Milk and other dairy foods are the major contributors of dietary calcium (30,44,45). Without consuming dairy products, it is difficult to meet dietary calcium recommendations (43,46-49). According to a government analysis, milk and other dairy foods provide 83% of the calcium in the diets of young children, 77% of the calcium in the diets of teenage girls, and found that women between 65% and 72% of the calcium in the diets of adults (44). A more recent investigation of calcium intakes of over 18,000 people aged 2 years and older in USDA's 1994-1996 and 1998 Continuing Survey of Food Intakes by Individuals (CSFII) found that milk, cheese, and yogurt alone and in mixed foods (e.g., macaroni and cheese, pizza) contributed 63% of dietary calcium intake (45). The remaining dietary calcium sources were grains (16%), vegetables (7%), meat, poultry and fish (5%), fruit (3%), and miscellaneous foods (7%) (45).
Foods naturally containing calcium, in particular foods from the Milk, Yogurt & Cheese Group, are the preferred source of calcium not only because of their high concentration of calcium, but also because they contain other essential vitamins and minerals (20,43,46-48). The American Dietetic Association recently stated "the best sources of calcium are dairy foods, since they provide you with calcium, phosphorus, vitamin D and calories. One cup of low-fat, fruit-flavored yogurt or milk provides about 300mg of calcium" (50). One researcher stated, "a diet devoid of dairy products will often be a poor diet not just in respect to calcium, but for many other nutrients as well" (48).
Studies in children and adolescents (44, 51-57) and adults (58-65) show that consumption of dairy products increases calcium intake and improves the overall nutritional quality of the diet. An investigation of the nutrient intake profiles of girls ages 13 to 18 revealed that milk drinkers consumed 80% more calcium, 59% more vitamin B12, 56% more riboflavin, 38% more folate, 35% more vitamin A, 24% more of each vitamin B6 and potassium, and 22% more magnesium than non-milk drinkers (44). When school-aged children included milk as part of their noon meal, intake of calcium as well as vitamin A, vitamin E, and zinc increased (51). Investigations in children and adolescents have found that intake of flavored milk positively affects calcium intake and overall diet quality (52,57).
Studies of children's beverage choices suggest that milk intake is a marker for a better quality diet. When beverage choices of over 4,000 children aged 2-5, 6-11, and 12-17 years were examined, milk consumption was shown to be positively associated with the likelihood of achieving recommended intakes of vitamin A, folate, vitamin B12, calcium, and magnesium in all age groups (53). In contrast, drinking carbonated sodas decreased the likelihood of meeting recommended intakes for most of the nutrients evaluated (53). In another study using data from USDA's 1994-96 CSFII to assess trends in beverage choices and the impact on nutrient intakes in over 700 young females aged 12 to 19 years, milk drinkers had a more nutritious diet than non-milk drinkers (54). The girls who did not drink milk had inadequate intakes of vitamin A, calcium, phosphorus, folate, and magnesium (54). Likewise, a two-month study of 30 children aged 6 to 13 found that excessive intake (more than 12 oz/ day) of sweetened drinks displaced milk from the diet, resulting in lower daily intakes of protein, calcium, phosphorus, magnesium, zinc, and vitamin A (55).
A recent 12-week randomized clinical trial of 28 boys between 13 and 17 years of age who were participating in a standardized strength training program found that, compared to the boys who drank juice, milk drinkers had a better nutrient intake profile (56). The boys who drank an additional three servings of milk/day had significantly higher intakes of vitamin A, vitamin D, riboflavin, calcium, and phosphorus than the juice drinkers (56). An analysis of dietary data for more than 3,000 children ages 6 to 17 showed that those who consumed more flavored dairy products such as flavored milk and yogurt were more likely to get at least 2 to 3 servings of dairy foods a day and consume more calcium and other nutrients, fewer added sugars, and less saturated fat overall than children who drank more than16 to 25 ounces of sodas and sweetened fruit drinks every day (57).
Studies in children and adults demonstrate that consuming dairy foods improves the overall nutritional quality of the diet. Moreover, dairy food intake does not significantly increase total calorie or fat intake, body weight, or percent body fat.
Studies in adults also support dairy foods' favorable nutrient combination (58-65). A longitudinal study in postmenopausal women in Australia found that women who increased their calcium intake by 1,000 mg/day by consuming fat free milk powder also increased their intake of other essential nutrients such as protein, potassium, phosphorus, magnesium, riboflavin, thiamin, and zinc (60). In contrast, the women who took calcium supplements (calcium lactate gluconate) increased only their intake of calcium and sodium (60). A randomized open trial in the U.S. found that increasing milk intake improved the overall nutritional quality of older adults' diets (62). In this investigation of adults who typically consumed a low intake of dairy foods (1.5 servings/day or less), those who increased their fluid milk intake by three eight-ounce servings/day for 12 weeks significantly increased their intake of calcium as well as other nutrients such as protein, vitamins A, D, and B12, riboflavin, phosphorus, magnesium, zinc, and potassium (62). Increasing milk intake reduced the prevalence of dietary shortcomings for several nutrients (62). Consuming yogurt also contributes to improving the nutritional quality of the diet (63).
Studies show that dairy foods improve the nutritional quality of the diet without significantly increasing total calorie or fat intake, body weight, or percent body fat (43,52,54,59,60,62,65). In fact, emerging research indicates that consuming calcium-rich dairy foods may have a beneficial effect on body weight (66,67). In addition, dairy foods such as milk are among the least expensive sources of calcium and, unlike supplements, naturally provide other essential nutrients important to health (48,68,69). A high dairy food intake is described as cost-efficient as well as cost-effective (48). Also, dairy foods are a preferable source of calcium because of calcium's relatively high absorption from milk compared to some other foods (14,43,70,71). Calcium may be poorly absorbed from foods rich in oxalic acid (e.g., spinach, sweet potatoes, beans) or phytic acid (unleavened bread, raw beans, nuts and grains, soy isolates) (14,70). Calcium absorption from soy beverages is 25% less efficient than calcium absorption from milk (71).
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