Abstract
Compressed bakers' yeast was treated with defatted rice bran extract to enrich it with thiamine. We then prepared bread containing 0.9-2.5mg thiamine per 100g using this thiamine-rich yeast, and fed it at 50g/day for 3 or 4 days to 19 healthy adults to assess the bioavailability of the thiamine. Urinary thiamine excretion and blood thiamine concentration on the final day of the test period were increased significantly in comparison with those on the first day, indicating that thiamine in the test bread was absorbed and had bioavailability. Multiple regression analysis showed that the blood thiamine concentration on the final day of the test period was positively correlated with the blood thiamine concentration on the first day, and the dietary animal protein ratio and mg thiamine intake per 1, 000kcal (4, 200kJ) on the final day of the test period. The urinary thiamine excretion level and blood thiamine concentration on the first day were lower than the reference values in 68% and 21% of the subjects, respectively, indicating that latent vitamin B1 deficiency might not be rare in Japan.
