LOS ANGELES  California, a national trendsetter in all matters edible, became the first state to ban trans fats in restaurants when Gov. Arnold Schwarzenegger signed a bill Friday to phase out their use.

Under the new law, trans fats, long linked to health problems, must be excised from restaurant products beginning in 2010, and from all retail baked goods by 2011. Packaged foods will be exempt.

New York City adopted a similar ban in 2006  it became fully effective on July 1  and Philadelphia, Stamford, Conn., and Montgomery County, Md., have done so as well.

But having the requirement imposed on the most populous state’s 88,000 restaurants, as well as its bakeries and other food purveyors, is a major gain for the movement against trans fats. That movement has been led by scientists, doctors and consumer advocates who trace the largely synthetic fat to a variety of ailments, principally heart disease.