This prospective analysis was conducted to evaluate the role of mother-daughter beverage choices in meeting calcium recommendations during middle childhood in a sample of non-Hispanic white girls. This research showed that the girls’ calcium intakes from ages 5 to 9 y reflected the relative proportions of milk and sweetened beverages in their diets. Furthermore, the girls who met calcium recommendations were served milk more frequently than were the girls who failed to meet calcium recommendations and had mothers who drank more milk than did the mothers of girls who did not meet calcium recommendations. Milk availability to the daughters at meals and snacks appeared to explain the mother-daughter similarities in milk intake. Calcium intake from age 5 to 9 y predicted bone mineral status at age 9 y, which is evidence that maternal influences on daughters’ beverage choices are relevant to the girls’ bone health. Although cross-sectional data have shown parent-child similarities in intakes of calcium and calcium-containing foods (23
), the findings of the current longitudinal research showed that mother-daughter similarities in beverage choices were pervasive across middle childhood and appeared to influence the girls’ calcium intakes during that period in a manner that is associated with bone mineral status. These longitudinal influences are particularly noteworthy given that the girls’ milk intakes exerted considerable leverage on the ability to meet current recommendations for calcium intake.
In the current study, girls who met calcium recommendations from ages 5 to 9 y showed markedly different patterns of milk and sweetened beverage intakes than did those girls who consumed less calcium than recommended. Furthermore, the patterns of sweetened beverage and milk intakes that distinguished girls who met and did not meet calcium recommendations did not vary appreciably with time, which suggested that such patterns are maintained throughout middle childhood from the end of the preschool period. The girls who met calcium recommendations consumed, on average, 395 mL/d (13 fl oz/d) of milk, which represented 50% of all beverages consumed and roughly 50% of their total daily calcium intakes. This intake is ≈158 mL (5 oz or ⅔ cups) greater than the mean milk intake for 6 –11-y-old children reported in the Continuing Survey of Food Intakes by Individuals 1994 –1996 (15
). The girls who met the recommendations also showed modest increases in milk intake from ages 5 to 9 y, whereas those girls who consumed less than the AI for calcium showed decreases in milk intake during the same period. Furthermore, this research found that the girls who met the AI had sweetened beverage intakes that were < 355 mL/d (12 oz/d) from ages 5 to 9 y and were 18% lower than those of girls who consumed less than the AI. Data from the third National Health and Nutrition Examination Survey (1988 –1994) indicate that children aged 6 –11 y consume 6.8% of total daily energy from soft drinks and fruit drinks (36
). In the current study, girls who met the AI consumed a similar percentage of total daily energy from sweetened beverages (6.6% of total energy intake). In contrast, sweetened beverages represented 9% of the total daily energy intake and 50% of all beverages consumed by girls who failed to meet calcium recommendations from ages 5 to 9 y, with a mean intake > 355 mL/d (12 fl oz/d). Sweetened beverages may contribute energy (8
) to the diet but offer little other nutritional value relative to 100% fruit juice and milk (17
) and have been associated with an increased risk of obesity in childhood (38
). Soft drink consumption, in particular, has been associated with low micronutrient intakes, including calcium, in children and adolescents (16
). Harnack et al (18
) observed that 6–12-y-old children who were nonconsumers of soft drinks had calcium intakes that were 26% higher than those of children who consumed > 266 mL/d (9 fl oz/d).
Our findings corroborate the well-documented negative relation between milk and sweetened beverages in the diets of children and adolescents (13
). Whether sweetened beverages displace milk from the children’s diets or reflect the choices of low-milk consumers has been debated. The prospective nature of this investigation offers the advantage over previous cross-sectional analyses on this topic of evaluating individual changes in beverage intakes over time. In the current study, girls who consumed less than the recommended amounts of calcium showed decreases in milk and increases in sweetened beverage intakes. Similarly, higher average intakes of sweetened beverages from 5 to 9 y were associated with greater decreases in milk intake from 5 to 9 y, although the size of this relation was modest. The strongest evidence of the displacement of milk by sweetened beverages in the young girls’ diets would be provided by showing that the increases in the girls’ soft drink consumption were closely associated with decreases in milk intake over the same period of time.
Changes in the girls’ milk intake from ages 5 to 9 y were not associated with changes in their consumption of sweetened beverages over the same period. Thus, these prospective data do not provide strong evidence that sweetened beverages displace milk in young girls’ diets. Rather, the findings indicate that milk intake during middle childhood decreases in avid consumers of sweetened beverages. Unfortunately, inferences regarding the causality of this relation are difficult to draw without data on the girls’ relative preferences for and exposure to both beverages. Such data are critical for understanding the extent to which reducing the availability of sweetened beverages to young girls might positively influence milk intake in those who tend to consume large amounts of sweetened beverages.
The findings of this research provide new evidence that the availability of milk at meals and snacks has a strong positive influence on the milk intake of young girls. The mothers and daughters had similar patterns of sweetened beverage and milk intakes. The mothers’ sweetened beverage intake, however, did not differentiate girls who met the recommendations from those who did not. Rather, the mothers’ milk intake was positively associated with the daughters’ milk intake and was higher in girls who met the AI than in girls who consumed less than the AI. Previous studies have reported mother-daughter similarities in the amount (21
) and type (22
) of milk consumed during childhood and in lifetime milk intakes (35
). In the current study, the mother-daughter similarity in milk intake was statistically mediated by the extent to which the mothers made milk available to their daughters at meals and snacks. This finding suggests that maternal milk consumption drives the extent to which milk is made available to daughters, and that milk availability at meals and snacks is the main influence on the milk intake of young girls. This interpretation is qualified by the fact that the questions asked did not assess who served the milk to the daughters but rather only how often milk was served. Because most of the mothers in this sample reported being responsible for the feeding of their children (91% reported being responsible for child feeding “most of the time” or “always”), maternal reports of milk-serving practices likely reflect maternal behavior. An influence of availability on intake is consistent with the findings of studies that showed a positive association of children’s fruit, juice, and vegetable intakes with the availability of those foods in the home and at neighborhood food establishments (42
). Taken together, these findings suggest that making milk and other calcium-rich foods routinely available to young girls is necessary to ensure that such foods are consumed in the amounts needed to achieve adequate calcium intakes.
Diets low in milk are associated with low calcium intakes and low bone mineralization in children (45
). In the current study, the mean calcium intake from ages 5 to 9 y was positively related to BMD at age 9 y and showed a weak positive association with BMC. This finding is consistent with many different lines of evidence that suggest a positive role of dietary calcium intake in bone health. These findings are consistent with those of many other studies that showed positive associations between spontaneous calcium intake and bone mineral status in girls (46
). Additionally, whereas the positive effects of supplemental calcium on bone mineral status are not retained after supplementation ends (51
), the benefits of milk-derived calcium supplements persist 3–5 y after discontinuation in prepubertal girls (54
). Finally, milk intake during childhood and adolescence was associated with higher bone density and lower fracture risk in adulthood (10
), even when statistically adjusted for current milk and calcium intakes (56
In addition to its role in bone health, there is growing interest in the potential role of calcium in weight maintenance (57
). In the current study, the girls who met the calcium recommendations had higher energy intakes, but not higher BMI z
scores, than did the girls who failed to meet the recommendations. The extent to which these findings might reflect a weight-sparing effect of calcium, however, is beyond the substantive focus of this investigation and is not adequately addressed by the data presented herein.
This investigation described beverage patterns associated with meeting calcium recommendations in a sample of prepubertal, non-lactose-intolerant, non-Hispanic white girls. This population is considered to be at risk of developing osteoporosis in adulthood on the basis of ethnicity and sex. The extent to which these findings generalize to other racial or ethnic groups or to boys is unclear; for instance, black children tend to consume less milk and less carbonated soda but more fruit drinks than do non-Hispanic white children (61
). An important research need is to identify dietary patterns that contribute to adequate calcium intake in girls with low milk and dairy intakes, including those with perceived or actual intolerances to lactose and those who dislike milk and dairy products. The influence of season on dietary intake may also qualify the generalizability of the results reported herein. Dietary data were collected primarily in the summer and early fall. The data for the adolescents showed that milk intake is lower in summer, whereas that of fruit juice and soft drinks is higher than in other seasons (16
). Despite this potential limitation, however, the mean milk intake in the current sample was similar to that reported for 6–11-y-old female participants in the Continuing Survey of Food Intakes by Individuals 1994–1996. Also, the contribution of all beverages to total energy in this sample is similar to the 20% of total daily energy intake for 6–11-y-old participants in the third National Health and Nutrition Examination Survey (36
These longitudinal data provide new evidence that young girls’ calcium intakes and their consequent relation to bone mineral status reflect mother-daughter beverage intake patterns that are established well before the rapid growth and bone mineralization seen in adolescence. In the current study, greater sweetened beverage intakes, lower milk intakes, and greater decreases in milk intakes over the 5-y period clearly differentiated girls who did not meet calcium recommendations from those who did meet recommendations. Perhaps most noteworthy is that these distinguishing beverage intake profiles appeared to vary little from ages 5 to 9 y, which indicates that such patterns may be in place by the end of the preschool period. Furthermore, we found that the frequency with which milk was made available at meals and snacks was a strong predictor of the girls’ milk intakes. As a result, the single relatively simple routine of serving milk may have a central role in supporting habits that promote adequate calcium during periods of bone growth and bone mineral accrual. The current study and others (62
) show that calcium intake tracks moderately across childhood. For this reason, prevention efforts aimed at optimizing girls’ calcium intakes need to begin in the preschool years and focus on ways to increase routine exposure to calcium-rich foods. Future research should expand these findings to consider the role of beverage availability in settings outside the home (eg, daycare centers and school) and the social influences of peers and caregivers within these settings.