By Michael Hastings | Journal Food Editor

I love olive oil. But I'm starting to think twice about it after a Science Cafe talk May 12 at Foothills Brewing.

The talk was sponsored by SciWorks, Reynolda Gardens and Sigma Xi, the Scientific Research Society, a nonprofit international group of scientists.

Science Cafe is a lecture series designed to help the general public meet practicing scientists and learn about their work, said Camilla Wilcox, curator of education at Reynolda Gardens.

"What you want to do is expose people to scientific discussion the way you expose them to music or art. This city is so full of scientists, and people have so few opportunities to sit down with them and learn what they do."

Fats as related to heart disease The scientist last week was Lawrence Rudel, a professor of pathology and biochemistry at Wake Forest University School of Medicine.

Rudel's specialty is lipids, or fats, and he has spent more than 20 years studying their effects on the body. In particular, he has studied fats and their relation to atherosclerosis and coronary heart disease. "It's a big, long, hard word, atherosclerosis. But it's just hardening of the arteries," he said.

Atherosclerosis is also called clogging of the arteries, because it involves a buildup on the artery walls. When that buildup restricts or clogs blood flow, it can cause a heart attack.

Clogged arteries are affected by diet and cholesterol in the body. Cholesterol is a component of fat, so the type and quantity of fat in a person's diet affects cholesterol levels and the risk of heart disease.

Healthy vs. unhealthy fat Nutritionists and such organizations as the American Heart Association recommend olive oil because it is high in monounsaturated fats, considered a healthy fat. Avocados and many nuts also are high in monunsaturated fats.

Nuts as well as fish and many plant oils (including soybean and safflower) are high in polyunsaturated fat, which are also considered good.

Trans fats, found in shortening and other partially hydrogenated oils, and saturated fats, found mostly in animal products, are considered bad.

These recommendations are based on what the fats do in respect to cholesterol in the body.

We're told to look for a good balance of HDL, or good cholesterol, and LDL, or bad cholesterol.

Monounsaturated fats and polyunsaturated fats both have relatively low LDL and relatively high HDL, so they are considered healthy fats that reduce the risk of atherosclerosis and coronary heart disease. In contrast, saturated fats and trans fats increase the risk of coronary heart disease.

"We want to make the HDL go up and limit the bad guys, the LDL," Rudel said.

Earlier studies have made monounsaturated fat look good with low LDL and high HDL. And studies of the Mediterranean diet, where olive oil is common, show those people have a low incidence of heart disease.

But Rudel's research shows that's not the whole story.

"The Mediterranean diet is not just olive oil," Rudel said. It also has lots of vegetables, beans and bread, and less meat and animal products than the typical American diet.

Rudel did a five-year study of three groups of 15 monkeys each to compare the incidence of atherosclerosis with varying fat diets. One had a diet high in saturated fat, one high in monounsaturated fat and one high in polyunsaturated fat.

The saturated-fat group had the worst good/bad cholesterol ratio. The polyunsaturated group had a good ratio, and the monounsaturated group had the best ratio. All of this was in line with predominant scientific thought.

But then Rudel found something surprising. The monounsaturated-fat group had just as much atherosclerosis as the saturated fat group.

"I wasn't expecting that. I was shocked," Rudel said.

With a good LDL/HDL ratio, that group should have had less incidence of atherosclerosis.

What Rudel found is that the risk of coronary heart disease is not just related to the good-bad cholesterol ratio. It's also related to the type and quantity of bad cholesterol particles that the body carries in the bloodstream.

Specifically, he noted something interesting about one of the enzymes in the liver that makes cholesterol that is carried in the blood. Animals with high levels of an enzyme called ACAT2 also had a high incidence of atherosclerosis.

And when he experimented on genetically-altered mice with ACAT2 removed from their bodies, levels of atherosclerosis were 85 percent lower than in animals that produce ACAT2.

Worst of all, ACAT2 seems to have a particular liking for the fatty acid that comes from monounsaturated fat, so that it promotes the production (in the liver) of more bad cholesterol particles that then circulate and get deposited in the arteries. "When you eat a lot of monounsaturated fat, you are just handing ACAT2 a club to beat you up," Rudel said.

Rudel is confident of the results, he said, because he has since repeated the monkey experiment three times with mice. "It comes out the same every time," he said.

He also cited recent evidence published in the American Journal of Clinical Nutrition that concludes that monounsaturated fat may not be good for humans in terms of coronary heart disease.

The good news is that researchers may use this information about ACAT2 to develop a heart drug that saves a lot of people from having heart attacks. Drug companies are beginning to consider this approach, Rudel said.

The bad news is that monounsaturated fats, including the olive oil I love, may not be as good for us as most people think.

I'm rationalizing that I can keep eating olive oil and other monounsaturated fats in moderation because they are high in the antioxidant Vitamin E and nutrients that help develop and maintain the body's cells.

"Olive oil may have some other good properties," Rudel said, "but not when it comes to coronary heart disease."

¦ Michael Hastings, the Journal's Food editor, can be contacted by phone at 727-7394, e-mail at mhastings@wsjournal.com, or mail at c/o Winston-Salem Journal, P.O. 3159, Winston-Salem, NC 27102. His most recent columns can be read on our Web site at www.journalnow.com.