Adolescents and calcium: what they do and do not know and how much they consume

To assess knowledge about calcium and dietary intake among a sample of adolescents.

A survey consisting of 24-h dietary recall and 14 questions assessing knowledge about calcium was administered to 1117 adolescents (52% girls and 48% boys) attending the ninth grade in five public schools.

A majority (98%) believed that dietary calcium is healthy, strengthens the bones (92%), and may prevent osteoporosis (51%), but only a few were aware of the role of calcium in neuromuscular function (20%) and blood pressure regulation (15%). About 60% knew that adolescence is a critical period for peak bone mass accretion. Only 19% were aware of the recommended dietary allowance (RDA) of calcium for adolescents [4 servings (1200 mg)/day]. The majority knew that dairy products are the main dietary source of calcium, but only 10% were aware of the calcium content of various dairy products. Only 45% knew about nondairy sources of calcium. The adolescents' main sources of calcium information were health teachers (55%) and parents (46%), while only 38% reported that their health care providers had discussed health benefits of calcium. Dairy products accounted for most of the reported daily calcium intake, and the majority (79%) reported consuming dairy products daily. "Dislike" and allergy were the main reasons given for not consuming dairy products. One third reported daily supplementation with vitamins and minerals, 68% of which contained 100-200 mg of elemental calcium. Calculated calcium intake (foods, beverages, and supplements) was 536 +/- 19 mg/24 h (45% of RDA) in girls and 681 +/- 28 mg/24 h (57% of RDA) in boys (p < 0.0001).

While adolescents are aware of the main health benefits of calcium, they lack specific information about daily requirements and calcium content of the various dietary sources. This lack of information may contribute to adolescents' suboptimal intake of calcium.