Urinary salt excretion and stomach cancer mortality among four Japanese populations.

A relationship between salt intake and the occurrence of stomach cancer has been suggested by both epidemiologic and experimental data. To test this hypothesis, urinary excretion of salt in 24 hours and dietary intake of salt were measured in four male populations with different levels of stomach cancer mortality. Age-adjusted mortality rate of stomach cancer showed a high correlation (r2 = 0.995) with the average amount of salt excretion in 24-hour urine. This strong correlation, however, was not shown (r2 = 0.265) with dietary salt intake calculated from the standard food-composition table. The results confirmed the important role of salt in the development of stomach cancer in Japan, and raised the problem of evaluating the level of salt intake by using the uniform composition table.