Abstract
On the basis of objective thiamine balance studies, the vitamin B1 requirement of the adult is estimated to be 350 μg. per 1000 calories. The recommended daily intake is regarded as 500 μg. per 1000 calories. Only 73% of the so-called normal subjects, who were not restricted as to choice of diet, excreted sufficient quantities of thiamine in the urine to pass all the thiamine clearance tests.