the brain senses an increase in the blood pressure, it sends a signal through the blood vessels to dilate the vessel walls, thereby allowing more blood to pass through. However, the process requires omega-6 and omega-3 fatty acids, which are often in short supply in the body, especially in old age.
"Basically your body doesn't produce enough of the chemical to dilate the blood vessels," Holloway says. "When we get older we need lots of things, and this is one of them."
Ann Yelmokas McDermott, a researcher at Tufts University's Friedman School of Nutrition Science and Policy in Boston, argues the broader issue is finding the proper balance between these two fats. People can't just take supplements of both because they compete for the same enzymes within the body, she says.
"The omega-6 takes care of one set of problems, and the omega-3 takes care of another set of problems. We need them both. But the ratio has to be correct," McDermott says. "The American diet is very high in omega-6 rather than omega-3 fats. It's thought that it should be the inverse for optimal health."
She argues that we should take in four parts omega-6 fats to one part omega-3 fats. Yet the ratio for most American eaters is 9-1. In Japan, where more people eat fish and live longer, the ratio is 1-1. In some European diets, the ratio is 12-1, McDermott says.
To find a better ratio, people can make a few simple substitutions in their diets. For example, instead of safflower oil, which has 77 parts omega-6 to one part omega-3, try canola oil, which is 2-1. Instead of margarine, 13-1, try butter, 1.5-1.
"What does this research mean to human beings? It shows that food can affect health and have medicinal properties," McDermott says. "Our bodies can't create these fatty acids themselves. So they're a big deal to our health."
What To Do
To compare the ratios of the two fatty acids in various foods, visit the University of Montana. Or learn about the benefits of fish from the American Heart Association.
