Researchers also looked at foods sold in school stores, snack bars and other related sales and found that these pose the same health and diet risks in school-aged children.
To investigate, researchers analyzed data from more than 2,300 children in grades 1 through 12 from schools across the U.S.
Interviewers administered questionnaires to obtain 24-hour food intake data on a given school day.
Among those surveyed, 22 percent of school children consumed competitive or vended food items in a school day. Usage was highest in high school, where 88 percent of schools had vending machines, compared to 52 percent of middle schools and 16 percent of elementary schools.
Children who ate from vending machines had significantly higher sugar intakes and lower dietary fiber, vitamin B levels and iron intakes than non-consumers.
Soft drinks accounted for more than two-thirds of beverages offered in school vending machines and stores. Desserts and fried snacks were the most commonly consumed vended items among elementary school children and beverages other than milk and fruit juice were the most commonly consumed items among middle and high school students.
Other frequently consumed vended foods included candy, snack chips, crackers, cookies, cakes and ice cream.
The results did not show a significant difference in students' consumption of these items based on family income or race and ethnicity.
Researchers warn that the foods children are exposed to early on in life influence the pattern for their eating habits as adults and that the consumption of vended foods and beverages currently offered in U.S. schools is detrimental to children's diet quality. They note that childhood obesity, resulting from poor dietary choices, such as those found in this study, greatly increases the risk for many chronic diseases.
Currently in Canada, significant steps are being taken to promote healthy foods available in schools. In Ontario, the provincial government is phasing in a healthy eating initiative that will see candy, energy drinks and fried foods no longer being sold in schools.
For more information on Ontario's new School Food and Beverage Policy, click here.
Looking to get the teen in your life to eat healthier? Pick up Leslie Beck's book Healthy Eating for Preteens and Teens - a comprehensive and reader-friendly guide to diet, nutrition and food.
All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.