WASHINGTON — At a three-to-one ratio, parents of school-age children support strong national nutrition standards for all foods and beverages sold to students during school, according to a poll released by The Pew Charitable Trusts, the Robert Wood Johnson Foundation (R.W.J.F.), and the American Heart Association (A.H.A.).

The finding comes as the U.S. Department of Agriculture begins the implementation of “Smart Snacks in School” nutrition standards, which set nutritional limits on food and beverages sold in vending machines, school stores and a la carte cafeteria menus. The revision is the first national snack food and beverage guidelines update in more than 30 years. To meet the standards, a snack food must be a fruit, a vegetable, protein, dairy, or whole grain, have fewer than 200 calories, and be low in fat, sodium, and sugar.

The new standards for the most part meet the findings in the Pew poll. Parents overwhelmingly support (91%) requiring schools to provide a serving of fruits and vegetables with every meal, and most parents (75%) think salt should be limited in meals.