A school milk promotion program increases milk consumption and improves the calcium and vitamin D intakes of elementary school students

Journal of the Canadian Dietetic Association, Winter 1998 by Ransome, Kimberley, Rusk, Jacquie, Yurkiw, Mary Anne, Field, Catherine J

Abstract/Resume

This study evaluated the effect of the Alberta School Milk Program (ASMP) on usual calcium and vitamin D intake among elementary students. A semi-quantitative food frequency questionnaire was used to estimate daily intake of food and supplement sources of calcium and vitamin D. Samples were drawn from schools from Calgary and the surrounding region in Alberta, Canada. Participants in the ASMP and demographically matched non-participants were randomly selected. Parents completed and returned 803 questionnaires of 1350 distributed to students aged six-12 years (59% response rate), 783 questionnaires were analyzed. Students at risk for habitually consuming below government recommendations were identified using Canadian Recommended Nutrient Intakes (RNI). Data were analyzed to determine what proportion of students met the minimum number of suggested servings of dairy products as recommended in Canada's Food Guide to Healthy Eating. Descriptive statistics, one-way analysis of variance and Chi-square analysis were used to assess the effect of independent variables with estimated food, calcium and vitamin D intake. Participants reported higher intakes of calcium and vitamin D (P

(Can J Diet Prac Res 1998; 59:190-198)

Les auteures ont evalue l'effet de 1'Alberta School Milk Program (ASMP) sur l'apport usuel de calcium et de vitamine D chez des eleves du primaire. Un questionnaire de frequence de consommation semi-quantitatif a servi a estimer l'apport quotidien d'aliments et de supplements de calcium et de vitamine D. Les echantillons ont ete tires d'ecoles de Calgary et de la region environnante en Alberta, Canada. Les participants de l'ASMP et des non-participants apparies sur le plan demographique ont ete choisis au hasard. Les parents ont rempli et retoume 803 questionnaires sur un total de 1350 distribues aux eleves de 6 a 12 ans (taux de reponse: 59 %); 783 questionnaires ont ete analyses. A l'aide des Apports nutritionnels recommandes (ANR), on a depiste les eleves a risque en raison d'une consommation habituellement inferieure aux recommandations gouvemementales. Les donnees ont ete analysees pour determiner quelle proportion d'eleves respectaient le nombre minimum de portions de produits laitiers que recommande le Guide alimentaire canadien pour manger sainement. Les auteures ont utilise des statistiques descriptives, une analyse de variance simple et l'analyse du X^sup 2^ pour evaluer l'effet des variables independantes avec les apports estimes en aliments, en calcium et en vitamine D. Les apports en calcium et en vitamine D provenaient surtout (P

(Rev can prat rech dietet 1998; 59:190-198)

INTRODUCTION

During childhood, adequate dietary calcium and vitamin D enhances bone mineral density, especially during marked periods of growth (1-3). Dietary Reference Intakes (DRI) for calcium have been recently proposed based on intake levels associated with maximum retention of body calcium (4). DRI suggest an association between optimal intake of calcium and decreased risk of chronic disease (4). Therefore, ensuring calcium needs are met during childhood is thought to be one of the most important factors in reducing the risk of developing osteoporosis later in life (1-3). Studies however, consistently report that children's calcium intake is below current recommendations (5-10). Recently, a North American study conducted between 1978 and 1988 reported a decline (17%) in calcium intake among children due to a decrease in milk consumption (5). In children, the risk of calcium inadequacy increases with age (10,11), with adolescent females consistently identified as having food intakes that place them at greater risk (10,12). Due to higher food intakes, adolescent males tend to be at lower risk for inadequate calcium intake (11). Socio-economic status is also reported to impact on the consumption of calcium rich foods (12). Using seven-day weighed food diaries, Doyle, et al (12) reported that inner city school children were at high nutritional risk due to limited consumption of a variety of foods and breakfast skipping (33%). Since many foods in the milk products group require refrigeration, it is likely that key nutrients such as calcium and vitamin D will not be included in the midday meal unless otherwise provided by the school.

The absorption and utilization of calcium is reliant on adequate stores of vitamin D (13,14). In Northern regions, where endogenous cutaneous synthesis of cholecalciferol is low (15), inclusion of common dietary sources of vitamin D, such as vitamin D fortified milk, reduces the risk of inadequacy. The optimal range of ultraviolet light required for the formation of cholecalciferol is 290-340 nm (15). In Alberta, at a latitude exceeding 50 deg , the synthesis of cholecalciferol may be limited for five months of the year (15). This increases the reliance on dietary sources of vitamin D. In Canada, fluid milk is vitamin D fortified. One of the methods used to promote increased intake of calcium and vitamin D by children is through school-based milk programs.