Abstract We studied the effects of milk and milk product intake on bone health in Japanese adult women (n=1252; 19-80 years of age), high school girls (n=2651; 15-18 years of age), and high school boys (n = 2110; 15-18 years of age). The data for subjects who performed and did not perform exercise (described herein as with-exercise and no-exercise) were analyzed separately to see whether exercise habits would modify the effects of dairy product intake on bone density. In this study, bone status was evaluated by the Osteo Sono Assessment Index (OSI). The term Z -score was used in the statistical analysis and is defined as the ratio of an individual's OSI to the average OSI of the Japanese at a specific age and sex. Weekly intake of milk and other milk products, as well as exercise habits, was surveyed via a questionnaire. The Z -score of adult women dropped as their weekly milk intake increased, although not enough to be statistically significant ( P Z -score was highest in the subgroup with an intake of 4 to 5 times a week and lowest in the subgroup with an intake of once a week or less ( P Z -score of high school boys rose as their intake frequency of milk increased in both the with-exercise ( P P Z -score of the with-exercise girls rose with increased intake frequency of milk, up to a certain point. The Z -score was highest in the subgroup with a milk intake of 4 to 5 times a week; however, it dropped in the subgroup with a daily intake of milk ( P Z -score of the no-exercise girls did not exhibit any correlation with milk consumption. These results suggest that extensive milk intake reduces the bone density of women, including high school girls, and exercise habits modify the effects of dairy product intake on the bone health of high school students.
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