* Proposed USDA rules to limit fat, salt, sugar
* Snacks should contain 200 calories or less
* Plan allows some soft drinks for older students
* One-third of U.S. youth are overweight or obese
WASHINGTON, Feb 1 (Reuters) - Snacks sold in U.S. schools would need to be lower in fat, salt and sugar and include more nutritious items like fruits, vegetables and whole grains, under standards proposed on Friday by the U.S. Department of Agriculture.
The proposal, more than a year overdue, also calls for a limit of 200 calories on items sold during the school day at vending machines or other venues outside the school lunch line.
The proposed rules are the second step in a larger effort to improve the foods U.S. students have access to during the school day under a 2010 child nutrition law. One-third of U.S. children and teenagers are overweight or obese.
The proposed rules would cover some 50 million children attending more than 100,000 schools that are part of the school lunch program. Many U.S. children eat more than half of their calories at school.
There was wide agreement by food and beverage companies, consumer advocates and public health experts on the need to offer students healthier choices
"If a student buys a snack from a vending machine or a slice of pizza from the a la carte line, it should be healthy," said Risa Lavizzo-Mourey, head of the Robert Wood Johnson Foundation, which focuses on health care. "These proposed nutrition standards, the first update in more than 30 years, are long overdue and badly needed."
"ENOUGH JUNK FOOD FOR 2 BILLION CANDY BARS"
Children buy an estimated 400 billion calories of junk food a year at school, the same calorie count that could be found in 2 billion candy bars, said a group of retired military leaders who back the proposed rules.
The group, called Mission: Readiness, has warned that one in four young Americans is too heavy for military service.
Agriculture Secretary Tom Vilsack, who has described his own struggles with weight as a child, said the higher standards for snack bars, vending machine and cafeterias will mean "the healthy choice is the easy choice for our kids."
USDA said the rules would not cover items sold at after-hours activities, such as sporting events. They also would allow for "important traditions," such as parents sending cookies or cupcakes to school for a child's birthday, or "occasional fundraisers and bake sales."
In general, foods sold at school could not provide more than 35 percent of their calories through fat or sugar. Salt content also would be limited.
For beverages, USDA called for schools to be able to sell water, low-fat and fat-free milk, and 100 percent juices, with smaller 8-ounce (240-ml) portions created for younger students.
High school students could buy 20-ounce servings of various calorie-free beverages, and 12-ounce servings of drinks that have 75 calories or less but not during lunch or breakfast.
The soft drink industry said it has shifted to lower-calorie drinks in school vending machines and it welcomed USDA's proposal. The number of calories shipped to schools in beverages is down by 90 percent in six years, it said.
The public has 60 days to comment on the proposal before USDA issues any final ruling. USDA said schools will have at least one full school year after the final rule is issued to implement the changes.
Vending machines are in just 13 percent of U.S. elementary schools but are in two thirds of middle schools, where student are 11 to 14 years old, and in 85 percent of high schools. USDA says more than 80 percent of school districts have restricted or banned sugary drinks and more than 75 percent put limits on snack foods or banned them.