Behavioral Intervention in Adolescents Improves Bone Mass, Yet Lactose Maldigestion Is a Barrier.

Calcium intake during adolescence is important for attainment of peak bone mass. Lactose maldigestion is an autosomal recessive trait, leading to lower calcium intake. The Adequate Calcium Today study aimed to determine if a school-based targeted behavioral intervention over one year could improve calcium intake and bone mass in early adolescent girls. The school-randomized intervention was conducted at middle schools in six states over one school year. A total of 473 girls aged 10-13 years were recruited for outcome assessments. Bone mineral content (BMC) was determined by dual energy X-ray absorptiometry. Dietary calcium intake was assessed with a semi-quantitative food frequency questionnaire. Baseline calcium intake and BMC were not significantly different between groups. After the intervention period, there were no differences in changes in calcium intake and BMC at any site between groups. An unanticipated outcome was a greater increase in spinal BMC among lactose digesters than lactose maldigesters in the intervention schools only (12 months) (6.9 ± 0.3 g vs. 6.0 ± 0.4 g, p = 0.03) and considering the entire study period (18 months) (9.9 ± 0.4 vs. 8.7 ± 0.5 g, p < 0.01). Overall, no significant differences between the intervention and control schools were observed. However, lactose digesters who received the intervention program increased bone mass to a greater extent than lactose maldigesters.

Oxidation of serum low-density lipoprotein (LDL) and antioxidant status in young and elderly humans.

The incidence of atherosclerosis increases with age, as do various indices of free-radical mediated damage, e.g., lipid peroxidation. Because lipid peroxidation plays a prominent role in lipoprotein oxidation, likely a prelude to atherosclerosis, we compared the susceptibility of lipoproteins to oxidation in young (19-30 years) and elderly (59-86 years) groups. Although we found no significant differences in serum malondialdehyde (MDA) or oxidized LDL antibodies (OLAB) between young and elderly lipoproteins, MDA was directly related to OLAB regardless of age (r = 0.322, p = 0.005) and there was a trend for lower OLAB levels (30.5%, p = 0.079) in the elderly compared to the young population. Overall, serum antioxidant status was either similar or greater in the elderly group compared to the young group, likely reflecting antioxidant supplementation by the elderly group. OLAB was inversely related to Vitamin C (r = -0.310, p = 0.008) and Vitamin E intake (r = -0.277, p = 0.018) from foods and supplements. Serum levels of Vitamin C and Vitamin E were significantly higher (18.5%, p = 0.021 and 58.1 %, p < 0.001, respectively) in the elderly group compared to the young group and the ratio of Vitamin E to Vitamin C was significantly higher (30.4%, p = 0.042) in the serum of the elderly group. Oxidation of serum LDL and antioxidant status were not affected by age; however, the ratio of serum Vitamin E to Vitamin C was higher in the elderly group which may affect Vitamin E recycling.

Development of a food frequency questionnaire to estimate calcium intake of Asian, Hispanic, and white youth.

OBJECTIVE: To develop a food frequency questionnaire (FFQ) that estimates calcium intake of Asian, Hispanic, and white youth living in the western United States. DESIGN: A list of 80 foods was assembled to create an FFQ to measure calcium intake. Evaluation of the FFQ spanned four consecutive weeks. An FFQ was completed during Week 1 and Week 4, and a 24-hour dietary recall was completed during Week 2 and Week 3.Subjects/setting A convenience sample of 162 Asian, Hispanic, and white youth ages 10 to 18 years was selected. Statistical analyses performed Percent agreement, paired t tests, Pearson correlation coefficients of cube-root transformed values, and deattenuated Pearson correlation coefficients of cube-root transformed values were used to evaluate the FFQ. RESULTS: The correlation between calcium intake estimates, when measured by first and second administrations of the FFQ, was 0.68 (Pearson's r) for the total sample. Correlations differed by age, sex, and ethnic subgroups as follows: 10 to 13 years (r=0.62), 14 to 18 years (r=0.73), male (r=0.73), female (r=0.64), Asian (r=0.77), Hispanic (r=0.72), and white (r=0.48). The correlation between calcium intakes as estimated by the second FFQ vs the average of the two 24-hour dietary recalls was 0.54 (deattenuated Pearson's r) for the total sample. This correlation differed by age, sex, and ethnic subgroups as follows: 10 to 13 years (r=0.46), 14 to 18 years (r=0.59), male (r=0.65), female (r=0.45), Asian (r=0.64), Hispanic (r=0.18), and white (r=0.57). CONCLUSIONS: A unique dietary survey has been developed to estimate calcium intake among Asian, Hispanic, and white youth in the United States.

Calcium intake of Asian, Hispanic and white youth.

OBJECTIVE: To examine calcium intake and food sources among Asian, white and Hispanic youth, in order to develop and target interventions to improve calcium intake. METHODS: Cross-sectional survey with two 24-hour dietary recalls one week apart. Calcium intake was evaluated in 167 male and female adolescents of Asian, Hispanic and white ethnicity, ages 10-18 years, from six states. Main outcome measures were mean daily calcium intake (mg/day). STATISTICAL ANALYSES PERFORMED: t tests, Chi-square and analysis of variance for differences by age, ethnicity and gender, multiple regression of factors influencing calcium intake. RESULTS: Overall median calcium intake was 938 mg/day with 868 mg/day for Asians, 1180 mg/day for whites and 896 mg/day for Hispanics. Daily milk intake was the primary predictor of calcium intake with Asian ethnicity and female gender each showing a negative association to calcium intake in multiple regression models. CONCLUSIONS: Milk intake was the primary factor positively influencing calcium intake, while Asian ethnicity and female gender negatively influenced calcium intake. Thus, interventions to improve calcium intake should focus on improving milk intake of Asians and females.

Perspectives on intake of calcium-rich foods among Asian, Hispanic, and white preadolescent and adolescent females.

OBJECTIVE: Declining calcium intake among adolescents warrants attention. Our objective was to identify influences on adolescents' consumption of calcium-rich foods. DESIGN: Focus groups were conducted with girls representing 2 age groups (11 to 12 or 16 to 17 years) and 3 macroethnic groups (Asian, Hispanic, or white). SETTING: Public schools in 10 states. PARTICIPANTS: A convenience sample (n = 200) was recruited through schools. VARIABLES MEASURED: Focus groups (n = 35) were audiotaped and transcribed. Influences relative to consumption of milk or other calcium-rich foods were identified. ANALYSIS: Comments were coded as motivators or barriers within each focus group. Content analysis procedures were used to compare ethnic and age groups. RESULTS: A barrier to milk consumption that was more common among older girls and Asian groups was the limited expectation within families for drinking milk. Many controlled their own beverage choices, and milk, even if liked, was only one option. Milk was positively associated with strength and bone health, but these attributes were viewed as being more important for boys than girls. Milk was associated with breakfast, school lunches, cereal, and desserts. White girls had the most positive reactions to milk and Hispanic girls the most negative. All groups were positive toward pizza, ice cream, and cheese. CONCLUSIONS AND IMPLICATIONS: To improve calcium intake among teens, interventions should include a family component, stress the benefits of milk for girls, and focus on breakfast.