Dietary habits and bone stiffness in females aged 18-19 years.

We measured bone stiffness in females aged 18-19 years and observed a mean stiffness of less than 100 (90.2 +/- 10.0). The mean bone stiffness and physique values (height, weight, chest circumference) in these subjects were lower than those in females aged 15-16 years evaluated in our previous study (Yukiko et al., 1997). When the subjects in this study were classified into two groups with a chest circumference > or = and < the mean value (82.2 cm), the former group showed a significantly greater height (p < 0.05), body weight (p < 0.01), and bone stiffness (p < 0.05) than the latter group. When the subjects were classified according to the degree of obesity (BMI), the obese group (BMI > or = 26.0) showed higher bone stiffness (p < 0.05) than the lean group (BMI < or = 20.9). Females in this age range are concerned about their physique and often on a diet, and bone stiffness was higher in those who had dieted than those who had not (p < 0.05). When the subjects were classified according to the age of menarche into two groups with menarche at age < 11 years and > or = 11 years, bone stiffness was higher, chest circumference was about 3 cm greater, and body weight was about 8 Kg higher in the former group than in the latter group. Concerning dietary habits, about 46% of the females aged 18-19 years skipped at least one of the 3 meals. The diet balance (principle food, main dish, side dish, and soup) was poorer (p < 0.01) in the females aged 18-19 years than those aged 13-16 years in our previous study (Yukiko et al., 1997) for breakfast, lunch, and supper. The mean number of consumed food items per day was 15 in the females aged 18-19 years and 21 in those aged 13-16 years, and the mean number of consumed vegetable items was 4.4 in the former and 6.6 in the latter. There was a positive correlation between bone stiffness and the number of consumed food items as well as physique in females aged 12-13 years but not in those aged 18-19 years, suggesting that physical growth has been already completed before the age of 18-19 years. Blood biochemical examinations showed abnormal values in neutral fat, total cholesterol, or serum iron in about 39% of the females aged 18-19 years. Abnormal values were less frequently observed in the group with a mean number of consumed food items > or = 15 than the group with a mean number < 15. The group with abnormal blood biochemical examination values showed significantly higher incidences of "Tend to yawn during the daytime", "Do not defecate every day" and "Have shoulder-low back stiffness" than in the group without abnormal values (p < 0.01).