California will phase out certain ultraprocessed foods from school meals over the next decade under a first-in-the-nation law signed Wednesday by Gov. Gavin Newsom.

The law seeks to define ultraprocessed foods, the often super-tasty products typically full of sugar, salt and unhealthy fats.

The legislation requires the state’s Department of Public Health to adopt rules by mid-2028 defining “ultraprocessed foods of concern” and “restricted school foods.”

Schools have to start phasing out those foods by July 2029, and districts will be barred from selling them for breakfast or lunch by July 2035. Vendors will be banned from providing the “foods of concern” to schools by 2032.

Newsom signed the measure Wednesday at a local middle school in Los Angles.

Newsom issued an executive order earlier this year requiring the Department of Public Health to provide recommendations by April on limiting harms from ultraprocessed foods.

The Democratic governor signed a law in 2023 banning certain synthetic food dyes from school meals.

Legislatures across the country have introduced more than 100 bills in recent months seeking to ban or require labeling of chemicals that make up many ultraprocessed foods, including artificial dyes and controversial additives.

Americans get more than half their calories from ultraprocessed foods, which have been linked to a host of health problems, including obesity, diabetes and heart disease.

However, studies haven’t been able to prove that the foods directly cause those chronic health problems.

Some school districts in California are already phasing out foods the law seeks to ban.

Michael Jochner spent years working as a chef before taking over as director of student nutrition at the Morgan Hill Unified School District about eight years ago. He fully supports the ban.

Now they don’t serve any ultraprocessed foods, and all their items are organic and sourced within about 50 miles (80 kilometers) of the district, Jochner said.

They removed sugary cereals, fruit juices and flavored milks, and deep-fried foods such as chicken nuggets and tater tots from their menus, he said.

Many of their dishes are made from scratch or semi-homemade, including an item that has long been a staple in U.S. school cafeterias: pizza.

Defining ultraprocessed foods has been tricky. The most common definition is based on the four-tier Nova system developed by Brazilian researchers that classifies foods according to the amount of processing they undergo.

Researchers often describe ultraprocessed foods as the types of products that contain industrially made ingredients that you won’t find in a home kitchen.

But some highly processed foods –— think tofu, certain types of whole-grain bread and infant formula – can be healthful. And it’s not clear whether it’s the processing of the foods or the combination of nutrients such as sugar, fat and salt that leads to poor health outcomes.

U.S. health officials recently launched an effort to come up with a federal definition of ultraprocessed foods, saying there are concerns over whether current definitions “accurately capture” the range of foods that may affect health.

Some critics of the ban say it is too broad and could unintentionally limit access to nutritious foods.

“For foods served in schools, food and beverage manufacturers meet the rigorous unique safety and nutrition standards set by the USDA and state agencies," John Hewitt with the Consumer Brands Association said in a statement.

He added the brands the association represents are committed to “providing safe, nutritious and convenient” products.

The California School Boards Association is concerned about the cost for districts to phase out these foods in the next few years. There is no extra money attached to the bill.

The law could raise costs for school districts by an unknown amount by potentially making them purchase more expensive options, according to an analysis by the Senate Appropriations Committee.

AP Video by Terry Chea