Toronto's board of health is considering how it might phase out trans fats from city restaurants.

On Monday, city councillors on the board asked Toronto's medical officer of health, Dr. David McKeown, to report by September on how it might be done.

The move comes as New York City restaurant owners get ready for a July 1 ban on oils, shortenings and margarines containing trans fats. Eating establishments in that city will have until July 2008 to eliminate artificial trans fats from all other foods.

Trans fats are made by converting liquid oils to a semi-solid form. They help foods last longer and enhance flavour, but raise the level of "bad" cholesterol in the body while depleting "good" cholesterol, which helps protect against heart disease.

In June 2006, a federal task force report recommended legislation to limit trans fats in processed foods. It called for a limit of two per cent of total fat content in spreadable margarine and five per cent in all other foods.

Ten months later, a report by the Heart and Stroke Foundation and Toronto Public Health called for the federal government to act immediately on the task force's recommendations and to eliminate harmful trans fat from Canada's food supply.

In the meantime, McKeown has asked Toronto restaurants to voluntarily limit their use of trans fats.

He said he wants to meet with federal Health Minister Tony Clement to see how the government plans to respond to the task force report before making his own recommendations.