Laura Agard

Date of Award


Level of Access

Open-Access Thesis

Degree Name

Master of Science (MS)


Food and Nutrition Sciences


Susan Sullivan

Second Committee Member

Richard Cook

Third Committee Member

Phillip Pratt


Calcium is an essential nutrient required for normal growth and development of the skeleton and teeth. Adequate calcium intake is critical during early adolescence to optimize peak bone mass and decrease the risk of osteoporosis later in life. Previous researchers, however, have concluded that adolescent girls consume insufficient calcium to meet the demands of rapid skeletal growth. National surveys conducted prior to 1997 showed that t.he major sources of calcium for adolescent girls were milk and milk products. Shortly after the new Dietary Reference Intakes (DRI's) for calcium were released in 1997, calcium fortified foods became more readily available on the market. Sources of calcium and calcium intake levels of adolescent girls need to be reassessed to determine the role of calcium-fortified foods, which are increasing in prevalence in the food supply. This research is part of the Seasonal Bone Study, a longitudinal, observational study of bone mineralization in adolescent girls at the University of Maine. The specific hypothesis tested was that the total calcium intake of adolescent girls is significantly greater than in the past, and that calcium-fortified foods are a significant source of dietary calcium. One objective was to compare the mean calcium intake of the subjects in this study to that of the Adequate Intake (AI) and to mean calcium intakes of adolescent females from previous national and Maine studies. The other objective was to compare the sources of calcium intake of the subjects in this study to those of adolescent females from the USDA 198 1 - 1988 Nationwide Food Consumption Survey. In January and February of 2001, twenty-four females between the ages of 9.7 to 12.3 years kept 24-hour food records on four discontinuous days consisting of three week days and one weekend day. After the four days of food records were completed, each record was reviewed and the foods and beverages were classified into the following categories: milk and milk products, milk as an ingredient, calcium-fortified non-grains, calcium-fortified grains, grains, and other. The mean daily calcium intake of adolescent females in this study was 1039 mg, which is significantly higher (p<0.01) than in many previous surveys, yet remains significantly lower (p<0.01) than the A1 of 1300 mg. The most significant sources of calcium in this study were milk and milk products, which is consistent with previous research. Furthermore, calcium fortified foods contributed 7% of the total calcium intake, with 30% of breakfast cereals consumed being calcium-fortified. The results of this research suggest that calcium intake of adolescent girls may have improved in recent years. It is not possible from this study, however, to determine if the intake for the whole population has increased. Thus, national surveys should be conducted. Although the calcium intake of adolescent girls in this study was higher than in previous studies, calcium intake was still suboptimal. Furthermore, calcium-fortified foods were not a major source of calcium in this study. These results imply that further attention to increasing calcium intakes in adolescent females is warranted.