3. REVIEW OF LITERATURE
The term literature review refers to an extensive and systematic examination of publications relevant to research project. Before starting any research, a literature review of previous studies and experiences related to the proposed investigation must be done.

Studies related to:

1. Changing trends in adolescents’ eating pattern.
2. Promoting factors of junk food
3. Health hazards of junk food
4. Effectiveness of Health Teaching Programme

Studies Related to Changing Trends in Adolescents’ Eating Pattern:

A National Health and Nutrition Examination survey was conducted in USA to determine the adolescent’s beverage consumption trends and causes. The sample consisted of 73, 345 individuals aged 12-16 years. The results of the study showed that, for this age group sweetened beverage consumption increased and milk consumption decreased. Over all energy intake from sweetened beverages increased by 85% and was reduced by 38% for milk, with a 278 total calorie increase. This trend was associated with increased proportion of adolescents consuming sweetened beverages, and reduction in milk consumption. This study recommended the beneficial impacts of reduced soft drink and fruit drink intake

A cross sectional study was conducted in USA to describe foods and beverages consumed at schools in terms of number of serves. The data have been collected from 1001 children aged 4-12yrs. Food and beverage intake was assessed using a school food checklist. The result of the study showed that 39% of children had fruit bars, 59% had packed snacks (potato, corn chips) and 26% had chocolates during their lunch and coffee breaks. Ten percent of children reported using the canteen and fast foods were the most frequently purchased items. A reduction in energy dense snacks and the promotion of healthy sandwiches would improve the healthiness of school lunch .

A study to determine the food habits of teenagers and important food sources of energy was conducted in USA by using one 24-hour recall method. Data was obtained from 17 teenagers. Foods were categorized into 51 groups and ranked according to contribution of key nutrients, energy and fiber. The result showed that a high intake of nutrient-poor foods, particularly high sugar beverages and salty snacks among teenagers.

A Nationwide Food consumption survey to determine overall trends of total energy intake by food location and food type in diets of adolescents and young adults was conducted. This study used a nationally representative sample of 16,810 individuals, aged 12-29 yrs. The results of the study showed that both adolescents and young adults obtaining less of their energy intake at home and more at restaurants and fast food places. Significant increase in consumption of pizza, cheeseburgers, and salty snacks and decreases in consumption of desserts and certain milk and meat products by both age groups were shown. Many of them had a poor knowledge on health effects of fast foods. This study recommended that, healthy food choices outside the home need to be insisted.

A study to examine trends in beverage consumption and evaluate the impact of beverage choices on the nutrient intakes of females in the age group of 12-19 years was conducted by using a semi-structured questionnaire. There were 732 females aged 12-19 years in Continuing Survey of Food Intakes by Individuals. The results showed that milk intake decreased by 36% While at the age of 16 years only 36% consumed milk and drank a high amount of whereas that of sodas and fruit drinks almost doubled. At the age of 12 years 78% drank milk and had lowest soda intake. soda. Those who did not drink milk had inadequate intake of vitamin A, foliate, calcium, phosphorus and magnesium. This study indicates nutrition education should be provided to parents of adolescent children with ideas of ensuring the adequacy of their children’s calcium intakes .

A pilot education project was conducted in high schools of Canada to study the nature, extent and quality of snacking among children aged 12-15 years. An observation checklist was used to assess the snack consumption pattern of 20 children. Findings showed that 41% of all energy was obtained from foods consumed as snacks...

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