Many Hong Kong people have a poor understanding of what constitutes a healthy diet, a survey by Reader's Digest has said.

Conducted in May, polling about 400 people with an average age of 40, the research found that although 52 percent of the interviewees said they had a good cardiovascular condition, many had an insufficient understanding of what a healthy diet was.

About 40 percent had the wrong idea about fat and 84 percent had a poor knowledge of "trans" fat, it said.

"Some interviewees thought all fat was harmful," Fiona So, research and advertising services director with Reader's Digest, said yesterday.

Sylvia Lam, chairman of the Hong Kong Dietitian Association, said: "A wrong understanding of fat makes people choose unhealthy foods and increases the risk of cardiovascular disease.

"Fat is a necessary nutrient.

"Apart from providing energy and necessary fatty acids, it helps the body to build cell membranes and absorb vital vitamins," she said.

Saturated fat and trans fat provide bad cholesterol and are bad for the health, Sylvia said.

Trans fat is a type of unsaturated fat, like margarine, where liquid oil is transformed into solid form through hydrogenation.

Trans fat, which is used to make food more crunchy and tasty, is mainly found in manufactured foods like pastries and chips.

"Trans fat is more harmful than saturated fat because it increases bad cholesterol while lowering the good ones," she said.

To have an idea of the amount of trans fat in food, a medium-sized portion of French fries contains 8 g, while a doughnut has 5 g and an apple pie 5 g.

The American Heart Association advises eating not more than 2 g of trans fat per day based on a diet of 2,000 calories, Sylvia said.

We should eat more unsaturated fats, such as olive oil, nuts and fish with omega 3 fatty acids. They can lower the risk of heart disease and strokes, she said.

She also said Hong Kong people should be careful when reading food labels. For example, a label that reads "no trans fat" may still contain saturated fat.

Godwin Leung, a specialist in cardiology said cholesterol is an "invisible killer" and many patients with heart disease had no obvious symptoms. Heart disease is the second biggest killer in Hong Kong.

He recommended people over 20 check their cholesterol levels once every five years. Those with high blood pressure and cholesterol should check every year.

He said to lower the risk of heart disease people should adopt a healthy lifestyle that includes a balanced diet and exercising five times a week for at least 30 minutes each time.

(China Daily September 4, 2007)