of 153 geriatric patients aged 65 to 93 years were deficient in thiamin as determined by a transketolase activation coefficient greater than 1.27. Status became normal in all patients after the administration of 20 mg of thiamin daily for 12 days. No dietary information was provided.

A depletion-repletion study of 10 active, healthy elderly women (aged 52 to 72 years, 9 of whom were 63 years or older) measured urinary thiamin excretion after various thiamin intakes (Oldham, 1962). Eight young women aged 18 to 21 years were also studied. On a thiamin intake of less than 0.40 mg/day, the urinary thiamin excretion decreased more quickly for the older than for the younger women. By day 11 or 12, the thiamin excretion of the older women averaged only 0.153 µmol/day (0.05 µg/day), and they complained of fatigue, headaches, and irritability and canceled social engagements. Comparable results were not seen for the younger women until day 19 or 20. When thiamin intake was increased, the older women’s urinary thiamin excretion did not increase as quickly as did that of the younger women. The authors concluded that the thiamin requirement of elderly women is higher than that of young women and that the ratio of thiamin to energy must be higher, but the highest thiamin intake level tested, 0.81 mg/day, showed a very wide range of urinary thiamin excretion, especially after 6 days at this intake.

In a randomized, double-blind treatment trial of either 10 mg of thiamin or placebo (Wilkinson et al., 1997), treated subjects who had low TPP concentrations twice when measured before randomization were reported to experience subjective benefits (improved quality of life) and lower blood pressure and weight; those with only one low TPP value prior to randomization did not benefit from treatment.

Although there are some data to suggest that requirements might be somewhat higher in the elderly than in younger adults (e.g., Oldham, 1962), there is also a concomitant decreased energy utilization that may offset this. Further study of this question needs to be conducted. Thus the EAR is assumed to be the same for elderly and younger adults.

The EAR for thiamin for adults ages 50 and older is set at the same level as for younger adults—1.0 mg/day for men and 0.9 mg/ day for women.