Abstract
The chief calcium sources of Japanese are pulses, vegetables and fishes. The Ca intake from daily diet of Japanese is about 400mg per day person, which is lower than its allowance (600mg). Generally speaking, the Ca intake from milk or dairy products are very poor compared with tnat by European or American.
The author has carried out his study in order to calculate Ca intake of citizens from the daily drinking water, then 977 samples of well water in Tokyo-To were collected as samples of this investigation. Their contents of Ca and Mg were determined by Chelatometry. The results are as follows:
1. The Ca contents of well water were 1-117p.p.m. and those of Mg were 1-70p.p.m.
2. The Ca contents of tap water samples originated from the River Tama were 14p.p.m., and those originated from the River Edo were 20p.p.m.
The Ca in take of citizens in Tokyo is about 60mg per day, provided that they take about 3000ml of water in a day.
