The present study was undertaken to investigate the relationship between thiamin intake and its biochemical status in 60 free-living (30 male, 30 female) elderly subjects (>or = 65 years).Dietary intake was estimated using a 3-nonconsecutive-day food record. Biochemical status was assessed by measuring the stimulating effect of thiamin pyrophosphate (TPP) on transketolase activity (TPP effect) in hemolyzed erythrocytes, which is a functional test indicative of metabolic availability of thiamin.Average daily thiamin intake was above the recommended requirement (>0.4 mg/1000 Kcal) for each gender; however, almost half of the total study population had TPP effect>14%, suggesting thiamin deficiency. There was no correlation between thiamin intake and TPP effect.These findings raise questions about the reliability of dietary intake in assessing metabolic availability of thiamin in the elderly.