Volume 80, Number 2 March/April 2009
Bone Health. Consuming an adequate intake of nutrient-rich dairy foods during childhood and adolescence is important for optimizing bone health, which may help reduce the risk of fractures in childhood and adolescence and osteoporosis in later adulthood (18,28,29). Achieving genetically determined peak bone mass, 90% of which is reached sometime during late adolescence and the early 20s, helps to reduce the risk of fractures and osteoporosis (28,29). Because 99% of the body’s calcium is stored in bones and vitamin D enhances calcium absorption, it is not surprising that these nutrients are critical to bone health. Dairy foods are a major dietary source of calcium and provide other nutrients such as vitamin D (if fortified), phosphorus, protein, potassium, magnesium, and vitamin A that support bone health (12,28,29).
According to a recent study, an adequate intake of dairy foods beginning in childhood improves bone health in adolescence (30). This study examined data from 106 children initially aged 3 to 5 years who participated in the Framingham Children’s study. At the end of 12 years, adolescents (15 to 17 years) who consumed two or more servings of dairy foods a day as children had significantly higher bone mineral content, bone area, and bone mineral density than those who consumed less than two servings a day (30).
A recent meta-analysis of data from randomized controlled trials and observational studies in children found a non-significant increase in total body bone mineral content with increased calcium/dairy intake (31). However, when the analysis was limited to three clinical trials of children with low baseline intakes of calcium, increasing calcium/dairy food intake increased total body bone mineral content by an amount approximately 25 times greater than in children whose baseline calcium intake was adequate (31). Pooled data from two randomized controlled studies showed that calcium/dairy foods plus vitamin D increased bone mineral content of the spine (31).
Recognizing widespread vitamin D insufficiency in children and adolescents, and the importance of vitamin D in bone and overall health, the AAP doubled the recommended intake of vitamin D to 400 IU/day for infants, children, and adolescents (7). Consuming three or four servings of vitamin D-fortified milk not only provides 300 IU or 400 IU of vitamin D, respectively, but also other “nutrients of concern” for children and adolescents (i.e., calcium, potassium, magnesium) (6,12). Some yogurts and cheeses are also fortified with vitamin D.
Scientific evidence indicates that consuming recommended servings of dairy foods during childhood and adolescence helps to reduce the risk of several diet-related chronic diseases that take root in childhood and are carried over into adulthood.
Government agencies and health professional organizations recognize the importance of calcium and calcium-rich foods such as milk, cheese, and yogurt for children’s and adolescents’ bone health (18,28,32,33). The 2005 Dietary Guidelines for Americans states that “the consumption of milk products is especially important for children and adolescents who are building their peak bone mass and developing lifelong habits” (6).
For children and adolescents with lactose intolerance, the Dietary Guidelines (6) and the AAP (18,34), along with several other government and health professional organizations, recommend dairy foods (e.g., lactose-free milk, yogurt with live, active cultures, aged cheeses) as the first option. The AAP, in its report on lactose intolerance, encourages children and adolescents with lactose intolerance to consume dairy foods to obtain enough calcium, vitamin D, protein, and other nutrients essential for bone and overall health (34). The report also indicates that, while rice and soy beverages are generally free of lactose, the nutrient content of these beverages is not equivalent to cow’s milk (34). Also, Caucasian, African American, and Hispanic children have been shown to prefer the taste of flavored (chocolate) lactose-free 1% milk compared to milk substitute beverages such as flavored (chocolate) low-fat soy beverages (35).
A Healthy Blood Pressure.
Hypertension (high blood pressure) and pre-hypertension is a significant public health issue for children and adolescents (36). Overweight children and adolescents are among population groups most at risk for high blood pressure (37). Prevention, starting early in life, is of utmost importance because high blood pressure in the early years increases the risk of hypertension in adulthood (38) and hypertension is a risk factor for heart disease, stroke, and kidney disease (37). The Dietary Approaches to Stop Hypertension (DASH) clinical trial demonstrated that consuming a low-fat diet containing two to three servings of low-fat dairy foods and eight to ten servings of fruits and vegetables a day significantly lowered blood pressure in adults (39). Similarly, consuming a DASH-like dietary pattern characterized by high intakes of dairy foods, fruits, and vegetables has been shown to beneficially affect blood pressure in children and adolescents (40,41).
Healthy Body Weight. Almost one-third (23 million) of children aged 2-19 years are either overweight or obese (1,20). Because overweight children are at increased risk of becoming overweight or obese adults, and obesity is associated with immediate and/or long-term health risks such as high blood pressure, type 2 diabetes, and metabolic syndrome, prevention of pediatric overweight is a public health priority (2,37,42,43).
Despite the belief that dairy foods are “fattening,” accumulating scientific evidence indicates that recommended intakes of dairy foods do not adversely affect children’s body fat level and may protect against adding excess body fat or body weight (17,44-46). Data from the Framingham Children’s study found that higher intakes of dairy foods in early childhood (3 to 6 years) were associated with decreased gain of body fat in early adolescence (10 to 13 years) (44). According to a recent investigation using data from two of the National Health and Nutrition Examination Surveys (NHANES), 1988-1994 and 1999-2002, adolescent girls (12-16 years) who consumed three or more servings of dairy foods a day had a lower body mass index (BMI) and lower body fat level than did girls who consumed 1-<3 servings of dairy foods a day (45). Similarly, adolescent boys who consumed four or more servings of dairy foods a day had lower BMI levels and body fat than did those who consumed fewer than two dairy servings a day (45).
Research demonstrates that children and adolescents who drink either flavored or white milk consume more nutrients and have a lower or comparable BMI than non-milk consumers (17). A randomized controlled trial in 98 overweight and obese Chilean children (aged 8-10) found that replacing sugar-sweetened beverages with approximately three servings of flavored milk a day had no effect on percent body fat, but significantly increased lean body mass, and for boys, increased height (46). According to the Dietary Guidelines, adding small amounts of sugar to nutrient-rich foods such as reduced-fat milk helps enhance their palatability and improves nutrient intake without adding excessive calories (6).
Access to low-fat and fat-free dairy foods – milk (including white, flavored, lactose free), cheese, and yogurt – in federal child nutrition programs can help children meet their nutrient needs and may help reduce their risk for several chronic diseases.
A recent review of more than 90 human studies, including randomized controlled trials and observational studies among a range of ages, found a strong link between high calcium and dairy food intakes and improved body composition (47). Although further study is needed to clarify the relationship between dairy food/calcium intake and body composition in children and adolescents (48), the Dietary Guidelines states that children (and adults) should not avoid milk and milk products because of concerns that these foods lead to weight gain (6). To prevent overweight and obesity in children and adolescents, a recent Expert Committee convened by the American Medical Association and consisting of 15 health professional organizations recommended a nutritionally balanced diet containing two to three servings of low-fat or fat-free dairy foods, consistent with USDA’s MyPyramid (www.mypyramid.gov) (2).