Body density and skinfold thickness of 59 boys and 52 girls aged 15 to 18 years was measured, and the correlations between body density and skinfold thickness were examined. Body density was determined by the water displacement volumetry and the skinfold thicknesses were measured at three sites, triceps, subscapula and abdomen (adjacent to umbilicus) for boys and two sites, triceps and subscapula for girls, using a Eiken-type caliper designed in our laboratory. The value of body density determined was 1.0728 for boys and 1.0409 for girls in the mean of subjects aged 15-through-18-year-old (Table 1). The correlation coefficients of the body density with the skinfold at each site and with the sum of skinfolds showed values ranging from -0.73 to -0.83 (Table 2). A proposal of the skinfold index (skinfold (arm+back)×body surface÷body weight) was made in the correlation with the body density. In this index, the value of (skinfold×body surface) will represent the volume of subcutaneous fat tissue of the whole body and dividing this value by body weight will mean a good approach to the body fat content ratio. From this reason, it is considered that using this skinfold index for prediction of body density or body fat is more reliable. The various regression equations for predicting the body density from the skinfolds are given in Tables 3 and 4. Among these equations, equations No. 4 and No. 5 for boys and No. 9 for girls are simpler and useful, and equations No. 6 and No. 10 has been more reliable by using the skinfold index.
In June 1972 we had the opportunity to visit and investigate the dietary condition of senior high school students (age, averaging about 16 years old) of the Narbonne High School which is located at the suburbs of Los Angeles, California, U. S. A. and the results are given below. 1) The physique condition of the students: average height and weight was 175.4cm. and 62.5kg. for males, 167.3cm. and 54.0kg. for females. 2) Their daily living condition compared to senior high school students of Kitakyushu City, who are 16 years old, showed that hours at school and studying hours at home are much more less, and out-of-door play-time and helping domestic work at home are conspicuous. 3) The food they took: vegetables and fruits were little in amount. For breakfast they had cereals, milk or orange juice, and scrambled eggs. For supper as for cereals, they took bread, rice or corn together. With bread they took many kinds of dishes such as meat dishes, vegetable salad and milk. Especially, they drank a large amount of milk. 4) For in-between snacks, the high school students of Los Angeles took coca-cola, milk or cookies in this order in comparison. The high school students of Kitakyushu City took fruit, juice or ice cream.
Not few investigators have story interest on the relation between food intake and mortality. From the viewpoint of Dr. Kondo, we have also been motivated to survey Yonaguni Island of the Ryukyu Islands. Dr. Kondo suggested that food consumption in this island would be characteristic and biased to the large intake of fish and meat. But nobody can exactly describe the status of food in Yonaguni Island because no dietary survey on its inhabitants has been conducted. We had a happy chance to do make a dietary survey there in October 1973, in jointwork of the Yaeyama Health Center. Subjects; The subjects of this survey were fifty eight families selected at random from three hamlets (Sonai, Kubra and Hikawa) Results; The results are shown below. 1. The intake of calories, protein, fat and vitamin C was estimated to be higher than the average of the Japanese National Nutrition Survey of 1971. On the other hand calcium and vitamin B2 was estimated as fairly lower than national levels. 2. In comparison with those surveys, the amount of several food items; fish, meat, green and yellow vegetables in Yonaguni are estimated to be higher than the National Level and Okinawa Island. 3. Food intake patterns differ among the three hamlets, which compose the community of an isolated island. 4. On the other hand, there is little difference in food preparation among them. 5. From above it may be said that the dietary intake of the hamlets is in unity, whereas food preparation is definite as the whole island.
This experiment was made in order to clarify the difference in growth rate for rats between the purified whole egg protein and lactalbumin. It was shown that body weight gain was 7.0 and 5.9g/day, and protein efficiency ratio (PER) was 4.2 and 3.8, for the whole egg protein and lactalbumin, respectively. It was concluded that the purified whole egg protein is preferable to be taken as the reference protein for assay purposes in the rat.