Adult thiamine requirements and the continuing need to fortify processed cereals.

Erythrocyte transketolase activity as measured by a new fluorimetric method was used to define the tissue thiamine status of an age-stratified sample of 42 adults. Concurrent 7-day dietary assessments were made. 26% of subjects (6/21 men, 5/21 women) were biochemically abnormal. Subjects who were biochemically normal had mean daily thiamine intakes that were 41% (for men) and 36% (for women) greater than those for biochemically abnormal subjects. Differences in absolute thiamine intake (mg/day) were greater and more significant (p = 0.007 and 0.005) than the corresponding differences in thiamine intake expressed as mg/1000 kcal (p = 0.04). Absolute daily thiamine requirement (1.22 mg for men, 1.03 mg for women) was more useful in predicting biochemical thiamine status than thiamine intake expressed as mg/1000 kcal. The withdrawal of thiamine fortification of processed cereals would have serious implications for public health.