Washington ? Lunch programs are improving in many big school districts nationwide, a preventive medicine group said Tuesday.

Fifteen of the 18 districts that the nonprofit Physicians Committee for Responsible Medicine surveyed earned passing grades of C’s or better for the healthiness of their offerings. Four earned A’s or A-minuses. No school district’s lunch program did that well in the group’s last survey, conducted in 2004.

Elementary school lunchrooms received points for meeting U.S. Department of Agriculture standards, which dictate that less than 30 percent of calories per meal come from fat and only 10 percent come from saturated fat. They also earned points for offering vegetables and fruits and having nutritious options such as juice in vending machines.

Also graded were the schools’ efforts to encourage eating healthy foods and to educate students about nutrition.