'Bad fat' reduces body's defences, study shows

WASHINGTON - A single meal high in saturated fat can affect the arteries and stop the body from protecting itself against heart disease and stroke, new research says.

A similarly calorie-laden meal that substitutes healthy vegetable fat has far fewer ill effects, says the study by a team at the Heart Research Institute in Sydney.

Published this week in the Journal of the American College of Cardiology, the study illustrates how daily bad habits add up, over the years, to heart disease, heart attacks and strokes.

Saturated fats include all animal fats found in meat and dairy products, as well as coconut and palm oils. Most other vegetable fats are polyunsaturated or monounsaturated.

"This study helps to flesh out just why we shouldn't eat too much saturated fat," said Robert Vogel, a cardiologist who did not work on the study.

"Traditionally, we think of unhealthy foods as raising cholesterol or raising blood pressure, but this demonstrates that depending on what you eat, you can actually change the effect of HDL - typically thought of as 'good' cholesterol - from protective to detrimental," Dr Vogel said.

"This opens up new insights and avenues for research."

In the study, Stephen Nicholls and his colleagues fed two meals of carrot cake and a milkshake to 14 healthy volunteers aged 18 to 40, then checked their blood. The two meals were identical, except that one was high in coconut oil, a saturated fat, while the other was high in safflower oil, a healthier polyunsaturated fat.

Three hours after volunteers had the saturated fat, the lining of their blood vessels was less able to expand the arteries in order to increase blood flow.

The polyunsaturated meal reduced this ability slightly but the results were not statistically significant, said Dr Nicholls, a cardiologist from Ohio.

Six hours after the saturated fat meal, researchers found that high density lipoprotein, the HDL or "good" cholesterol, was less able to control inflammation inside the arteries. Inflammation is linked with heart disease.

By contrast, the polyunsaturated meal seemed to boost the anti-inflammatory abilities of HDL.

"The take-home, public-health message is this: It's further evidence to support the need to aggressively reduce the amount of saturated fat consumed in the diet," Dr Nicholls said.

- REUTERS