Already known as a trendsetter in terms of nutrition, California Friday became the first state in the country to ban trans fats in restaurants and retail baked goods.

The new law signed by Gov. Arnold Schwarzenegger is supposed to promote healthy eating and clean up the American diet.

The law phases out oil, shortening and margarine containing trans fats from restaurants’ menus by 2010 and baked goods by 2011. The move will not stop the sale of popular foods such as French fries and doughnuts, but will only change the way they are cooked.

Trans fatty acids, or trans fats, are usually found in partially hydrogenated oils, which are frequently used at fast-food restaurants and bakeries because they have a longer shelf life than other types of oil. But several studies showed that trans fats can rise the levels of bad cholesterol and lower the so called “good cholesterol.” This contributes to heart disease and other health problems.

Dr. Junaid Khan, an Oakland cardiac and thoracic surgeon and an American Heart Association spokesman, who is a supporter of the bill, assured the Californian consumers nobody was trying to “outlaw chocolate.”

“California is a leader in promoting health and nutrition, and I am pleased to continue that tradition by being the first state in the nation to phase out trans fats,” Schwarzenegger said, as quoted by The Washington Post.

Opponents of the legislation argued that it was not clear whether substitutes for trans fats would be better for public health, but Michael Jacobson, executive director of Center For Science in the Public Interest, said that evidence showed that trans fats were the most harmful and that any substitution would mean an improvement, the Washington Post reports.